Browse Topic: Aerodynamics

Items (7,126)
This study evaluates the effectiveness of two hybrid computational aeroacoustic methods—Lighthill wave model and perturbed convective wave model—in simulating HVAC duct noise in the automotive industry. Using component-level acoustic testing of a Ford HVAC duct, simulations were conducted at varying airflow rates to assess the accuracy of both models in predicting duct noise. The Lighthill wave model, suitable for noise analysis in regions outside turbulent flow areas, showed a good correlation with experimental data, especially in the frequency range of 100 Hz–5000 Hz, but sometimes struggled with pseudo-noise effects at low frequencies near turbulent regions. The perturbed convective wave model, which is suitable for noise analysis anywhere in the flow domain, underpredicted sound pressure levels at low frequencies as well. Both models underpredicted high-frequency noise (>5 kHz) due to insufficient mesh and time-step sizes. Despite these limitations, the Lighthill wave model
Nam, Jee-WhanMendel, MarcGolberg, Igor
Multiple-ion-probe method consists of multiple ion probes placed on the combustion chamber wall, where each individual ion probe detects flame contact and records the time of contact. From the recorded data, it is also possible to indirectly visualize the inside of the combustion chamber, for example, as a motion animation of moving flame front. In this study, a thirty-two ion probes were used to record flames propagating in a two-stroke gasoline engine. The experiment recorded the combustion state in the engine for about 3 seconds under full load at about 6500 rpm, and about 300 cycles were recorded in one experiment. Twelve experiments were conducted under the same experimental conditions, and a total of 4,164 cycles of signal data were obtained in the twelve experiments. Two types of analysis were performed on this data: statistical analysis and machine learning analysis using a linear regression model. Statistical analysis calculated the average flame detection time and standard
Yatsufusa, TomoakiOkahira, TakehiroNagashige, Kohei
New regulations introduced by the Fédération Internationale de l’Automobile (FIA) for the 2026 Formula 1 season mark the first instance of active flow control methods being endorsed in Formula 1 competition. While active methods have demonstrated significant success in airfoil development, their broader application to grounded vehicle aerodynamics remains unexplored. This research investigates the effectiveness of trapped vortex cavity (TVC) technology in both active and passive flow controls, applied to a NACA0012 airfoil and an inverted three-element airfoil from a Formula 1 model. The investigation is conducted using numerical methods to evaluate the aerodynamic performance and potential of TVC in this paper. In the single-airfoil case, a circular cavity is placed along the trailing edge (TE) on the suction surface; for the three-element airfoils, the cavity is positioned on each airfoil to determine the optimum location. The results show that the presence of a cavity, particularly
Ng, Ming KinTeschner, Tom-Robin
Automotive signal processing is dealt with in several contributions that propose various techniques to make the most out of the available data, typically for enhancing safety, comfort, or performance. Specifically, the accurate estimation of tire–road interaction forces is of high interest in the automotive world. A few years ago the T.R.I.C.K. tool was developed, featuring a vehicle model processing experimental data, collected through various vehicle sensors, to compute several relevant virtual telemetry channels, including interaction forces and slip indices. Following years of further development in collaboration with motorsport companies, this article presents T.R.I.C.K. 2.0, a thoroughly renewed version of the tool. Besides a number of important improvements of the original tool, including, e.g., the effect of the limited slip differential, T.R.I.C.K. 2.0 features the ability to exploit advanced sensors typically used in motorsport, including laser sensors, potentiometers, and
Napolitano Dell’Annunziata, GuidoFarroni, FlavioTimpone, FrancescoLenzo, Basilio
As the automotive industry increasingly shifts toward electrification, reducing vehicle drag becomes crucial for enhancing battery range and meeting consumer expectations. Additionally, recent regulations such as WLTP can require car manufacturers to provide reliable drag data for vehicles as they are configured, as is the case in Europe. Vehicle and tire manufacturers can assess tire impacts on vehicle performance through testing. However, to improve designs, it is essential to identify which tire features influence the flow field and overall vehicle performance. Physical tests measure tire behavior under load, but isolating contact patch and tire bulge effects is difficult, as both change together. Simulation allows independent analysis of these factors—something that physical testing alone cannot achieve. This paper investigates the aerodynamic impact of realistic tire deformation parameters—specifically, bulge and contact patch deformations—using PowerFLOW® from Dassault Systèmes
Martinez Navarro, AlejandroParenti, GuidoShock, Richard
Emerging zero-emission-powertrain concepts are providing opportunities to re-shape heavy trucks for improved aerodynamic performance. To investigate the potential for energy savings through aerodynamic improvements, with a goal to inform operators and regulators of such benefits, a multi-phase project was initiated to design and evaluate aerodynamic improvements for Class 8 tractor-trailer combinations. While the focus was battery-electric and hydrogen-fuel-cell powered trucks, improvements for internal-combustion powered trucks were also examined. Previously-reported activities 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 a new aerodynamic tractor concept, with comparison to a conventional North American Class 8 tractor with a modern
Ghorbanishohrat, FaeghehMcAuliffe, BrianO'Reilly, Harrison
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, KatlynnBest, ScottNasr Esfahani, VahidSenft, VictorStevenson, StuartWittmeier, Felix
In this study, the aerodynamics and surface flow field of a 1/5 scale SUV vehicle model called “AeroSUV” were experimentally investigated. The aerodynamics and surface flow field investigations were carried out in the wind tunnel at Hiroshima University with a Reynolds number ReL = 1.2×106, 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 surface 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 surface 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
Hijikuro, MasatoShimizu, KeigoNakashima, TakujiHiraoka, Takenori
Understanding the formation and behaviour of sprays and aerosols generated by vehicles traveling on wet surfaces is crucial due to their impact on vehicle soiling, visibility, and autonomous driving. These sprays and 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 critical importance of understanding the physical properties of these sprays and aerosols for the testing and validation of sensors used in environmental perception and recognition, field data on this subject remains limited. The formation and behaviour of these sprays and 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 wheel houses and other surfaces, resulting in either coalescence or further
Otxoterena, PaulKallhammer, Jan-ErikEriksson, PeterRonelov, Erik
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, JaiSoares, Renan F.
With the increasing prevalence of electric vehicles (EVs), decreasing vehicle drag is of upmost importance, 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 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 coast-down testing. The following study implements a singular wind-averaged drag (WAD) coefficient which is derived from a 3-point yaw curve to show the impact of yaw 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 where the ambient wind generally produces a few degrees of yaw
Kaminski, MeghanD'Hooge, AndrewBorton, Zackery
In this work, a modified Ahmed body with both upsweep and downsweep was used to create a complex wake. The time-averaged streamline topology revealed that the wake was composed primarily of a torus past the vertical base and two pairs of streamwise-oriented vortices on the upper and lower slant edges. Several vortex identification methods including three-dimensional (3D) (Q−, λ2−, Ω−criteria, and Liutex method) and two-dimensional (2D) (Γ1−criterion) methods were compared to determine the effectiveness in identifying complex wake structures. Of the 3D methods analyzed, none produced wholly satisfactory results. The Q− and λ2−criteria were plagued by well noted issues; failing to separate shear from rotation and threshold sensitivity which led to inconsistently identifying the weaker torus. The Ω−criterion addressed all of these concerns, especially identifying the torus consistently. However, the identified torus structure did not reflect the physical structure observed using the
Aultman, MatthewDuan, Lian
In traffic scenarios, the spacing between vehicles plays a key 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 vehicles
Mosavati, MaziarGuzman, ArturoLounsberry, ToddFadler, Gregory
The natural wind experienced on public roads can increase the yaw angle and therefore drag coefficient (CD), which may contribute to the discrepancy between catalog fuel economy and actual fuel economy. 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. 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 theoretical calculations for the impact of yaw angle on fuel economy
Onishi, YasuyukiNichols, LarryMetka, Mattmasumitsu, YasutakaInoue, Taisuke
Novel experimental and analytical methods were developed with the objective of improving the reliability and repeatability of coast-down test results. The methods were applied to coast-down tests of a SUV and a tractor-trailer combination, for which aerodynamic wind-tunnel data were available for comparison. The rationale was to minimize the number of unknowns in the equation of motion by measuring rolling and mechanical resistances and wheel-axle moments of inertia, which was achieved using novel experimental techniques and conventional rotating-drum tests. This led to new modelling functions for the rolling and mechanical resistances in the equation of motion, which was solved by regression analysis. The resulting aerodynamic drag coefficient was closer to its wind-tunnel counterpart, and the predicted low-speed road load was closer to direct measurements, than the results obtained using conventional methods. It is anticipated that applying the novel techniques to characterize the
Tanguay, Bernardde Souza, Fenella
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, FlorianDalvi, AshwiniFlad, DavidSharkey, Patrick
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 that includes all appropriate bearing and power transmission system design parameters. During the assembly process, some of the parameters related to the roller positions cannot be controlled. These parameters include the actual position of the first roller compared to the vertical axis, the relative position of the rollers between the bearing rows, and others. This work presents a sensitivity analysis of the effects of those uncontrollable parameters on the analytical model. The sensitivity study determines the percentage change
Gruzwalski, DavidMynderse, James
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 non-linearly with vehicle 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 aerodynamic load is significantly less than that of the 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 non-linearity’s: the nonlinear
Patil, HarshvardhanWilliams, Daniel
As global warming and environmental problems are becoming more serious, tires are required to achieve a high level of performance trade-offs, such as low rolling resistance, wet braking performance, driving stability, and ride comfort, while minimizing wear, noise, and weight. However, predicting tire wear life, which is influenced by both vehicle and tire characteristics, is technically challenging so practical prediction method has long been awaited. Therefore, we propose an experimental-based tire wear life prediction method using measured tire characteristics and the wear volume formula of polymer materials. This method achieves practical accuracy for use in the early stages of vehicle development without the need for time-consuming and costly real vehicle tests. However, the need for improved quietness and compliance with dust regulations due to vehicle electrification requires more accuracy, leading to an increase in cases requiring judgment through real vehicle tests. To address
Ando, Takashi
This paper is a continuation of a previous effort to evaluate the post-impact motion of vehicles with high rotational velocity within various vehicle dynamic simulation softwares. To complete this goal, this paper utilizes a design of experiments (DOE) method. The previous papers analyzed four vehicle dynamic simulation software programs; 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 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. A total of 32 trials were conducted which analyzed ten factors. Aerodynamics, a factor included in the previous DOE, was not included within this DOE because it does not exist within Virtual Crash. The same three response variables from the previous DOE were measured to determine
Roberts, JuliusCivitanova, NicholasStegemann, JacobBuzdygon, DavidThobe, Keith
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 multi-discipline 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°C and 38°C ambient conditions
Zhou, ShuaiLiu, HuaijuYu, HuiliYan, XuYan, Junjie
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 investigation aimed at assessing energy reduction in 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 conducted 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 two sets of L4 capable light duty vehicles, including the Stellantis Pacifica PHEV minivan and Stellantis RAM Truck, examined in various lead and following vehicle
Poovalappil, AmanRobare, AndrewSchexnaydre, LoganSanthosh, PruthwirajBahramgiri, MojtabaBos, Jeremy P.Chen, BoNaber, JeffreyRobinette, Darrell
For Formula SAE 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 downforce 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
Yang, Chengyue
As automotive technology advances, the need for comprehensive environmental awareness becomes increasingly critical for vehicle safety and efficiency. This study introduces a novel integrated wind, weather, and motion sensor designed for moving objects, with a focus on automotive applications. The sensor’s potential to enhance vehicle performance by providing real-time data on local atmospheric conditions is investigated. The research employs a combination of sensor design, vehicle integration, and field-testing methodologies. Findings prove the sensor’s capability to accurately capture dynamic environmental parameters, including wind speed and direction, temperature, and humidity. The integration of this sensor system shows promise in improving vehicle stability, optimizing fuel efficiency through adaptive aerodynamics, and enhancing the performance of autonomous driving systems. Furthermore, the study explores the potential of this technology in contributing to connected vehicle
Feichtinger, Christoph Simon
The lateral dynamic and kinematic models of the electric towbarless towing vehicle (TLTV)–aircraft system, incorporating active front steering for the TLTV, are formulated to evaluate the impact of crosswind on the aircraft’s towing trajectory. This analysis considers scenarios with varying towing velocities and crosswind directions and intensities. To mitigate crosswind-induced disturbances affecting the aircraft’s motion, A high-speed and low-speed Model Predictive Control (MPC) strategy for the active front steering of a TLTV is proposed. This strategy is designed to optimize the TLTV’s steering performance under varying operational conditions, addressing the distinct dynamic characteristics of high-speed and low-speed towing scenarios. Simulation results demonstrate that the proposed control method achieves exceptional performance in both speed regulation and path tracking during towing operations.
Zhu, HengjiaBai, ZehaoXu, YitongZhang, Wei
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
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 CFD derived drag and lift coefficients for different road vehicle shapes and simple bodies tested in a closed wall tunnel with a wide range of blockage ratios has become available and provides some additional insight into the blockage phenomenon. In this paper a process is developed to derive the parameters influencing wind tunnel blockage corrections from CFD data. These are shown to be reasonably effective for correcting the measured drag and lift coefficients at blockage ratios up to 10%.
Howell, JeffButcher, DanielGleason, Mark
In order to manage the serious global environmental problems, the automobile industry is rapidly shifting to electric vehicles (EVs) which have a heavier weight and a more rearward weight distribution. To secure the handling and stability of such vehicles, understanding of the fundamental principles of vehicle dynamics is inevitable for designing their performance. Although vehicle dynamics primarily concerns planar motion, the accompanying roll motion also influences this planar motion as well as the driver's subjective evaluation. This roll motion has long been discussed through various parameter studies, and so on. However, there is very few research that treats vehicle sprung mass behavior as “vibration modes”, and this perspective has long been an unexplored area of vehicle dynamics. In this report, we propose a method to analytically extract the vibration modes of the sprung mass by applying modal analysis techniques to the governing equations of vehicle handling and stability
Kusaka, KaoruYuhara, Takahiro
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 commercial vehicles 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 modern 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 energy use, and potential savings thereof, from implementing various fleet configurations for different operational duty cycles. An energy-use analysis was implemented to estimate the energy-rate contributions associated
McAuliffe, BrianGhorbanishohrat, Faegheh
The Guangzhou Automotive Group Co., Ltd (GAC Group) wind tunnel, located in Guangzhou, China, is a state-of-the-art facility that uniquely integrates world-class aerodynamic flow quality, acoustic capability, and thermal conditions into a single system for the development of passenger vehicles. This closed return, ¾ open jet wind tunnel features a nozzle with a cross-section of 20 m2 and a 2.5 MW fan, capable of delivering a maximum wind speed of 200 km/h. The wind tunnel is equipped with a ±90° turntable, a boundary layer control system, and a 5-belt moving ground plane system for aerodynamic tests. Comprehensive acoustic treatments in the test section and throughout the wind tunnel circuit establish a hemi-anechoic test environment with minimal background noise levels for acoustic tests. For thermal tests, the wind tunnel includes a 4-wheel chassis dynamometer system downstream of the turntable, with temperature control ranging from 20°C to 60°C and humidity control between 15% and
Bender, TrevorNasr Esfahani, VahidLiu, ZhengYang, HuiLi, ShuyaSong, XinLiu, ManMa, Zhijian
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 preload setting 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 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 that includes
Gruzwalski, DavidMynderse, James
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
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 pose an engineering challenge during vehicle development. Vehicles that exhibit bimodal wake behavior need to have their drag values recorded over a sufficient time period to take into account the low frequency shift in drag signal, therefore, simulating such vehicle configurations in CFD could consume substantial CPU hours resulting in an expensive and inefficient vehicle design iterations process. As an alternative approach to running simulations for long periods of time, the impact of adding artificial turbulence to the inlet on wake behavior and its potential impact on reduced runtime for design process is investigated in this study. By adding turbulence to the upstream flow, the wake
DeMeo, MichaelParenti, GuidoMartinez Navarro, AlejandroShock, RichardFougere, NicolasRazi, PooyanOliveira, DaniloLindsey, CraigYu, ChenxingBreglia Sales, Flavio
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 three bodies that generate large wakes to examine the interference phenomena in solid wall wind tunnels and the effects that they have 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 0.4% to 14% blockage enabling an approximation of free air conditions as a reference
Gleason, MarkRiegel, Eugen
With increasing attention to complex aerodynamic conditions such as crosswinds, gusts, road turbulence, and vehicle drafting, 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 empty wind tunnel, and wind tunnel with static and dynamic active turbulence generation system, the mechanisms underlying these
Jia, QingQin, LanweiZhao, CivilWang, YikunXia, ChaoYang, ZhigangWei, Huanxia
This paper introduces a new approach for measuring changes in drag force across different vehicle configurations using an on-road testing technique. The method involves fixing the vehicle’s power across configurations and then measuring the resulting speed differences. A detailed formulation is provided on how these speed variations can be used to calculate the change in drag force for each configuration. The OBD II port is used to access and record additional data necessary for the calculations. The method is applied to both a passenger car and a commercial van to evaluate drag changes for different vehicle add-ons. A roof sign was installed at various positions along the roof of the vehicles to assess drag increases, while novel rear appendages were fitted to both vehicles to evaluate the resulting drag reductions. Detailed CFD simulations were performed on the road-tested configurations to compare the simulated drag changes with those measured on the road. Excellent agreement was
Connolly, Michael GerardIvankovic, AlojzO'Rourke, Malachy J.
As the first pure electric flagship sedan under the Geely Galaxy brand, a challenging aerodynamic target was set at the early stage of Geely Galaxy E8 for reducing electric power consumption and improving vehicle range. In response, the aerodynamic team formulated a detailed development plan and an overall drag reduction strategy. After conducting numerous loops of simulations and wind tunnel tests, along with continuous cross-disciplinary communication and collaboration, a product with outstanding aerodynamic performance was successfully developed. During the aerodynamic development of the E8, the primarily utilized steady-state simulations sometimes revealed significant discrepancies when compared to wind tunnel test results, particularly in schemes such as the air curtain, aerodynamic rims, and rear light feature optimizations. Some trends were even contradictory. Further investigations demonstrated that unsteady simulation methods captured different flow field information
Li, QiangLiu, HuanYang, TianjunLiang, ChangqiuZhu, ZhenyingLiao, Huihong
The research presented in this paper proposes an effective numerical approach based on computational fluid dynamics (CFD) to analyze the flow structure around the Formula 1 rear wing. The study investigates the influence of endplates on the flow behavior and aerodynamic attributes of the wing. Additionally, it examines the implementation of louvers and cutouts to manipulate the interaction of multiple vortices, thereby mitigating the strength of primary wingtip vortices and the consequent induced drag. Three-dimensional steady-state computations were conducted using the ANSYS® commercial suite. The FLUENT™ solver, employing Reynolds-averaged Navier–Stokes (RANS) equations modeled with a two-equation shear stress transport (SST) k-ω turbulence model, was utilized for the analysis. Post-processing and visualization of the flow field in the near wake region downstream of the rear wing were performed using Tecplot®. Validation of the turbulence model was achieved through the quasi-3D NACA
Kalsi, Mandeep SinghJoshi, Upendra Kumar
From humble Chevrolet Bolts to six-figure Lucid Airs, every EV can reverse its electric motors to slow the vehicle while harvesting energy for the battery, the efficient tag-team process known as regenerative braking. Today's EVs do this so well that traditional friction brakes, which clamp onto a spinning wheel rotor or drum, can seem an afterthought. Witness Volkswagen's decision to equip its ID.4 with old-fashioned rear drum brakes, with VW claiming drums reduce EV rolling resistance and offer superior performance after long periods of disuse.
Ulrich, Lawrence
This work deals with computational investigations of the component performances of Advanced Hexacopters under various maneuverings of the focused mission profiles. The Advanced Hexacopter is a kind of multirotor vehicle that contains more propellers and flexible arms, which makes this multirotor very maneuverable and aerodynamically efficient. This Hexacopter was designed specifically to execute multi-perspective applications along with enhanced payload-carrying capability. This Advanced Hexacopter contains a frame composed of modified arms equipped with coaxial rotors, which servo motors control. By providing specific and simple inputs to the microcontroller, the Hexacopter can autonomously undergo forward and backward maneuverings. The primary objective of this study is to analyze and compare different propeller configurational clearance sets that improve the maneuvering capability of this unmanned aerial vehicle (UAV), specifically emphasizing forward/backward and side maneuvering
Raja, VijayanandhNarayanan, SidharthElangovan, LogeshArumugam, LokeshSourirajan, LaxanaRaji, Arul PrakashKulandaiyappan, Naveen KumarGnanasekaran, Raj KumarMadasamy, Senthil Kumar
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 PriyadharshiniRajendran, MahendranArumugam, ManikandanRaji, Arul PrakashSakthivel, PradeshStanislaus Arputharaj, BeenaL, NatrayanGanesan, BalajiRaja, Vijayanandh
The paper present numerical effects of supercritical airfoil SC (2) 0414 having circular cavities at three different chord wise locations from leading to trailing edge. Here passive control method is widely applied by altering the \baseline airfoil surface coordinates to ascertain the aerodynamic behavior of the cavity at 40 %, 50 % and 60 % of the chord length respectively. The cavity shapes were deformed using Bezier curve to observe vortex pattern in the cavity region. Structured meshing was employed. The analysis was performed on SC 2 (0) 414 two-dimensional airfoil using commercial CFD ANSYS Fluent software where Spalart- Allmaras 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 150) at Mach number 0.85. The study highlights the aerodynamic characteristics of lifting coefficient, drag coefficient and lift to drag ratio. It was observed that the cavity in suction surface
Pushparaj, Catherine VictoriaP, Booma DeviD, PiriadarshaniGanesan, BalajiGanesan, Santhosh KumarRaja, Vijayanandh
The thermoelectric generator system is regarded as an advanced technology for recovering waste heat from automotive exhaust. To address the issue of uneven temperature distribution within the heat exchanger that limits the output performance of the system, this study designs a novel thermoelectric generation system integrated with turbulence enhancers. This configuration aims to enhance convective heat transfer at the rear end of the heat exchanger and improve overall temperature uniformity. A multiphysics coupled model is established to evaluate the impact of the turbulence enhancers on the system's temperature distribution and electrical output, comparing its performance with that of traditional systems. The findings indicate that the integration of turbulence enhancers significantly increases the heat transfer rate and temperature uniformity at the rear end of the heat exchanger. However, it also leads to an increase in exhaust back pressure, which negatively affects system
Chen, JieDing, RenkaiWang, RuochenLiu, WeiLuo, Ding
Current work details the preliminary CFD analysis performed on custom-built race car by Team Sakthi Racing team as part of Formula SAE competition using OpenFOAM. The body of the race car is designed in compliance with FSAE regulations, OpenFOAM utilities and solvers are used to generate volumetric mesh and perform CFD analysis. Formula student tracks are typically designed with numerous sharp turns and a few long straights to maintain low speeds for safety. In order to enhance the cars’ performance in sharp turns, the race car should be equipped with aerodynamic devices like nose cone and wings on both the rear and front ends within the confines of the formula student racing rules. Thus, efficient aerodynamic design is highly critical to maximizing tire grip by ensuring consistent contact with the track, reducing the risk of skidding, and maintaining control, especially during high-speed maneuvers. In this work, the performance and behavior of the race car, both with and without the
Rangarajan, KishorePushpananthan, BlesscinAnumolu, LakshmanSelvakumar, KumareshJayakumar, Shyam Sundar
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
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, NarendraOlcmen, SemihKolhe, Pankaj
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 PedreiraBraga, Sérgio Leal
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 FabianTerra, Rafael Tedim
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