Browse Topic: Mathematical analysis

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Elucidation of Flow Mechanisms Modulating Vehicle Wind Noise by Using Large-Scale CFD Simulation2026-01-06144/7/2026
In vehicle development, noise reduction is critical for ensuring passenger comfort. As electric vehicles become prevalent and engine noise is minimized, wind noise becomes more noticeable. Modulated wind noise, which causes a sense of fluctuation due to atmospheric turbulence, wind gusts, and preceding vehicle wakes, can cause significant discomfort. This noise is characterized as a high frequency sound above 1 kHz, modulated at low frequencies owing to the wind velocity and direction fluctuating at several Hz. The mechanisms behind wind noise modulation are not fully understood, and no established countermeasures have been developed. This is because wind noise perceived through the side window is primarily caused by the A-pillar vortex and door mirror wake, which coexist as complex turbulent flows around the vehicle. Therefore, identifying the source of modulated wind noise around vehicles under fluctuating wind conditions is difficult. This study aims to identify the source of the
Tajima, Atsushi, Hirata, Takumi, Ikeda, Jun, Kamiwaki, Takahiro, Wakamatsu, Junichi, Tsubokura, Makoto
Optimization Method for Vehicle Shape to Drastically Reduce Aerodynamic Drag in Heavy-Duty Vehicles2026-01-06034/7/2026
Since air drag is proportional to the square of the speed, it is expected that reducing air drag will significantly improve fuel efficiency for on-highway trucks and buses, which are often driven at high speeds. Therefore, the purpose of this study is to propose an optimization method for vehicle shape to drastically reduce aerodynamic drag in heavy-duty vehicles. Using NSGA-II, one of a genetic algorithm, the overall vehicle shape was optimized with drag coefficient (CD) and lift coefficient (CL) values as objective functions and design variables as parameters in a total of 13 locations. Among the Pareto solutions, an 86% reduction in CD was achieved compared to the base shape when the CD value was the lowest. Since the CL value remains low with this shape, it can be seen that driving stability does not deteriorate. Among the design variables in optimization, it was confirmed that the corner radius of the vehicle side was particularly effective in reducing the CD value. In addition
Kawano, Daisuke
Vibration Analysis of Rectangular and Circular Plates with Fixed Edges: Analytical and Computational Validation2026-28-01082/12/2026
This study presents a comparative investigation of the vibration characteristics of rectangular and circular plates with fixed edges using analytical, numerical, and computational approaches. Analytical models based on classical plate theory were employed to calculate natural frequencies and mode shapes, while finite element analysis (FEA) was performed in a CAE tool to provide high-fidelity simulation results. A detailed mesh convergence study confirmed numerical stability, with frequency variations below 1% between successive refinements. Analytical predictions showed excellent agreement with simulation results for lower modes, with errors as low as 0.25% for the rectangular plate and 2.65% for the circular plate. However, higher modes exhibited significant deviations, with errors reaching up to 29.01% for rectangular and 181.52% for circular geometries, highlighting the limitations of closed-form solutions in capturing complex vibrational behavior. Python-based computational tools
N, Suhas, R, Sanjay, Bhaskara Rao, Lokavarapu
Modeling and Validating Foreseeable Misuse in Safety of the Intended Functionality: A Case Study of Automated Emergency Braking12-09-03-001712/31/2025
This study presents a structured evaluation framework for reasonably foreseeable misuse in automated driving systems (ADS), grounded in the ISO 21448 Safety of the Intended Functionality (SOTIF) lifecycle. Although SOTIF emphasizes risks that arise from system limitations and user behavior, the standard lacks concrete guidance for validating misuse scenarios in practice. To address this gap, we propose an end-to-end methodology that integrates four components: (1) hazard modeling via system–theoretic process analysis (STPA), (2) probabilistic risk quantification through numerical simulation, (3) verification using high-fidelity simulation, and (4) empirical validation via driver-in-the-loop system (DILS) experiments. Each component is aligned with specific SOTIF clauses to ensure lifecycle compliance. We apply this framework to a case of driver overreliance on automated emergency braking (AEB) at high speeds—a condition where system intervention is intentionally suppressed. Initial
Kang, Do Wook, Kim, Woojin, Jang, Eun Hye, Chang, Mi, Yoon, Daesub, Jang, Youn-Seon
Numerical Analysis of the Performance of an Engine with a Pre-Chamber Equipped with an Air Injector Operating in TJI Mode2025-36-018712/18/2025
The sustainability of the transportation sector demands the continuous development of new technologies in internal combustion engines, aiming at reducing pollutant and greenhouse gas emissions while increasing fuel conversion efficiency. Pre-chamber (PC) ignition systems have recently emerged as an important technological pathway to explore. These systems generate turbulent combustion gas jets capable of accelerating flame propagation in the main chamber. The use of this mechanism enables a more homogeneous and efficient combustion, as well as allowing an increase in the compression ratio, resulting in improvements in engine performance and a reduction in pollutant emissions. One of the strategies to further enhance the benefits of pre-chambers is the introduction of air injectors. The objective of this modification is to promote the cleaning of residual gases that remain in the pre-chamber after combustion, mitigating adverse effects such as mixture dilution and ignition instabilities
Rocha, Hiago Tenório Teixeira Santana, Oliveira, Wender Pereira de, Filho, Fernando Antonio Rodrigues, Baeta, José Guilherme Coelho, Guzzo, Márcio Expedito, Assis, Marcelo Suman Silva, Moreira, Thiago Augusto Araujo
Monte Carlo Methods for Evaluating Flight Performance of Sounding Rockets in the International Rocket Engineering Competition2025-36-010612/18/2025
In the launch of sounding rockets, several factors can affect their performance, including uncertainties in aerodynamic design, environmental conditions at the launch site (e.g., wind and temperature), and propulsion-related aspects like the thrust curve and possible deviations. Given these variables, conducting extensive simulations becomes essential to map their influence on the flight. Monte Carlo simulation is a numerical analysis technique that uses random numbers to solve complex problems involving uncertainties and stochastic variables. In rocketry, this method helps analyze the rocket’s flight behavior while accounting for uncertainties in key inputs. In this context, this study presents the Monte Carlo method for simulating university-level sounding rockets, enabling an assessment of the sensitivity of key parameters. To conduct this analysis, five variables were taken into account, including wind, propulsion uncertainties, aerodynamic coefficient uncertainties, and mass
Oliveira Junior, Wilson Luiz de, Fazzolari, Heloise Assis, Paiva Carvalho, Carlos Alberto de
Lateral Force Analysis of Clamping Devices and Nose Landing Gear in Cornering Conditions2025-99-030612/17/2025
To further investigate the effects of the clamping mechanism’s tilt angle and the nose landing gear’s turning angle on the lateral force of the nose landing gear during turning with a towbarless tractor, as well as the changes in the lateral force difference between the inner and outer hinges, a three-dimensional model of the towbarless tractor and the aircraft was first created using SolidWorks software. The dynamic simulation of the model under different conditions was then conducted using Adams software, followed by the analysis of the simulation results. The results indicate that introducing a positive clamping angle leads to an increase in the clamping mechanism’s tilt angle and a decrease in the nose landing gear’s turning angle as the turning radius and speed increase. Consequently, the lateral force difference between the inner and outer hinges of the nose landing gear increases, ranging from 40 kN to 70 kN. To ensure the stability of the clamping device and reduce the lateral
Gao, Jianshu, Hao, Shiyu, Liu, Ziao
An AI-Powered Wearable Device to Expedite Wound HealingTBMG-5414011/12/2025
Waiting for a wound to heal is incredibly frustrating. First, it must clot; then an immune system response is needed; followed by scabbing and scarring — and that’s not even getting into the pain part.
Model-Based Design and Numerical Analysis of a Downsized Centrifugal Pump for Engine Cooling Applications2025-32-007811/3/2025
The water pump is the crucial component of the engine cooling system. It is usually designed considering as rated conditions the ones evaluated when the engine delivers its maximum power. This results in an overdesign of the pump, considering that almost never the engine delivers the maximum power, in usual operation. At these conditions, in fact, flow rate and pressure delivered reach the maximum values, which are not needed to cool the engine in most probable operating conditions. In fact, considering the real operating conditions during a typical driving mission or a homologation cycle, the mechanical power is far away from the maximum datum, as well as the cooling flow rate and pressure delivered by the pump. To a so unbalanced design for the pump corresponds a low efficiency of it, being the technology oriented to use a centrifugal type, whose efficiency is quite dependent on speed of revolution and flow rate delivered. Hence, modifying the design point of the pump causes a
Di Battista, Davide, Deriszadeh, Ali, Di Prospero, Federico, Di Giovine, Giammarco, Di Bartolomeo, Marco, Fatigati, Fabio, Cipollone, Roberto
Numerical Analysis of Combustion Stability and Efficiency Improvement in Ammonia Engine Utilizing Passive Turbulent Jet Ignition (PTJI)2025-32-004911/3/2025
Ammonia, a carbon-neutral fuel, is a promising candidate for next-generation engine applications. However, its low flame speed (~7cm/s) and prolonged ignition delay (~10ms at stoichiometric conditions) impose significant challenges in achieving stable and efficient combustion across varying operating conditions. At high-speeds, incomplete combustion due to limited residence time reduces efficiency, while at low-speeds, ignition instability and low combustion temperatures hinder reliable operation. To address these challenges, the Passive Turbulent Jet Ignition (PTJI) system has been proposed to enhance turbulence-driven mixing and improve ignition characteristics. This study focuses on optimizing a PTJI system for ammonia-fueled engines using a three-phase methodology. First, the 800cc 2-cylinder gasoline engine was modified for ammonia using numerical analysis, and a baseline analysis of the combustion characteristics was conducted. Next, a turbulent intensity study within the PTJI
Ju, Kangmin, Kang, Hyun-Ung, Kim, Jeong Hyeon
Numerical Analysis of Deformation Adjustment on Wide Subgrade in Permafrost Region by Prefabricated Bridge-Type Pavement2025-99-005710/17/2025
Uneven thawing of frozen soil in the subgrade of wide highway leads to settlement difference of the pavement, which affects the driving comfort. The prefabricated bridge-type pavement mitigates the disease of wide subgrade in permafrost region by applying prefabricated slabs in the subgrade. In order to verify the deformation adjustment effect on wide subgrade of prefabricated bridge-type pavement, earth-filled pavement and prefabricated bridge-type pavement numerical models were established and subgrade mechanical behaviors were analyzed under frozen soil thawing in active layer, frozen soil thawing in localized deteriorated zone and vehicle loading. Comparative analysis of pavement settlement of earth-filled pavement and prefabricated bridge-type pavement under various cases is carried out. The results show that the maximum settlement of prefabricated bridge-type pavement decreases by about 32%~48%, and the settlement difference decreases by about 45%~65%, which has a good adjustment
Yu, Yuanqing, Zhang, Li, Wang, Shan, Cheng, Litao
Dynamic Analysis of Automotive Wheel Bearings2025-01-03669/15/2025
Bearings are essential mechanical components that support external loads and facilitate rotational motion. With the increasing demand for high-performance applications in industries such as semiconductors, aerospace, and robotics, the need for accurate and robust performance evaluation has intensified. Traditionally, bearing performance has been assessed using static or quasi-static theoretical approaches. However, these methods are limited in their ability to capture time-dependent behaviors, which are critical in real-world applications. In this study, a rigid body dynamics analysis was proposed to evaluate the time-dependent behavior of bearings. The methodology was first applied to a deep groove ball bearing, and the results were compared with those obtained from bearing theory to validate the approach. Subsequently, the method was extended to an automotive wheel bearing, and the time-dependent contact angles and ball loads were analyzed under axial and radial loading conditions
Lee, Seungpyo
Numerical Analysis of In-Nozzle Flow of Methanol Injectors for Large Marine Two-Stroke Engines2025-24-00699/7/2025
A statistical method for analyzing momentum deflection angles of fuel injectors based on Computational Fluid Dynamics (CFD) simulation of the internal nozzle flow is proposed. This method is especially relevant for large marine two stroke engines where the spray is often deflected due to an eccentric and asymmetric design of the internal injector geometry. Unsteady Reynolds-Averaged Navier-Stokes (URANS) CFD simulations are employed to analyze the internal flow of different cavitating injectors which have four and five nozzle holes, respectively, for a 50 cm bore and a 95 cm bore dual-fuel engine operating on methanol. The in-nozzle flow dynamics vary from one to another significantly. The use of the statistical analysis on the distribution of deflection angles at the fuel nozzle hole exit further assists at explaining differences in measured surface temperatures of the exhaust valve bottom and piston bowl. The corrected spray angles obtained from these in-nozzle simulations also serve
Quist, Nicolai Arent, Matlok, Simon, Pang, Kar Mun, Norman, Thomas Schaldemose, Mayer, Stefan, Walther, Jens Honoré
Numerical Analysis of the Combustion Process in a Hydrogen-Fueled Pre-Chamber Combustion Engine2025-24-00129/7/2025
Direct injection hydrogen internal combustion engine (ICE) has emerged as a promising alternative fuel due to its potential to enable clean and sustainable energy systems. However, the rapid injection of low-density hydrogen leads to strong mixture stratification and strong flame-turbulence-wall interactions. This challenge is exacerbated in the high-performance engine under study operating at a high engine load (indicated mean effective pressure of about 20 bar) and speed (7500 revolutions per minute). Furthermore, to target high efficiencies, restrict abnormal combustion behaviors, and inhibit oxides of nitrogen emissions, a lean-burn combustion strategy with a global equivalence ratio of 0.4 was applied, where diffusive-thermal (DT) instability effects further complicate the flame characteristics. Additionally, to promote engine performance, the pre-chamber (PC) combustion concept was applied, further complicating the turbulent flame dynamics. To address the modeling challenges and
Mortellaro, Fabio Santi, Menaca, Rafael, Liu, Xinlei, Im, Hong G., Tonelli, Roberto, Medda, Massimo
Experimental and Numerical Analysis of Direct Injection Process for Hydrogen-Fuelled Internal Combustion Engines2025-01-03077/2/2025
In the context of the clean transport sector, there has been growing interest in the use of hydrogen in internal combustion engines due to its potential to nearly eliminate all engine-out criteria pollutants, while maintaining high thermal efficiency through the use of a lean combustion process. In direct injection configurations, mixing process is significantly influenced by hydrogen jet dynamics. First, a comprehensive experimental campaign was conducted in a constant volume vessel to assess the performance of a hydrogen injector using the Schlieren technique. The jet behavior was analyzed by varying injector recess, injection pressure, and back pressure. Subsequently, the case study was replicated in a 3D Computational Fluid Dynamics (CFD) environment, addressing the complexities associated with modeling under-expanded jets. The model was first validated against experimental data, both in terms of jet morphology and through three geometric indices. Then, a simplified simulation
Pucillo, Francesco, Piano, Andrea, Millo, Federico, Giordana, Sergio, Rapetto, Nicola, Vargiu, Luca
Numerical Analysis of Direct-Injection and Combustion Inside a H2 Engine2025-01-03017/2/2025
The direct injection of hydrogen (H2) inside internal combustion engines (ICEs) is gaining large research interest over the port-fuel injection strategy, because of several advantages as higher volumetric efficiencies, increased power output and reduced risks of abnormal combustion. However, the required high pressure ratios across the injector nozzle produce moderate-to-high under-expanded jets, characterized by complex flow structures. This poses a challenge for the numerical modelling of the mixture preparation by means of 3D computational fluid dynamics (CFD) approaches. In this work, a validated 3D-CFD methodology has been employed to simulate the closed-valve cycle of a direct injection H2 engine equipped with a centrally mounted hollow-cone injector and a non-axisymmetric piston bowl. First, injection and mixture preparation have been studied considering an early injection at the beginning of the compression stroke, and a delayed injection in the second half of the compression
Capecci, Marcolucio, Sforza, Lorenzo, Lucchini, Tommaso, D'Errico, Gianluca, Pezza, Vincenzo, Tosi, Sergio
Analysis of Combustion Characteristics of a Small 2-Stroke Opposed Piston Engine Using an Optically Accessible Engine and Numerical Analysis2025-01-02236/16/2025
As global warming becomes more serious, decarbonization of internal combustion engines, which emit a large amount of carbon dioxide, is being promoted. It is predicted that many vehicles will still be equipped with engines in 2035, and a variety of powertrains will be required in the future. Therefore, we focused on the opposed-piston engine as an internal combustion engine specialized for power generation applications. The opposed-piston engine is characterized by its light weight due to the absence of a cylinder head, low S/V ratio due to the ultra-long stroke, reduced cooling loss due to the long stroke, and reduced vibration due to the offsetting of the reciprocating inertial forces of the left and right pistons. We believe that the engine for power generation can achieve the required high efficiency operation and vibration reduction. Therefore, in this study, combustion analysis of a two-stroke opposed-piston engine with features of low vibration, high efficiency, and high output
Yamazaki, Yoshiaki, Watanabe, Sou, Okawara, Ikumi, Otaki, Yusuke, Liu, Jinru, Iijima, Akira
Life Cycle Assessment of Hydrogen Generation through Steam Methane Reforming: A Focus on Co-Product Allocation between Steam and Electricity2025-01-01816/16/2025
This research presents a numerical analysis of the environmental impacts associated with using hot steam as a co-product in hydrogen production through Steam Methane Reforming (SMR) of renewable gas sources. As hydrogen production technology advances rapidly, reducing emissions and addressing environmental concerns, particularly greenhouse gas (GHG) emissions, have become essential. This study examines the SMR process with a focus on the environmental effects of utilizing hot steam as a co-product for electricity generation or facility heating. The analysis evaluates renewable feedstocks, including landfill gas, animal waste, food waste, and wastewater sludge, to determine their viability for sustainable hydrogen production. Key pollutants, such as carbon monoxide and nitrogen oxides, along with GHGs, are assessed to identify the most environmentally advantageous feedstock options. This work aims to provide insights to promote sustainable hydrogen production practices.
Rosyadi, Ahmad Adib, Lim, Ocktaeck
Numerical Analysis of Variable Cross Section Weather-Strip Contact Sealing Performance & Stick Slip Behavioral Study2025-01-01355/5/2025
This study focuses on the numerical analysis of weather-strip contact sealing performance with a variable cross-sectional design, addressing both static and dynamic behaviors, including the critical issue of stick-slip phenomena. By employing finite element modeling (FEM), the research simulates contact pressures and deformations under varying compression loads, DCE (Door Closing Efforts) requirements, typical in automotive applications. The analysis evaluates how changes in the cross-sectional shape of the weather-strip affect its ability to maintain a consistent sealing performance, especially under dynamic vehicle operations. The study also delves into stick-slip behavior, a known cause of noise and vibration issues, particularly improper/ loosened door-seal contact during dynamic driving condition. This study identifies key parameters influencing stick-slip events, such as friction coefficients, material stiffness, surface interactions, sliding velocity, wet/dry condition
Ganesan, Karthikeyan, Seok, Sang Ho, Sun, Hyang Sun
Transient Failure Analysis of Alloy Steel Welded Joints under Sudden Tension Load Condition05-18-03-00254/21/2025
The study aims to evaluate the transient failure behavior of welding joints that are exposed to sudden tensile loading. The Mohr–Coulomb criterion’s fundamental theories are examined and evaluated. The failure function of Mohr’s envelope is first expanded into a polynomial in terms of the stress components (σp , τxy ) on the failure region up to the third order. Using ANSYS software, the transient failure response of welding joints was simulated. The Runge–Kutta fourth-order computational technique was employed to perform numerical analysis on transient failure response. Python software is used to develop a computer code for the time-dependent failure response of welding joints. The welded joint specimen is tested with the help of a UTM machine. The analytical results are compared with experimental results. A fractography study was carried out on the welded joint of the failure surface. In this context, the main focus is on SEM and EDS methods to determine the exact type of failure
Chavan, Shivaji, Raut, D. N.
Numerical Studies on the Relation between the Multiple Auto-Ignition and Pressure Wave in the Premixed Charge2024-32-00794/18/2025
The relation between the multiple auto-ignition in the premixed charge with fuel concentration distribution and associated pressure wave are numerically investigated. This study assumes that the auto-ignition phenomenon in the end-gas of PCCI combustion, a next-generation combustion method which is expected to achieve both low fuel consumption and low emissions at a high level. Detailed numerical analysis considering the elementary chemical reactions of the compressible reacting fluid flow described in the one-dimensional coordinate system with high spatial and time resolution was performed to clarify the detailed phenomena of the onset of the multiple auto-ignition and the pressure wave propagation in the gas.
Iizumi, Kota, Yoshida, Kenji
Enhancements in Hydrogen Low Pressure Injection on Small Two-Stroke Engines2024-32-00474/18/2025
The use of small 2-stroke crankcase scavenged engines running on hydrogen is very attractive for low power rates, when low cost and compact dimensions are the fundamental design constraints. However, achieving optimal performance with hydrogen fuel presents challenges, including uneven air-fuel mixtures, fuel losses, and crankcase backfiring. This research focuses on a small 50cc 2-stroke loop-scavenged engine equipped with a patented Low-Pressure Direct Injection (LPDI) system, modified for hydrogen use. Experimental results demonstrate performance comparable to the gasoline counterpart, but further optimizations are needed. Consequently, CFD-3D simulations are employed to analyses the injection process and guide engine development. The numerical analysis focuses on a fixed operating condition: 6000 rpm, Wide Open Throttle (WOT), with a slightly lean mixture and injection pressure fixed at 5 bar. A numerical model of the entire engine is set up with the primary objective of improving
Caprioli, Stefano, Schoegl, Oliver, Oswald, Roland, Kirchberger, Roland, Mattarelli, Enrico, Rinaldini, Carlo Alberto
Numerical Investigation of Gas Diffusion Layer Properties in PEMFC2025-01-83144/1/2025
This study numerically analyzed the gas diffusion layer (GDL) in proton exchange membrane fuel cells (PEMFCs). The GDL, composed of carbon fibers and binder, plays a critical role in facilitating electron, heat, gas, and water transport while cushioning under cell compression. Its microstructure significantly influences these properties, requiring precise design. Using simulations, this study explored GDL designs by varying fiber and binder parameters and calculated gas diffusivity under wet conditions. Unlike previous studies, a novel model treated carbon fibers as beam elements with elastic binder connections, closely replicating structural changes under compression. Key properties analyzed include permeability, electrical conductivity, and gas diffusion efficiency under wet conditions. The optimized designs enhanced these properties while balancing trade-offs between electrical conductivity and mass transport. These findings provide valuable guidelines for advancing PEMFC technology
Ota, Yuki, Dobashi, Toshiyuki, Nomura, Kumiko, Hattori, Takuya, Maekawa, Ryosuke
Numerical Analysis of Capillary Performance of Various Lattice Structures for Vapor Chamber Application2025-28-00622/7/2025
Additive manufacturing has made it possible for the design of increasingly complex structures that require precise manufacturing. This may be particularly beneficial for heat pipe and vapor chamber design – particularly for the wick structure, a very important component. This study uses numerical simulation to analyze three different types of lattice structures of increasing complexity, in terms of their capillary performance. This is one of the most important parameters which determine the wick efficacy. Simple cubic, Column and Octet lattice models are computationally designed and CFD is used to simulate capillary action in a pipe of 0.4 mm inner radius for 2 milliseconds, after validation of the numerical model with existing experimental results. It is found that the Octet lattice (with the most complex inner structure) has the greatest capillary rise in the same amount of time. The rate of rise is not uniform for any structure, but is highest for Octet. This study demonstrates the
Sundararaj, Senthilkumar, Hudge, Ajay, Basuroy, Suhashini, Kang, Shung-Wen
Enhancing Thermal Performance of Trapezoidal Porous Medium Solar Ponds Experimental and Numerical Analysis2025-28-02072/7/2025
This research investigates the potential of salt gradient solar ponds (SGSPs) as a sustainable and effective solution for thermal energy storage. The study examines the design, construction, and performance of SGSP systems that incorporate coal cinder, comparing their performance with traditional SGSPs without coal cinder. A combination of experimental and numerical approaches is used to evaluate the thermal characteristics and energy efficiency of these systems. The findings indicate that the salt gradient solar pond with coal cinder (SGSP-CC) achieves notably higher temperatures across the Upper Convective Zone (UCZ), Non-Convective Zone (NCZ), and Lower Convective Zone (LCZ), with measured temperatures of 42.57°C, 56.8°C, and 69.86°C, respectively. These represent increases of 7.53%, 12.01%, and 15.49% over those in the conventional SGSP (SGSP-C). Additionally, the energy efficiency gains in the UCZ, NCZ, and LCZ for the SGSP-CC are noteworthy, with increases of 38.06%, 39.61%, and
J, Vinoth Kumar
Forced Vibration Analysis of Cracked Functionally Graded Beams2025-28-01692/7/2025
This study investigates the forced vibration characteristics of a functionally graded material (FGM) beam possessing a square cross-section and featuring a V-shaped crack. The FGM beam exhibits a gradual transition in mechanical composition from a ceramic to a metallic surface. Employing finite element analysis software, a comprehensive numerical analysis is conducted to evaluate the frequencies and mode shapes of the cracked FGM beam under simply supported boundary conditions. The study meticulously explores the effects of various crack parameters, including crack opening width, depth, and location. The findings highlight the significant influence of the crack opening width on the frequencies, indicating that wider cracks result in decreased frequencies across all mode shapes. Conversely, the impact of crack depth and location on the dynamic behavior of the cracked FGM beam within the studied ranges appears relatively minor. These insights offer valuable perspectives into the
D, Manish, C V, Prasshanth, N, Suhas, Bhaskara Rao, Lokavarapu
Research on the Optimization of Metal Bipolar Plate Welding Process Based on Box-Behnken Design-Response Surface Method2025-01-70811/31/2025
Metal bipolar plates are important components of fuel cells, playing a role in conducting electricity, gas, and heat during the operation of fuel cells. The sealing and joint quality of the bipolar plates have a significant impact on the performance and service life of fuel cell stacks. In actual production, laser technology is often used for welding bipolar plates, and the welding quality is ensured by laser process parameters when using the same equipment. Therefore, in order to further optimize the laser welding process of metal bipolar plates, this paper selects three laser parameters for single-factor analysis to evaluate the impact of each parameter on laser welding quality. The Box-Behnken design-response surface method is used for multi-factor analysis, with process parameters as inputs and weld quality parameters as outputs, to assess the sensitivity of each laser process parameter to laser welding quality, and to fit a nonlinear function. Based on the results, the optimal
Li, Wei, Chang, Guofeng, Xu, Huasheng, Huang, Ziheng
Numerical and Experimental Analysis of Tip Clearance Effect of Low-Speed Axial Flow Fan2024-01-600912/20/2024
The objective of the present study is to identify suitable tip clearances and volumetric flow rates for low-speed axial flow fans. The numerical analysis for this study is carried out using the Reynolds-averaged Navier–Stokes equation with the k-omega SST turbulence model to perform steady-state simulations. The results demonstrate that optimum performance is achieved with a tip clearance of 1 mm and a maximum volumetric flow rate of 10.74 m3/s. The novelty of this proposed work lies in enhancing the efficiency of axial flow fans with a circular arc cambered airfoil by using optimal tip clearance and volumetric flow rates through steady-state simulations. This method can be applied in the turbo machinery field and all types of jet engines to improve the performance of domestic and international flights, meeting future demands and expectations.
Vala, Jignesh R., Patel, D. K., Darji, Anand P., Balaji, K.
Stress Field near Crack Tips in Pressurized Thick-Walled Cylinders with Single and Multiple Cracks in Linear Elastic Fracture Mechanics: Analytical and Numerical Analysis of Stress Field and Crack Behavior05-18-01-000410/4/2024
Arrays of radial cracks often appear at the bore of pressurized cylinders, posing potential safety risks and leading to possible structural failures. This article presents an analytical approach to evaluate the stress field arising from single or multiple uniform radial cracks in thick-walled pressurized cylinders within the context of linear elastic fracture mechanics (LEFM) under mode-I loading. This formulation is based on the fundamental equations of elasticity and approximations of stress intensity factors (SIF) reported in the literature. Hence, the SIF were revisited and their range of validity was highlighted. The study considers two types of internal pressure loading: one applied only to the cylinder’s inner surface with no pressure on the crack faces and another applied to both the inner surface and the crack faces. The influence of the number and length of cracks relative to cylinder thickness on the stress field is analyzed. A finite element model of the pressurized vessel
Methia, Mounir, Benslimane, Abdelhakim, Bechir, Hocine, Aït Hocine, Nourredine
Preliminary Analysis of the Energy Performance of a Mild Hybrid Vehicle with Focus on e-Motor Dynamic Modeling2024-24-00129/18/2024
Nowadays, the increase in the global population and the rise in living standards lead to a growing number of cars on the roads, resulting in an increase in emissions. It becomes crucial for society to make efforts to modernize the entire vehicle fleet to emission standards adequate for combating climate change, accelerating the natural turnover of older vehicles whenever possible. For this reason, the following study delves into the category of mild hybrid electric vehicles, which can be easily obtained through retrofitting practices from existing vehicles, thus enabling the enhancement of a large number of cars using minimal materials and requiring minimal time. The present paper focuses on the performance of the traction electric machine, whose dynamic model - based on the equivalent circuit model of a surface synchronous permanent magnet electric motor - is shown to allow for an accurate representation of instantaneous power and efficiency during its operation. Still, this motor
Federici, Leonardo, Lombardi, Simone, Tribioli, Laura, Bella, Gino
Numerical Analysis of the Expansion–Deflection Dual-Bell Nozzle Performance2024-01-60038/23/2024
The objective of this paper is to identify the optimum supersonic Mach number for expansion–deflection dual-bell nozzle. The numerical analysis is carried for expansion–deflection dual-bell nozzle (EDDBN) with different free stream conditions. Numerical study observes that the transition pressure ratio and Mach contours are studied through inside and outside of the nozzle. The results proved that increasing the Mach number leads to decrease in the static pressure as well as reduce the performance of EDDBN nozzle. The analysis was carried out for four different Mach number, out of which Mach number 1.2 provides the optimum results. In the present study, the influence of Mach number behavior affects the pressure and Mach configuration inside and outside of the EDDBN nozzle. This novel concept is used in supersonic vehicles for higher performances. Also, it provides a way to improve the existing nozzle design configuration.
Balaji, K., Kalekar, Yashdeep, Naik, Atharva, Walave, Gurudas, Charapalle, Samruddhi
A Transient Numerical Analysis of a Dissipative Expansion Chamber Muffler2024-01-29356/12/2024
Expansion chamber mufflers are commonly applied to reduce noise in heating, ventilation, and air-conditioning (HVAC) or exhaust systems. In dissipative mufflers, sound-absorptive materials, such as microperforated plates (MPP), are applied to achieve an enhanced and more broadband mitigation effect. Computational acoustics (CA) analyses of mufflers are usually carried out in the frequency domain, assuming time-harmonic excitation. However, certain applications require time-domain simulations. From a computational point of view, such transient analyses are more challenging. A transformation of the governing equations involving frequency-dependent material parameters into the time domain induces convolution integrals. We apply the recently proposed finite element (FE) formulation of a time-domain equivalent fluid (TDEF) model to simulate the transient response of dissipative acoustic media to arbitrary unsteady excitation. Like most time-domain approaches, the formulation relies on
Maurerlehner, Paul, Mayrhofer, Dominik, Mehrgou, Mehdi, Kaltenbacher, Manfred, Schoder, Stefan
SAE TOMORROW TODAY: Unsupervised Learning Makes Scalable Autonomy a Reality134596/12/2024
Artificial intelligence that teaches itself? That's the gist of unsupervised learning. And it offers far-reaching implications for the future autonomous driving--and much more. As a pioneer in unsupervised learning, Helm.ai employs an AI-first approach to building autonomous driving software using an in-house unsupervised learning technology called Deep Teaching which leverages insights from applied mathematics and compressive sensing. Deep Teaching enables Helm.ai to train on vast volumes of data more efficiently without the need for large scale fleets or human annotation, moving the world closer to fully autonomous self-driving systems. The company licenses their software to automakers for high-end ADAS L2+/L3 products and uses the same scalable AI approach for L2/L3 ADAS through L4. To learn more about this exciting breakthrough, we sat down with Vlad Voroninski, CEO & Co-Founder of Helm.ai, to discuss unsupervised learning, Deep Teaching, and the future of autonomous driving.
Hineman, Marcie
Numerical Investigation of the Aerodynamic Characteristics of a Missile Geometry at Mach 42024-26-04436/1/2024
The aim of this paper is to present a numerical analysis of high-speed flows over a missile geometry. The N1G missile has been selected for our study, which is subjected to a high-speed flow at Mach 4 over a range of Angle of attack (AoA) from 0° to 6°. The analysis has been conducted for a 3-dimensional missile model using ANSYS environment. The study contemplates to provide new insights into the missile aerodynamic performance which includes the coefficient of lift (CL), coefficient of drag (CD) and coefficient of moment (CM) using computational fluid dynamics (CFD). As there is a lack of availability of data for missile geometries, such as free stream conditions and/or the experimental data for a given Mach number, this paper intends to provide a detailed analysis at Mach 4. As the technology is advancing, there is a need for high-speed weapons (missiles) with a good aerodynamic performance, which intern will benefit in reduction of fuel consumption. In order to meet the
Padmanabha, M Ananth, Prasad, Bhoomika, Sivasubramanian, Jayahar
Analysis for Effect of Angle of Attack on Coefficient of Lift of Wing Structure2024-26-04506/1/2024
Dimensional optimization has always been a time-consuming process, especially for aerodynamic bodies, requiring much tuning of dimensions and testing for each sample. Aerodynamic auxiliaries, especially wings, are design dependent on the primary model attached, as they influence the amount of lift or reduction in drag which is beneficial to the model. This study aims to reduce the time period taken to finalize the design parameter for the same. For a wing, the angle of attack is essential in creating proper splits to incoming winds, even under high velocities with larger distances from the separation point. In the case of a group of wings, each wing is then mentioned as a wing element, and each wing is strategically positioned behind the previous wing in terms of its vertical height and its self-angle of attack to create maximum lift. At the same time, its drag remains variable to its shape ultimately maximizing the CL/CD ratio. A high value of CL indicates a significant component of
Hujare, Pravin P, Hujare, Deepak P, Choudhary, Prateek, Sakat, Abhishek, Karanjkar, Rushil
Output-Based Approach for Tiltrotor Whirl Flutter Bifurcation AnalysisF-0080-2024-10775/7/2024
ABSTRACT This paper investigates an output-based approach for tiltrotor whirl flutter bifurcation analysis. The approach uses free decay output data for a quantity of interest at various forward speeds to estimate the system's recovery rate to equilibrium while capturing its variation with amplitude. The recovery rate is then extrapolated to predict the bifurcation diagram, which gives the limit-cycle oscillation amplitude for the quantity of interest as a function of the forward speed. The approach is demonstrated using output data from transient simulations of a notional tiltrotor model with polynomial structural nonlinearities. The approach accurately predicts the tiltrotor whirl flutter speed and limitcycle oscillation amplitudes while only requiring two free decays. This approach can facilitate whirl flutter bifurcation analyses of tiltrotor systems exhibiting nonlinear dynamics.
Gali, Sai Vishal, Riso, Cristina
Numerical Analysis for Active Noise Control of Rotor based on Dynamic Variable-diameter MethodF-0080-2024-12595/7/2024
ABSTRACT Helicopters in high-speed forward flight often generate High-Speed Impulse (HSI) noise, presenting a major challenge for noise control and narrowing the range of helicopter use. This paper proposes a novel method for active noise reduction by adjusting the rotor diameter length, effectively delaying HSI noise onset and reducing HSI noise impact. Utilizing the CLORNS solver and the Ffowcs Williams-Hawkings (FW-H) equation, this approach was tested on the AH-1G rotor through simulation analysis. The study simulated the rotor's dynamic diameter length changes, analyzing the effect of crucial parameters on the sound field. Results indicate that this method significantly controls the production of rotor high-speed pulse noise, achieving a noise reduction of up to 2dB at critical operational points. This research aids in formulating specific rotor noise control laws and expands the range of scenarios for helicopter usage.
Ding, Yan, Zhao, Guoqing, Wang, Bo, Zhao, Qijun, Chen, Xi
Extension of the Analytic Vortex Ring State Model for eVTOL ApplicationF-0080-2024-10835/7/2024
ABSTRACT The engineering model determining the onset of Vortex Ring State (VRS) was applied to eVTOL aircraft, and the effect of different landing trajectories and aircraft drag was investigated. Next, the new model to compare the VRS susceptibility according to the different blade geometries and trajectories is proposed by extending Ahlin & Brown's model to incorporate the two-dimensional thrust and inflow distribution on the rotor disc. For validation, two different trajectories crossing the boundary of the onset of the VRS were simulated, and the results were compared with the Vorticity Transport Method (VTM). Furthermore, the disturbance distribution of moderately and highly twisted blades are compared. The extended model can capture the physical phenomena by the distribution of the disturbances and reflect the effect of blade geometries and trajectories. It is essential to investigate the model further through a correlation analysis using experiments or numerical analysis.
Hong, Yoonpyo, Jeong, Taemin, Yee, Kwanjung
Sliding-Window Matrix Pencil Method for Whirl Flutter Bifurcation AnalysisF-0080-2024-12715/7/2024
ABSTRACT This paper investigates a sliding-window matrix pencil method for predicting flutter points and limit-cycle oscillation amplitudes of nonlinear aeroelastic systems that experience whirl flutter. The approach applies the matrix pencil method to a short time window that slides along the free decay of a quantity of interest, quantifying the variation in the system's recovery rate to equilibrium with amplitude. The recovery rates at each amplitude and various forward speeds are extrapolated to predict the critical forward speed of zero recovery rate at those amplitudes. This process yields a set of limit-cycle oscillation solutions that can be visualized as a bifurcation diagram. The approach is demonstrated using output data from transient simulations of a propeller-nacelle test case with hardening structural nonlinearities. The impact of each parameter in the sliding-window matrix pencil method is first characterized via sensitivity analyses. Next, the bifurcation diagram is
Warren, Theodore, Riso, Cristina
A Novel Approach for Mechanical Characterization of Angle-Ply Composite Laminates2024-01-24354/9/2024
Composites made of continuous fibers generally have higher strength-to-weight ratios in fiber directions as compared to those made of discontinuous fibers. However, the latter tend to display quasi-isotropic properties which can be of advantage when directions of mechanical loading can vary. For many real-world applications such as robust design of vehicle body components for crashworthiness, impact loads are stochastic in nature both in terms of magnitude and direction. Hence, in order to realize the true potential of laminated composites with continuous fibers, instead of orthotropic laminates which are most common due to the ease of design and manufacturing, angle-ply laminates are necessary. The latter category of laminates introduce a high degree of flexibility in design options but are also simultaneously challenging in terms of mechanical characterization due to the presence of a larger number of material parameters, as compared to orthotropic laminates, with coupled normal and
Tanaya, Sushree, Deb, Anindya
Numerical Analysis of Mixing of Bio-Hybrid Fuels in a Direct Injection Engine with a Pre-Chamber Ignition System2024-01-26194/9/2024
Numerical analyses of the liquid fuel injection and subsequent fuel-air mixing for a high-tumble direct injection engine with an active pre-chamber ignition system at operation conditions of 2000 RPM are presented. The Navier-Stokes equations for compressible in-cylinder flow are solved numerically using a hierarchical Cartesian mesh based finite-volume method. To determine the fuel vapor before ignition large-eddy flow simulations are two-way coupled with the spray droplets in a Lagrangian Particle Tracking (LPT) formulation. The combined hierarchical Cartesian mesh ensures efficient usage of high performance computing systems through solution adaptive refinement and dynamic load balancing. Computational meshes with approximately 170 million cells and 1.0 million spray parcels are used for the simulations. The influence of a lateral ethanol injection on the tumble flow motion and the entrainment into the pre-chamber is analyzed for stoichiometric and lean fuel conditions for an early
Wegmann, Tim, Meinke, Matthias, Fleischmann, Maximilian, Pischinger, Stefan, Schröder, Wolfgang
Detecting the Anomalies in LiDAR Pointcloud2024-01-20454/9/2024
LiDAR sensors play an important role in the perception stack of modern autonomous driving systems. Adverse weather conditions such as rain, fog and dust, as well as some (occasional) LiDAR hardware fault may cause the LiDAR to produce pointcloud with abnormal patterns such as scattered noise points and uncommon intensity values. In this paper, we propose a novel approach to detect whether a LiDAR is generating anomalous pointcloud by analyzing the pointcloud characteristics. Specifically, we develop a pointcloud quality metric based on the LiDAR points’ spatial and intensity distribution to characterize the noise level of the pointcloud, which relies on pure mathematical analysis and does not require any labeling or training as learning-based methods do. Therefore, the method is scalable and can be quickly deployed either online to improve the autonomy safety by monitoring anomalies in the LiDAR data or offline to perform in-depth study of the LiDAR behavior over large amount of data
Zhang, Chiyu, Han, Ji, Zou, Yao, Dong, Kexin, Li, Yujia, Ding, Junchun, Han, Xiaoling
A Numerical Analysis of Terrain and Vehicle Characteristics in Off-Road Conditions through Semi-Empirical Tire Contact Modelling2024-01-22974/9/2024
In the last decades, the locomotion of wheeled and tracked vehicles on soft soils has been widely investigated due to the large interest in planetary, agricultural, and military applications. The development of a tire-soft soil contact model which accurately represents the micro and macro-scale interactions plays a crucial role for the performance assessment in off-road conditions since vehicle traction and handling are strongly influenced by the soil characteristics. In this framework, the analysis of realistic operative conditions turns out to be a challenging research target. In this research work, a semi-empirical model describing the interaction between a tire and homogeneous and fine-grained soils is developed in Matlab/Simulink. The stress distribution and the resulting forces at the contact patch are based on well-known terramechanics theories, such as pressure-sinkage Bekker’s approach and Mohr-Coulomb’s failure criterion. The force exerted by the soil on the sidewall of the
Zerbato, Luca, Vella, Angelo Domenico, Galvagno, Enrico, Vigliani, Alessandro, Data, Silvio, Sacchi, Matteo Eugenio
Numerical Analysis of Different Hydrogen Injector Characteristics in a Constant Volume Chamber2024-01-26934/9/2024
Hydrogen is anticipated to play a pivotal role as a green energy carrier in both heavy industry and transportation. Utilizing hydrogen directly in internal combustion engines (ICE) could offer several advantages compared to alternative technologies. To achieve this objective, a proper understanding of the physical mechanisms and dynamics involved in the injection of this fuel is needed. This study applied high-fidelity computational fluid dynamics (CFD) simulations to describe the flow characteristics of hydrogen injection using hollow- and single- and multi-solid-cone injectors and their effect on mixing quality and characteristics in a constant volume quiescent environment. A reference hollow-cone configuration was used to validate the model. The results indicate that solid-cone configurations achieve greater penetration due to the flow patterns they generate. However, an increase in the number of holes leads to reduced penetration length, projected area, and induced turbulence
Moreno Cabezas, Kevin, Zaihi, Abdullah, Liu, Xinlei, Aljohani, Bassam, Wu, Hao, Ben Houidi, Moez, Roberts, William L., Im, Hong G.
Numerical Analysis of Different Injectors for Kerosene/Hydrogen-Peroxide and Ethanol Amine/Hydrogen-Peroxide for Satellite Thruster2023-01-51802/23/2024
In a satellite thruster the function of injector plays a major role in controlling the combustion. This paper presents the numerical simulation of two most used injectors namely, impinging doublet, and triplet using Ansys fluent. The injectors are designed for the non-toxic, green propellants used in satellite thrusters. The present study focuses on the design and simulation of the injectors with 2 variant of green propellants i.e., Kerosene/Hydrogen-peroxide and Ethanol Amine/Hydrogen-peroxide. The objective of the study is to investigate the performance of the two injectors in terms of atomization, combustion efficiency and thrust generation. Theoretical design calculations were performed for a 20 N bi-propellant satellite thruster. A comparative study on the condensed combustion products and injector was carried out using NASA CEA Run code and Ansys fluent, respectively. The ethanol amine/hydrogen-peroxide injector showed better performance in terms of combustion efficiency. The
Chidvilas, N.V., Suraj, V., Balaji, Kota, G., Dinesh Kumar
Design and Numerical Analysis of Double-Base Swirl Injector for Ethanol/Hydrogen-Peroxide Based Liquid Propellant Rocket Engine2023-01-51002/23/2024
This paper presents a study of numerical cold flow analysis of double-base swirl injector design using Ansys Fluent. The study focuses on the design validation and development of double-base liquid-liquid swirl injector for Ethanol(Fuel) and Hydrogen Peroxide(Oxidizer) based liquid propellant rocket engine. The green propellant contains 80% Ethanol (C2H5OH) as fuel and 60% Hydrogen Peroxide (H2O2) as oxidizer. A comprehensive data, obtained from NASA CEARun code, of performance parameters and carbon monoxide and carbon dioxide emission of most commonly used propellant is compared with ethanol and hydrogen-peroxide based propellant is presented for reference. Secondly, the paper presents the theoretical design model of Swirl Injector, and numerical cold flow study of swirl injector model. For this the 3D models of fuel and oxidizer swirl nozzles are designed separately as per the theoretical design parameters. Poly-hexacore type fluent meshing is used to generate valid mesh. A 3-D
Kumar, G. Dinesh, Agarwal, Abishek Garg
Exploring the Mechanical and Morphological Characteristics of Hybrid-Reinforced Polymer Composites2023-01-51812/23/2024
This study focuses on the development of a hybrid composite, incorporating natural fibers—specifically, banana and flax fibers—within a polyester resin matrix. Different volume ratios of banana and flax fibers were systematically employed to create the composite, with a particular emphasis on achieving optimal fabrication processes through compression molding. The mechanical properties of the resulting hybrid composite were comprehensively assessed through tensile, impact, and flexural testing using a Universal Testing Machine (UTM). Morphological analysis, facilitated by a Scanning Electron Microscope (SEM), provided insights into the internal structure of the composite. Additionally, numerical analysis utilizing ANSYS software was employed to further understand the composite's behavior. The findings unveiled that the hybrid composite demonstrated superior strength compared to single-fiber composites. This research contributes to advancing our understanding of hybrid composites
Velmurugan, Santhosh, Janakiraman, Thiagarajan, Nandhini, S., Ganesha Rathinam, M.
Thermal Management of an Automotive Headlamp2024-26-02861/16/2024
These days, the use of virtual simulations through the Computational Fluid Dynamics (CFD) methodology is increasing exponentially during the development phase of an automotive headlamp. Thereupon, the automotive industries are becoming competent enough to build an ingenious and creative design with optimal performance within the coherent time. A considerable amount of heat is generated inside the headlamp when it is switched on for a longer time. Hence it becomes vital to reduce the risks if any during the development phase by providing an adequate thermal management strategy within the headlamp. The present study conducted an experimental analysis on an automotive headlamp to decide its thermal characteristics and behavior. Numerical analysis was also performed to determine the airflow and temperature distributions within a headlamp. This study also focuses on finding the main hotspot regions over the headlamp through virtual simulations. The methodology shows a consensus with the
Kolhe, Shailesh Madhukar
A Combined Experimental and Numerical Analysis on the Aerodynamics of a Carbon-Ceramic Brake Disc15-17-02-00091/4/2024
Composite ceramic brake discs are made of ceramic material reinforced with carbon fibers and offer exceptional advantages that translate directly into higher vehicle performance. In the case of an electric vehicle, it could increase the range of the vehicle, and in the case of conventional internal combustion engine vehicles, it means lower fuel consumption (and consequently lower CO2 emissions). These discs are typically characterized by complex internal geometries, further complicated by the presence of drilling holes on both friction surfaces. To estimate the aerothermal performance of these discs, and for the thermal management of the vehicle, a reliable model for predicting the air flowing across the disc channels is needed. In this study, a real carbon-ceramic brake disc with drilling holes was investigated in a dedicated test rig simulating the wheel corner flow conditions experimentally using the particle image velocimetry technique and numerically. The simulation was performed
Rouina, Samaneh, Barigozzi, Giovanna, Abdeh, Hamed, Palomino Solis, Daniel A., Iavarone, Paolo
Numerical Analysis and Optimization of Heat Transfer for FSAE Radiator for Various Sidepod Designs2023-28-005511/10/2023
Heat transfer optimization is a crucial aspect of the design process for Formula Student race cars, particularly for the radiator, usually housed in a side pod. For the car to operate at peak performance, a well-designed radiator-sidepod system is essential such that it can dissipate heat generated by the engine faster, for the car to run in optimal performance. Testing the car physically for various radiator-sidepod design iterations is a very difficult task, also considering the costs to manufacture the radiator-sidepod setup. The objective of this study is to develop a comprehensive methodology for analysing heat transfer through radiator setup using Computational Fluid Dynamics and to validate it through experimental investigations, to enhance performance and efficiency of the radiator setup. It further explains how to find out its heat transfer efficiency, and to choose the right radiator-sidepod setup, giving optimal performance. The flow of coolant inside the radiator, as well
Suresh, Sankar, Sundar, Mahima, Bhaskara Rao, Lokavarapu
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