Browse Topic: Aerodynamics

Items (7,159)
Find
Verification of the Impact of Coefficient of Drag Variation due to Natural Wind on Fuel Consumption based on Actual Driving Data2025-01-8778To be published on 04/01/2025
It is often assumed that the actual fuel economy on public roads is affected by natural wind and that this could be contributing to discrepancy between catalog fuel economy and actual fuel economy, owing to the increased yaw angle and drag coefficient (CD). However, the impact of yaw characteristics alone on fuel economy during actual driving has not been verified or proven as it is difficult to obtain actual driving data under uniform conditions. For this reason, shape optimization is normally performed at zero-yaw through the aerodynamic development phases. In this paper, two vehicles with different yaw sensitivity characteristics are driven simultaneously, and fuel economy measurements are performed simultaneously with ambient airflow, environment, and vehicle conditions, and the results where the conditions of the two vehicles match are extracted to clarify the impact of the differences of yaw characteristics on fuel economy. The obtained results matched the values predicted by
Onishi, Yasuyuki, Nichols, Larry, Metka, Matt, masumitsu, Yasutaka, Inoue, Taisuke
Technical Paper
On-Road Investigation of Energy Saving Opportunity for Autonomous Light-Duty Vehicles through Automated Vehicle-Following in Safe Distance Scenarios2025-01-8029To be published on 04/01/2025
Reducing aerodynamic drag through vehicle following is one of the energy reduction methods for connected and automated vehicles with advanced perception systems. This paper presents the results of an experimental investigation aimed at assessing energy reduction in manually driven light-duty vehicles through on-road tests of reducing the aerodynamic drag by vehicle following. This study provides insights into the effects of lateral positioning in addition to intervehicle distance and vehicle speed, and the profile of the lead vehicle. A series of tests were employed to analyze the impact of these factors, conducted under realistic driving conditions. The research encompasses various light-duty vehicle models and configurations, with advanced instrumentation and data collection techniques employed to quantify energy-saving potential. The study featured a two set of L4 capable light duty vehicles, including the Stellantis Pacifica PHEV minivan and Stellantis RAM Truck, examined in
Poovalappil, Aman, Robare, Andrew, Schexnaydre, Logan, Santhosh, Pruthwiraj, Bahramgiri, Mojtaba, Bos, Jeremy P., Chen, Bo, Naber, Jeffrey, Robinette, Darrell
Technical Paper
Tire wear life prediction using machine learning technique2025-01-8757To be published on 04/01/2025
As global warming and environmental problems are becoming more serious, tires are required to accomplish balanced performance such as low rolling resistance, wet braking performance, driving stability, and ride comfort, while minimizing wear, noise, and weight. Furthermore, to respond to the rapid changes in the market environment, there is a strong demand for tire performance prediction and testing methods adapted to MBD. In MBD, Magic Formula and Ftire are used in performance design to predict handling and stability and ride comfort. However, predicting tire wear life, which is affected by both vehicle and tire characteristics, is difficult. And practical prediction method for estimating tire wear life has long been awaited. So, we had proposed an experimental-based tire wear life prediction method that using actual measurement tire characteristics and an abrasive wear volume formula. This method achieves accuracy that can be practically used in the early stages of vehicle
ANDO, TAKASHI
Technical Paper
Numerical Investigation on Motorsport Overtake Manoeuvre in Crosswind Conditions2025-01-8773To be published on 04/01/2025
Existing technical literature has primarily focused on the upstream wake effects of single-seater race cars during overtaking, often neglecting the critical factor: crosswinds. This study presents a quantitative computational fluid dynamics (CFD) analysis of how crosswinds impact the aerodynamic loads of interacting race car models during an overtake manoeuvre. For numerical validation purposes, a wind tunnel experimental campaign was carried out on a 35%-scale hill climb race car model to evaluate aerodynamic forces and wake pressure mappings at different ride heights. RANS-based simulations were performed to assess the impact of crosswinds (β = 2°, 6°, 10°) on an isolated race car. Subsequently, a quasi-static approach was used to quantify the effect of crosswind (β = 10°) on an overtaking car under different path strategies. The findings indicated that the overtaking car's performance remained largely stable when a driver opts for overtake paths against the crosswind direction (i.e
Makhija, Jai, Soares, Renan F.
Technical Paper
Simulating the DrivAer Notchback Car Model using Wall-Function LES2025-01-8777To be published on 04/01/2025
This paper summarizes work on the application of a new and fully parallelized native GPU-based finite-volume solver on the DrivAER Notchback configuration using a wall-function LES approach. A series of meshes generated using a Rapid-Octree strategy have been investigated, and results for drag, surface pressure coefficient and velocity profile are compared with available experimental data
Menter, Florian, Dalvi, Ashwini, Flad, David, Sharkey, Patrick
Technical Paper
Sensitivity Analysis of the Vehicle Dynamic Simulation Software Package Within Virtual Crash 5 Using Design of Experiments (DOE2025-01-8693To be published on 04/01/2025
Previous papers have utilized a design of experiments (DOE) to evaluate the sensitivity of vehicle dynamics simulation of the postimpact motion of a vehicle that included high initial rotational rates. The previous papers analyzed four vehicle dynamic simulation softwares; HVE (SIMON and EDSMAC4), PC-Crash and VCRware, and applied the DOE to determine the most sensitive factors present in each simulation software. This paper will include Virtual Crash 5 into this methodology to better understand the significant variables present within this simulation model. This paper will follow a similar DOE to that which was conducted in the previous paper. 32 trials were conducted which analyzed ten factors. Aerodynamics, a factor included in the previous DOE, was not included within this DOE due to Virtual Crash 5 not accounting for that factor. The same three response variables from the previous DOE were measured to determine the effect of the various factors. These response variables are the x
Roberts, Julius, Civitanova, Nicholas, Stegemann, Jacob, Buzdygon, David, Thobe, Keith
Technical Paper
Design and Evaluation of a Conceptual Zero-Emission Truck Model Considering Aerodynamic Efficiency2025-01-8784To be published on 04/01/2025
Emerging zero-emission-powertrain concepts for heavy trucks are providing opportunities to re-shape the vehicle for improved aerodynamics, leading to improved energy efficiency and range resulting from reduced drag. A multi-phase project was initiated to investigate the possibility of improving the aerodynamic efficiency of Class 8 trucks with internal-combustion, battery-electric, and hydrogen-fuel-cell powertrains. Early phases included a scaled-model wind-tunnel test that demonstrated the potential for up to 9% drag reduction from simple shape adaptations, with a follow-up CFD study providing guidance towards further optimization. This paper presents wind-tunnel-test results using a high-fidelity 30%-scale model of the final design concept, with comparison to a conventional North American Class 8 truck with a modern aerodynamic package and identical wheelbase. The study included the investigation of the new model along with individual parts such as air dams, underbody panels, grill
Ghorbanishohrat, Faegheh, McAuliffe, Brian, O'Reilly, Harrison
Technical Paper
Investigation of Skin Friction Topology on the AeroSUV Using GLOF Meter2025-01-8782To be published on 04/01/2025
In this study, the aerodynamics and skin flow field of a 1/5 scale SUV vehicle model called “AeroSUV” were experimentally investigated. The aerodynamics and skin flow field investigations were carried out in the wind tunnel at Hiroshima University with a Reynolds number ReL = 1.2×10^6, baseline yaw angle β = 0° and crosswind conditions β = 5°, 10° and 15° for two rear ends, Estateback and Fastback. The results provide aerodynamic information and detailed skin flow field information for a standard middle-class SUV vehicle with different rear ends, which is important for automotive design. By applying GLOF measurements to automotive aerodynamics, the skin friction topology was revealed in detail as skin flow field information that is useful for understanding the physics of the flow. The skin friction topology clearly shows the separation lines, reattachment lines, and focus points associated with the separation flow, longitudinal vortices and recirculation vortices of this vehicle model
Hijikuro, Masato, Shimizu, Keigo, Nakashima, Takuji, Hiraoka, Takenori
Technical Paper
Characterisation and variabilities of aerosols produced by tyres rotating on wet surfaces2025-01-8763To be published on 04/01/2025
Understanding the formation and behaviour of aerosols generated by vehicles traveling on wet surfaces is crucial due to their impact on vehicle soiling, visibility, and autonomous driving. These aerosols can reduce visibility for other drivers, contribute to traffic accidents, and reduce the operational capabilities of sensors for driving assistance systems and future autonomous vehicles. Despite the importance of understanding the physical properties of these aerosols is crucial for testing and validating sensors for environmental perception and recognition, field data on this topic is scarce. The formation and behaviour of these aerosols are complex. A fraction of the trailing droplets and ligaments originates directly from the tyres, while the remainder is generated upon the impact of the particles ejected from the tyres with the vehicle’s surfaces, resulting in either coalescence or further disintegration. Aerodynamic forces also significantly influence the formation of these
Otxoterena, Paul, Kallhammer, Jan-Erik, Eriksson, Peter, Ronelov, Erik
Technical Paper
CAATS - Automotive Wind Tunnel Calibrations2025-01-8762To be published on 04/01/2025
Wind tunnel calibration is necessary for repeatable and reproducible data for all industries interested in their output. Quantities such as wind speed, pressure gradients, static operating conditions, ground effects, force and moment measurements, as well as flow uniformity and angularity are all integral in an automotive wind tunnel’s data quality and can be controlled through appropriate calibration, maintenance, and statistical process control programs. The purpose of this technical paper is to (1) provide a basis of commonality for automotive wind tunnel calibration, (2) help customers and operators to determine the calibration standards best suited for their unique automotive wind tunnel and, (3) complement the American Institute of Aeronautics and Astronautics recommended practice R-093-2003(2018) Calibration of Subsonic and Transonic Wind Tunnels as specifically applied to the automotive industry. This document compiles information from various automotive wind tunnel customers
Bringhurst, Katlynn, Best, Scott, Nasr Esfahani, Vahid, Senft, Victor, Stevenson, Stuart, Wittmeier, Felix
Technical Paper
Aerodynamic Effect on Vehicle Handling2025-01-8754To be published on 04/01/2025
Vehicle handling is significantly influenced by aerodynamic forces, which alter the normal load distribution across all four wheels, affecting vehicle stability. These forces, including lift, drag, and side forces, cause complex weight transfers and vary nonlinearly with the vehicle's apparent velocity and orientation relative to wind direction. In this study, we simulate the vehicle traveling on a circular path with constant steering input, calculate the normal load on each tire using a weight transfer formula, calculate the effect of lift force on the vehicle on the front and rear, and calculate the vehicle dynamic relation at steady state because the frequency of change due to aero load is significantly less than that of yaw rate response. The wind velocity vector is constant while the vehicle drives in a circle, so the apparent wind velocity relative to the car is cyclical. Our approach focuses on the interaction between two fundamental nonlinearities: the nonlinear aerodynamic
Patil, Harshvardhan, Williams, Daniel
Technical Paper
On the critical importance of physical modelling for the analysis of coastdown data2025-01-8774To be published on 04/01/2025
Novel experimental and analytical methods were developed, with the objective of improving the reliability and repeatability of aerodynamic and road-load results derived from coastdown tests. The new methods were applied in the context of a coastdown test campaign conducted using a SUV and a tractor-trailer. Both vehicles had been tested in the NRC 9m Wind Tunnel, providing aerodynamic comparison-points. The rationale behind the novel techniques was to minimize the number of unknowns in the equation of motion by measuring directly the following parameters: axle mechanical resistance, rolling resistance at low speed and wheel-axle moments of inertia. This was achieved, respectively, by means of an axle-deceleration apparatus, a low-speed hauling facility and a wheel-oscillator developed for this study. In addition, the speed-dependence of tire rolling resistance was measured at a private laboratory, via rotating-drum tests, and modeled using a previously-validated exponential formulation
de Souza, Fenella, Tanguay, Bernard
Technical Paper
Comparison of Vortex Identification Methods on a Complex 3-Dimensional Bluff Body Wake2025-01-8776To be published on 04/01/2025
In automotive base flows, slight changes in geometry can lead to significant changes in base drag brought on by large-scale changes in the wake structure. Properly identifying these structures and their differences can lead to insight into the causal mechanisms of these wake changes. Thus, designers can take advantage of this insight to better design automotive vehicles for reduced drag. However, properly characterizing aerodynamic structures has been a challenge for decades. In this work, we utilized Improved Delayed Detached-Eddy Simulations (IDDES) to simulate flow around an Ahmed body with a modified base to have both upsweep and downsweep simultaneously. This yielded a complex 3-dimensional flow field with multiple regions of separation, recirculation, and vortical structures. These structures were identified using several different vortex identification methods; ∆−, Q−, λ2−, and Ω− criteria. Of these methods, only the Ω− criterion was able to successfully separate the shear layer
AULTMAN, MATTHEW, Duan, Lian
Technical Paper
An Investigation of the Inter-Vehicle Distances and Lateral offsets on Aerodynamic Forces and Wake Structures of Vehicles Platooning2025-01-8769To be published on 04/01/2025
In traffic scenarios, the spacing between vehicles plays a crucial role, as the actions of one vehicle can significantly impact others, particularly with regards to energy conservation. Accordingly, modern vehicles are equipped with inter-vehicle communication systems to maintain specific distances between vehicles. The aerodynamic forces experienced by both leading vehicles (leaders) and following vehicles (followers) are connected to the flow patterns in the wake region of the leaders. Therefore, improving our understanding of the turbulent characteristics associated with vehicles platooning is important. This paper investigates the effects of inter-vehicle distances on the flow structure of two vehicles: a small SUV as the leader and a larger light commercial van as the follower, using a Delayed Detached Eddy Simulation (DDES) CFD technique. The study focuses on three specific inter-vehicle distances: S = 0.28 L, 0.4L, and 0.5L, where S represents the spacing between the two
Mosavati, Maziar, Guzman, Arturo, Lounsberry, Todd, Fadler, Gregory
Technical Paper
Design Parameter Impact of Wind-Averaged Drag Optimization2025-01-8772To be published on 04/01/2025
With the increasing prevalence of electric vehicles (EVs), decreasing vehicle drag is increasingly important, as range is a primary consideration for customers and has a direct bearing on the cost of the vehicle. While the relationship between drag and range is well understood, there still exists a discrepancy between the label range and the real-world range experienced by customers. One of the factors influencing the difference is the ambient wind condition that modifies the resultant air speed and yaw angle, which is typically minimized during SAE coastdown testing. Previous work has put forward a methodology to derive this wind-averaged drag (WAD) from either a full yaw sweep or a more efficient 3-point yaw curve while also showing the impact to drag coefficient as compared to the zero-yaw condition. This leads to an interesting dilemma for the vehicle aerodynamicist: whether to optimize the vehicle's exterior shape for low wind (zero yaw) conditions or for real-world conditions
Kaminski, Meghan, D'Hooge, Andrew, Borton, Zackery
Technical Paper
A Sensitivity Study of Frequency Response Method for Setting Bearing Preload Due to Uncontrollable Parameters2025-01-8520To be published on 04/01/2025
Roller bearings are used in many rotating power transmission systems in the automotive industry. During the assembly process of the power transmission system, some types of roller bearings (e.g., tapered roller bearings) require a compressive preload force. Those bearings' rolling resistance and lifespan strongly depend on the preload set during the installation process. Therefore, accurate setting of the preload can improve bearing efficiency, increase bearing lifespan and reduce maintenance costs over the life of the vehicle. A new method for bearing preload measurement has shown potential for both high accuracy and fast cycle time using the frequency response characteristics of the power transmission system. One open problem is the design of the production controller which relies on a detailed sensitivity study of the system frequency response to changes in the bearing and system design parameters. Recently, an analytical model was developed for multi-row tapered roller bearings
Gruzwalski, David, Mynderse, James
Technical Paper
Time Step Analysis of Sliding Mesh Rotation Modeling2025-01-8626To be published on 04/01/2025
This paper analyzes the accuracy and computational cost of increasing the time-step size on a production vehicle while using Sliding Mesh (SM) for the rotation modeling of the wheels with two turbulence models (Unsteady Reynolds-Averaged Navier-Stokes (URANS) and Delayed Detached-Eddy Simulations (DDES)). The current recommendations of using a SM model are too computationally expensive to be used in a consistent manner, especially compared to a Moving Reference Frame (MRF) model for the wheels. While changing the time-step size from 1x - 50x, 1x being the current recommendations of 1 degree of rotation on the wheels per time-step, a CFD analysis of a mass-production vehicle model was compared to wind tunnel data using time-averaged flow. The DDES simulations were more robust at larger time steps compared to the URANS simulations. The drag coefficients and flow field was more consistent to the wind tunnel data for SM compared to using a MRF rotation model for the wheels even at the
Struk, Michael, AULTMAN, MATTHEW, Disotell, Kevin, Duan, Lian, Bianco, Antonello, Metka, Matt, Khasdeo, Nitin, Ramsay, Thomas
Technical Paper
Meteorolgical Aspects of the Operational Design Domain -- Enhancing Road and Rail Safety and Efficiency through Integrated Wind, Weather, and Motion Sensing Technology2025-01-8100To be published on 04/01/2025
In recent years, integrated sensor systems have significantly advanced environmental monitoring, providing essential insights for addressing various environmental challenges. This paper introduces a novel wind, weather, and motion sensor, designed primarily for automotive environments but also applicable to rail systems. The paper explores how these sensors enhance the safety and efficiency of vehicles by detecting critical environmental parameters. Key concepts such as the Operational Design Domain (ODD) and Operational Domain (OD) are discussed, emphasizing their importance in the deployment of connected, automated, and autonomous vehicles. The distinction between ODD and OD is illustrated using real-world examples, highlighting the necessity for advanced detection and response capabilities in complex driving scenarios. Furthermore, the paper delves into the significance of road-related atmospheric conditions like temperature, humidity, pressure, and wind. Current state-of-the-art
Feichtinger, Christoph Simon
Technical Paper
Modeling and Simulation analysis of an electric vehicle in normal and hot ambient conditions: energy consumption and driving range2025-01-8151To be published on 04/01/2025
With better performance and usage of clean and renewable energy, electric vehicles have ushered in more and more consumers’ favor nowadays. However, insufficient driving range especially in hot and cold ambient conditions still greatly restricts the extensive application of electric vehicles. This paper presents a methodology of establishing mechanics-electricity-thermodynamics coupled full vehicle model in AMESim to investigate the energy consumption and driving range of an electric vehicle in normal and hot ambient conditions. Full vehicle energy consumption test was carried out in the climate chamber to check the accuracy of simulation results. Firstly, basic framework of the full vehicle model established in AMESim was introduced. Next, modeling details of sub-systems including vehicle dynamic system, electrical system, coolant circuit system, air-conditioning system and control strategy were illustrated. Then, full vehicle energy consumption tests were carried out in 23℃ and 38
ZHOU, Shuai, Liu, Huaiju, YU, Huili, Yan, Xu, Yan, Junjie
Technical Paper
Development and performance optimization of FSAE Racing Active Ground effect system based on fan drive2025-01-8001To be published on 04/01/2025
For FSAE cars, a significant increase in downforce can enable the car to score more points in the race and enhance the competitiveness of the vehicle. This paper focuses on the development of an active ground effect system driven by fans for the FSAE racing car . The system is designed to considerably increase the downforce of the racing car through the forced airflow generated by the fan, enable the dynamic adjustment of the aerodynamic balance of the racing car during the driving process, and achieve the vertical force control on the racing wheels, thereby improving the performance of the racing car. The Star-CCM+ software was employed to conduct CFD simulation to investigate the influence of different flow fans on downpressure and optimize the layout and position of the fan. Due to the limited power that the car can carry, the paper will also simulate and calculate the range of pneumatic balance adjustment and vertical force control capability provided by the different openings of
yang, chengyue
Technical Paper
Energy Savings and Range Extension from Aerodynamic Improvements of Emerging Zero-Emission Heavy Vehicle Concepts2025-01-8787To be published on 04/01/2025
An energy-use analysis is presented to examine the potential energy-savings and range-extension benefits of aerodynamic improvements to tractors and trailers used in commercial transportation. The impetus for the study was the observation of aerodynamically-redesigned/optimized tractor shapes of emerging zero-emission tractors that have the potential for significant drag reduction over conventional aerodynamic tractors. Using wind-tunnel test results, a series of aerodynamic performance models were developed representing a range of tractor and trailer combinations. From current-day day-cab and sleeper-cab tractors to aerodynamically-optimized zero-emission cab concepts, paired with standard dry-van trailers or low-drag trailer concepts, the study examines the potential of implementing various fleet configurations for different operational duty cycles. An energy-use analysis was implemented to estimate the energy-rate contributions associated with inertial accelerations, grade forces
McAuliffe, Brian, Ghorbanishohrat, Faegheh
Technical Paper
Bimodal Wake Cycling with Turbulent Flow2025-01-8766To be published on 04/01/2025
The vehicle wake region is of high importance when analyzing the aerodynamic performance of a vehicle. It is characterized by turbulent separated flow and large low pressure regions that contribute significantly to drag. In some cases the wake region can oscillate between different modes which can provide engineering challenges during vehicle development. Vehicles that exhibit bimodal wake behavior need to have their drag values recorded over a sufficient time period. When simulating such a vehicle in CFD this can be a problem as the period of oscillation can be very long, on the order of 10’s of seconds or minutes. Running such simulations with sufficient time to capture the average drag would be prohibitively expensive in terms of CPU hour cost during the vehicle design process. As an alternative to running a long simulation it is possible to influence the wake behavior through the use of turbulence. By adding turbulence to the upstream flow the wake can be prevented from settling
DeMeo, Michael, Parenti, Guido, Martinez Navarro, Alejandro, Shock, Richard, Fougere, Nicolas, Razi, Pooyan, Oliveira, Danilo, Lindsey, Craig, Yu, Chenxing, Breglia Sales, Flavio
Technical Paper
A Sensitivity Study of Frequency Response Method for Setting Bearing Preload Due to Manufacturing and Design Variation2025-01-8518To be published on 04/01/2025
Roller bearings are used in many rotating power transmission systems in the automotive industry. During the assembly process of the power transmission system, some types of roller bearings (e.g., tapered roller bearings) require a compressive preload force. Those bearings' rolling resistance and lifespan strongly depend on the preload set during the installation process. Therefore, accurate setting of the preload can improve bearing efficiency, increase bearing lifespan and reduce maintenance costs over the life of the vehicle. A new method for bearing preload measurement has shown potential for both high accuracy and fast cycle time using the frequency response characteristics of the power transmission system. One open problem is the design of the production controller which relies on a detailed sensitivity study of the system frequency response to changes in the bearing and system design parameters. Recently, an analytical model was developed for multi-row tapered roller bearings
Gruzwalski, David, Mynderse, James
Technical Paper
Modal Analysis Approach for Analysis and Design of Vehicle Transient Behavior2025-01-8794To be published on 04/01/2025
In order to solve the increasingly serious global environmental problems, the automobile industry is rapidly shifting to EVs and plug-in hybrid EVs, so vehicle weights are increasing. In addition, the use of low rolling resistance tires to improve energy efficiency is increasing. In order to ensure the maneuverability and stability of such vehicles, it is becoming increasingly necessary to design performance based on better understanding of the basic principles of vehicle dynamics. Vehicle dynamics is fundamentallilly based on planar motion, but the accompanying roll motion also affects the planar motion and also driver's subjective evaluation. Vehicle dynamics analysis considering roll has been discussed by parameter studies, by characteristic analysis using equivalent models, or by characteristic root analysis. However, with the exception of R.S Sharp's report, which mentions the three vibration modes of motorcycles, there are very few examples of vehicle dynamics analysis in terms
Kusaka, Kaoru, Yuhara, Takahiro
Technical Paper
Investigation of the Blockage Phenomenon in Closed Wall Wind Tunnels During the Testing of Bluff Automotive Bodies with Large Wakes in Yawed Configurations2025-01-8786To be published on 04/01/2025
Abstract 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 very 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 author and similarly to those studies uses the computational fluid dynamics analysis of four bodies that generate large wakes to examine the interference phenomena in solid wall wind tunnels and the effects that they have on the pressures, forces and force increments 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 0.4% to 14% blockage enabling an approximation of free air
Gleason, Mark, Riegel, Eugen
Technical Paper
Impact of Active Turbulence Generation System in 3/4 Open-Jet Wind Tunnel: Flow Structures, Shear Layer, and Low-Frequency Fluctuations2025-01-8783To be published on 04/01/2025
With increasing attention to complex aerodynamic conditions such as crosswinds, gusts, road turbulence, and vehicle queuing, accurately reconstructing these unsteady and turbulent environments in automotive wind tunnels has become a significant challenge. Addressing this challenge is crucial for broadening experimental conditions and advancing research in unsteady aerodynamics. However, the integration of turbulence generation systems impacts low-frequency fluctuation phenomena, leading to pressure and velocity inaccuracy, and also affects the flow structure in the test section as well, especially in the jet shear layer. In this paper, the impact of an active turbulence generation system on turbulence characteristics and flow structures within jet shear layer in a wind tunnel is numerically investigated. By comparing the flow structure among the blank wind tunnel, and wind tunnel with static and dynamic active turbulence generation system, the mechanisms underlying these configurations
Jia, Qing, Qin, Lanwei, Zhao, Civil, Wang, Yikun, Xia, Chao, Yang, Zhigang, Wei, Huanxia
Technical Paper
The aerodynamics development of the New Range Rover2025-01-8781To be published on 04/01/2025
The New 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 underfloor 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 out-going 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. This
Chaligné, Sébastien, Gaylard, Adrian Philip, Simmonds, Nicholas, Turner, Ross
Technical Paper
A Wide Belt Correction Strategy for Belt-Whip and Wheel Ventilation Drag2025-01-8770To be published on 04/01/2025
The increased importance of aerodynamics to help with overall vehicle efficiency necessitates a desire to improve the accuracy of the measuring methods. To help with that goal, this paper will provide a method for correcting belt-whip and wheel ventilation drag on single and 3-belt wind tunnels. This is primarily done through a method of analyzing rolling-road only speed sweeps but also physically implementing a barrier. When understanding the aerodynamic forces applied to a vehicle in a wind tunnel, the goal is to isolate only those forces that it would see in the real world. This primarily means removing the weight of the vehicle from the vertical force and the rolling resistance of the tires and bearings from the longitudinal force. This is traditionally done by subtracting the no-wind forces from the wind at testing velocity forces. The first issue with the traditional method is that a boundary layer builds up on the belt(s), which can then influence a force onto the vehicle’s
Borton, Zackery
Technical Paper
Consideration of Factors Influencing Closed Jet Wind Tunnel Blockage Corrections for Road Vehicles2025-01-8771To be published on 04/01/2025
Experimental studies of wind tunnel blockage for road vehicles have usually been conducted in model wind tunnels. Models have been made in a range of scales and tested in a working section of fixed size. More recently CFD studies of blockage have been undertaken, which allow a fixed vehicle size and the blockage is varied by changing the cross section of the flow domain. This has some inherent advantages. A very recent database of drag and lift coefficients for different road vehicle shapes and simple bodies examined in a closed wall tunnel with a wide range of blockage ratios has become available and provides some additional insight into the blockage phenomenon. This paper shows how some of the parameters influencing blockage can be derived from the CFD data and provides some tentative proposals for correcting the measured drag and lift coefficients
Howell, Jeff, Gleason, Mark, Butcher, Daniel
Technical Paper
Design of FSAE Racing Car Non-linear Variable Section Wing Composite Material Wing Beam and Wing Rib Truss Structure2025-01-8002To be published on 04/01/2025
Aerodynamic kit design plays a pivotal role in the overall performance of race cars, particularly in the context of Formula SAE (FSAE) competitions. These kits significantly contribute to improved handling stability, cornering speed, and overall vehicle control by manipulating airflow to generate downforce. In FSAE competitions, achieving high levels of downforce is critical, as it allows the car to maintain higher speeds through corners without sacrificing grip. However, a major challenge in designing these aerodynamic kits is balancing the need for substantial downforce with the imperative of minimizing weight to avoid compromising the vehicle's acceleration and energy efficiency. This paper focuses on designing a high-performance aerodynamic kit specifically tailored for FSAE race cars, using advanced materials and techniques. The complex shapes required to optimize aerodynamic performance necessitate the use of composite materials, such as laminated plates, which offer high
Cui, Jiarong
Technical Paper
Ascertainment of Optimized Profile of Hybrid Vortex Bladeless Turbine for Unmanned Surface Vehicles using Progressive Computational Studies2025-28-0185To be published on 02/07/2025
This work addresses an innovative method for improving energy harvesting in Bladeless wind turbines (BWT) by implementing profile modifications to the wind turbine for fixing it in Unmanned Surface Vehicles (USV). The streamlined flow undergoes a transformation and generates a vortex in the vicinity of the structure when the wind impacts the BWT. As the velocity increases, the wind strikes the structure with greater force, resulting in an imbalance that causes the structure to vibrate. To convert this vibrational energy of the wind turbine into electrical energy, the research investigates the use of a variety of profile modifications to capitalize on the aerodynamic effect generated by the structure. The entire cylindrical shape is altered to tapered shape, airfoil shapes with coordinates such as NACA 0012, 0015, 0018, 4412 and 4420. In addition to these shapes, hybrid models were also constructed by merging models made from two airfoil coordinates, including NACA 0018 & 4412, NACA
Veeraperumal Senthil Nathan, Janani Priyadharshini, Rajendran, Mahendran, Arumugam, Manikandan, Raji, Arul Prakash, Sakthivel, Pradesh, Stanislaus Arputharaj, Beena, L, Natrayan, Ganesan, Balaji, Raja, Vijayanandh
Technical Paper
CFD Analysis On the Effect Of Circular Cavity at Different Location of Airfoil Surface2025-28-0074To be published on 02/07/2025
The paper presents the effect of cavity at different position of the airfoil on lift coefficient, drag coefficient and lift to drag ratio respectively. Here the analysis performed on SC (2) 0414 3D airfoil by using commercial CFD ANSYS FLUENT. The passive control method is applied by modifying the baseline airfoil surface coordinates to ascertain the aerodynamic behavior of the cavity at 40 %, 50% and 60 % of the chord length successfully where spalart turbulence model technique is chosen to solve boundary layer problems on adverse pressure gradient and tested at extended range of angle of attack -150 to 180. A structured meshing method was used. RANS, Reynolds averaged Navier-Stokes, was the solver used for the unsteady simulations. At Reynolds numbers (Re) of 10× 104 , the coefficients of lift, drag, pressure were observed. The study highlights the aerodynamic characteristics and stall effects at desired angle of attack. It is observed that the cavity at 40 % of the chord length
Pushparaj, Catherine Victoria, P, Booma Devi, D, Piriadarshani, Ganesan, Balaji, Ganesan, Santhosh Kumar, Raja, Vijayanandh
Technical Paper
The Use of Pressure Constructs in Aerodynamics May Lead to Misinformation01-17-03-002001/06/2025
From biology, to genetics, and paleontology, these fields share the DNA as a common and time-proven tool. In science, pressure may be such a tool, shared by thermodynamics, material science, and astrophysics, but not by aerodynamics. Pressure is a shorthand for a force acting perpendicular to a surface. When this surface is reduced to zero, so should the pressure. The wing area of an aircraft acts as a reference area to calculate its parasite drag coefficient. In this scenario, the parasite drag acts as a force over the wing area. If the wing area is reduced to zero, its parasite drag does not, as the fuselage is still generating parasite drag. The ratio of the parasite drag and wing area is an example of a pressure construct that uses a physically irrelevant reference area and has no absolute zero. Pressure constructs, more frequently used than pressures in aerodynamics, are a math-based parameter that preserve dimensional propriety according to the Buckingham Pi theorem but lacks a
Burgers, Phillip
Journal Article
Exploring Shock Wave–Boundary Layer Interaction Using Rainbow Schlieren Deflectometry01-18-01-000212/24/2024
The flow structure and unsteadiness of shock wave–boundary layer interaction (SWBLI) has been studied using rainbow schlieren deflectometry (RSD), ensemble averaging, fast Fourier transform (FFT), and snapshot proper orthogonal decomposition (POD) techniques. Shockwaves were generated in a test section by subjecting a Mach = 3.1 free-stream flow to a 12° isosceles triangular prism. The RSD pictures captured with a high-speed camera at 5000 frames/s rate were used to determine the transverse ray deflections at each pixel of the pictures. The interaction region structure is described statistically with the ensemble average and root mean square deflections. The FFT technique was used to determine the frequency content of the flow field. Results indicate that dominant frequencies were in the range of 400 Hz–900 Hz. The Strouhal numbers calculated using the RSD data were in the range of 0.025–0.07. The snapshot POD technique was employed to analyze flow structures and their associated
Datta, Narendra, Olcmen, Semih, Kolhe, Pankaj
Journal Article
Ground Height and Pitch Angle Influence on the Aerodynamic Behavior of a Production Pickup Truck2024-36-001112/20/2024
The fuel economy performance of road vehicles is one of the most important factors for a successful project in the current automotive industry due to greenhouse effect gases reduction goals. Aerodynamics and vehicle dynamics play key roles on leading the automaker fulfill those factors. The drag coefficient and frontal area of the vehicle are affected by several conditions, where the ground height and pitch angle are very relevant, especially for pickup trucks. In this work, we present a combined study of suspension trim heights and aerodynamics performance of a production pickup truck, where three different loading conditions are considered. The three weight configurations are evaluated both in terms of ground height and pitch angle change considering the suspension and tires deflection and these changes are evaluated in terms of drag coefficient performance, using a Lattice-Boltzmann transient solver. Results are compared with the baseline vehicle at road speed condition, where both
Buscariolo, Filipe Fabian, Terra, Rafael Tedim
Technical Paper
Assessing Road Load Predictions: A Comprehensive Review and Comparative Analysis of Real-World versus Numerical Simulation2024-36-015712/20/2024
Road loads, encompassing aerodynamic drag, rolling resistance, and gravitational effects, significantly impact vehicle design and performance by influencing factors such as fuel efficiency, handling, and overall driving experience. While traditional coastdown tests are commonly used to measure road loads, they can be influenced by environmental variations and are costly. Consequently, numerical simulations play a pivotal role in predicting and optimizing vehicle performance in a cost-effective manner. This article aims to conduct a literature review on road loads and their effects on vehicle performance, leveraging experimental data from past studies from other researchers to establish correlations between measured road loads and existing mathematical models. By validating these correlations using real-world measurements, this study contributes to refining predictive models used in automotive design and analysis. The simulations in this study, utilizing five distinct empirical
Pereira, Leonardo Pedreira, Braga, Sérgio Leal
Technical Paper
Optimization of a 2-D Multi-Element Rear Wing on a Formula 1 Car2024-36-010312/20/2024
The aerodynamic force produced by external flows over two-dimensional bodies is typically decomposed into two components: lift and drag. In race cars, the lift is known as downforce and it is responsible for increasing tire grip, thereby enhancing traction and cornering ability. Drag acts in the direction opposite to the car’s motion, reducing its acceleration and top speed. The primary challenge for aerodynamicists is to design a vehicle capable of producing high downforce with low drag. This study aims to optimize the shape of a multi-element rear wing profile of a Formula 1 car, achieving an optimal configuration under specific prescribed conditions. The scope of this work was limited to a 2-D model of a rear wing composed of two 4-digit NACA airfoils. Ten control parameters were used in the optimization process: three to describe each isolated profile, two to describe their relative position, and two to describe the angles of attack of each profile. An optimization cycle by finite
Souza Dourado, Guilherme, Hayashi, Marcelo Tanaka
Technical Paper
A Comprehensive Analysis of Various Airfoils for Unmanned Aerial Vehicles/Micro Aerial Vehicles Application01-17-03-001712/13/2024
The purpose of this study is to analyze different airfoils using various tools like X-Foil and Reynolds-averaged Navier–Stokes (RANS) computational fluid dynamic (CFD) analysis (ANSYS Fluent) and compare both the results with wind tunnel experimental data to choose an aerodynamically efficient airfoil, which is suitable for an unmanned aerial vehicle/micro aerial vehicle (UAV/MAV) and its operational domain of Reynolds number. The main objective of this analysis is to identify and give us an understanding of the airfoil that has a higher value of Cl max and minimum possible value of Cd. This article discusses various low Reynolds number airfoils, i.e., for the range of Reynolds number between 50,000 and 200,000, which is mostly used for MAVs. Also, between the range of 100,000 and 200,000 for UAVs, which have displayed considerable performance in the past. The article also presents an effort to understand the phenomenon of laminar separation bubbles
Roy, Indranil, Rao, Sameera
Journal Article
Automotive Grade Coaxial Cable Performance SpecificationUSCAR29 (Historical)12/06/2024
This document specifies dimensional, functional and visual requirements for Automotive grade coaxial cable. This material will be designated AG for general-purpose automotive applications or AG LL for low loss applications. It is the responsibility of the user of this cable to verify the suitability of the selected product (based on dimensional, mechanical, electrical and environmental requirements) for its intended application. It is the responsibility of the supplier to retain and maintain records as evidence of compliance to the requirements detailed in this standard
USCAR
Specification
Aerodynamic Analysis of Electric Cargo Scooter with Unified Modelling and Simulation2024-28-017312/05/2024
Aerodynamic analysis is a primary requirement in the development of electric scooters to predict the impact of air flow around the vehicle on critical performance parameters including the overall range, vehicle stability due to wind loads, air cooling of electric motor and battery. Any new design of vehicle requires an aerodynamic evaluation to estimate the variations in drag forces with speed. It is prohibitively expensive and time consuming to perform full-scale model wind tunnel tests on each variant of the vehicle configuration for wide range of driving scenarios. Physics-based 3D simulation is the preferred approach in the present context and the use of Computational Fluid Dynamics (CFD) for such cases has been well understood and established. Although only the external shape changes make a difference to external aerodynamics, sometimes even a small variation in shape could trigger unwanted flow behavior leading to large drag forces, or enhance the vehicle performance by reducing
Balachandran, Karthik, Das, Alok, Shinde, Pranav
Technical Paper
Characterization of Cut and Chip Damage in Ultra Low Rolling Resistance Tire for Electric Vehicles2024-28-017512/05/2024
Since the inception of battery driven electric vehicles in the automotive world, there has been a constant challenge in maximizing the range of an electric vehicles through various means including battery technology, vehicle weight optimization, low drag coefficients etc. The tires being a viscoelastic composite material have now become a vital to the range performance of an EV. The rolling resistance of a tire is now become a hotter topic than ever. The rolling resistance coefficient (RRC) is the measure of energy loss during rolling due to viscoelastic dissipation in the tire. The viscous dissipation in tire arises due to hysteresis in the various components of a tire including tread, sidewall, inner liner, apex etc rubber compounds. The internal friction between layers of body ply, steel belts and tread crown ply also contribute to the internal heat generation. Therefore, the development of ultra-low RRC tires is a serious challenge for tire engineers. Nevertheless, the recent
Mishra, Nitish, Singh, Ram Krishnan
Technical Paper
Inertia-Dynamometer Disc Brake Drag Measurement Test Procedure for Vehicles Less Than 4540 kg GVWRJ2923_202412 (Current)12/03/2024
The SAE J2923 procedure is a recommended practice that applies to on-road vehicles with a GVWR below 4540 kg equipped with disc brakes
Brake Dynamometer Standards Committee
Recommended Practice
AI-Trained Vehicles Can Adjust to Extreme Turbulence on the Fly24AERP12_0712/01/2024
Researchers at Caltech took an important step toward using reinforcement learning to adaptively learn how turbulent wind can change over time, and then uses that knowledge to control a UAV based on what it is experiencing in real time. California Institute of Technology, Pasadena, CA In nature, flying animals sense coming changes in their surroundings, including the onset of sudden turbulence, and quickly adjust to stay safe. Engineers who design aircraft would like to give their vehicles the same ability to predict incoming disturbances and respond appropriately. Indeed, disasters such as the fatal Singapore Airlines flight this past May in which more than 100 passengers were injured after the plane encountered severe turbulence, could be avoided if aircraft had such automatic sensing and prediction capabilities combined with mechanisms to stabilize the vehicle. Now a team of researchers from Caltech's Center for Autonomous Systems and Technologies (CAST) and NVIDIA has taken an
Magazine Article
Enabling High-Capacity Space CommunicationTBMG-5220312/01/2024
Researchers have achieved data rates as high as 424Gbit/s across a 53-km turbulent free-space optical link using plasmonic modulators — devices that uses special light waves called surface plasmon polaritons to control and change optical signals. The new research lays the groundwork for high-speed optical communication links that transmit data over open air or space
Magazine Article
Computational Modeling of Aerodynamic Design Trends for a Production SUV Subjected to Incremental Design Changes: Roof Spoiler and Underbody Geometry15-18-01-000611/21/2024
In this work, we evaluated computational fluid dynamics (CFD) methods for predicting the design trends in flow around a mass-production luxury sport utility vehicle (SUV) subjected to incremental design changes via spoiler and underbody combinations. We compared Reynolds-averaged Navier–Stokes (RANS) using several turbulence models and a delayed detached eddy simulation (DDES) to experimental measurements from a 40% scale wind tunnel test model at matched full-scale Reynolds number. Regardless of turbulence model, RANS was unable to consistently reproduce the design trends in drag from wind tunnel data. This inability of RANS to reproduce the drag trends stemmed from inaccurate base pressure predictions for each vehicle configuration brought on by highly separated flow within the vehicle wake. When taking A-B design trends, many of these errors compounded together to form design trends that did not reflect those measured in experiments. On the other hand, DDES proved to be more
Aultman, Matthew, Disotell, Kevin, Duan, Lian, Metka, Matthew
Journal Article
AI Helps UAVs Predict Oncoming TurbulenceTBMG-5207411/19/2024
Magazine Article
GPS-BASED MOBILITY POWER ANALYSIS OF MILITARY VEHICLES2024-01-331111/15/2024
ABSTRACT Determining the required power for the tractive elements of off-road vehicles has always been a critical aspect of the design process for military vehicles. In recent years, military vehicles have been equipped with hybrid, diesel-electric drives to improve stealth capabilities. The electric motors that power the wheel or tracks require an accurate estimation of the power and duty cycle for a vehicle during certain operating conditions. To meet this demand, a GPS-based mobility power model was developed to predict the duty cycle and energy requirements of off-road vehicles. The dynamic vehicle parameters needed to estimate the forces developed during locomotion are determined from the GPS data, and these forces include the following: the gravitational, acceleration, motion resistance, aerodynamic drag, and drawbar forces. Initial application of the mobility power concept began when three U.S. military’s Stryker vehicles were equipped with GPS receivers while conducting a
Ayers, Paul, Bozdech, George
Technical Paper
INVERSE DYNAMICS APPROACH TO ESTABLISH MOBILITY MARGINS2024-01-392011/15/2024
ABSTRACT An inverse dynamics approach is applied to assess the relationship and establish an adjustable balance between acceleration performance, slip energy efficiency, and mobility margins of a wheel of a vehicle with four wheels individually-driven by electric DC motors. The time history of the reference wheel torques are recovered which would enable the motion at the desired linear velocity. Target velocity profiles are applied which provide different rates of acceleration. The profiles are simulated in stochastic terrain conditions which represent continuously changing, uncertain terrain characteristics with various quality of rolling resistance and peak friction coefficient. A wheel mobility margin is determined to track how close a driving wheel is to immobilization. When moving in drastically changing stochastic terrain conditions, boundaries are adjusted to accommodate changes in the resistance to motion in order to guarantee the motion while not exceeding limits which would
Paldan, Jesse, Vantsevich, Vladimir, Gorsich, David, Jayakumar, Paramsothy, Moradi, Lee
Technical Paper
Fuel Economy and Mobility of Multi-Wheel Drive Vehicles: Modeling and Optimization Technology2024-01-311511/15/2024
ABSTRACT A distinctive feature of unmanned and conventional terrain vehicles with four or more driving wheels consists of the fact that energy/fuel efficiency and mobility depend markedly not only on the total power applied to all the driving wheels, but also on the distribution of the total power among the wheels. As shown, under given terrain conditions, the same vehicle with a constant total power at all the driving wheels, but with different power distributions among the driving wheels, will demonstrate different fuel consumption, mobility and traction; the vehicle will accelerate differently and turn at different turn radii. This paper explains the nature of mechanical wheel power losses which depend on the power distribution among all the driving wheels and provides mathematical models for evaluating vehicle fuel economy and mobility. The paper also describes in detail analytical technology and computational results of the optimization of wheel power distributions among the
Vantsevich, Vladimir V., Gray, Jeremy P.
Technical Paper
Research on Drag Reduction Matching of Modular Flying Cars Based on Nested Configuration2024-01-701611/15/2024
This paper investigates the drag reduction matching of modular flying cars based on a nested configuration. To address the high aerodynamic drag issue of traditional modular flying car configurations, a nested design scheme is proposed. In this scheme, the cabin is extracted from a low-drag car and combined with the flying module using a nested approach, achieving aerodynamic matching between the cabin, driving module, and flying module. First, the conceptual design of the new modular flying car and the parameters of each module, including the driving module, cabin module, and flying module, are introduced. Then, computational fluid dynamics (CFD) methods are utilized to numerically simulate the aerodynamic characteristics of the new flying car, and the results are compared with the existing typical modular flying car, AIRBUS. The research results show that the nested modular flying car exhibits superior aerodynamic performance in both driving and flying modes. Compared to the typical
Li, Yanlong, Ye, Shengfei, Zhou, Hua
Technical Paper
Items per page:
1 – 50 of 7159