Browse Topic: Motorsports

Items (134)
CAD-Based Optimization of a Race Car Front Wing2020-01-06244/14/2020
The aerodynamics of the front wing of modern race cars are critical to the performance of the vehicle. The Formula 1 line up represents the state of the art in this field as there are some very complex aerodynamic designs on display. It is strange, however, that there is no agreement on twist direction for the multiple wing sections of the front wing. This paper addresses this question by posing it as an optimization problem. The geometry of the wings has been simplified so that the twist of the upper sections could be studied in isolation. The whole assembly consisted of only two high lift surfaces. The forward wing remained fixed for the study, and twist of the secondary wing became the primary focus. Its geometry was generated by lofting a set of cross-sections at specified angles to create the surface. The resulting geometry was automatically meshed and then evaluated using CFD. This fully automated process was then used to find an ideal twist distribution of the secondary wing. The results show that a higher angle of attack at the tip of the wing produces superior aerodynamic performance. One of the advantages of this approach is that the final output of the process will be a CAD geometry, as opposed to a modified FEM. It avoids a manual step of putting the results back into CAD before being able to share the optimal geometry with other design teams. By removing a manual step, it makes it possible to integrate this method with other disciplines such as structural analysis and enable MDO.
Tolchinsky, IlyaCarrigan, TravisDawson, Joshua
Chevy reveals 2020 Corvette Stingray convertible, C8.R racer19AUTP11_1411/1/2019
Reinforcing the Corvette's long association with astronauts, Chevrolet unveiled the convertible version of its all-new, mid-engine-layout 2020 Corvette Stingray in Cape Canaveral in early October. Executive chief engineer Tadge Juechter, underscoring the car's no-compromises performance and comparatively affordable price, called it a “no-lose proposition” for enthusiasts considering the new Corvette but also desiring a more open-top experience. When it goes into production in the first quarter of 2020, the Corvette Stingray convertible will start at $67,495 - $7,500 more than the 2020 Stingray coupe, which was widely celebrated for its aggressive $59,995 base price. Although called a convertible, there is no fabric to be seen: the 2020 Corvette Stingray convertible uses a folding-hardtop design in which the center roof section folds in two pieces and stores above the rear-mounted engine. From some angles the new Corvette convertible will be difficult to distinguish from the standard Stingray coupe, even with the roof open. The giveaway is the glass rear hatch on the coupe that exposes the engine to view. The convertible does without this glass cover, but uses an upright section of glass behind the driver flanked by pronounced buttresses. The bodywork covering the engine is solid, with a rear-opening section that more closely resembles a conventional trunk.
Visnic, Bill
Using Computational Fluid Dynamics for the Design, Assessment and Optimization of an Aerodynamic Body Kit on a Newly Designed Formula SAE Collegiate Competition Vehicle2019-01-06424/2/2019
Formula SAE Collegiate Competition teams now regularly integrate aerodynamic body kits with their vehicles which have significant benefits in producing downforce. This use of body kits (or aero packages) and the improvement to vehicle aerodynamics they provide, have resulted in these systems becoming a necessity for any team wishing to remain competitive in Formula SAE (FSAE). To address this the Lawrence Technological University (LTU) Formula SAE team incorporated an aerodynamic body kit into their 2018 vehicle. Using computational fluid dynamics (CFD) an aerodynamic analysis was performed comparing the efficacy of a car that did not have an aero package to a car that did. Two separate simulation programs were employed to effectively and accurately assess this change. By using both SolidWorks and SimScale software to generate data, the results of each were compared to assess the accuracy of each. These programs were selected due to their accessibility to engineering students, as well as their parent companies being LTU Formula SAE team sponsors. Simulations were run under different conditions to determine the optimal design of the aero package, as well as to understand how the body kit performed at different velocities. It is expected that the approaches used and understanding gained from this initial effort will serve as a foundational body-of-knowledge for future LTU teams. Those LTU teams each year will be able to modify and refine these now-available CFD tools to assess and optimize their aero package for each new vehicle they design and build annually.
Alemara, MohammedMcCann, MorganFletcher, RobertAl-Qarishey, HusseinFine, Joshua
Design of High-Lift Airfoil for Formula Student Race Car02-12-01-000212/5/2018
A two-dimensional model of three elements, high-lift airfoil, was designed at a Reynolds number of 106 using computational fluid dynamics (CFD) to generate downforce with good lift-to-drag efficiency for a formula student open-wheel race car basing on the nominal track speeds. The numerical solver uses the Reynolds-averaged Navier-Stokes (RANS) equation model coupled with the Langtry-Menter four-equation transition shear stress transport (SST) turbulence model. Such model adds two further equations to the k − ω SST model resulting in an accurate prediction for the amount of flow separation due to adverse pressure gradient in low Reynolds number flow. The k − ω SST model includes the transport effects into the eddy-viscosity formulation, whereas the two equations of transition momentum thickness Reynolds number and intermittency should further consider transition effects at low Reynolds number. Starting with a baseline design using the understanding of high-lift airfoils, all elements were arranged using an Eppler E421 profile. The lift coefficient was improved by varying the flaps’ overlaps, gaps, and deflection angles sequentially, thus testing 31 rigging combinations. Finally, these data were plotted to choose the best rigging in terms of maximum lift coefficient and to better understand the sensitivity of lift and drag coefficients to these parameters. Lift coefficient improved by 8.9% compared to the baseline design. It was also found that the lift coefficient increased 5.9 times when compared to a single-element Eppler E421 airfoil.
Mahgoub, Abdelrahman IbrahimEl-Zaabalawy, HashimAboelsoud, WalidAbdelaziz, Mohamed
Methodical Selection of Sustainable Fuels for High Performance Racing Engines2018-01-17499/10/2018
As the importance of sustainability increases and dominates the powertrain development within the automotive sector, this issue has to be addressed in motorsports as well. The development of sustainable high-performance fuels defined for the use in motorsports offers technical and environmental potential with the possibility to increase the sustainability of motorsports at the same or even a better performance level. At the moment race cars are predominantly powered by fossil fuels. However due to the emerging shift regarding the focus of the regulations towards high efficient powertrains during the last years the further development of the used fuels gained in importance. Moreover during the last decades a huge variety of sustainable fuels emerged that offer a range of different characteristics and that are produced based on waste materials or carbon dioxide. This study investigates the question of which sustainable fuels offer the characteristics suitable for high-performance race engines. Equivalents to gasoline, diesel and natural gas are examined separately in order to present the options with various engine concepts. The requirements for a high-performance fuel are defined based on experimental investigations emphasizing among other characteristics the importance of the knock resistance for gasoline-like fuels and the ignitability for diesel-like fuels. Furthermore the characteristics of the sustainable alternatives are analyzed. On the basis of the experimental results a comparison is carried out to match the fuel requirements with the characteristics and to select the optimal equivalent for fossil gasoline, diesel and natural gas. Moreover the sustainable fuels are evaluated with an environmental analysis including the fuel life cycle. The results show a potential to reduce the greenhouse gas emissions per mega joule energy content by up to 88%. This research assesses the broad variety of sustainable biologic and synthetic fuels concerning the potential use in motorsports and the resulting environmental benefits.
Schwarz, LeaBargende, MichaelDreyer, StefanBaretzky, UlrichKotauschek, WolfgangWohlgemuth, SebastianBach, Florian
Control Optimization of a Charge Sustaining Hybrid Powertrain for Motorsports2018-01-04164/3/2018
The automotive industry is aggressively pursuing fuel efficiency improvements through hybridization of production vehicles, and there are an increasing number of racing series adopting similar architectures to maintain relevance with current passenger car trends. Hybrid powertrains offer both performance and fuel economy benefits in a motorsport setting, but they greatly increase control complexity and add additional degrees of freedom to the design optimization process. The increased complexity creates opportunity for performance gains, but simulation based tools are necessary since hybrid powertrain design and control strategies are closely coupled and their optimal interactions are not straightforward to predict. One optimization-related advantage that motorsports applications have over production vehicles is that the power demand of circuit racing has strong repeatability due to the nature of the track and the professional skill-level of the driver. The repeatable behavior from lap to lap allows for the efficient utilization of dynamic programming (DP) techniques to optimize vehicle speed and power management for a given race track, which is the focus of this research. The DP strategy is derived and described in detail using a hybrid rallycross vehicle as an example. The DP strategy minimizes lap time while sustaining battery charge at the end of each lap. Constraints on engine torque, electric motor power, battery capacity and tire friction are incorporated into the proposed strategy. The DP also generates an execution map that can be used for real-time on-vehicle implementation. This map includes optimal vehicle speed and power management strategies for all possible situations that the vehicle can experience during the real racing event.
Zhu, QilunSong, ShixinTan, XiaopingSong, ChuanxuePrucka, Robert
The Effect of Inlet Turbulence Specifications on the RANS CFD Predictions of a NASCAR Gen-6 Racecar2018-01-07364/3/2018
Turbulence modeling and the specific boundary conditions are among the two major simulation physics setup variables that affect the prediction veracity of a CFD simulation. The existing literature is rich with studies investigating the effect of the inlet boundary conditions on the predictability of a CFD simulation, and it is recognized that the turbulence characteristics of the freestream flow, viz. the turbulence intensity and length scale, can impact the simulation results significantly, even with the same turbulence model. However, none of these studies encompasses the significance of these two boundary specifications on the CFD analysis of a realistic racecar model. Against this backdrop, the purpose of this study is to systematically investigate the effect of different freestream turbulence specifications on the CFD predictions of the aerodynamic characteristics of a latest generation NASCAR Cup racecar model. Finite volume CFD simulations are carried out with: (a) five turbulence intensities of 0.1%, 0.5%, 1%, 5%, and 10% with a fixed turbulence length scale of 1 mm to examine the effect of the inlet turbulence intensity variability, and (b) five turbulence length scales, ranging from 0.1 mm to 10 mm, with a fixed turbulence intensity of 0.5% to evaluate the effect of turbulence length scales. This study reveals that the effects resulting from the choice of these two parameters are confined to their smaller values, as the Cup racecar aero characteristics tend to be independent of the freestream specifications at larger values of these two variables. Although one could expect very large values of either of these two parameters on a racetrack, these large values are too high and unrealistic in a wind-tunnel environment.
Fu, ChenUddin, MesbahSelent, Christian
On the Aerodynamics of an Enclosed-Wheel Racing Car: An Assessment and Proposal of Add-On Devices for a Fourth, High-Performance Configuration of the DrivAer Model2018-01-07254/3/2018
A modern benchmark for passenger cars - DrivAer model - has provided significant contributions to aerodynamics-related topics in automotive engineering, where three categories of passenger cars have been successfully represented. However, a reference model for high-performance car configurations has not been considered appropriately yet. Technical knowledge in motorsport is also restricted due to competitiveness in performance, reputation and commercial gains. The consequence is a shortage of open-access material to be used as technical references for either motorsport community or academic research purposes. In this paper, a parametric assessment of race car aerodynamic devices are presented into four groups of studies. These are: (i) forebody strakes (dive planes), (ii) front bumper splitter, (iii) rear-end spoiler, and (iv) underbody diffuser. The simplified design of these add-ons focuses on the main parameters (such as length, position, or incidence), leading to easier manufacturing for experiments and implementation in computational studies. Consequently, a proposed model aims to address enclosed-wheel racing car categories, adapting a simplified, 35% scaled-model DrivAer Fastback shape (i.e. smooth underbody, no wheels, and with side mirrors). Experimental data were obtained at the 8 ft x 6 ft Cranfield Wind Tunnel using an internal balance for force and moment measurements. The aerodynamic performance of each group of add-on was assessed individually in a range of ride heights over a moving belt. All cases represent the vehicle at a zero-yaw condition, Reynolds number (car length-based) of 4.2 × 106 and Mach number equal to 0.12. The proposed high-performance configuration (DrivAer hp-F) was tested and a respective Reynolds number dependency study is also provided. In line with the open-access concept of the DrivAer model, the CAD geometry and experimental data will be made available online to the international community to support independent studies.
Soares, Renan FranciscoKnowles, AndrewGoñalons Olives, SergioGarry, KevinHolt, Jennifer
Computational Investigations on the Aerodynamics of a Generic Car Model in Proximity to a Side-Wall2018-01-07044/3/2018
This paper discusses a realistic approach of simulating a generic idealized car model (Ahmed body) moving in close proximity to a Side-wall using transient CFD. This phenomenon is very important in motorsports where racing very close to the safety barrier is very common. Driving in close proximity to a Side-wall alters the aerodynamic characteristics of the vehicle significantly, however, only a handful of published work exists in this area. Additionally, the experimental studies conducted in the past suffer from certain inadequacies especially in properly emulating the Side-wall, which cast some uncertainty as to their applicability to the real world. As such, the present study attempted to imitate the real world flow phenomenon by taking a non-traditional CFD approach in which the body is translated relative to the stationary surrounding fluid and Side-wall instead of the classical method of flowing air over a stationary object. This was achieved by using a newer meshing technique for overlapping grids called the “Overset” or “Chimera” mesh. The initial challenging task was to predict accurately the flow over the rear slant of the 25o slant angle Ahmed body model where previous studies struggled to achieve accurate enough predictions using the eddy-viscosity turbulence models. In the present study, the SST turbulence model with modified closure coefficients is utilized to accurately predict flow characteristics in the initial separated shear layer and, as well as, the flow reattachment over the rear slant. Compared to the eddy viscosity CFD simulations of an isolated 25-degree slant angle Ahmed body seen in existing literature, the results presented in this paper show significantly better correlations with the experiments in terms of overall aerodynamic characteristics, like drag and lift, and flow characteristics like pressure and velocity in the wake region. The wall proximity studies show a strong influence of the presence of the wall on the overall aerodynamic characteristics of vehicle body. When compared with the experimental studies, although both show similar trends, however, there exist significant differences between the experimental and CFD predicted results, which tend to worsen as one approaches the wall. These differences can be attributed to the fact that the CFD emulation of the flow around the side-wall is more realistic compared to the experimental implementation.
Uddin, MesbahMallapragada, SrivatsaMisar, Adit
Virtual Optimization of Race Engines Through an Extended Quasi Steady State Lap Time Simulation Approach2018-01-05874/3/2018
Minimizing the lap time for a given race track is the main target in racecar development. In order to achieve the highest possible performance of the vehicle configuration the mutual interaction at the level of assemblies and components requires a balance between the advantages and disadvantages for each design decision. Especially the major shift in the focus of racecar powerunit development to high efficiency powertrains is driving a development of lean boosted and rightsized engines. In terms of dynamic engine behavior the time delay from requested to provided torque could influence the lap time performance. Therefore, solely maximizing the full load behavior objective is insufficient to achieve minimal lap time. By means of continuous predictive virtual methods throughout the whole development process, the influence on lap time by dynamic power lags, e.g. caused by the boost system, can be recognized efficiently even in the early concept phase. As a first step, this paper presents a novel method that combines detailed 1D (one dimensional) gas dynamic engine models with the quasi steady state (QSS) lap time method. This allows for a predictive comprehension of lap time influence for different engine design parameters with the possibility to operate in an environment of detailed description of vehicle dynamics. Moreover, the direct application of 1D-CFD (computational fluid dynamics) engine models also increases the efficiency of the used virtual engineering tools. In a second step, this paper gives an insight into a model supported development process of a lean boosted 4-cylinder race engine. An evaluation of the model’s predictive capabilities and a sensitivity study of basic boost system parameters are also part of this publication.
Malcher, SimonBargende, MichaelGrill, MichaelBaretzky, UlrichDiel, HartmutWohlgemuth, Sebastian
A Feasibility Study on Driver Model Based Lap Time Simulation Using Genetic Algorithms2017-01-96795/18/2017
Lap time simulation has always been a topic of interest in the automotive industry as it summarizes the whole dynamic performance of an automobile in a single value. During the development of road and race cars, to avoid expensive testing and to prove different design solutions, it is useful to simulate the maximum performance of the vehicles. The cars are driven to their limits to exploit their capabilities, where their dynamic behaviour can be highly non-linear. The vehicle models need to replicate these characteristics as precisely as possible. Due to this, the problem of achieving the minimum lap time with a certain car around a race track is a challenging problem to solve. A method to evaluate the minimum lap time is presented, approaching the optimal solution by coupling a driver model, a simulation environment and genetic algorithms to perform the optimization. The algorithm also offers the possibility to add vehicle parameters to be optimized regarding the lap time. The process can be adapted to different vehicle, track and driver models. Not being limited to a single simulation environment, the high flexibility of this method allows it to work with diverse software. The optimization algorithm uses a newly developed penalty function to improve the convergence and accuracy. Real tests on a race track have been performed to assess the correlations between the measurements and the suggested method, revealing its high accuracy.
Irlinger, FranzBaleato Varela, Alvaro
Analysis of Underhood Temperature Fields using Linear Superposition2017-01-01383/28/2017
The analysis of thermal fields in the underhood region is complicated by the complex geometry and the influence of a multitude of different heat sources. This complexity means that running full CFD analyses to predict the thermal field in this region is both computationally expensive and time consuming. A method of predicting the thermal field using linear superposition has been developed in order to analyse the underhood region of a simplified Formula One race car, though the technique is applicable to all vehicles. The use of linear superposition allows accurate predictions of the thermal field within a complex geometry for varying boundary conditions with negligible computational costs once the initial characterisation CFD has been run. A quarter scale, rear end model of a Formula One race car with a simplified internal assembly is considered for analysis, though the technique can also be applied to commercial and industrial vehicles. Different parts of the internal assembly are used as heat sources in order to simulate the thermal boundary conditions of a real-world underhood zone. The method utilises a combination of initial CFD analyses and subsequent post-processing within MATLAB in order to rapidly predict the thermal field under varying boundary conditions. Predictions of the thermal field using linear superposition are generated in under a second for a six million node domain. These predictions are compared to CFD analyses with the same explicit boundary conditions, which represent the current industry design methodology for thermal management strategy. Comparisons between the methods are presented for varying thermal boundary conditions and are extended to varying inlet boundary conditions using additional scaling factors. Current limitations of this approach and recommendations for future development are also discussed.
Lim, ChrisIreland, PeterCollett, Nicholas
Turbulence Models and Model Closure Coefficients Sensitivity of NASCAR Racecar RANS CFD Aerodynamic Predictions2017-01-15473/28/2017
Cost benefit and teraflop restrictions imposed by racing sanctioning bodies make steady-state RANS CFD simulation a widely accepted first approximation tool for aerodynamics evaluations in motorsports, in spite of its limitations. Research involving generic and simplified vehicle bodies has shown that the veracity of aerodynamic CFD predictions strongly depends on the turbulence model being used. Also, the ability of a turbulence model to accurately predict aerodynamic characteristics can be vehicle shape dependent as well. Modifications to the turbulence model coefficients in some of the models have the potential to improve the predictive capability for a particular vehicle shape. This paper presents a systematic study of turbulence modeling effects on the prediction of aerodynamic characteristics of a NASCAR Gen-6 Cup racecar. Steady-state RANS simulations are completed using a commercial CFD package, STAR-CCM+, from CD-Adapco. Three turbulence models are included in this study: the realizable and AKN variants of the k − ε model, and the SST k − ω model. The a1 coefficient for the SST k − ω model is slightly modified in order to investigate the sensitivity of this modeling constant on the veracity of predictions. The aerodynamic characteristics investigated include the force and moment coefficients, and front-to-rear downforce balance. In addition, the turbulence model dependence of the flow around the vehicle, particularly at some key locations in the wake region, will be analyzed. Although the flow features in the wake of this racecar show a discernable dependence on the choice of the turbulence model, this difference did not translate into a significant difference in the prediction of force coefficients.
Fu, ChenUddin, MesbahRobinson, ClayGuzman, ArturoBailey, David
The Development of a Small Restricted Turbocharged Racecar Engine2016-32-006111/8/2016
This paper summarized the development methodology and technical experiences on Formula Student racecar engines acquired by Jilin University from 2011 to 2015. This series of engines are all based on 600cc 4-cylinder motorcycle gasoline engines and were modified to turbocharged engines which met the Formula Student technical regulations, in order to achieve higher power output, wider torque band as well as lower fuel consumption. During the development process, multiple research projects have been conducted surrounding the turbocharging technology. These research projects have covered multiple areas including the matching of the flow rate characteristics of the engine and the turbocharger, the design of intake and exhaust systems, research on the wastegate as well as its actuator, the tuning and control of the boost pressure as well as the design of the lubrication system for the turbocharger, etc. The utilized research methods included 1D CFD engine performance analysis, 3D CFD fluid analysis as well as the engine dyno test. The experiment and analysis results showed that, the developed engine, with the installation of a 20mm intake restrictor, was able to retain over 95% of the maximum power output of the stock engine while having a maximum torque output of 130% of the stock engine. In the meantime, the minimum BSFC at WOT was reduced by 15%. The turbocharger worked smoothly with the lubricant ideally sealed, all of which satisfied the comprehensive requirements of a Formula Student engine.
Wang, DaQian, DingchaoWang, Bo
Integrated Aero-Thermal Testing of a Race Car in a Full Scale Climatic Wind Tunnel2016-01-15884/5/2016
Wind tunnels with integrated aerodynamic and thermodynamic testing with yaw capabilities are not common. In this study however, an integrated aerodynamic and thermodynamic testing system with yaw capabilities is developed and applied in the climatic wind tunnel at the University of Ontario-Institute of Technology (UOIT). This was done by installing an incremental force measuring system (FMS) on the large turntable that features a chassis dynamometer. The testing system was utilized to implement an integrated aero-thermal test on a full-scale race car. An efficient testing protocol was developed to streamline the integrated testing process. The FMS was used to enhance the test car’s stability, cornering speed, and fuel efficiency by using aerodynamic devices. These objectives were achieved by installing a high rear wing to increase the rear downforce, a modified front splitter extension to produce a front downforce gain, and front canards to contribute to drag reduction. In addition, a thermodynamic test was conducted to study the effect of yaw on upperbody and underbody temperature distribution during the car’s operational condition. Temperature analysis from this test revealed that radiator performance was jeopardized in yaw. It also showed that some aerodynamic devices (such as a rear diffuser) can contribute negatively to the underbody cooling performance of the car. The implications of this study demonstrate that the climatic wind tunnel at UOIT is a viable tool for integrated motorsport testing, which can be used to achieve a significant competitive advantage.
Abdel-Rahman, AbdallaAgelin-Chaab, MartinElfstrom, GaryKomar, John
The New Interchangeable Three-belt System in the IVK Full-Scale Wind Tunnel of University of Stuttgart: Design and First Results2016-01-15814/5/2016
With its recent wind tunnel upgrade, FKFS installed the first interchangeable three-belt / five-belt-system (FKFS first®) in a full scale automotive wind tunnel. With the five-belt system, which today is a state-of-the-art ground simulation technique, the system is ideally suited for production vehicle development work. The five-belt system offers high flexibility, quick access to the underfloor and vehicle fixation, and setting the vehicle’s ride height by the restraint device. The first results of the five-belt system have already been published in SAE 2015-01-1557 [1]. The three-belt system on the other hand, offers a much more sophisticated ground simulation technique which is necessary especially for sports and racing cars. For such vehicles with very low ground clearances, it is important to have a more accurate ground simulation, in order to capture the same aerodynamic modes of action and response as on the road. In difference to a single belt system, the measurement of forces on the three-belt system is more accurate, since the center belt is not part of the balance system. This results in a lower static balance load and smaller parasitic forces. This paper describes the design of the interchangeable three-belt / five-belt system and presents first results for different vehicles including passenger cars and race cars.
Wittmeier, FelixMichelbach, ArminWiedemann, JochenSenft, Victor
Spoilers Optimization to Reduce the Induced Stresses on a Racing Helmet2016-01-16124/5/2016
Aerodynamics is one of the most important factors in the development of racing cars. At the speeds of formula cars reach the formula cars, the driver's neck can be subjected to stresses resulting from the aerodynamic forces acting on the helmet; developing an aerodynamic project that takes into account the comfort of the driver without affecting performance is certainly considered a challenging activity. The aim of the present work is to develop a low-pitching-momenthelmet for formula racing cars optimizing the shape and location, applying some aerodynamic appendices. This goal is pursued by adopting an approach based on both experimental and numerical activities. First, the aerodynamic configuration of an existing helmet was examined; through a testing campaign in the wind tunnel facilities of Perugia University, pressures acting on the helmet were scanned at various speeds and data about aerodynamic drag were collected. Flow visualization methods were even performed to locate the separation of the fluid flow from the helmet. Based on experimental results a validated mathematical model of the helmet was implemented to perform numerical analysis using the CFD/3D package Star-CCM+. The model was used to analyze the configuration of the flow around the helmet in the actual case that the helmet is inserted in the formula vehicle. Finally, a CFD/3D optimization was set up to obtain geometry optimization of the appendices of the helmet, as a function of the proposed target. All the steady state CFD analysis was carried out using the k-ω RANS turbulent model.
Mariani, FrancescoRisi, FrancescoBartolini, NicolaCastellani, FrancescoScappaticci, Lorenzo
Technology Choices for Optimizing the Performance of Racing Vehicles2016-01-11734/5/2016
In the continuous search for technology to improve the fuel economy and reduce greenhouse gas emission levels from the automotive vehicle, the automotive industry has been evaluating various technological options. Since the introduction of stringent legislative targets in Europe as well as in the United States of America in late 20th Century, one of the viable options identified by the industry was the application of alternative powertrain. On the motorsport arena, changes introduced by the Formula 1 governing body (FIA) for the high-performance racing engines also focuses on fuel economy. FIA regulation for 2014 restricts the fuel-flow rate to a maximum of 100kg/hr beyond 10,500 rev/min and prescribe fuel flow rate below 10,500 rev/min operating conditions for the F1 Engines. In addition, Formula1 and Le Mans racing regulations actively promote the integration of the hybrid powertrain in order to achieve optimum fuel economy. Therefore, the aim of the present work is to evaluate available technology choices and measure efficiency in terms of fuel consumption and CO2 emission level. This technology mining exercise has been carried out using a powertrain simulation tool based on a mid-size light duty vehicle. The benchmark powertrain architecture for a light-duty vehicle is based on legislative drive cycle. The technologies tested on the drive cycles are also to be tested in a racing prototype car (LMP1), around a lap at Le Mans Circuit. This report presents a systematic methodology for assessing technology choices for racing vehicle using powertrain simulation tool. It presents a merit matrix based on fuel economy, drive cycle energy analysis, to evaluate the powertrain ability to harvest the available energy on a given drive cycle.
Bengolea, FedericoSamuel, Stephen
CFD Investigation of the Effect of the Salient Flow Features in the Wake of a Generic Open-Wheel Race Car2015-01-15394/14/2015
It is well known that in motorsport the wake from an upstream vehicle can be detrimental to the handling characteristics of a following vehicle, in particular in formulae with high levels of downforce. Previous investigations have been performed to characterize the wake from an open wheel race car and its effect on a following car, either through the use of multiple vehicles or purpose-built wake generators. This study investigates how the wake of an upstream race car impacts the aerodynamic performance of a following car in a close-following scenario. Wakes are imposed on the inlet of a CFD simulation and wake parameters (eg: velocity deficit, trailing vorticity) are directly manipulated to investigate their individual impacts on the following vehicle. The approach provides a useful alternative to the simulation of multi-vehicle cases but a better simulation could be achieved by including wake unsteadiness from the upstream vehicle. Arguably the most significant impact of a wake on the following vehicle was found to be the rearward movement of the vehicle center of pressure. Secondary flow (eg: upwash, vorticity) on a bulk scale had the beneficial impact of moving the wake up and over the following vehicle but more localized impacts could be positive or negative according to the detailed interaction with downstream vehicle features.
Newbon, JoshuaDominy, RobertSims-Williams, David
New FKFS Technology at the Full-Scale Aeroacoustic Wind Tunnel of University of Stuttgart2015-01-15574/14/2015
For many years FKFS has operated the full-scale aeroacoustic wind tunnel of University of Stuttgart. To keep this wind tunnel as one of the most modern ones of its kind, it has again been upgraded significantly. The upgrade improved the aerodynamic as well as the aeroacoustic performance and accelerated the operational processes. Additionally, new innovative features have significantly enlarged the test capabilities. A new patented, modular belt system (FKFS first®) allows high performance measurements for race cars in a 3-belt mode as well as efficient measurements for production vehicle development in a 5-belt mode. The belt system is accompanied by a new, larger turntable and a new under-floor balance which enables high-accuracy measurements of forces and moments also for a high resolution in time. For the elimination of parasitic forces generated at the wheel drive units, a specific correction procedure has been implemented, which is patented, too (FKFS pace®). A new type of boundary layer conditioning system rounds up the enhanced road simulation. Unsteady aerodynamics can be investigated by means of a unique, active side wind generator (FKFS swing®). It consists of 8 wing-like profiles with independent drives which can deflect the whole airflow around the car in the test section with a frequency of up to 10 Hz. This system can also be used for unsteady aeroacoustics. The acoustic performance of the wind tunnel has been improved mainly by acoustic linings in the first diffuser. Special patented profiles in the nozzle (FKFS besst®) and a Helmholtz resonator suppress low frequency pulsations of the open jet very efficiently. The profiles also reduce the high-frequency broad-band noise of the wind tunnel.
Blumrich, ReinhardWiddecke, NilsWiedemann, JochenMichelbach, ArminWittmeier, FelixBeland, Oliver
Formula SAE Frame Torsional Stiffness Study using FEA2014-36-02349/30/2014
The Formula SAE competition has the purpose to stimulate the engineering students to work in teams to develop a concept, design and build small racing vehicles. In this competition, students are motivated to build a high performance car, reliable and with low development cost. The success of the team in the competition is determined with a detailed analysis of all aspects involved. Considering the frame development, some key points must be considered for the structural performance: stiffness, durability, modal and safety response. This papers focus on the stiffness analysis to verify if the frame torsional stiffness is compatible with the respective suspension for the level of performance required. The study was performed using the frame of 2012 Formula SAE from Instituto Mauá de Tecnologia using beam elements to model the frame structure in a FEA (Finite Elements Model) software to simulate the system stiffness. The vehicle mass and CG properties to support the studies were obtained in laboratory measurements. The FEA calculated frame torsional stiffness was then compared to the suspension stiffness using analytical methods, making it possible to assess the compatibility between the frame and the suspension. This compatibility was checked in terms of an objective criteria based on the comparison of the roll stiffness distribution versus lateral load transfer distribution. Finally, these results led to the correct identification of the balance between the stiffness values of the frame and suspension for the vehicle proposed, allowing potential improvements for the frame structure in terms of mass and cost.
Costa, João Augusto daVilela, Daniel
Simulation Considerations for Commercial Vehicles in Strong Crosswind Conditions2014-01-24529/30/2014
Aerodynamic testing of heavy commercial vehicles is of increasing interest as demands for dramatically improved fuel economy take hold. Various challenges which compromise the fidelity of wind tunnel simulations must be overcome in order for the full potential of sophisticated aerodynamic treatments to be realized; three are addressed herein. First, a limited number of wind tunnels are available for testing of this class of vehicle at large scales. The authors suggest that facilities developed for large or full-scale testing of race cars may be an important resource. Second, ground simulation in wind tunnels has led to the development of Moving Ground Plane (MGP, aka Rolling Road (RR)) systems of various types. Questions arise as to the behavior of MGP/RR systems with vehicles at large yaw angles. It can actually be deduced that complete simulation of crosswind conditions on an open road in a wind tunnel may be impractical. This is due to the fact that the atmospheric crosswind develops a deep boundary layer profile, such that the resultant inflow seen by the moving vehicle is effectively curved. Finally, prevailing methods of boundary corrections for automotive testing have focused largely on drag, with reasonably symmetric flow fields. Relatively long vehicles at large yaw angles develop highly asymmetric flow fields, so more complex boundary correction methods need to be developed. Although computational simulation of real-world conditions (i.e. with crosswind) may seem to be a little easier, various options need to be carefully explored for best results.
Britcher, ColinMokhtar, WaelWay, Stephen
ASURT Formula Student Brake Design2014-01-24879/28/2014
The Braking System is the most crucial part of the racing vehicle. There is no doubt, that if only one minority failure in the braking system took place, this would be more than enough reason to cause the racing team disqualification from the competition. Time is the main and the most important criteria for any racing competition; on the other hand the formula student “FS UK SAE” competition care the most about developing the automotive engineering sense in the students by putting them under strict rules normally taken from the original version “formula 1” to encourage their creativity to reach the optimum performance under these strict rules. One of the most important rules is “No Braking by wire”, and the obvious consequences are more stopping distance and time. Braking distance is a critical facture in achieving racing success in a competitive domain. This report will cover using the bias bar, dynamic weight distribution “before and after braking” and carefully choosing the braking and suspension system components dimensions, in order to fulfill the main functions of “ABS and EBD” which are preventing the wheels from lock-up and preventing side skid of the vehicle during cornering in the different dynamic tests with full consideration of the maximum approachable deceleration of the vehicle without locking up without using any kind of electronic “actuators or control”. Mathematical model “Matlab” and Physical model “AME SIM” will be used to support the report's results.
Barakat, Mohamed Samy
Design, Analysis, and Simulation of an Automotive Carbon Fiber Monocoque Chassis2014-01-10524/1/2014
While many composite monocoque and semi-monocoque chassis have been built there is very little open literature on how to design one. This paper considers a variety of issues related to composite monocoque design of an automotive chassis with particular emphasis on designing a Formula SAE or other race car monocoque chassis. The main deformation modes and loads considered are longitudinal torsion, local bending around mounting points, and vertical bending. The paper first considers the design of elements of an isotropic material monocoque that has satisfactory torsional, hardpoint, and vertical bending stiffness. The isotropic analysis is used to gain insight and acquire knowledge about the behavior of shells and monocoque structures when subjected to a vehicle's applied loads. The isotropic modeling is then used to set initial design targets for a full anisotropic composite analysis. The flexibility in composite layout and core design coupled with the superior material properties of carbon fiber composites is used to design and move toward an optimized monocoque composite design and layup to obtain satisfactory torsional, hardpoint and bending stiffnesses with minimal weight. Finally, some fatigue analysis considerations are outlined with emphasis on the endurance limit of the monocoque for a specific life span. The methods presented in this paper should be helpful in designing a monocoque structure chassis for FSAE race car or other applications.
Wu, JingsiAgyeman Badu, OwusuTai, YonchenGeorge, Albert R.
Powertrain Model for Selection of Reduction Ratio and Estimation of Energy Requirement2014-01-17814/1/2014
This paper presents a mathematical model of an electric driveline consisting of one battery pack, two independent Permanent Magnet DC (PMDC) motors and motor-controllers and two fixed-ratio planetary gearboxes, all located inside the rear frame of the vehicle. The proposed analysis has been performed with the objective of: (i) Determination of acceleration run time for a straight patch of 75 meters; (ii) Determination of lap times and energy consumption for endurance track of 23 laps. A model of a PMDC motor and motor controller has been developed based on response analysis by conducting experiments on a jig setup. The motor controllers are compared for two control modes- Speed mode and Torque mode. A simplified race car model for longitudinal vehicle dynamics is derived from forces acting on the car including the effect of losses due to drag forces, rolling resistance, transmission inefficiency and inertial losses due to rotary elements. The effect of reduction ratio on acceleration run times and endurance lap times and energy consumption is compared and an optimum gear ratio is finalized considering acceleration performance and mass and inertia of resulting gearbox. An estimate of maximum energy utilized during the endurance run is obtained based on motor current profile and speed-torque characteristics, and the battery pack size and configuration is decided accordingly. The cells for the battery pack have been selected after extensive market research based on constraints like energy requirement, weight and maintenance cost. This concludes the entire mathematical model for the driveline of the vehicle pertaining to the most optimized performance.
Sakhalkar, SiddheshDhillon, ParveenBakshi, SoovadeepKumar, PranayArora, Puneet Singh
Implementation of an Electronic Differential Using Torque Vectoring2014-01-17764/1/2014
This paper involves the study of implementation of an active electronic differential using torque vectoring in an electric rear wheel drive vehicle. The proposed system works in a closed loop taking feedback in real time from sensors which provides inputs for steering angle, throttle position, angular velocity of wheels, yaw rate, yaw acceleration, longitudinal acceleration and lateral acceleration. The objective of this system is to i) increase the stability and the vehicle response to the driver while turning, and ii) use the traction available on the driven wheels more efficiently. The system involves applying a torque difference between the rear driven tires to create a moment about the centre of mass that causes yaw acceleration and aids in turning the car by increasing yaw rate. The effect of drag forces and the lateral forces on the tires have been included. An optimized desired moment is calculated which is applied via torque difference while turning. A Permanent Magnet DC (PMDC) motor model and a model for the motor controller in torque mode have been developed based on experimental response analysis on a jig setup. A detailed race car model for longitudinal vehicle dynamics is derived from forces acting on the car including the effect of losses due to drag forces, rolling resistance, transmission inefficiency and inertial losses. To validate the proposed system, various throttle profiles and steering inputs are simulated on the vehicle model during a turn. The results are compared to the case when vehicle is turning without using torque differential.
Sakhalkar, SiddheshDhillon, ParveenKumar, PranayBakshi, SoovadeepArora, Puneet Singh
The Effect of Upstream Turbulence on an Exposed Wheel Wake2014-01-06164/1/2014
As open-wheeled racing cars frequently race in close proximity, a limiting factor on the ability to overtake is the aerodynamic performance of the vehicle while operating in a leading car's wake. Whilst various studies have examined the effectiveness of wings operating in turbulent flow, there has been limited research undertaken on the aerodynamic effect of such conditions on wheels. This study describes the influence of upstream turbulence on the wake flow features of an isolated wheel, since the flow field of a wheel will generally be turbulent (due to the wakes of upstream cars and/or bodywork). Pressure distributions and velocity vector plots are examined, which were obtained using a four-hole pressure-sensitive Cobra probe on a traverse 2.5 diameters downstream of the wheel axle line, in smooth and turbulent flow. This analysis also compares the effect of upstream turbulence on the wake for the rotating and stationary wheel; as well as investigating the sensitivity of the wake to the wheel-to-road gap in smooth and turbulent flow. The study found that, at 2.5 diameters downstream, the overall wake width of the stationary wheel decreased with increased levels of turbulence, it also showed that the effect on the wake of increasing the wheel-to-road gap was independent of the level of turbulence in the flow. Both rotating and stationary wheel wake maps also displayed a higher minimum pressure with nominally turbulent flow, than those displayed by the corresponding wake maps with nominally smooth flow, and a much more gradual transition to free-stream pressure.
James, Matthew R.Watkins, SimonWatts, Matthew
Physical Modeling and Simulation Analysis of an Advanced Automotive Racing Shock Absorber using the 1D Simulation Tool AMESim2013-01-01684/8/2013
Shock absorbers are crucial components of a vehicle's chassis, responsible for the trade-off between stability, handling, and passenger comfort. Their role is to filter the disturbances imposed to the vehicle body, typically by passive energy dissipation through hydraulic oil. The aim of this research paper is to investigate the physical behavior of an advanced automotive racing shock absorber, known as TTR, developed by Öhlins Racing AB. This goal is achieved by developing a detailed lumped parameter numerical model of the entire TTR suspension in the 1D simulation tool, AMESim. TTR features a through-rod piston design, fully adjustable high and low speed compression and rebound adjusters, and a gas reservoir. The developed numerical model is capable of capturing the physics behind the real shock absorber damping characteristics, under both static and dynamic conditions. In particular, the model is presented in two levels of progressive physical complexity, in order to improve the numerical predictions of dynamic damping characteristics. Several physical phenomena are considered, such as the dynamics of the hydraulic volumes, the static and viscous frictions and the pressure-induced elastic deformation of the solid boundaries. Model validation is discussed, based on different types of measurements for both the individual hydraulic components and the entire shock absorber model. The coupled hydraulic and mechanical modeling together with the measurement comparisons, thoroughly discussed in the paper, allows discovering the influence of each single component on the shock absorber static and dynamic performance.
Sadeghi Reineh, MaryamPelosi, Matteo
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