Browse Topic: Engines

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Exhaust Emissions Tests of Small Gasoline Engines Used as Drives for Power Generators and Handheld Machinery in Real-Operating Conditions2026-01-5080To be published on 10/01/2026
The paper presents the results of investigations on the exhaust emissions carried out under real-world operating conditions of gasoline engines used in lawnmowers and power generators. During the operation of these engines, the authors measured the emissions of the following exhaust gaseous components: CO, HC, NOx, and CO2. For the measurements, the authors used Axion R/S+, a PEMS (Portable Exhaust Emission System) analyzer. The presented method is a new approach to exhaust emissions measurements performed on small engines. The emission coefficient, as a related value of the emission of harmful compounds and CO2, was proposed. Additionally, some remarks related to the measurement method were made. The paper presents the modal analysis of the investigations of the exhaust emissions from engines and the total mass of gaseous compounds. Moreover, the obtained results of the exhaust emissions from the power generator engine were compared with the applicable emission standards, and the real emissions of CO and HC+NOx were, respectively, about 10% and 38% higher than Stage II standards. Based on the investigation results, the authors considered the possibilities of using the said measurement method in real-world operating conditions, applying the PEMS equipment for small gasoline engines.
Lijewski, Piotr, Markiewicz, Filip, Fuć, Paweł, Dobrzyński, Michał, Wiśniewski, Sławomir
Methods for Designing Rotating Components for Compliance to ISO 1940 Balance Requirements using Generic 3D CAD Software2026-01-75659/22/2026
The benefits of specifying balance requirements in terms of an ISO 1940 balance quality grade instead of traditional mass-distance based requirements are discussed along with methods to convert ISO 1940 balance quality grades into permissible imbalance limits at the bearing supports. Methods are developed to determine the expected imbalance values at bearing supports using mass property data from generic 3D CAD software packages without the need for Finite Element Analysis. Practical exercises are presented using these methods to assess a part’s compliance to ISO 1940 while still in the conceptual 3D CAD design stage. These practical exercises cover the selection of appropriate geometric tolerances to ensure part balance without the need for post fabrication balancing as well as the design of nonsymmetrical components for ISO 1940 balance compliance. Citation: J. Srodawa, “Methods for Designing Rotating Components for Compliance to ISO 1940 Balance Requirements Using Generic 3D CAD Software,” In Proceedings of the Ground Vehicle Systems Engineering and Technology Symposium (GVSETS), NDIA, Novi, MI, Aug. 11-13, 2026.
Srodawa, John
Initial Thermal Evaluation of 422 Martensitic Stainless Steel Piston in a High-Output Diesel Engine2026-01-75649/22/2026
A piston manufactured with a crown comprised of grade 422 martensitic stainless steel and skirt manufactured from 4140 steel was instrumented with fifteen thermocouples and a wireless telemetry system. Piston temperature data were collected at five engine operating conditions and compared to two additional instrumented pistons with crown and skirt both made of 4140 martensitic steel, which is traditionally used for heavy-duty diesel applications. Thermal finite element modeling was used to predict the increase in operating temperature of the 422 piston relative to the 4140 piston and help understand instrumentation uncertainty. Previous research of candidate high-temperature alloys indicated that 12Cr martensitic steel alloys, such as alloy 422, offer several potential benefits when used in a diesel piston application, including increased high-temperature oxidation resistance and strength. The potential benefits of alloy 422 may however be partially negated by the expected increased piston operating temperature due to the alloy’s lower thermal conductivity. In this work 422 alloy resulted in no statistically significant change in piston temperatures relative to the baseline 4140 steel during engine testing. The 422 alloy is poised to offer a dual durability advantage because the initial results show it can achieve superior oxidation resistance without operating at the higher temperatures that would accelerate such degradation. Maximum piston temperature capability is expected to be a critical design limit in next generation diesel engines with greater power density, lower heat rejection, and improved fuel economy. Citation: E. Gingrich, et. al., “Initial Thermal Evaluation of 422 Martensitic Stainless Steel Piston in a High-output Diesel Engine,” In Proceedings of the Ground Vehicle Systems Engineering and Technology Symposium (GVSETS), NDIA, Novi, MI, Aug. 11-13, 2026.
Gingrich, Eric, Tess, Michael, Grunin, Arkady, Korivi, Vamshi, Sebeck, Katherine, Pierce, Dean, Wang, Yiyu, Muralidharan, Govindarajan, Pillai, Rishi, Haynes, James A., Will, Kurt
Stuck-Assist: A Large Multimodal Model-Based Stuck Recovery Assist for Driving on Off-Road Deformable Terrains2026-01-75139/22/2026
Recent advancements in off-road autonomy have shown significant progress in perception, planning, and control frameworks, including end-to-end learning approaches. Comprehensive results have been demonstrated in both simulation and real-world experiments; however, there are significant challenges in critical cases that need further evaluation. One such challenge is the immobilization of autonomous ground vehicles (AGVs) in unstructured off-road environments, which can significantly impact agriculture, space exploration, military operations, and search and rescue missions. Addressing this problem requires recovery strategies that are context-sensitive, adaptable to terrain and vehicle conditions, and effective in integrating multimodal inputs. To this end, this paper investigates the use of a large multimodal model (LMM) providing higher-level planning assistance with human-in-the-loop evaluations for vehicle recovery after immobilization in unstructured off-road terrain. The experimental simulation platform developed was based on the Algoryx (AGX) Dynamics engine for high-fidelity terramechanics interaction and vehicle physics combined with Unreal Engine 5. This platform was further integrated with a driving simulator equipped with steering wheel and pedal interfaces for human-in-the-loop experiments. We evaluated ten representative unstuck scenarios across two deformable terrains (loose sand and compact sand) under two modes: an unskilled baseline, where participants attempted recovery unaided, and a co-intelligence mode, where participants used LMM advisory instructions. The results show that LMM assistance improved stuck recovery rates by 70% compared to unaided and unskilled human driving.
Bhosale, Mayuresh, Whitson, Jordan A., Vahidi, Ardalan, Jia, Yunyi
Patching an Engine Control Module to Enhance Security2026-01-75219/22/2026
The architecture of Controller Area Network (CAN)-based protocols offers straightforward, centralized, and cost-efficient methods for various Electronic Control Units (ECUs) to communicate via the CAN bus. However, the CAN protocol was not designed with security as a priority. The CAN bus used in vehicles lacks built-in security features, (i.e., messages are broadcast without authentication or encryption). This makes CAN vulnerable to eavesdropping, spoofing, and replay attacks. Any compromised node can inject false messages (e.g., impersonating the brakes or engine controller) with no cryptographic checks to stop it. The protocol’s primary integrity safeguard, a Cyclic Redundancy Check (CRC), was designed solely for detecting transmission errors and is easily manipulated, offering no real protection against malicious adversaries. Implementing cryptography on CAN is challenging due to CAN’s most popular limited 8-byte data payload, real-time latency requirements, and the need for compatibility with millions of existing CAN devices. To address this issue, this study focuses on developing a Cryptographic Message Authentication Code (CMAC) Intrusion Detection System (IDS) implementation for CAN bus communication using existing ECUs.
Beer, Spencer, Jepson, Jake, Nogin, Aleksey, Daily, Jeremy
Deep Learning-Based Rotor Temperature Estimation for Rare-Earth-Free Motors2026-01-75069/22/2026
This paper presents a deep learning-based approach for online rotor temperature estimation in electrically excited synchronous motors (EESMs). Accurate rotor temperature estimation is critical for ensuring safe operation, improving performance, and enabling reliable thermal management of electric traction motors. Recurrent neural network (RNN) architectures, including gated recurrent unit (GRU) and long short-term memory (LSTM) networks, are investigated to develop a data-driven thermal virtual sensor capable of capturing the temporal dynamics of motor operation. Experimental data collected from a 190 kW EESM prototype are used to train and evaluate the proposed models. A systematic training, testing, and 10-fold cross-validation framework is employed to assess prediction accuracy and generalization capability. The results demonstrate that the GRU-based model achieves higher prediction accuracy than the LSTM model while maintaining comparable inference latency. The proposed approach provides an efficient and lightweight solution for real-time rotor temperature estimation suitable for embedded motor control applications.
Tatari, Farzaneh, Aligoudarzi, Mohsen Mirza
Development of a UAV Platform for Remote Inspection and Visualization2026-01-75119/22/2026
This paper details the development of an intelligence and inspection platform consisting of an attritable sub-250g UAV, a ground control station, and a visualization interface for users. The UAV architecture combines onboard obstacle detection and avoidance along with simultaneous localization and mapping to have full autonomous navigation inside of complicated GPS-denied environments. The ROS 2-to-Unreal Engine data pipeline allows for sensor fusion, data cleansing, and initial analysis as well as creation of a high-fidelity real-time 3D digital twin. The visualization interface allows users to easily identify critical features and turn data into intelligence to support decision making by soldiers and first responders.
Lee, Yeen K., Bainard, Sean, Shaughnessy, Michael, Bolger, Matt, Koepp, R. Tucker, Salehzadeh, Roya, Mallory, Stephen, Mynderse, James A., Guillen, Pedro, Hernandez, Margarita
AI-Driven Predictive Sonification for Human-on-the-Loop Ground Vehicle Autonomy2026-01-75039/22/2026
Ground vehicle autonomy increasingly depends on human-on-the-loop (HOTL) supervision, yet supervisors are often overloaded by visual interfaces that can obscure emerging risks. This paper presents an AI-driven predictive sonification architecture that converts short-horizon forecasts of platoon behavior into structured auditory cues for supervisory monitoring. A forecasting engine predicts future vehicle interaction states and evaluates predicted and active violations to generate a composite risk indicator. When risk exceeds defined thresholds, a sonification module conveys risk magnitude and trajectory through changes in pitch, loudness, modulation, and spatial panning. The paper describes the system architecture, sonification design, operational use cases, and a planned human-subject evaluation. The proposed framework is intended to improve early awareness of emerging instability and support more timely supervisory intervention.
Plotzke, Zachary R., Mohammadi, Alireza, Cheung, Calvin M.
Exploring the Benefits of Multiple Injections in a Premixed Charge Compression-Ignition Engine Operated with Modified Injector Orientation and Diesel–Gasoline Blends03-19-05-00259/22/2026
The current study examines the combined effects of injection strategy, injector configuration, and fuel blending on the combustion performance and emission behavior of a light-duty compression-ignition (CI) engine operated in premixed charge compression-ignition (PCCI) combustion mode. Experiments were conducted in PCCI combustion mode using a diesel–gasoline blend (D80G20, 80% diesel and 20% gasoline by volume). A modified injector configuration, with a split-injection scheme comprising pilot and main injection events, was implemented to enhance mixture preparation and control combustion characteristics. The baseline configuration utilized PCCI mode with diesel (D100) and an inclined injector orientation. The results indicate that blending gasoline into diesel prolongs ignition delay and facilitates charge premixing, hence improving the stability of the PCCI combustion regime. Using a vertically oriented injector with a symmetric spray pattern significantly improves air–fuel mixing, and split-pulse injection enables more accurate control of combustion phasing. Among the tested strategies, the D80G20 blend, combined with a vertical injector and optimized split injection, achieved the highest brake thermal efficiency at 60% load, improving by 10.1% over the baseline case. In addition, unburned hydrocarbon (HC) and carbon monoxide (CO) emissions were significantly reduced by 54.1% and 49.4%, respectively. Additionally, the load extension was increased to 77%, which is limited to 60% of the engine-rated load in PCCI with diesel fuel. The current integrated approach provides a viable pathway to implement the PCCI mode to improve engine thermal efficiency and reduce pollutant emissions without significant hardware modifications, thereby supporting the transition to cleaner combustion technologies.
Ranjan, Ashish Pratap, Krishnasamy, Anand
Adaptive Neural Network Fuel Mass Correction for Structural Model Error Compensation in Diesel Engines with Variable Biodiesel Properties2026-24-00239/21/2026
Compression-ignition engines operating with biodiesel blends often exhibit variability in fuel properties, such as density, viscosity, and cetane number, which can lead to systematic deviations in injected fuel mass when using conventional physics-based models. These deviations can reduce combustion efficiency and increase brake-specific fuel consumption (BSFC). This study proposes a lightweight neural network–based approach to compensate for structural errors in baseline injection models, using a single-layer perceptron trained on the relative error (delta) between actual and modeled injected mass. By normalizing engine and fuel parameters and introducing a small amount of measurement noise, the network learns to predict a corrective factor that adapts the injected mass to match the desired target under varying fuel conditions. Simulation results demonstrate that the neural correction significantly reduces systematic bias: in test cases with intentionally introduced structural error, the average injection deviation of −1.7% in the baseline model is reduced to approximately 0.002% after correction. Root-mean-square (RMS) error over training and validation datasets remains below 0.16%, indicating robust generalization. The proposed method offers a computationally efficient solution suitable for embedded engine control units, requiring minimal additional complexity while ensuring precise fuel delivery. By eliminating bias caused by fuel property variability, the approach has the potential to improve fuel economy, reduce emissions, and maintain consistent engine performance under a wide range of operating conditions. This framework provides a practical path for integrating adaptive, data-driven correction mechanisms in diesel engines operating with heterogeneous or variable biofuels.
Gutierrez, Marcos, Taco, Diana
Passive Thermal Management Through Vapor Chamber Integration of a PMSM E-Motor installed on UAV for Urban Mobility Applications2026-24-00109/21/2026
Thermal management is a critical design challenge for Permanent Magnet Synchronous Motors (PMSMs) employed in Unmanned Aerial Vehicle (UAV) propulsion systems, where high power density and compact integration lead to significant heat generation. Excessive temperatures can compromise efficiency, reliability, and component lifetime, making the development of effective and lightweight cooling solutions essential. This study investigates the integration of a vapor chamber as a passive thermal management solution for a commercially available PMSM intended for UAV applications, whose thermal performance is evaluated under external airflow conditions representative of low-speed flight and hovering. Unlike conventional active cooling systems, the proposed approach does not require moving parts, external power input, or additional control devices. Heat transfer is driven by phase-change mechanisms within a sealed enclosure: as the local thermal load increases, the working fluid evaporates in the hotter regions and condenses in the cooler ones, redistributing heat autonomously without external intervention — a self-regulating behavior particularly suited to the constraints of UAV propulsion systems. A simplified three-dimensional model of the motor housing was developed, and steady-state conjugate heat transfer simulations were performed in ANSYS Fluent to evaluate the thermal performance of the system. Three configurations were analyzed: a baseline motor without vapor chamber, a configuration with an integrated vapor chamber, and a configuration combining the vapor chamber with an external copper fin array. The vapor chamber was modeled using an equivalent porous-medium approach for the wick structure, coupled with a multiphase formulation to capture liquid–vapor interactions within the core. The results demonstrate that vapor chamber integration significantly reduces peak pole temperature, with reductions ranging from 38K to 159K (approximately 10% to 31% relative to the baseline configuration) depending on operating conditions. At higher thermal loads, the device transitions from a liquid-filled regime to an active two-phase operation, enhancing heat transfer through evaporation and condensation. The addition of an external copper fin array further improves thermal performance, achieving a maximum pole temperature reduction of 203K (approximately 33% relative to the baseline) under low-airflow, high-load conditions. A key finding of this study is the strong coupling between the external fin array and the internal phase-change behavior of the vapor chamber: by lowering the condensation-side temperature, the fins promote a more active two-phase regime, enhancing overall heat transfer performance beyond what either component achieves independently. These results highlight the potential of vapor chamber technology, particularly when combined with extended surfaces optimized for the dominant flight regime, as a lightweight, passive, and self-regulating cooling strategy for compact UAV electric propulsion systems.
Benedetti, Silvia, Lombardi, Simone, Federici, Leonardo, Chiappini, Daniele
Analysis of Full Torque Determination in a Diesel Engine Operating in Dual Fuel mode with Hydrogen and Diesel2026-24-00149/21/2026
A 15kW diesel engine is modified in the laboratory to operate in dual fuel combustion mode. The engine is a three-cylinder, displacement of 1 Liter, originally fueled with diesel in its baseline configuration. The engine is modified by installing three PFI injectors, positioned toward the intake valves within the intake manifold. Hydrogen injection is synchronized with valve opening during the engine cycle using controlled delay units. The standard diesel injection system, managed by the original ECU, initiates combustion of the premixed air/hydrogen charge. The dual fuel operation is tested at 2000 rpm maximum torque. To maintain this condition, both diesel quantity through accelerator input and hydrogen flow via injectors duration are adjusted. Constraints included reducing diesel fuel and avoiding knock caused by excessive hydrogen. The engine operated reliably under all tested conditions. A maximum hydrogen energy substitution HES of 70% is achieved at high load, though higher values increased PPRR. A premixed equivalence ratio of 0.40 is identified as the limit before self-ignition occurred. To prevent this and achieve maximum power, an alternative strategy is introduced. Starting from diesel-only maximum torque, diesel is gradually reduced while hydrogen is increased. Rated torque is successfully achieved with an HES up to 45%. These results demonstrate that dual fuel operation can significantly reduce fossil fuel consumption while maintaining performance. It provided combustion stability and knock limits carefully managed through appropriate control of mixture composition. Further optimization could enhance efficiency and emissions performance in future applications.
Mancaruso, Ezio, Rossetti, Salvatore, Cameretti, Maria Cristina
Optimal Eco-Driving for Electric and Conventional Refuse Trucks: A Comparative Analysis of Actual Speed, Energy Efficiency, and Travel Time2026-24-00319/21/2026
Achieving significant reductions in energy consumption and CO₂ emissions in the transportation sector is a key challenge for sustainable mobility, particularly for vocational trucks operating under demanding driving and duty cycles. Beyond technological advancements in powertrain design, energy efficiency can be improved through optimized driving strategies. In this context, eco-driving has emerged as an effective approach to reduce energy consumption by optimizing the speed profile under given operational constraints. Eco-driving optimization strategies are particularly well suited for predefined and repetitive driving cycles, such as those typically encountered in waste collection. This work presents a comparative analysis between electric and internal combustion engine powertrain configurations applied to refuse trucks and vehicles, highlighting the impact of intrinsic differences on optimal speed profiles, energy consumption, and travel time. Both configurations are required to follow identical routes characterized by speed limits, mandatory stops, and comfort-related constraints. To address the optimization problem, the conventional longitudinal dynamics equations are reformulated from a time speed domain to a spatial speed domain through spatial discretization. The spatial domain is subsequently discretized, enabling the formulation of an optimization problem solved using dynamic programming to determine the optimal speed profile along real-world routes. The optimization framework is based on the minimization of a cost function composed of two main terms, normalized energy consumption and travel time variation, and a shape factor introduced to balance the tradeoff between energy efficiency and travel time. The objective of the study is to compare the two powertrain configurations under identical routes and constraints, analyzing energy consumption and travel time, and to identify the optimal compromise between time and energy consumption for each case. The results provide insights into the effectiveness of eco-driving strategies and underline the influence of powertrain architecture on optimal driving behavior.
Giacobbo, Andrea, Beltrami, Daniele, Villani, Manfredi, Tribioli, Laura, Iora, Paolo, Uberti, Stefano
Electrical Waveform Analysis of Spark Discharge for Monitoring Conditions Inside Prototype Prechambers2026-24-00139/21/2026
Using renewable fuels like hydrogen in internal combustion engines requires new combustion strategies and ignition systems like pre-chamber sparkplugs. This necessitates novel measurement and monitoring techniques to gain insights into the phenomena arising from the use of new fuels and components. For understanding the phenomenon of pre-chamber ignition, it is important to observe how sparks behave inside them. The spark-elongation under certain conditions inside a particular pre-chamber, its location at a given time during discharge, and the flow conditions during spark discharge are all significant factors in gaining insight into this phenomenon. However, such information is difficult to obtain from inside a pre-chamber due to the difficulty of gaining optical access. In such cases, the electrical waveform analysis could prove useful. During this study, the electrical parameters are used to calculate the spark length, providing information about the igniting volume inside a pre-chamber during the spark discharge. This was achieved by modifying the Kim and Anderson equation to meet the specific requirements of the study, which involved correlating it to the optical spark length obtained in a spark wind tunnel test bed under conditions similar to those in an engine. This modified equation was then used to calculate the spark length inside different prototype pre-chambers and sparkplug to compare and contrast the conditions. Information about the flow conditions inside the pre-chamber was also obtained from the spark length, given that the surrounding flow influences spark elongation. This methodology was first validated in the spark wind tunnel test bed before pre-chambers were tested in the engine. Testing different prototype pre-chambers provided valuable insights into the flow conditions, demonstrating the technique's effectiveness in understanding the factors that make a pre-chamber design suitable for a particular fuel and set of conditions, and why it is less effective in other situations. This study proves that electrical waveform analysis is a key tool for monitoring the performance of prototype pre-chambers designed for renewable fuels, such as hydrogen.
Kottakalam, Saraschandran, Nenzel, Markus, Rottenkolber, Gregor
Thermal Management of Pre-Chamber Spark Plugs for the Mitigation of Abnormal Ignition in Hydrogen-Fueled Engines – An Experimental and Numerical Study2026-24-00079/21/2026
The internal combustion engine will continue to contribute to global mobility, particularly when operated with carbon dioxide low-carbon fuels. Pre-chamber ignition systems are increasingly investigated to improve efficiency, emissions, and combustion stability. In combination with hydrogen as a carbon-free fuel, they extend the lean operating limit while ensuring reliable ignition under demanding conditions. A key challenge is the thermal management of pre-chamber spark plugs. While the thermal behaviour of conventional spark plugs is well understood, limited knowledge exists for pre-chamber systems. Chamber geometry, material selection, manufacturing, and installation strongly influence thermal loading, where elevated local temperatures may contribute to knock, pre-ignition, and material degradation. The objective of this study is to establish a system-level understanding of pre-chamber thermal behaviour. Experiments are conducted on a single-cylinder research engine using hydrogen and research octane number 95 (RON 95) as a reference fuel. Dedicated temperature measurements identify thermal hotspots and assess parameter sensitivities. For the investigated configuration (14:1 compression ratio (CR), 1500 revolutions per minute (rpm), 12 bar indicated mean effective pressure (IMEP)), measurements and conjugate heat transfer (CHT) simulations suggest wall temperatures are not the primary contributor to pre-ignition. Reduced pre-ignition is observed with increasing scavenging bore diameter, indicating a strong influence of mixture preparation and residual gas effects. A coupled CHT model is integrated into a computational fluid dynamics (CFD) simulation with moving boundaries. The model includes realistic wall thicknesses, temperature-dependent material properties, and calibrated boundary conditions, enabling cycle-resolved analysis of heat fluxes and temperature fields for pre-chamber optimization.
Nenzel, Markus, Alkezbari, Ahmad Anas, Rottenkolber, Gregor
A Computational Study of High Efficiency Wankel Rotary Engines using a Passive Pre-Chamber2026-24-00019/21/2026
Wankel rotary engines are renowned as compact machines with high power-to-weight ratios, which make them suitable for use as range extenders for battery electric vehicles or as propulsion systems for unmanned aerial vehicles. However, their overall efficiency and emissions still need significant improvement to meet to the stringent regulations comparable with classical reciprocating 4-stroke engines. With the aim of improving these shortcomings, this work focuses on the application of a passive pre-chamber in order to enhance the combustion phase and the overall efficiency and emissions of such engines. Computational fluid dynamics (CFD) simulations were conducted for the commercial AIE 225CS rotary engine, configured with port fuel injection and fully-premixed gasoline combustion. The engine was extensively tested in a previous project while different CFD models were validated against experimental data in previous studies by the same authors. In particular, the present work examines the engine performance with two pre-chamber configurations with different volumes. The volume and nozzle specifications were determined to have geometrical characteristics similar to those of the theory of Gussak, with volumes directly comparable with that of the two spark park plug recesses of the original engine, leading to significantly large nozzle diameters in the pre-chambers. In addition, the effect of spark advance was investigated to capture the development of the flame and jets and the resulting effects on the indicated pressure cycle. Consistent with previous findings, heat losses were found to be a critical aspect for the different configurations of engine. Nevertheless, the application of pre-chamber shows some potential to improve efficiency by accelerating combustion phase, leading to a relative increase of 7.4% on the indicated efficiency. This suggests an important new path in the development of Wankel engines as a viable solution to efficient utilisation of decarbonised and innovative future fuels in compact systems.
Vorraro, Giovanni, Im, Hong G., Turner, James
Experimental and Numerical Investigation of Hydrogen Direct Injection in a CI Engine2026-24-00049/21/2026
Compression ignition (CI) engines are widely used in the transportation sector due to their high torque and efficiency. However, the current climatic framework limits their application, favouring the adoption of low- and zero-carbon technologies. In this context, hydrogen represents a viable energy source for driving CI engines towards clean combustion. The benefits of hydrogen enrichment in diesel engines have been extensively investigated, particularly in port fuel injection (PFI) configurations. In contrast, the addition of a hydrogen direct injection system within a Common Rail engine remains largely unexplored. In this work, a piezo-actuated outward-opening direct injector fuelled by hydrogen was investigated through a combined experimental and numerical approach. The experimental campaign was conducted on an optically accessible single-cylinder research engine (SCRE), with the injector mounted in the cylinder head. Different injection strategies were explored in terms of duration, while the start of injection (SOI) was fixed at 2° after the inlet valve closure (IVC). In parallel, numerical simulations were performed to analyse the injection process into the engine. Firstly, a zero-dimensional model was developed to provide a preliminary estimation of the pressure within the system during the injection phase. Subsequently, computational fluid dynamics (CFD) simulations were performed to obtain a more detailed prediction of the injection process. The numerical framework reproduced the transient injection phase by modelling the near-nozzle jet development and its interaction with the in-cylinder charge. Based on the combined experimental and numerical results, the effective discharge coefficient of the injector is evaluated under different injection durations, enabling a quantitative assessment of its performance.
Episcopo, Domenico, Rossetti, Salvatore, Mancaruso, Ezio, Saponaro, Gianmarco, Lorusso, Leonardo, Camporeale, Sergio, Laera, Davide
Multi-Level CFD and System Simulation Approach for Optimization of Cooling Circuits in High Power Density Powertrains2026-24-00099/21/2026
This paper presents a CFD-based optimization workflow for the simulation and development of automotive cooling circuits, integrating three-dimensional steady-state analyses with one-dimensional transient modeling. The objective of the activity is to establish a robust methodology that links detailed component-level thermal characterization to system-level dynamic simulations, enabling the assessment of cooling performance under both driving and charging operating conditions. The thermal behavior of the cooling circuit components was first investigated using three-dimensional steady-state simulations performed with Ansys Fluent. For each relevant operating point, the fluid flow and heat transfer were resolved in full 3D, and temperatures were monitored at multiple locations within the components and along the circuit. The steady-state analyses provided spatially resolved temperature fields and heat transfer characteristics for a range of boundary conditions representative of real operating scenarios. From these results, temperature and performance maps were generated, describing the relationship between operating conditions, heat loads, and thermal responses of the components. These maps were then used for the calibration of one-dimensional models implemented in GT-Suite. The calibrated 1D models reproduce the thermal behavior observed in the 3D CFD simulations while allowing efficient simulation of the entire cooling system under transient conditions. This multi-level approach enables the combination of detailed local physics from CFD with the computational efficiency required for system-level dynamic analyses. Transient simulations were carried out in GT-Suite to evaluate the thermal response of the cooling circuit during both driving and charging phases. The driving phase accounts for variable thermal loads and flow conditions associated with vehicle operation, while the charging phase represents operating conditions specific to battery recharging scenarios. The calibrated 1D models were used to simulate the evolution of temperatures throughout the system over time, considering the interactions between components and the overall thermal inertia of the circuit. The results show that the designed cooling system is capable of maintaining component temperatures within the targeted limits across the analyzed operating conditions. The thermal containment is achieved for all components included in the cooling circuit under both dynamic driving and charging scenarios. The electric motor is oil-cooled and therefore is not part of the water-based cooling circuit addressed in this study. The proposed CFD-to-1D workflow provides a consistent and transferable methodology for the thermal development of cooling systems of high power density electrified powertrains. The novel contribution lies in (i) the application of the multi-level framework to a heavy-duty platform with SiC-based power modules and dedicated on-board charger developed within the Horizon Europe POWERDRIVE project, (ii) a DOE-based map generation strategy that preserves the conjugate heat transfer interactions between actively cooled components (power modules, OBC) and passively cooled neighbors (busbar, capacitors) within the reduced-order representation, and (iii) the integration of the reduced-order maps within a single transient system-level model covering both vehicle-at-rest charging and dynamic driving operating modes. This activity is carried out within the framework of the Horizon Europe project POWERDRIVE.
Chiappini, Daniele, Tribioli, Laura, Rodionov, Artem
Comparative Analysis of BEV Performance from Simulated Environment and Physical Hardware Platform2026-24-00059/21/2026
The proliferation of simulation environments has accelerated technological progress across various scientific domains by offering a cost-effective and time-efficient framework for data acquisition and analysis. In the automotive sector, high-fidelity modelling of vehicle components and driving scenarios bypasses the logistical constraints associated with hardware procurement and the intensive requirements of large-scale testing infrastructures. However, pre-calibrated or native software models often imply simplified hypotheses, missing relevant aspects of the entire powertrain-to-wheel energy chain. This study presents a comparative analysis of battery performance within a battery electric vehicle (BEV) by synchronizing virtual simulations with experimental hardware at the test bench. The methodology involves the concurrent modelling of the driving environment, the vehicle chassis, and the propulsion system, followed by the execution of identical driving cycles on a physical platform. The experimental setup comprises a fully instrumented BEV featuring an integrated electric motor and battery pack, specifically configured for high-precision signal acquisition. The virtual section starts with the development of a digital twin within a commercial simulation suite, parameterized according to the vehicle specific dynamic and energy requirements. This is followed by the integration of the electric propulsion system and a battery pack model based on the equivalent circuit model method. To ensure high fidelity, the battery model is experimentally calibrated via multi-step pulse discharge tests performed on the physical hardware. Subsequently, various driving scenarios from the simulated environment are translated into speed-time profiles and are replicated on the real vehicle using a PID-controlled actuator on the accelerator pedal. The battery pack that serves the vehicle is monitored during the cycle to collect information on the electrical performance. Finally, a comparison between the simulated and real battery behaviour is performed. This dual approach used in the present work, which compares the simulation accuracy against real-world performance, provides critical insights into the inherent advantages and technical boundaries of digital modelling in electromobility applications.
Sequino, Luigi, Sementa, Paolo, Altieri, Nunzio, Vaglieco, Bianca Maria, Sorrentino, Chiara
Neural-Network-Enhanced Air-Standard Thermodynamic Modeling for Spark-Ignition Engines Fueled with Low Heating Value Alternatives2026-24-00169/21/2026
This study presents a computational framework that integrates an air-standard thermodynamic engine model with artificial neural networks to predict the performance of spark-ignition (SI) engines operating with alternative fuels of reduced lower heating value (LHV). A deterministic thermodynamic simulator was developed in Excel, incorporating engine geometric parameters (compression ratio, bore, stroke, displacement), operating speed, and fuel properties, with particular emphasis on LHV as the dominant energetic descriptor. The model computes in-cylinder states, thermal efficiency, indicated mean effective pressure, and power output under idealized air-standard assumptions. To extend predictive capability beyond fixed-parameter analyses, a feedforward neural network was trained using datasets generated from systematic parametric sweeps of engine geometry, speed, and fuel LHV. The neural network captures nonlinear interactions between compression ratio, combustion energy release, and performance indicators, enabling rapid estimation of engine response when substituting conventional gasoline with lower-LHV alternative fuels. Results demonstrate that the hybrid thermodynamic–neural approach accurately predicts trends in efficiency degradation and power reduction associated with decreasing LHV, while identifying compensatory design adjustments, particularly through compression ratio optimization. The methodology provides a low-cost and computationally efficient tool for preliminary evaluation of alternative liquid fuels in SI engines without resorting to complex CFD or experimental campaigns. This work contributes a transparent, reproducible modeling strategy suitable for early-stage engine design studies and fuel screening, supporting sustainable fuel transitions in spark-ignition propulsion systems.
Gutierrez, Marcos, Taco, Diana
System Dynamics Modeling of Global Electric Vehicle Adoption: Market Transition Time Toward a Single-Dominant Transport Technology2026-24-00179/21/2026
This study presents a system dynamics framework to estimate the global transition time toward electric vehicle (EV) dominance. The model, adapted from the 'Growth of a Field' archetype, captures the mutual reinforcement between EV adoption, charging infrastructure deployment, and cost reductions via learning curves. By solving a system of differential equations in Python, we simulate the nonlinear feedbacks that drive technological diffusion within a finite market. The model explicitly represents the dynamics of the EV fleet, charging infrastructure stock, and cumulative production, where adoption is influenced by infrastructure availability and declining battery costs. Sensitivity analysis reveals how variations in the base adoption rate—representing early policy and behavioral factors—affect tipping points. For instance, doubling the initial adoption propensity reduces the time to 50% market penetration from 30 to 20 years. Monte Carlo simulations are incorporated to assess probabilistic forecasts and the robustness of transition timelines under uncertainty. The results highlight infrastructure deployment as a critical bottleneck and quantify the leverage of early incentives. This framework provides a transparent, extensible tool for strategic planning in the automotive and energy sectors.
Gutierrez, Marcos, Taco, Diana
Structural Robustness and Regime-Dependent Uncertainty in a Reduced-Order Physics Model for Vehicle Fuel Consumption Using Monte Carlo Analysis2026-24-00159/21/2026
Accurate prediction of vehicle fuel consumption typically relies either on simplified empirical correlations or on high-fidelity simulations that are computationally expensive. However, the structural robustness of reduced-order physics-based models under parametric uncertainty has not been systematically quantified. In particular, the interaction between model simplifications and uncertainty in vehicle and fuel properties across different operating regimes remains insufficiently investigated. This study presents a reduced-order physics-based framework derived from fundamental force and energy balances to estimate fuel consumption in L/100 km. The model includes aerodynamic drag, rolling resistance, inertial effects, drivetrain efficiency, and fuel lower heating value. Unlike purely empirical formulations, the proposed structure preserves physical interpretability while remaining computationally efficient. Monte Carlo simulations are employed to propagate simultaneous uncertainties in vehicle mass, drag coefficient, rolling resistance, engine efficiency, and fuel energy content. Thousands of randomized realizations are executed to quantify output variability, compute confidence intervals, and evaluate robustness indices. In addition, regime-dependent dominance transitions are analyzed by comparing urban and highway operating conditions. Results show that parameter influence is strongly dependent on speed regime: mass and rolling resistance dominate in low-speed conditions, while aerodynamic parameters become dominant at high speeds. Fuel energy content and efficiency exhibit nearly linear inverse relationships with consumption. The reduced-order structure demonstrates stable variance behavior under realistic uncertainty ranges, supporting its suitability for parametric studies and alternative fuel assessment. The proposed framework contributes a systematic evaluation of structural robustness in simplified physics-based fuel consumption models and provides a scalable methodology for uncertainty-aware automotive performance analysis.
Gutierrez, Marcos, Taco, Diana
Thermal Effects and Combustion Behavior of Hydrogen and Natural Gas in a Heavy-Duty Gas Engine2026-24-00039/21/2026
To accelerate the adoption of renewable fuels in heavy-duty transportation, a conventional diesel engine was retrofitted to operate on gaseous fuels. This approach supports the transition from diesel to renewable energy carriers while maximizing the reuse of existing engine platforms. However, converting a liquid-fuel engine to gaseous operation does not inherently ensure stable or efficient performance. Gaseous fuels require external ignition, and hydrogen, with its low minimum ignition energy and wide flammability range, places particularly high demands on combustion development. In spark-ignited heavy-duty gas engines, port fuel injection (PFI) is widely used because of its simpler integration and lower fuel-pressure requirements compared with direct injection (DI). However, PFI reduces volumetric efficiency and increases sensitivity to abnormal combustion, including backfire and pre-ignition. DI can mitigate these limitations by enabling fuel delivery after intake valve closure and allowing later injection timings, thereby improving system efficiency and mixture formation control. Experiments were conducted on a 1991 cc single-cylinder research engine representative of heavy-duty applications. Two fuel supply systems were evaluated: low-pressure PFI up to 15 bar and high-pressure DI up to 200 bar. Two novel injector designs were tested with hydrogen and natural gas to assess the effects of fuel type, pressure level, load, and speed. The cylinder head was instrumented with ten thermocouples to evaluate local thermal distribution. In parallel, exhaust emissions, including NOx, hydrogen slip, and unburned hydrocarbons, were analyzed to link injection strategy, mixture formation, combustion behavior, emissions, and thermal loading.
Rößlhuemer, Raphael, Fitz, Patrick, Fellner, Felix, Prager, Maximilian, Jaensch, Malte
Simulation-Based Development and Evaluation of Heat-Quantity-Based Thermal Operating Strategies for Automotive Applications2026-24-00129/21/2026
Thermal management of hybrid electric vehicle (HEV) powertrains requires the simultaneous conditioning of multiple components operating at fundamentally different temperature levels. For thermal management systems, which directly couple the thermal circuits of the internal combustion engine (ICE), electric motor and inverter (EMINV), and traction battery (BAT) for example via controllable three-way valves and a ring-circuit, the decision of when and which components to couple has a direct impact on overall powertrain efficiency. Existing thermal operating strategies rely on empirically defined temperature thresholds and fixed component priority rankings, without quantifying the actual efficiency benefit associated with each coupling decision. This paper presents the development and simulation-based evaluation of a heat-quantity-based thermal operating strategy for a prototype HEV at TU Darmstadt. The strategy introduces three new computational modules — a Q-Indicator quantifying the thermal surplus or deficit of each component, an η-Indicator evaluating real-time component efficiencies as a function of temperature and operating point, and a Δη module computing the combined efficiency gain of each potential coupling pair prior to actuation. Coupling is executed only when the combined efficiency delta is positive, replacing empirical prioritization with a quantitative, efficiency-driven decision mechanism. The strategy is evaluated against an uncoupled baseline (REF-0) and a temperature-threshold-based predecessor strategy (REF-1) across a representative commuter cycle at ambient temperatures of −10 °C, 0 °C, and +30 °C using a co-simulation environment comprising a 1D ring-circuit fluid model in AVL Cruise M and a backward-facing 0D drivetrain model in MATLAB/Simulink. The results demonstrate measurable improvements in battery preconditioning and system efficiency at cold and moderate ambient temperatures. The heat-quantity-based strategy achieves comparable or superior thermal outcomes to the threshold-based approach while activating ring-circuit coupling more selectively. At warm ambient conditions, the strategy correctly withholds intervention based on a negative efficiency delta evaluation, confirming robust scenario-adaptive behavior. The findings highlight the potential of efficiency-driven coupling logic as a generalized and physically grounded basis for thermal operating strategy development in electrified powertrains.
Stenger, Erik, Fiore, Luis, Weimer, Niko, Beidl, Christian
Tailoring ICEs Towards Future Global Market Requirements – Multi-Fuel Capability To Ensure Next Decade Market Success2026-24-00309/21/2026
The entire mobility industry currently faces enormous regulatory demands due to the Paris agreement and its corresponding initiatives to eliminate the business sector-related greenhouse gas emissions (GHG) emissions. A major focus is hereby set on wide-spread electrification of all kinds of applications, but from current perspective it is obvious that a quick and complete shift is highly unlikely, especially with view on heavy and challenging industrial and commercial applications. In line with this, it’s apparent that internal combustion engines (ICEs) maintain to play an important role in the overall propulsion system line-up. For compliance with the engaged CO2 reduction policies and efficiency improvement demands, a fast and broad replacement of fossil fuels needs to be realized. Due to the specific properties of carbon-neutral fuels and as well the variety of the range of industrial applications, different types of alternative fuels are considered. These novel fuels can be subdivided into preferred solutions for smaller or on-highway applications vs heavy off-highway and marine applications, or simply according to local or national preferences or policies. As of now, Hydrogen as well as Methanol/Ethanol is highly attractive for on-highway applications as well as construction/agricultural applications, the heavier and larger applications tend to more energy-dense energy carriers like NH3 and partially Methanol/Ethanol. In addition, to support a smooth transition to fully carbon-neutral operation, intermediate dual-fuel layouts are requested, partially requiring a full redundancy between classical Diesel operation and powering with new fuels. This complexity and variety in customer demands provide a major challenge for globally operating OEMs as future engines designs and definitions need to be developed under extreme cost pressure. The paper at hand delivers an interesting approach to design and develop modern ICE platforms for the anticipated multi-fuel case, aiming at superior key performance indicators concerning power output and efficiency, while maximizing the degree of commonality between the individual engine versions and variants. This flexibility and modularity needs to be incorporated in the base engine design, especially in the top end of the assembly, as it implicates different demands in air delivery and as well the transition from a diffusive combustion system to a pre-mixed combustion principle. This affects on one hand the installation of key sub-systems like fuel injection and ignition, but as well also the decision about an appropriate compression ratio and the definition of an adjusted in-cylinder charge motion. The article closes with recommendations for a future multi-fuel engine definition and an assessment concerning the major design changes in contrast to a refined and optimized Diesel engine layout.
Koerfer, Thomas, Dhongde, Avnish, Yadav, Jaykumar
Emissions Reduction Assessment in Buses During Real Driving Tests using Hydrogen-Methane Blends as Fuel2026-24-00069/21/2026
Increasing concern over climate change on planetary scale and urban pollution on a local spatial dimension are the pressing needs which invite to reduce greenhouse gas emissions in transportation as well as pollutant emissions. Both goals have prompted governments, industry stakeholders, and researchers to pursue innovative pathways toward sustainability in the on-the-road transportation sector trying to interpret this concept on the three requested dimensions, social, economic and environmental. Within this framework, hydrogen–methane mixtures have emerged as a promising alternative fuel solution which in someways match the three expectations. This primary solution matches the needs of urban transportation by buses, representing a further innovation step after the diesel-fuel to methane conversion. Hydrogen is characterized by carbon-free combustion, while methane is a comparatively clean and widely available fossil fuel. When blended, these two fuels can lower overall emissions relative to the use of pure CNG, while still being compatible with existing internal combustion engines if the content of hydrogen in the blend do not exceed 20 % by volume. Greater shares till to 35-40 % are compatible simply re-setting the ignition time according to the engine load. This compatibility makes the adoption of such blends both economically viable and technically achievable in the short to medium term, also increasing the market demand for hydrogen, reducing its cost. The social dimension of this choice is also saved, re-focusing attention on the reciprocating internal combustion engines which represent a great part of the industrial economy. This study describes the methodology adopted to assess the emissions performance of a hydrogen-methane-fueled (HCNG) bus for on-road emission testing. Two experimental campaigns were carried out: the first using conventional CNG, and the second employing an HCNG blend composed of 15% hydrogen and 85% CNG by volume. Tests were conducted along two routes, representing urban and extra-urban driving conditions, with different drivers and traffic conditions. The experimental results enabled a direct comparison between the two fuels. In both driving scenarios, a slight decrease in CO₂ emissions was observed when using the HCNG blend, corresponding to a reduction in fuel consumption. More significant decreases were recorded for pollutants such as CO, HC, and PN, whereas NOx emissions showed a modest increase of only a few percentage points. No modification has been implemented on the aftertreatment devices. The study indicates that the HCNG blend enhances vehicle responsiveness compared to conventional CNG and represents a step ahead in public urban transportation like the one from diesel fuel to methane.
Di Battista, Davide, Di Bartolomeo, Marco, Di Prospero, Federico, Di Diomede, Domenico, Cipollone, Roberto
Processing and Validating CFD Data for Estimating Inlet Dynamic Total-Pressure DistortionAIR6345A (Current)9/21/2026
The processes addressed in this AIR apply to the acquisition and validation of dynamic total-pressure and distortion data from CFD models simulating turbulent flows in inlets. The results of these processes can be used in the formation of an inlet-flow-distortion methodology that addresses turbine-engine operability assessments.
S-16 Turbine Engine Inlet Flow Distortion Committee
Business Approach to Cope with Automotive Market Uncertainty2026-24-00249/21/2026
The global automotive industry is facing an unprecedented convergence of uncertainties driven by geopolitical tensions, evolving trade policies, emissions related regulations, and increasingly volatile consumer demand. Shifting emissions legislation, including the EU’s tightened CO2 targets and long-term plans to phase out internal combustion engines, is imposing strategic and financial pressures on automakers and suppliers as they navigate divergent regional regulatory trajectories. Demand side volatility further complicates the landscape. Consumer preferences are fluctuating due to economic pressures, infrastructure constraints, and uneven EV adoption patterns. While some markets show stagnation in battery electric vehicle uptake, hybrids are rising as consumers seek cost efficient alternatives amid uncertain energy and regulatory environments. Within this unstable context, the transition toward Software Defined Vehicles (SDVs) is emerging as a critical strategic response. SDVs, characterized by centralized computing, updatable software architectures, and over the air feature deployment, offer automakers greater adaptability in addressing regulatory shifts and market dynamics. By decoupling hardware from software cycles, SDVs enable faster innovation, reduced development risk, and new digital revenue models, while virtualization and AI driven analytics enhance development efficiency and lifecycle value.
Cavanna, Filippo, Potenza, Luca
Use-Phase Emission Comparison of Battery Electric and Internal Combustion Engine Vehicles in Canada2026-01-50749/17/2026
The objective of this study was to evaluate the in-use emissions and energy consumption of similar model internal combustion engine (ICE) and battery electric vehicles (BEVs) in Canada. For the ICE vehicles (ICEVs), carbon dioxide (CO2) emissions were measured at the tailpipe. For the BEVs, the carbon intensity of different energy sources was used along with vehicle energy consumption to estimate the in-use CO2 equivalent (CO2e) emissions. Three ICEVs, the Ford Transit, Ford F-150, and Nissan Versa, and three BEVs, the Ford E-Transit, Ford F-150 Lightning, and Nissan LEAF, were tested over standard test cycles on a chassis dynamometer. The Nissan Versa, Nissan LEAF, Ford F-150, and Ford F-150 Lightning were tested at two temperatures, 25°C and −7°C, to investigate the effect of colder temperatures on emissions and energy consumption. The Ford Transit 150 and E-Transit were tested at two test weights, 2722 kg (6000 lb) and 3629 kg (8000 lb), to study the effects of cargo loading on emissions and energy consumption. In most conditions, the BEV use-phase CO2e emissions were found to be lower than those of the ICEVs. Results showed a significant increase in both emissions in ICEVs (up to 20%) and energy consumption in BEVs (up to 78.5%) at −7°C when compared to 25°C. Results also showed the significant effect of the carbon intensity of electricity on the CO2e emissions of BEVs, where more carbon-intensive electricity grids resulted in higher BEV CO2e emissions, even surpassing ICEV CO2 emissions in certain cold-temperature conditions.
Araji, Fadi, Humphries, Kieran, Hornung, Jeremy, Shantz, Emory
A Study on the Development of Brake Moan Analysis for CTBA Vehicles Using Simulation2026-01-08149/14/2026
Moan noise is a low-frequency noise occurring in the 170–500 Hz frequency ranges. While it frequently appears in vehicles equipped with a rear Coupled Torsion Beam Axle (CTBA), the exact cause, generation mechanism and clear solutions remain unidentified. For those reasons, we have developed a moan noise analysis method capable of representing the moan noise phenomenon in vehicles with rear CTBA along with an automation tool. From these results, we can use moan analysis models to reduce real moan noise problems. Consequently, this not only enhances customer satisfaction and vehicle quality but also significantly increases the work efficiency of vehicle designers through design modification in the preliminary stages of vehicle development
Kim, Sungho, Kim, Jeongkyu, Hwang, Jaekeun, Kang, Donghoon
Precision Simulation and Test of Drag Torque for Carbon Ceramic Disc Brakes with In-Wheel Electric Motor2026-01-08139/14/2026
Aiming at the industry pain points of low simulation accuracy and lack of authoritative closed-loop experimental verification for the drag torque of special brake calipers for in-wheel electric motors, this study takes the hub motor-integrated carbon-ceramic inboard caliper as the research object. The inboard caliper layout has been realized on Protean’s in-wheel motor products [12], while the matching integration of the C/C-SiC brake disc with such an inboard structure for a compact hub-motor layout is original and covered by Chinese invention patent CN120207087A[15]. The inboard caliper is defined as a special brake structure installed on the inner side of the brake disc/hub motor cavity (distinguished from the traditional outboard caliper mounted on the outer side of the brake disc), which is specially adapted to the compact assembly space of in-wheel motors and realizes structural integration of braking and driving systems. This study proposes a high-precision finite element simulation method coupling the nonlinearity of piston seal material with bilateral parallel return springs. The simulation boundary conditions are calibrated by matching the bench test working conditions. To verify the simulation results, the drag torque bench test is carried out in accordance with the industry standard [13], realizing a complete closed loop of simulation modeling and experimental verification. Although a certain numerical deviation exists, the high consistency in core trends and key evolutionary nodes, together with a low error (≈5.6%) within the initial 0.9–1 rotation regime, demonstrates that the model reasonably reproduces the generation and attenuation mechanisms of drag torque during the early rotation stage.
Meng, Dejian, Liu, Yuqi, hu, Pengfei, Li, Birui, Shao, Jiyong
Study on Temperature Rise and Heat Dissipation of Micro Electric Vehicle Drive Motor Based on Multi-Physics Coupling2026-99-11319/11/2026
This paper is mainly about heat dissipation and improvement technology, aiming at solving the problem that the driving motor of 4 low-speed electric vehicles has too high a rising speed when running under complicated working conditions. Core losses and conductor losses are calculated by using the finite element method as well as known empirical formulas, and magnetic eddy loss at three operating conditions (normal condition, maximum speed, and peak torque. The computed heat loads are then used to establish the complete 3- dimensional model of thermal analysis. As shown in Figure 3, without active cooling, the hottest conductors would be at about 141°C (Class-B Insulation limit). Therefore, three different liquid cooling designs (helical channel, serpent channel, and annular flow) have been designed and analyzed. A coupled thermal- fluid simulation has been performed on the helix structure, which showed better results, so we selected it to be optimized. The optimization is performed using central composite design, genetic algorithms for response surfaces, and multi-objective evolutionary optimization (NSGA-II). The objective function is to simultaneously achieve a low maximum working temperature as well as good heat transfer properties by changing the geometry of cooling channels. The cooling of the motor as well as the suction pressure was optimized, after which a decrease by up to 31.1°C (up 8.6% on the maximum temperature) was observed. Also, pressure drop reduction as much as 23% along with substantial increases in both the heat transfer performance and reliability.
Xi, Heyuan, Bai, Enjun, Ma, Wenyu, Tang, Fuyu, Liu, Zhiyi
Data-Driven Design of Copper Tube Drawing Algorithm for Automotive Air Conditioning Systems2026-99-11109/11/2026
As a critical component in thermal management systems, copper tubes are widely used in automotive radiators, condensers, and other parts. In copper tube production, the drawing process is essential for achieving target dimensions and performance specifications. However, as the copper tube industry evolves, nowadays manual drawing process design and traditional drawing algorithms struggle to meet increasingly diverse finished product specifications and complex manufacturing requirements. To address this issue, this study developed an intelligent drawing process design algorithm suitable for automotive copper tube production. This algorithm builds upon existing drawing without plug algorithms, floating plug drawing algorithms, and manually compiled drawing process sheets. It first learns the fundamental principles of drawing without plug algorithms, then derives the relationship between wall thickness changes before and after drawing using mathematical formulas. Subsequently, by analyzing the enterprise’s existing 297 drawing process sheets, the design principles of the drawing without plug algorithm were extracted. This established the number and positioning of required drawing without plug processes within different drawing procedures as the design principles for drawing without plug. Then, using the ‘Double decrement method’ from the floating plug drawing algorithm as an example and integrating the design principles of drawing without plug processes, we developed an intelligent drawing process design algorithm suitable for automotive copper tube production. Furthermore, we selected a typical drawing process sheet for comparison. Through comparative analysis of key parameters such as processing rate and relative wall thickness reduction coefficient, we validated that this algorithm yields more rational results compared to traditional methods. Utilizing this algorithm not only significantly reduces the workload for drawing process designers but also produces more optimal drawing process design outcomes. Compared to other floating plug drawing algorithms, this algorithm also demonstrates greater universality.
Yue, Fengli, Zhang, Jiakun, Liu, Jinsong, Meng, Dezhi
Application Layer - DiagnosticsJ1939-73_202609 (Current)9/9/2026
SAE J1939-73 defines the SAE J1939 messages to accomplish diagnostic services and identifies the diagnostic connector to be used for the vehicle service tool interface. Diagnostic messages (DMs) provide the utility needed when the vehicle is being repaired. Diagnostic messages are also used during vehicle operation by the networked ECUs to allow them to report diagnostic information and self-compensate as appropriate, based on information received. Diagnostic messages include services such as periodically broadcasting active diagnostic trouble codes, identifying operator diagnostic lamp status, reading or clearing diagnostic trouble codes, reading or writing ECU memory, providing a security function, stopping/starting message broadcasts, reporting diagnostic readiness, monitoring engine parametric data, etc. California-, EPA-, or EU-regulated OBD requirements are satisfied with a subset of the specified connector and the defined messages.
Truck and Bus Control and Communications Network Committee
Development of Engine Nozzle Characteristic Determination System2026-99-12429/4/2026
The determination of flight thrust for aircraft engines is an important means of evaluating engine and aircraft performance. The characteristics of the tail nozzle of the tested engine are an important data support for calculating flight thrust. In order to accurately evaluate the flight thrust of a certain type of engine, an “engine nozzle characteristic determination test system” is developed to obtain the thrust characteristic curve and flow characteristic curve of the nozzle. A calibration device and calibration process were designed for the experimental system to achieve in-situ calibration of the system.
Ren, Boyang, Jia, Wenjie, Song, Jiangtao
Research on Scalelike Adaptive Suction Flow for Wide-Speed Range Hypersonic Inlets2026-99-12529/4/2026
As critical components of aircraft, hypersonic inlets utilize shock wave compression effects to pressurize incoming flow. The interaction between shock waves and the boundary layer tends to generate separation zones, and it adversely affects inlet performance. As a method to significantly enhance inlet performance, suction technology can substantially reduce the size of separation zones when they form in the inlet. However, when the inlet is started and operating normally, suction configurations may cause mainstream leakage and make it difficult to meet the requirements of inlets with wider speed ranges. This paper designs an adaptive scaliform suction structure that utilizes a lift-generating design to induce a slight upward deflection of high-speed near-wall flow. It can reduce high-speed mainstream leakage without compromising the effectiveness in low-speed separation zones. Numerical simulations are employed to evaluate its suction performance in both inlet separation zone flow fields and supersonic mainstream flow fields. The internal flow mechanisms of the scaliform suction structure are investigated, and differences in its behavior across various suction flow fields, as well as its interference with the mainstream, are discussed. The study reveals that when the height of the scaliform suction structure is approximately 1/8 of the incoming flow’s velocity boundary layer height, the suction flow coefficient in the separation zone is twice that in the hypersonic mainstream. Furthermore, the loss in Mach number and total pressure recovery coefficient of the near-wall supersonic mainstream is controlled within 5%. This structure exhibits an adaptive suction capability for separation zones, thereby extending the starting speed range of the inlet.
Zhao, Xuening, Zhao, Yilong
Design and Analysis of Transmission Line Tower Erection Equipment2026-99-12409/4/2026
In response to the industry's problems of transportation difficulties, low efficiency, and high safety risks during the erection of high-voltage transmission line towers in mountainous areas, this paper proposes a light tower erection device that integrates connection, assembly, and fixing functions. The device adopts 180 mm Q345 equal-angle steel tower legs and is equipped with a hydraulic drive system. The tower body is raised through the coordinated work of the main and secondary hydraulic cylinders. In contrast, the vertical and horizontal hydraulic cylinders are used for auxiliary descent and precise fine adjustment. Its modular and lightweight structural design meets the transportation needs in narrow spaces in mountainous areas. The specifications of the hydraulic cylinder are determined by mechanical calculation, and the structural strength of the square tube and the main and secondary hydraulic cylinder connecting rods is verified by finite element analysis. Kinematic simulation confirms that the operating performance of the device is stable. This device provides an efficient and reliable piece of technical equipment for the construction of transmission lines in mountainous areas, which has important engineering application value and broad promotion and application prospects.
Li, Hailong, Chen, Zhen, He, Longping, Wang, Zhongpan, Li, Cheng
Comprehensive Analysis of Torsional Vibration Response in Marine Propulsion Shafting Systems2026-99-12749/4/2026
The marine propulsion shafting system serves as the core component of ship power transmission, wherein torsional vibrations can easily lead to shaft cracking and failure. Thus, avoiding shafting resonance is vital for ship safety. Previous research primarily focuses on a single vibration mechanism of diesel engine propulsion shafting systems, lacking a comprehensive analysis of modal characteristics, frequency, and transient responses. This paper systematically investigates the torsional vibration characteristics of shafting systems, constructs a mathematical model for torsional vibrations, deduces a method for solving natural frequencies, and establishes a frequency-domain transfer function matrix using the Laplace Transform to theoretically derive the transient response of damped forced vibrations. Taking the propulsion shafting system of a low-speed diesel engine in a 10,000-ton oil tanker as an example, a multi-condition analysis based on a simplified shafting model is conducted. This includes modal solution analysis, 0–2000 Hz frequency sweep tests, and comparative experiments on transient responses under different excitation frequencies with a 1000 Nm torque. The study reveals the influence mechanism of the coupling between excitation frequency and natural frequency on the dynamic characteristics of the shafting system. By investigating torsional vibration patterns, this research provides a theoretical basis for vibration reduction design and resonance avoidance in marine propulsion shafting systems.
Zhang, Jiayi
Design and Performance Verification of a Wheel-Track Transformable Mobile Platform Based on a Four-Bar Mechanism for Rescue Scenarios2026-99-12469/4/2026
Contemporary disaster rescue operations face challenges due to complex and hazardous terrains. Existing rescue robots with single locomotion mechanisms (wheeled, legged, tracked) and some hybrid ones have limitations in adaptability, efficiency, or structure. To meet the dual demands of complex terrains and limited space, this paper proposes a wheel-track transformable mobile platform based on a four- bar mechanism, which adopts a modular structure. A servo motor drives the active link to adjust the spatial position of the movable link (equipped with movable wheels), enabling smooth switching between wheeled and tracked modes. Key link lengths are determined via kinematic analysis, and a two-stage gear transmission system is designed. Adams simulation verification shows the platform completes wheel-track mode conversion on flat ground without component interference and can lift the center of gravity (CG) to surmount obstacles during slope climbing. The platform's feasibility is verified, providing a technical reference for designing highly adaptable rescue robots suitable for small spaces and complex terrains in post-earthquake or post-disaster scenarios.
Ma, Shangyuan
Assembly Accuracy Optimization of Aero-engine Section Based on Dynamic Weighting Multi-Objective Optimization Algorithm2026-99-12729/4/2026
The pose-solving method for aero-engine component docking assembly often faces challenges such as slow convergence and susceptibility to local optima when dealing with complex optimization problems involving multiple features and constraints. This paper proposes an optimized assembly pose solution method for engine sections based on an improved multi-objective optimization algorithm. The method first preprocesses the high-density point clouds obtained from 3D scanning to extract geometry such as feature points, lines, and surfaces. It builds an assembly constraint model with geometric relations and process needs. It focuses on the pose solution phase: we transform the assembly problem into a nonlinear optimization problem to minimize parallelism error, gap error, and step error. In order to solve this multi-objective problem efficiently, we propose an iterative multi- objective optimization algorithm as the optimization engine and propose a dynamic weight allocation strategy. During iteration, the strategy adaptively adjusts the weight coefficients of three error terms in the overall fitness function due to the evolution of the population and convergence of each error term, guiding the search direction and balancing the algorithm's global exploration and local exploitation ability. Our results show that instead of adopting an optimization algorithm with fixed weights and a multi-Objective optimization system with fixed weight, the proposed pose solution method based on dynamic weight multi- objective optimization algorithm achieves a high accuracy and stability of the solution and can easily and accurately produce a good pose matrix which meets challenging assembly constraints, providing a practical theoretical framework and technical support for achieving high-quality automated engine assembly.
Huang, Mi, Wu, Guanghui, Su, Xun, Xu, Yongqian, Ding, Han, Liu, Xiaopeng
Experimental Testing and Finite Element Simulation on Tensile Mechanical Behavior of Nickel-based Superalloys2026-99-12249/4/2026
The accurate prediction of high-temperature mechanical behavior of GH3230, as a core material for the new generation of combustion chambers in China, is a key technical prerequisite for promoting engineering applications. This article is the first to conduct a systematic study on the tensile properties of the alloy at three typical service temperatures of 200°C, 550°C, and 900°C, combining high- temperature tensile testing with numerical simulation. Through metallographic observation, the excellent microstructure characteristics of the alloy, including no grain boundary defects, inclusion phase size less than 5 μm, and uniform distribution, were clarified. Based on this, a multi-temperature adaptive tensile simulation model was established. Experimental verification showed that the model can accurately reproduce stress-strain tensile curves at different temperatures, with prediction errors controlled within a reasonable range, effectively breaking through the limitations of traditional single-temperature simulation. This study not only provides an efficient and accurate new method for the performance analysis and safety evaluation of GH3230 in a wide temperature range but also provides practical technical means to support the component-level engineering application of this material. At the same time, the research results also provide a reference technical path and research ideas for the multi-temperature mechanical performance prediction of other nickel-based high-temperature alloys.
Qiao, Yongle, Xie, Jiahui, Li, Lei, Zhou, Jie, Zhu, Yankun, Wang, Yifei
Study on the Vehicle Unsteady Vibration Control with a Semi-Active Strut2026-99-12319/4/2026
Unsteady vibrations of vehicles, which can be easily perceived by the human body, may affect the driving experience and compromise driving comfort. However, the conventional three-point powertrain mounting system (PMS) often fails to offer a satisfactory solution. Here, a novel four-point PMS was proposed by introducing a semi-active strut (SAS), which can provide stronger damping in a low-frequency range to resolve this problem. Specifically, a thirteen degrees of freedom (DoFs) vehicle dynamic model (VDM) with four mounts was constructed, and the evaluation indices for unsteady vibration responses of the vehicle were determined and analyzed; Next, the PMS optimization design approach was employed to identify the proper position of installation and dynamic stiffness of the SAS, and meanwhile the 13 DoFs VDM and the force-sharing principle were used to identify the structural parameters of the strut; Last, comparative experiments were performed to analyze the effect of the strut on alleviating the unsteady vibration of the vehicle under varied unsteady vehicle states. The results showed that the SAS has significantly reduced the seat rail peak acceleration, verifying the effectiveness of our novel PMS in alleviating the unsteady vibration. The research provided a feasible solution to alleviate the unsteady vibration of vehicles and improve the driving experience.
Wang, Daoyong, Liu, Yongjiang, Ma, Bo
A Coaxiality Measurement Method Applicable to the Three Holes of an Engine2026-99-12269/4/2026
To address the measurement challenges posed by the large diameters and wide spans of engine crankshaft holes, cylinder holes, and camshaft holes, as well as the abnormal laser measurement data caused by oil film adhesion and local protrusion structures on their inner walls, this paper proposes a non-contact coaxiality measurement method based on a laser displacement sensor (LDS) and a threshold-modified least squares ellipse fitting (TMLSE) algorithm. The method first preprocesses the data through median filtering and then employs an adaptive distance threshold based on maximum inter-class variance to eliminate outliers caused by oil film scattering and protrusions, achieving robust fitting of the cross-sectional centers. Subsequently, the datum axis is established using the least squares midline method, ultimately enabling the evaluation of coaxiality error. In the simulation experiments, a dual-hole model with an inner diameter of 100 mm and a spacing of 700 mm was simulated, where the right hole was translated by 1.5 mm to introduce coaxiality error. Each cross-sectional point cloud included 10% protrusion points (protrusion height of 10 mm) along with random noise and data loss simulating the effects of oil film. To assess the robustness of the method, a systematic analysis was conducted on the influence of laser incidence angles [80°,89°]on measurement accuracy. The results show that across different incidence angles, the maximum deviation between the coaxiality error obtained by the TMLSE method and the theoretical value is only 0.1582 mm, which is significantly better than that of the RANSAC, MZC, and MIC methods. Meanwhile, TMLSE demonstrates stable and efficient computational speed. The simulation verifies that this method offers higher fitting accuracy and robustness under both optical interference and variations in installation angle, making it suitable for the precision measurement of key engine hole systems.
Yin, Jiakuo
CFD Numerical Simulation Study on Flow Field Characteristics of Umbrella-Frame Combined Impeller2026-99-12089/4/2026
For the mixing of hydroxy-terminated polybutadiene (HTPB) with silicon dioxide particles, this study adopts the Computational Fluid Dynamics (CFD) method to conduct a visual analysis on the fluid flow field characteristics generated by the umbrella-frame impeller (UF impeller) and umbrella-frame combined impeller (UFC impeller). Comparative studies are carried out from the dimensions of particle concentration distribution, fluid flow trend, vorticity, and path line. The results show that compared with the UF impeller, the UFC impeller, equipped with an upper blade structure, enables its generated flow field to cover the entire stirred tank more effectively, significantly improving the solid-liquid mixing efficiency. In addition, the fluid-structure coupled numerical method is used to analyze the structural deformation characteristics and stress distribution law of the impellers. The research findings can provide a reference for the optimization of dispersion and mixing processes of solid particles in high-viscosity fluids.
Li, Ruizheng, Sun, Zhenxing, Zhang, Yan, Wu, Qiong
Low-Cycle Fatigue Life Prediction Model Considering Mean Strain Effect for HTPB Propellant2026-99-12909/4/2026
In order to investigate the effects of different strain levels on the low-cycle fatigue life of hydroxyl-terminated polybutadiene (HTPB) propellant, a series of fatigue tests were conducted under various combinations of strain amplitude and mean strain. The results indicate that fatigue life exhibits a decreasing trend with increasing strain amplitude and mean strain, while the effect of mean strain on fatigue life gradually weakens as the strain amplitude rises. Additionally, a distinct trend is observed at high strain levels: the higher the strain amplitude is, the lower the coefficient of variation is. Based on the fatigue life data obtained from the tests, with strain amplitude as the characteristic parameter, a mean strain function is incorporated into the classical log-log linear model, and a stepwise fitting of model parameters is implemented using the chaotic adaptive genetic algorithm (CAGA) and the least squares method. For the selection of the mean strain function, the coefficient of determination is adopted as the goodness-of-fit criterion to evaluate the modeling accuracy of the power function, exponential function, and quadratic polynomial, respectively. Ultimately, the power function is identified as the most suitable mathematical form for characterizing the mean strain effect, leading to the establishment of a low-cycle fatigue life prediction model considering both strain amplitude and mean strain. Compared with the measured fatigue lives, more than 90% of the predicted lives obtained from the proposed model fall within the two-fold scatter band, and 100% within the three-fold scatter band. This demonstrates that the model’s prediction accuracy satisfies practical engineering requirements, thereby providing reliable data support for the development of propellant damage models and the assessment of cumulative damage in solid rocket motors (SRMs).
Jiang, Yuke, Sun, Haitao, Ai, Junzhuo, Shen, Zhibin, Yuan, Jiehong
Design and Validation of a 7-DoF Robotic Arm Featuring Hybrid Pneumatic-Electric Actuation2026-99-12229/4/2026
To enable more natural motion mapping between the human arm and a robotic counterpart while reducing control complexity, this paper presents a novel seven-degree-of-freedom (7-DoF) bionic robotic arm with hybrid pneumatic–electric actuation in an antagonistic configuration inspired by the skeletal structure and muscular actuation of the human upper limb. The design combines the high power density and intrinsic compliance of pneumatic artificial muscles with the precision and stability of electric motors, improving motion adaptability and payload-to-weight performance. Kinematic feasibility and motion smoothness for human-like waving are validated via forward kinematics and redundancy-resolved inverse kinematics, together with trajectory simulations. To quantitatively evaluate dexterity and operational range, Monte Carlo sampling is used to generate reachable postures across the workspace, producing a wrist activity map that characterizes attainable orientations and maneuverability. A prototype testbed is built to verify physical performance. Joint-angle tracking experiments for the wrist and elbow, as well as whole-arm coordinated-motion tests, demonstrate accurate trajectory tracking, smooth transitions, and stable motion. These results confirm the mechanical soundness and effectiveness of the proposed hybrid antagonistic actuation scheme. This work provides a practical basis for advanced control development and offers insights into hybrid actuation design for bionic robotic systems.
Dai, Yuanquan, Guo, Zhiqin, Zi, Mingkang, He, Zhaoyang, Song, Yongwei, Xie, Yinhui, Li, Jun
Coolant Filter Test ProcedureJ2709_202609 (Current)9/4/2026
This SAE Recommended Practice is applicable to coolant filters installed on mobile or stationary equipment. It describes a body of tests used to characterize the stuctural integrity and filtration performance of coolant filters.
Filter Test Methods Standards Committee
Assessment of Heat Transfer Correlations for Shell-and-Tube Heat Exchangers under Periodically Varying Exhaust Flow03-19-05-00229/2/2026
Waste heat recovery from internal combustion engines (ICEs) is one potential option to improve overall vehicle efficiency. Rankine cycles based on engine coolant and exhaust heat sources have demonstrated their effectiveness in enhancing brake thermal efficiency. Critical to their success is the design of the heat exchanger for the evaporator, with shell-and-tube heat exchangers (STHEs) a common hardware choice. However, little experimental data exists evaluating STHEs with the pulsating flow encountered in the exhaust of ICEs. In addition, correlations for periodically varying flow do not appear to be used in the modeling of STHEs. To alleviate this limitation, this study combined experiments using a pulsating exhaust heat source from an ICE under low loads at a single engine speed with a one+one-dimensional model to evaluate tube- and shell-side heat transfer correlations for a STHE without baffles. Four working fluids, water, ethylene glycol, propylene glycol, and a 50/50 ethylene glycol–water mixture, were examined. The combined thermodynamic properties of an ethylene glycol–water mixture were the most effective based on an evaluation of heat exchanger effectiveness, overall heat transfer coefficient, exergetic efficiency, and entropy generation. A Pearson correlation analysis identified the inlet working fluid temperature as the parameter most strongly correlated with STHE performance due to its higher enthalpy. From a modeling perspective, the pulsating flow correlation of Al-Haddad and Al-Binally predicted greater heat transfer rates in the STHE. In combination with all shell-side correlations tested, simulations still underpredict performance relative to experimental results. An optimized correlation developed specifically for the geometry of this unbaffled STHE matched the experimental data more closely but likely overpredicted shell-side heat transfer. Monte Carlo uncertainty propagation based on sensor uncertainties showed that the differences in effectiveness and overall heat transfer coefficient exceeded measurement uncertainty. Furthermore, sensitivity analysis demonstrated the importance of accurate thermophysical property values and indicated that the underprediction likely reflects coupled limitations in both tube- and shell-side formulations, with correlations on each side exerting a comparable influence on predicted heat transfer.
Spickler, Bailey, Segares Dominguez, Maria Luisa, McGowan, Raymond, Depcik, Christopher
An Effective Pathway for Off-Road Tier 5 Emission Compliance03-19-08-00418/31/2026
Proposed Tier 5 off-highway emission regulations for the 19–56 kW engine class pose significant technical and economic challenges. Unlike larger platforms, where selective catalytic reduction (SCR) is the standard nitrogen oxide (NOX) control strategy, engines in this class face cost and packaging constraints that limit complex aftertreatment adoption. This article investigates whether a production Tier 4 diesel engine and its existing aftertreatment can meet proposed Tier 5 limits through calibration and minor hardware changes alone, without major redesign or SCR. The approach combined a cooled exhaust gas recirculation (EGR) strategy with start of injection (SOI) timing optimization to manage the NOX–particulate matter (PM) trade-off, using the stock diesel oxidation catalyst (DOC) and diesel particulate filter (DPF) system for particulate control. An EGR/SOI design-of-experiments (DOE) sweep identified an optimal calibration, validated over both the ramped modal cycle (RMC) and non-road transient cycle (NRTC) per Title 13 California Code of Regulations (CCR) Section 2423 for certification of variable-speed engines in this power category. Results indicate that the system can be a viable pathway of meeting upcoming Tier 5 final emission standards.
Patil, Shubham Vishwanath, Michlberger, Alexander, Bachu, Pruthvi R., Amaral Garcia, Herbert, Smith, Edward M.
Objective Quantification of Harmonic Impulsive Sounds and Interval Prediction of Sound Quality in Hybrid Vehicle Engines10-11-01-00038/28/2026
Steady advancement is observed in global research on eco-friendly and sustainable transportation. Rapid technological evolution of hybrid electric vehicles (HEVs) is documented. Lower overall noise output and more compact structures are achieved in HEV engines relative to conventional internal combustion engines. The perceptibility of harmonic impulsive sounds is significantly enhanced by these design characteristics. A close correlation is observed between these acoustic phenomena and negative human auditory perceptions. These events are treated as a core focus for HEV noise, vibration, and harshness optimization. Accurate quantification of harmonic impulsive sounds is not achieved by conventional objective indicators. A favorable balance between reliability and accuracy is not established by existing subjective prediction models. Practical engineering applications of these methods are severely restricted. A novel objective quantification method for harmonic impulsive sounds is proposed in this study. The method is established based on time–frequency masking theory and tonal strength. Bench tests in a semi-anechoic chamber and subjective evaluation experiments with standardized rating scales are performed for data collection. Collected sound signals are decomposed through an integrated approach of wavelet transform and variational mode decomposition. Targeted feature extraction is completed for harmonic impulsive sounds. A quantitative index incorporating human auditory temporal and frequency masking effects is developed. The proposed index exhibits a significantly stronger correlation with subjective evaluation results than traditional objective metrics, confirming its superior ability to reflect actual perceived sound quality. An interval prediction model for sound quality evaluation is established based on support vector machines and kernel density estimation. Traditional objective metrics and the proposed index are introduced as key input parameters. Effective and reliable prediction of HEV engine noise subjective satisfaction is achieved by the model.
Lin, Xu, Liang, Xingyu, Shi, Zhiyuan
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