Browse Topic: Wind tunnel tests

Items (2,261)
Moving ground wind tunnels offer a more accurate test environment for ground vehicle drag coefficient measurement due to their highly realistic representation of the boundary layer phenomenon. However, historically most vehicles have been tested on static ground wind tunnels. As a result, the measured drag coefficient of these vehicles may not be sufficiently realistic for certification purposes. Therefore, it is valuable to build statistical models to estimate moving ground wind tunnel drag coefficient by using information from a static ground wind tunnel and other relevant vehicle characteristics such as presence of aerodynamic devices (spoilers, air dams, etc.). However, to build accurate statistical models, appropriate predictive features must be identified as a first step. In this paper, an aerodynamic feature selection study has been conducted to identify vehicle characteristics that contribute to drag coefficient estimation discrepancies between a static- and a moving ground
Singh, YuvrajJayakumar, AdithyaRizzoni, Giorgio
Open wheel race cars present a challenge to the aerodynamic designer because of the numerous wakes and vortices created by the various body components. The present study follows the development of a high-downforce race car and investigates possible vortex manipulations to increase its aerodynamic efficiency. The tools used for this study involved computational fluid dynamics and small-scale wind tunnel testing. Once the basic geometry of the racecar was finalized, cost effective measures were tested to improve its downforce to drag ratio. As an example, by fine tuning the position of different body components, such as the rear wing location relative to the underfloor diffuser exit, vehicle’s aerodynamic performance can be modified. The results of both the wind tunnel and the computational investigations indicated that such simple modifications can positively improve the race-car downforce to drag ratio. Also, once the baseline vehicle’s geometry was frozen and observing that the
Okpysh, ChristianKatz, JosephShute, Robin
The front wing of a Formula 1 car is one of the most important aerodynamic components in design development. Particularly, as it is the first to interact with the upcoming airflow, the aerodynamic flow structures generated will have a strong interaction with the remainder of the car’s components. In 2026, the Fédération Internationale de l’Automobile will introduce new regulations that incorporate new aerodynamic philosophies for the front wing, including active aerodynamics. This paper presents a design methodology study for the development of a Formula 1 2026 front wing, compliant with Issue 9 of the technical regulations. A computational-based, structured optimisation series was conducted to enhance the aerodynamic performance of a front wing concept with a focus on improving downforce, maximising efficiency, and enhancing trailing flow for the remainder of the car. The final front wing concept at 40%, running at 30 m/s, generated 189 N of downforce and 19 N of drag. Active
Jacoulot, SantiagoSoares, Renan F.Marshall, David W.
In high-end motorsport engineering, aerodynamic devices such as front and rear wings are prone to aeroelastic deformations under certain conditions, which can be exploited for vehicle performance gains. Considering the complex interactions between the aerodynamics and structures, experimental evaluation can prove to be a time-effective approach for design, optimisation, research and development regarding aeroelastic bodies. This study presents the development and experimental validation of a deformation tracking system using depth-sensing LiDAR (Light Detection and Ranging) camera technology. The system is based on the use of reflective markers mounted on a given model of interest; this project, a front wing model with a flexible, 3D printed flap element was used as a benchmark. Surface deformation is captured by post-processing point cloud data to extract three-dimensional displacement vectors. A series of controlled measurement tests were first conducted to assess accuracy and
Altinbas, KoraySoares, Renan F.
As automotive aerodynamic testing facilities evolve to capture more real-world behavior, updating the correlation between old and new technologies is essential. Recently, the three-member consortium of the United States Council for Automotive Research (USCAR) - General Motors, Ford Motor Company, and FCA US LLC - transitioned from full-size static ground plane facilities to 5-belt moving ground plane wind tunnel facilities. The primary objective of this study was to update the correlation data sets to maintain consistent and robust data sharing among companies, which is the cornerstone of USCAR efforts. To achieve this, a set of updated correlation data sets were calculated to replace the original correlation study results from 2008. Additionally, the methodology for applying correlation equations was revised from using averaged wind tunnel data to employing direct wind tunnel-to-wind tunnel correlation equations. In a two-phase correlation effort conducted in 2022 and 2025, the three
Nastov, AlexanderLounsberry, ToddMadin, TrevorLangmeyer, GregoryFadler, GregorySkinner, ShaunHorton, Damien
Flow simulation with conjugate heat transfer, which involves fluid flow, conduction, and radiation within solid components, is a vital capability that enables engineers to design and assess cooling systems for heat-producing parts such as brakes, powertrains, batteries, and power electronics in both gasoline and electric vehicles. In this study, we employ PowerFLOW®, which features a thermal solver capable of simultaneously modeling both fluid and solid domains within a unified framework. The fluid flow is simulated using the Lattice Boltzmann Method (LBM) with VLES turbulence modeling based on the RNG k–ε approach. The solid domain is solved using a finite volume method with second-order accuracy for thermal conduction, combined with surface-to-surface radiation modeling for thermal exchange between surfaces. This integrated approach streamlines the simulation workflow while enabling accurate representation of both conduction and radiation phenomena. We assess the accuracy of the
Mukutmoni, DevadattaShock, RichardLi, HanWanderer, JohnGopalaswamy, NathMiao, Ling
Aerodynamic wind noise is a critical challenge in modern automotive development, particularly with the rise of vehicle electrification and intelligent mobility, where cabin acoustic comfort is a key quality metric. While reliable, traditional methods like wind tunnel experiments and computational fluid dynamics (CFD) simulations are both costly and time-consuming. To address these challenges, we propose a novel Transformer-based framework for rapid and accurate wind noise prediction. Several model improvements, including the physical attention, geometry wave number embedding, hybrid FPS-random downsampling method and frequency separation output heads are properly employed to reduce the GPU memory cost and improve the prediction accuracy. This framework is pre-trained on a large-scale acoustic dataset of nearly 1,000 diverse vehicles generated using Improved Delayed Detached Eddy Simulation (IDDES). From a vehicle's point cloud coordinates, the model directly predicts the surface
Tang, WeishaoLiu, MengxinQin, LingDuan, MenghuaWang, ChengjunZhang, YufeiWang, Qingyang
MSIL (Maruti Suzuki India Limited), India’s leading automotive manufacturer, offers a diverse range of SUVs (Sports Utility Vehicles) in its portfolio. Traditionally, SUVs are associated with an assertive stance and a commanding road presence; however, this bold design language often compromises aerodynamic drag performance. Over the past decade, demand for this segment has surged, while CAFE (Corporate Average Fuel Economy) regulations have become increasingly stringent. To address this growing market need, MSIL conceptualized a new SUV - Victoris - targeted to deliver best-in-class aerodynamic efficiency in MSIL SUV portfolio. This paper details the aerodynamic development process using CFD (Computational Fluid Dynamics) and full-scale WTT (Wind Tunnel Testing). Initially, the aggressive styling of Victoris negatively impacted drag performance. Strategic exterior surface refinements and integration of aero components enabled recovery of aerodynamic efficiency. Key interventions
Dey, SukantaSingh, ShekharKumar, ChandanAlphonse, Felix Regin
Modern aeroacoustic wind tunnels are required to have flat axial static pressure distribution, very low background noise levels, and minimal low-frequency pressure fluctuations. These characteristics enable accurate measurement of aerodynamic forces acting on a vehicle as well as identification of noise sources. The collector of an open-jet or ¾ open-jet wind tunnel plays a critical role in achieving these goals. Collector self-generated noise contributes to the overall background noise level in the test section, and this contribution has become more significant as other noise sources, such as the main fan, have been addressed through improvements to acoustic treatment. Ever-increasing attention to detail is required to manage noise signatures as the overall facility noise floor is lowered. Furthermore, aspects of collector design that may be beneficial to aerodynamics or pressure fluctuation tend to be some of the worst offenders for noise generation. A new collector configuration was
Best, ScottNagle, Paul
A simulation-based aerodynamics model of the Honda Automotive Laboratories of Ohio (HALO) Wind Tunnel, a three-quarter open-jet (ground plane) configuration opened in 2022 for full-scale automotive testing, was initiated to support data fusion for more accurate surrogate models in vehicle engineering programs. The objective was to demonstrate that a matched set of boundary values between the physical wind tunnel and the three-dimensional numerical model yield correct responses for several key flow field quantities, starting with the baseline empty tunnel case: (1) streamwise static pressure distribution, (2) evolution of the free shear layers downstream of the nozzle exit plane, and (3) ground-plane boundary layer development. Pressure-based measurement probes were deployed in these regions using a four-axis overhead traverse to acquire validation data in the large facility, including instrument verification between a 14-hole probe and Pitot-static rake. Detached eddy simulation (DES
Patel, SajanDisotell, KevinEagles, Naethan
Wake effects modify the aerodynamic performance of a road vehicle when driving in traffic. Analysis of wind-tunnel measurements conducted in flows with wake characteristics, using a traffic-wake-simulation system, suggests that conventional uniform-wind performance coefficients can be scaled, using wake-flow-field information, to predict the influence of wake effects. This paper presents a flow-field-averaging method that estimates a dynamic-pressure correction and yaw-angle correction for application to uniform-wind data, to account for changes in performance due to wake effects. This first-order method is shown to provide reasonably-good accuracy when reverse correcting the wind-tunnel wake-effects measurements. Drag-coefficient data for light-duty-vehicle models, which showed wake effects exceeding 20%, were corrected to within 5% of uniform-wind values, while data for heavy-duty-vehicle models, which showed wake effects exceeding 15%, were corrected to within 2% of uniform-wind
McAuliffe, Brian
In this paper, the effects of aerodynamic interactions on the drag of a longitudinally-arranged two-vehicle system are examined by considering the influence of separation distance, cross winds, vehicle size and shape. Testing was undertaken at 30% scale in a large wind tunnel with road-representative freestream turbulence. Separation distances of 0.5, 1.0, and 2.0 vehicle lengths (L) were examined over a range of yaw angles between ±15°. A highlight of the current study is the characterization of platoon drag-reduction benefits for different sizes and shapes of the lead and follower models, by using a DrivAer model and an Aero-SUV model, each with slant-back (Notchback or Fastback) and square-back (Estateback) variants, providing four distinct model pairings. Drag reduction for the lead model appears to be affected mainly by the size of the follower model, while the follower model shows a much greater sensitivity to shape of the lead model. Larger drag reductions were observed at most
McAuliffe, BrianGhorbanishohrat, Faegheh
The difficulties of testing a bluff automotive body of sufficient scale to match the on-road vehicle Reynolds number in a closed wall wind tunnel has led to many approaches being taken to adjust the resulting data for the inherent interference effects. But it has been difficult to experimentally analyze the effects that are occurring on and around the vehicle when these blockage interferences are taking place. The present study is an extension of earlier works by the authors and similarly to those studies uses the computational fluid dynamics analysis of five bodies that generate small wakes to examine the interference phenomena in solid wall wind tunnels. This focuses on the effects on the pressures, and forces experienced by the vehicle model when it is in yawed conditions up to 20 degrees. This is accomplished by executing a series of CFD configurations with varying sized cross sections from approximately 0.4% to 14% blockage enabling an approximation of free air conditions as
Gleason, MarkRiegel, Eugen
This study estimates the impact on driving energy of differences in aerodynamic characteristics for yaw angle from natural wind during North American Highway mode driving. A previous study [1] clarified the potential to estimate the fuel consumption impact of natural wind by integrating the drag coefficient yaw characteristics and yaw angle occurrence probability. The natural wind was measured on a vehicle while driving a representative North American Highway test course [2]. Driving energy is predicted from the obtained yaw probability and the drag coefficient yaw sweep data in a wind tunnel. Measurements were conducted every weekday for 8 hours in 2023, covering 70% of the traffic volume. The validity of the measurement period was evaluated by the deviation from the annual average of wind direction and speed. Since yaw probability varies depending on the road environment, it is necessary to weigh the road environment type probability when calculating the driving energy. The
Onishi, YasuyukiNucera, FortunatoNichols, LarryMetka, Matt
Aerodynamic interactions between two 30%-scale passenger vehicles in close proximity were examined experimentally in a large wind tunnel, with a focus on longitudinal separations up to two vehicle lengths, lateral separations up to one lane width, and combinations thereof. Part 1 of this paper described the longitudinal following (platooning) configurations of these results, while this paper concentrates on adjacent-lane influences and lateral-offset effects when platooning at a single separation distance. Test models were based on the DrivAer and Aero-SUV open-access geometries, each with slant-back (Notchback or Fastback) and square-back (Estateback) variants. This provided four distinct model pairings, not all of which were tested in each positional arrangement. Adjacent-lane results matched the trends from a smaller-scale study in a different wind tunnel using the same geometry pair, with small-but-distinct differences attributed to different blockage ratios in the two wind-tunnel
McAuliffe, BrianGhorbanishohrat, Faegheh
Achieving an optimal balance between simulation accuracy and computational efficiency remains a central challenge in automotive aerodynamics. While the adoption of AI and machine learning (ML) methods in vehicle development is expected to grow significantly, the demand for highly scalable, computationally efficient, and accurate computational fluid dynamics (CFD) methods persists. The emergence of GPU (graphics processing unit) technology presents new opportunities to deliver cost-effective, high-fidelity, scale-resolving simulations to industrial users. A comprehensive evaluation of Simcenter STAR-CCM+’s parallel scalability and accuracy across extensive CPU and GPU resources was executed on the Frontier supercomputer at Oak Ridge National Laboratory (ORNL). Steady-state and transient aerodynamic scalability simulations were executed using the DrivAer notchback vehicle configuration. Simulation accuracy was evaluated through transient simulations employing the SST-DDES turbulence
Larsson, TorbjörnGrover, Ronald O.Landi, SimoneAltmann, PeterMcManus, LiamDowding, Steven
The Stellantis North America Aero-Acoustic Wind Tunnel (AAWT) has been upgraded with a cutting-edge 5-belt Moving Ground Plane (MGP) system, featuring an 8.5-meter center belt and four Wheel Spinning Unit (WSU) belts with advanced coatings for durability and visibility. The expanded 9.4-meter turntable enables ±90° yaw and supports vehicles with wheelbases from 1800 mm to 4500 mm and weights up to 5000 kg, accommodating the full Stellantis North America product range. The original 2-stage boundary layer control system was retained, with new tertiary slots added for improved flow quality. A high-stiffness, six-component Horiba balance with integrated calibration weights and tractive force measurement ensures accurate and precise measurements. Facility enhancements include a 550 m2 building addition for equipment and vehicle prep, a dedicated compressor container for clean air supply, and a vehicle underbody wash booth for efficient cleaning. Commissioning confirmed that flow quality
Lounsberry, ToddLadouceur, BrentFadler, Gregory
When driving in traffic, the wakes of leading vehicles reduce the wind speed experienced by a following vehicle, lowering its drag relative to isolated driving. These wake effects can persist to large inter-vehicle distances, on the order of hundreds of meters, while lateral convection due to cross winds can influence vehicles in adjacent lanes. Wind tunnel testing was conducted at 30% scale for light- and heavy-duty-vehicle models in a large wind tunnel with a traffic-wake simulation system, expanding upon a previous study that examined only heavy vehicles. Three variants of the DrivAer model, four variants of the AeroSUV model, and three variants of a zero-emission heavy-duty-truck model were tested with a range of simulated wake conditions that varied the type, forward distance, and lane position of the wake-source vehicle(s), for a range of yaw angles up to 11°. Results show drag reductions of up to about 10% for the heavy-duty-truck model, and up to about 20% for the passenger
McAuliffe, BrianGhorbanishohrat, FaeghehBarber, Hali
This paper reports on the Catesby Aero Research Facility (CARF), which began commercial operation in 2019, and summarizes facility characteristics and associated measurement technologies, with an emphasis on vehicle-mounted component-force measurement devices. CARF is a proving ground converted from a former railway tunnel approximately 2.74 km in length and surfaced with high-quality tarmac. The road-surface quality was specified to be comparable to that of SUBARU's proving ground and was achieved using established construction methods. The course is approximately straight with a small longitudinal grade. Key course specifications include an approximately 40 m2 blockage area, a 6 m road width (maximum 8.4 m), flatness σ < 0.5 mm, and a gradient of 0.57%. Relative to outdoor coast-down testing, the tunnel length enables continuous measurement to very low speeds, thereby improving repeatability. A six-component force sensor integrated into the hub unit enables on-road measurement of
Shimoyama, Hiroshi
A research team developed a smart strake system that dynamically adapts to flight conditions, showing a promising drag reduction in the wind tunnel with respect to passive strakes. This approach has the potential to save airlines hundreds of kilograms of fuel per flight. University of Washington Department of Aeronautics & Astronautics (A&A), Seattle, WA For decades, aircraft have carried a fundamental compromise between their engines and wing flow interactions by using strakes. These are small fins attached at the sides of engine nacelles that generate helpful vortices during takeoff and landing that boost lift and avoid stall, but create unwanted drag during cruise flight. Now, seven William E. Boeing Department of Aeronautics & Astronautics (A&A) undergraduates have advanced a solution that improves this trade-off, achieving up to 33 percent drag reduction, on the limited tested conditions, during cruise while maintaining critical safety benefits at high angles of attack. The team
The current work analyzes the effect of time-step size on the predictive capability and computational cost of the Sliding Mesh (SM) method for modeling flows around the rotating wheels of a mass-production luxury sport utility vehicle (SUV). Two unsteady turbulence models [Unsteady Reynolds-Averaged Navier–Stokes (URANS) and Delayed Detached Eddy Simulations (DDES)] were tested using time-step sizes ranging from the current recommended time-step size of 1 degree of rotation per time-step (1 D/TS) up to 50 degrees of rotation per time-step (50 D/TS). The flow field predictions compare favorably to the 1 D/TS case for a time-step size as large as 5 D/TS. Using this time-step size leads to a reduction in computational cost of approximately 80% for both unsteady methods. At a time-step of 5 D/TS, the computational cost of the SM method is comparable to the more commonly used Moving Reference Frame (MRF) method. However, drag and flow field predictions by the SM method at this larger time
Struk, MichaelAultman, MatthewDisotell, KevinDuan, LianBianco, AntonelloMetka, MatthewKhasdeo, Nitin
In this experimental work, a detailed analysis of the wind tunnel measurements on scaled motorbike models equipped with different front wings was performed considering four wing configurations operating at different Reynolds numbers and roll angles. Global forces acting on the models were measured by a high-resolution dynamometric balance, while velocity fields in the wake were measured by means of the Particle Image Velocimetry technique. Throughout the paper, overall models’ performances are investigated, demonstrating similar behavior for drag coefficients and various trends for lift coefficients. The without- and single-wing configurations were shown to have positive sign, and conversely, the double- and closed-wing cases—with negative sign—generated downforce due to the presence of significant upward velocities, which in turn modified the wake shape. Furthermore, the improvements in closed-wing configuration compared to without- and single-wing ones were noticeable, while slight
Moscato, GiorgioRomano, Giovanni Paolo
The Dual Throat Nozzle (DTN) is a unique nozzle configuration that enables fluidic thrust vectoring (FTV), improving aircraft maneuverability while reducing the mechanical complexity of traditional vectoring systems. In this study, a two-dimensional DTN was developed based on a validated NASA Langley model, incorporating a newly designed plenum geometry guided by area expansion ratio principles. Numerical simulations were carried out in ANSYS Fluent using a density-based, steady-state solver with the SST k–ω turbulence model to capture key compressible flow features such as shock waves, flow separation, and jet deflection. Secondary injection rates were determined using choked-flow relations, and a 12-case parametric study was conducted to analyze the effects of Nozzle Pressure Ratio (NPR), injection rate, and injection angle on thrust deflection and efficiency. The simulation results at NPR = 4 with 3% injection showed strong agreement with NASA experimental data, validating the
Suresh, VigneshM, AkashSenthilkumar, NikilSundararaj, SenthilkumarA, Garry KiristenSingh, Swaraj
In this study, the combustion and emission characteristics of a single-cylinder direct injection (DI) diesel engine fueled with Spirulina biodiesel along with diesel blends were examined using a combined CFD and thermodynamic simulation framework. Three test fuels, including pure diesel (D100), Spirulina biodiesel blends (B20 and B40), and pure Spirulina biodiesel (B100), were analysed at 1500 rpm under full load. In the first stage, CFD simulations were performed in ANSYS Fluent, where the Discrete Phase Model (DPM) was applied to capture spray atomization and droplet evaporation, while a non-premixed combustion model coupled with the RNG k-ε turbulence model was employed to resolve in-cylinder flow and heat release dynamics. Subsequently, the Diesel-RK software was utilised to predict engine performance and exhaust emissions based on compression ratios (18.5) and injection timings. Results from the CFD analysis revealed faster atomization and reduced ignition delay for biodiesel
Kumar, B Varun
This study presents a structured approach to the aerodynamic evaluation of commercial heavy-duty vehicles by categorizing the underlying flow physics into three primary phenomena: pressure-induced separation, geometry-induced separation, and flow diffusion. Furthermore, the study gives insights into the benefits of Detached Eddy Simulations (DES) over traditional Reynolds-Averaged Navier–Stokes (RANS) approaches by analyzing the flow behavior in cases that correspond to these phenomena. Fundamental insights on pressure and geometry-induced separation were developed through simulations of flow over a sphere and a rectangular cylinder at a Reynolds number of 2.8 × 106. Additionally, flow diffusion was investigated using a coaxial jet interacting with surrounding fluid at a Reynolds number of 2.1 × 104. These cases were analyzed using three turbulence modeling techniques: k-ε, k-ω SST, and DES. To demonstrate the practical relevance of these phenomena, a comprehensive aerodynamic
Sankar, HariHolay, SarangIkeda, MasamiSingh, Ramanand
In the automotive industry, external aerodynamic evaluations in digital environments are commonly conducted using simplified, large box tunnels with vehicle being static. These approaches are computationally efficient and ensure faster turnaround time. To closely replicate physical wind tunnel testing or real-world conditions, these simulations are often augmented with moving ground and rolling tire configurations. While such setups provide valuable directional feedback for aerodynamic drag improvements, they frequently exhibit significant discrepancies when compared to physical wind tunnel test data. It is observed that key factors such as wind tunnel blockage effects, boundary layer suctions, when not properly accounted for, distort the local flow field dynamics and introduce errors in the simulations. With OEMs aiming to accelerate time-to-market for new vehicle launches, many aspire to minimize reliance on physical testing and maximize use of digital methods for design sign-off
Sharma, Sandeep KumarChalipat, SujitMaiyya, Sandeep
The present work demonstrates a transient Fluid-Structure-Interaction (FSI) based numerical methodology for estimation of aerodynamic-induced flutter of the rear bumper of a Sports Utility Vehicle (SUV). Finite Volume Method (FVM) based High-fidelity transient full vehicle aerodynamic simulations were conducted for the estimation of the transient aerodynamic load. Subsequently, by mapping this transient aero load onto the surface of the rear bumper, Finite Element Method (FEM) based dynamic structural simulations were performed to predict its response. The results obtained through simulations were then compared against experimental wind tunnel test data of a prototype car with modified bumper for the specific test-case. The pressure and the time series data of rear bumper deflection were captured at multiple probe locations from wind tunnel experiments at 140 and 200 kmph. The distribution of pressure on the rear surfaces of the car was well captured by the aerodynamic simulation at
Choudhury, SatyajitYenugu, SrinivasaWalia, RajatZander, DanielGullapalli, AtchyutBalan, ArunAstik, Pritesh
The automotive industry is rapidly advancing towards autonomous vehicles, making sensors such as Cameras, LiDAR, and RADAR critical components for ensuring constant information exchange between the vehicle and its surrounding environment. However, these sensors are vulnerable to harsh environmental conditions like rain, dirt, snow, and bird droppings, which can impair their functionality and disrupt accurate vehicle maneuvers. To ensure all sensors operate effectively, dedicated cleaning is implemented, particularly for Level 3 and higher autonomous vehicles. It is important to test sensor cleaning mechanisms across different weather conditions and vehicle operating scenarios to ensure reliability and performance. One crucial aspect of testing is tracking the trajectory of the cleaning fluid to ensure it does not cause self-soiling of vehicles and affects the field of view or visibility zones of other components like the windshield. While wind tunnel tests are valuable, digitalizing
Mane, SuvidyaMakam, Sri Lalith MadhavVarghese, RixsonDesu, Harsha
The present work demonstrates a Fluid-Structure Interaction (FSI) based methodology that couples a Finite Volume Method (FVM) and Finite Element Method (FEM) based tools to estimate air guide deformation, thereby predicting accurate aerothermal performance. The method starts with a digital assembly step where the assembly shape and the induced stress due to assembly is predicted. A full vehicle Aerodynamic simulation is performed to extract the surface pressure on the air guide which is then used to estimate the extent of deformation of the air guides. Based on the extent a subsequent Aerodynamic simulation may be carried out to predict thermal efficiency. Comparison against pressure data and deflection data extracted from the wind tunnel experiments of vehicles has shown reasonable match demonstrating the accuracy and usefulness of the method.
Gadasu, RavishastriChoudhury, SatyajitUmesh, Acharya VaibhavKumar, SaravananYenugu, SrinivasaZander, DanielBeesetti, SivaHattarke, Mallikarjun
Reducing drag forces and minimizing the rear wake region are the main goals of evaluating exterior aerodynamic performance in automobiles. Various literature and experiments shows that the overall fuel computations of the road vehicle improves significantly with the reduction in aerodynamic drag force. In the road vehicle major components of the drag is due the imbalance in pressure between front and rear of the vehicle. At high vehicle speed, aerodynamic drag is responsible for approximately 30 to 40% of the energy consumption of the vehicle. In the recent year, cost of high-performance computing (HPC) has reduced significantly, which helped computational fluid dynamics (CFD) is an affordable tool to the automotive industry for evaluating aerodynamic performance of the vehicle during developing phase. The vehicles aerodynamic performance is greatly impacted by the dynamic environmental conditions it encounters in the real world. Such environmental conditions are difficult to replicate
Chalipat, SujitBiswas, KundanTare, Kedar
The automotive industry is encountering difficulties in balancing occupant thermal comfort with HVAC system energy efficiency, particularly under the hot Indian conditions, to meet user expectations and address range anxiety in electric vehicles. Front-loaded comfort-based approach simulations during the development stages have the potential to increase energy savings compared to the stages required at the end of product design. The focus of the current research targets HVAC energy consumers, such as blower flow rates, temperatures, and Cabin heaters, and investigates how these factors influence occupant overall comfort. Additionally, design elements like glass properties and the impact of solar radiation on human comfort are studied at the early concept stages to adopt an energy-based approach for comfort optimization. Simulations are conducted using GT-SUITE and GT-TAITherm software, integrated with CFD field maps platforms to obtain exact flow field predictions. The simulation
Bavrisetti, Sai Sampath KumarChothave, AbhijeetGummadi, GopakishoreKhan, ParvejThiyagarajan, RajeshRaju, KumarA Sr, Mahesh
Aerodynamics plays an important role in fuel economy and vehicle stability, aiming to deliver full performance while moving on the road. To develop the aerodynamics of vehicles at the early stages of a project, Computational Fluid Dynamics (CFD) simulations and wind tunnel test are the main tools used by automakers to help achieve the desired aerodynamic performance. One of the most relevant factors of CFD and wind tunnel test is how the floor under the vehicle is represented, which may lead to different aerodynamic behaviors. This work aims to investigate the effect of two types of floor configuration on a generic vehicle, with open geometry using CFD simulations. The DrivAer model has been widely studied both numerically and experimentally and provides an interesting source of comparison for 5-belt and static floor configurations, proposed by the study. In addition to the floor configuration analysis, the study also presents a comparison of ground heights for the previous cases
Buscariolo, Filipe FabianSchaffazick, LuizCamargo, DanielBedante, MurilloPeres, MatheusLattari, MateusKelley, MichaelSilveira, Rafael
A passive control device to mitigate shock-induced separation in a generic supersonic inlet model is computationally studied. The simulations were based on the Favre-averaged Navier–Stokes equations with the Spalart–Allmaras (SA) turbulence model. The shockwave was generated by an 8° turn supersonic inlet. The Mach number in the inlet was varied between 2.1 and 2.46. The baseline shockwave/boundary layer interaction (SBLI) simulation results compare favorably with experimental data. The passive device, in the form of a splitter plate, eliminates both the separation and flow unsteadiness. The splitter plate causes reduction in the total pressure of the boundary layer at the exit of the inlet due to increased skin friction on the floor and due to wake of the plate.
Olcmen, SemihWahidi, RedhaHegde, AmruthkiranDatta, Narendra
The current automotive development cycle is becoming shorter and shorter, therefore research is needed to improve the efficiency of wind noise transient calculation. This article summarizes 14 internal and external factors that affect the efficiency and accuracy of transient analysis of wind noise, and uses the ULH algorithm to design DOE for these 14 factors. A total of 200 efficiency improvement schemes are generated, and transient analysis is conducted on each of the 200 schemes. The simulation results and calculation time of wind noise inside the vehicle are statistically analyzed. And aerodynamic acoustic wind tunnel tests were conducted to verify this, with the optimization objectives of simulation values approaching 86.1 AI% (experimental values) and shortened calculation time. NSGA-II algorithm was used to optimize and obtain five sets of efficiency combination schemes that meet the requirements. Develop five appearance feature schemes for areas such as A-pillar and rearview
Li, XiangliangZhang, XiangdongLiu, XuelongWang, HaiyangHuang, Zhongyuan
Hydrogen direct injection is a promising strategy for enabling high-efficiency, low-emission powertrains. However, challenges related to mixture stratification and jet modeling persist, particularly under engine representative conditions. This study numerically investigates a simplified injector model, focusing on the downstream hydrogen jet behavior from of a hydrogen low-pressure direct-injection jet-forming cap under both constant-volume chamber (CVC) and engine conditions. The primary objective is to evaluate numerical methodologies and explore model simplification strategies that remain computationally feasible while preserving physical fidelity—particularly relevant for early-stage hydrogen injector development. Experimental data serve as validation benchmarks across operating regimes. In the CVC platform, large eddy simulations (LES) provide turbulence-resolving insights that inform the refinement of Reynolds-averaged Navier–Stokes (RANS) models. RANS simulations are then
Menaca, RafaelLiu, XinleiSilva, MickaelWu, HaoBen Houidi, MoezMohan, BalajiCenker, EmreAlRamadan, AbdullahSyed, IlteshamPei, YuanjiangRoberts, WilliamIm, Hong G.
In Diesel engines, charge motion usually consists of swirl and squish flow patterns. Traditionally, swirl generation is controlled through the design of the intake ports, presenting a trade-off between swirl and mass flow rate. An alternative approach to generate swirl is to use vortex-generating jets in the intake port. As a comparative basis for this approach a Pareto front was established between swirl and mass flow rate based solely on geometric variations. A new fully parametric geometry was deployed, with two intake ports per cylinder adhering to some constraints. Stationary flow-bench test setup was modeled, where a blower draws air through the intake ports at a constant pressure difference. The Pareto front was generated using semi-randomly selected geometries in combination with automated unsteady RANS (URANS) simulations, while scale adaptive simulations (SAS) were also employed on select geometries. These turbulence modeling approaches were explored using the OpenFOAM
Kahraman, Ali BerkRitter, JohannEilts, PeterScholz, Peter
Efficient propulsion technologies that utilize alternative fuels are becoming increasingly critical to achieve high efficiency at the vehicle scale while fulfilling global regulations in terms of emissions and criteria pollutants. In this scenario, hydrogen (H2) represents an important and appealing part of the solution due to its molecular composition and unique physical and chemical properties. With reference to internal combustion engines, much research is needed to overcome technical challenges that make H2 use not yet viable at the industrial scale. This work focuses on the computational modeling of some of the fundamental aspects of H2’s physical behavior, which can be useful to the development of high-pressure H2 injection systems. Computational fluid dynamics simulations are discussed with the goal of understanding the near- and far-nozzle behavior of H2 using single- and multi-hole nozzles. This study presents the validation of the computational framework against literature
Torelli, RobertoPark, Ji-WoongPei, Yuanjiang
In this article the transition of a laminar boundary layer (BL) over a flat plate is characterized using an acoustic technique with a pitot probe linked to a microphone unit. The probe was traversed along a BL plate at a fixed wind tunnel flow velocity of 5.5 m/s. A spectral analysis of the acoustic fluctuations showed that this setup can estimate the streamwise location and length of the BL transition region, as well as the BL thickness, by using the intermittency similitude approach. Further work is required to quantify the uncertainty caused by signal attenuation within the data acquisition system.
Lawson, Nicholas JohnZachos, Pavlos K.
In recent years, there has been a significant rise in research focused on estimating the base pressure (Pb) characteristics of convergent–divergent nozzles with sudden expansion regions. This study explores the use of geometrical parameters as a control strategy for nozzles experiencing abrupt expansion at supersonic Mach numbers within an axisymmetric duct. It focuses on four distinct novel expansion duct configurations: square nozzle (SN), step square nozzle (SSN), curved nozzle (CN), and double curved nozzle (DCN). In this work, the high-speed compressible flow investigation is carried out numerically using control volume method on the nozzle with a fixed area ratio (AR) and L/D nozzle. Standard k-ε turbulence model is used in the analysis to access the recirculation region formed near the nozzle walls. The recirculation zone directly influences the Pb and shock cell. For NPR range from 2 to 10, SSN and CN shows an increase in Pb, which further increases the thrust and decreases the
Raj, R. JiniKumar, P. DeepakPanchksharayya, D. V.Kousik Kumaar, R.Praveen, N.
Wind Tunnels are complex and cost-intensive test facilities. Thus, increasing the test efficiency is an important aspect. At the same time, active aerodynamic elements gain importance for the efficiency of modern cars. For homologation, such active aero-components pose an extra level of test complexity as their control strategies, the relevant drive cycles and their aerodynamics in different positions must be considered for homologation-relevant data. Often, active components have to be manually adjusted between test runs, which is a time-consuming process because the vehicle is not integrated into the test automation. Even if so, designing a test sequence stepping through the individual settings for each component of a vehicle is a tedious task in the test session. Thus, a sophisticated integration of the wind tunnel control system with a test management system, supporting the full homologation process is one aspect of a solution. The other is the integration of the vehicle’s active
Jacob, Jan D.
The unsteady wind conditions experienced by a vehicle whilst driving on the road are different to those typically experienced in the steady-flow wind tunnel development environment, due to turbulence in the natural wind, moving through the unsteady wakes of other road vehicles and travelling through the stationary wakes generated by roadside obstacles. This paper presents an experimental approach using a large SUV-shaped vehicle to assess the effect of unsteady wind on the modulated noise performance, commonly used to evaluate unsteady wind noise characteristics. The contribution from different geometric modifications were also assessed. The approach is extended to assess the pressure distribution on the front side glass of the vehicle, caused by the aerodynamic interactions of the turbulent inflow in straight and yawed positions, to provide insight into the noise generation mechanisms and differences in behaviour between the two environments. The vehicle response to unsteady wind
Jamaluddin, Nur SyafiqahOettle, NicholasStaron, Domenic
Currently, effective methods for analyzing the aerodynamic sound sources of Sport Utility Vehicles (SUVs) are still under development, and the relationship between sound sources and flow dynamics is not yet fully understood. This study presents a method for identifying multi-frequency sound dipole sources within the near-wall flow field by analyzing the relationship between unsteady flow field properties and dipole sources, thereby addressing the complex characteristics of aerodynamic sound sources on vehicle surfaces. Wind tunnel tests, along with full-scale (1:1) Large Eddy Simulation (LES) were conducted on a real SUV. The identification method was applied to analyze the location and magnitude of sound sources near the vehicle's surface. The results, validated using Acoustic Perturbation Equations (APE), indicated that the dipole sources are primarily distributed around the windward side of the front wheels, the side of the front headlights, the A pillar-side mirror-front side
Zhang, HaoJia, QingWang, Yigang
Sound source identification based on beamforming is widely used today as a spatial sound field visualization technology in wind tunnel experiments for vehicle development. However, the conventional beamforming technique has its inherent limitation, such as bad spatial resolution at the low frequency range, and limited system dynamic range. To improve the performance, three deconvolution methods CLEAN, CLEAN-SC and DAMAS were investigated and applied to identify wind noise sources on a production car in this paper. After analysis of vehicle exterior wind noise sources distribution, correlation analysis between identified exterior noise sources and interior noise were conducted to study their energy contribution to vehicle interior. The results show that the algorithm CLEAN-SC based on spatial source coherence shows the best capability to remove the sidelobes for the uncorrelated wind noise sources, while CLEAN and DAMAS, which are based on point spread functions have definite
He, YinzhiShen, HenghaoWu, YuZhang, LijunYang, ZhigangBlumrich, ReinhardWiedemann, Jochen
When a vehicle is driven at high speed, there exists intricate flow pattern and vortex shedding at the side window area with intense pressure fluctuation. A significant dynamic pressure difference between the vehicle's exterior and interior can render the side window sealing system vulnerable to aspiration. This susceptibility can lead to the generation of leakage noise, adversely affecting acoustic comfort in the vehicle's cabin. This paper delves into the aspiration properties of glassrun seal system under time-varying pressure difference. A nonlinear finite element model of the glassrun seal was established to simulate the quasi-static deformation of the sealing strip during installation process, which aims to obtain the deformed geometric shape and residual stress after this process. Then, the exterior flow field of the glassrun sealing area of a simplified vehicle model was calculated with CFD simulation to obtain the hydrodynamic pressure excitation acting on the outer surface of
Li, HanqiHe, YinzhiZhang, LijunZhang, YongfengYu, WuzhouJiang, ZaixiuBlumrich, ReinhardWiedemann, Jochen
Different approaches are undertaken to mitigate the impact of the transport sector on climate change. Alongside electrifying powertrains, sustainable e-fuels such as polyoxymethylene dimethyl ethers (OME) are considered a promising bridging technology for different applications. However, this requires that the engines are optimized for the new fuels. Accordingly, this study aims to optimize the numerical spray modeling of OME in CONVERGE. Based on the KH–RT break-up model, the spray simulations of three different commercial injectors for heavy-duty applications are analyzed regarding the predictability of the liquid and gaseous penetration lengths and the total simulation time. A sensitivity analysis is conducted for the turbulence model, mesh size, and spray parameters prior to optimizing the spray model and validating it with experimental results. While each parameter individually influences the different phases of the injection event, the sensitivity analysis reveals that the break
Zepf, AndreasHärtl, MartinJaensch, Malte
The current Range Rover is the fifth generation of this luxury SUV. With a drag coefficient of 0.30 at launch, it was the most aerodynamically efficient luxury SUV in the world. This aerodynamic efficiency was achieved by applying the latest science. Rear wake control was realised with a large roof spoiler, rear pillar and bodyside shaping, along with an under-floor designed to reduce losses over a wide range of vehicle configurations. This enabled manipulation of the wake structure to reduce drag spread, optimising emissions measured under the WLTP regulations. Along with its low drag coefficient, in an industry first, it was developed explicitly to achieve reduced rear surface contamination with reductions achieved of 70% on the rear screen and 60% over the tailgate when compared against the outgoing product. This supports both perceptions of luxury along with sensor system performance, demonstrating that vehicles can be developed concurrently for low drag and reduced rear soiling
Chaligné, SébastienGaylard, Adrian PhilipSimmonds, NicholasTurner, Ross
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