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Developing a Track Simulation Tool for Formula Student Race Cars using Python

Ain Shams University-Sherif Khedr, Hashim Elzaabalawy, Mohamed Abdelaziz
  • Technical Paper
  • 2019-01-1128
To be published on 2019-04-02 by SAE International in United States
Formula Student is a competition held on yearly basis in multiple countries around the world. Students from different universities participate in this competition implementing some of the most sophisticated techniques in design and analysis of Formula Student car performance. In this research a track simulation tool is developed to analyze the effect of different systems on the car performance, and to test the performance of the car on the Autocross track. The car is modeled as point mass in straight roads and corners. Intensive studies were carried out leading to the conclusion that, in some cases, point mass modeling leads to some inaccuracy and in others it provides the solution. Therefore, to reach more accurate solutions, the point mass model was replaced with the four degrees of freedom, or “bicycle”, model counterpart, and the difference between both models results are discussed. The results also showed how an unrealistic tire model, which might be used for simulation simplicity, will lead to unrealistic results. The bias ratio selected for the brake system versus human force applied on…

Evaluation of Ecosystem for Design Assessment and Verification by BAJA Dynamometer Capstone Team at the University of Nebraska

Imagars LLC; Portland State University-Baldur Steingrimsson
Portland State University-Bao Phan, Sung Yi
  • Technical Paper
  • 2019-01-0812
To be published on 2019-04-02 by SAE International in United States
This paper summarizes the outcome of an evaluation by capstone design teams from the Department of Mechanical and Materials Engineering at the University of Nebraska, Lincoln, of the Ecosystem for Team Design and Assessment. The Ecosystem is a design decision support tool whose main goal is to identify design oversights early in the design process, guide designers through the design process, and teach proper design techniques. It is capable of automatically assessing students’ design work against ABET compliant learning outcomes. The Ecosystem offers many additional features found useful by capstone design teams, such as automatic generation of formatted project reports as well as interfaces to tools for team communications (Google Drive, Dropbox or OneDrive) or development (e.g., SolidWorks, CATIA, NX Unigraphics or AutoCAD). The Ecosystem was recently evaluated by a capstone team working on an automated straw flattening machine and again during a following semester by a team designing a dynamometer used for measuring the engine power of a BAJA race car. The paper draws upon the improvements of the Ecosystem software completed during the…

Increasing the aerodynamic performance of a Formula Student race car by means of active flow control

TU Berlin (Technical University)-Ben Steinfurth, Arne Berthold, Steffen Feldhus, Frank Haucke, Julien Weiss
  • Technical Paper
  • 2019-01-0652
To be published on 2019-04-02 by SAE International in United States
This article involves an experimental study regarding the capability of fluidic actuators to increase the aerodynamic performance of a four-element race car rear wing. Sweeping jet actuators are integrated in the upper flap, of which the angle of attack is increased by up to Δα_F3=40° with reference to a passively optimized setup. Different velocities of the emitted sweeping jets are applied to study the influence of momentum coefficients c_μ=0.04,…,0.98 %. To prove the general feasibility of the approach, the separate rear wing is assessed first before implications on a realistic race car model are investigated inside a large-scale wind tunnel. Employing particle image velocimetry, flow visualization techniques as well as pressure and force measurements, we show that the velocity field on the suction side of the upper flap is characterized by flow separation of different degrees when the angle of attack is increased beyond Δα_F3=20° (rear wing only) and Δα_F3=30° (complete race car). Generally, the employed fluidic devices have a positive impact for all of the investigated angle of attack modifications in terms of the…

A Study of an Energy-Enhanced Multi-Spark Ignition System in a Constant-Volume Combustion Chamber

Shanghai Jiao Tong Univ-Min Xu
Shanghai Jiao Tong University-Chang ye
  • Technical Paper
  • 2019-01-0728
To be published on 2019-04-02 by SAE International in United States
Multi-spark ignition is widely used in high-speed internal combustion engines such as racing cars, motorcycles and outboard motors in attempts to overcome the long charging duration. But under lean fuel or strong turbulence conditions, due to the limited spark duration, some applications are too short to provide reliable ignition events. In order to extend the ignitability limit and reduce the combustion variation, an energy enhanced high-frequency multi-spark ignition system is developed in this study. The principle of this ignition system is based on the capacitor discharge, it can generate 5-20kHz high-frequency high-energy ignitions. Firstly, the circuit structure design and control strategy of the proposed ignition system is presented. Secondly, the discharge curve and ignition energy are measured and analyzed. Finally, by means of high-speed photography technology, detailed experiments are investigated by using the direct image and shadowgraph methods simultaneously comparing with traditional multi-spark ignition system in the constant-volume combustion chamber. Results show that the energy-enhanced multi-spark ignition system can increase ignition success probability and extend lean burn limit effectively.

Improving the Michigan Tech Formula SAE Design Process

Michigan Technological University-James De Clerck, Austin Arenz
PARTsolutions, LLC-Timothy Thomas
  • Technical Paper
  • 2019-01-0807
To be published on 2019-04-02 by SAE International in United States
Michigan Tech Formula SAE is a student-led team that designs and builds an open-wheel race car to compete with similar teams from other universities in early May each year. The team has adopted a vehicle development process where the design, build, and test/compete phases happen in consecutive years. This process is motivated by the need to perform validation testing in the fall prior to competition due to Houghton winters lingering well into April. In order to compete every year, all three phases are always in-process to ensure the consecutive completion vehicles. As a student organization, Formula SAE membership has a two to three year turnover rate. This limited organizational memory results in redesign rather than re-use of parts. Simple parts are easier to re-model than manually search a directory structure for an existing design. This redundant work is wasted effort and is often results in repeating poor design features that had been improved by previous team members. Michigan Tech Formula SAE has worked with PARTsolutions to implement a CAD database to enable easy access to…

Numerical Analysis of Underbody Diffusers with Different Angles and Channels

CATARC-Xuelong Liu, Qinglu Chen
Jilin University-Jie Tian, Yingchao Zhang
  • Technical Paper
  • 2019-01-0668
To be published on 2019-04-02 by SAE International in United States
The basic structure of large-scale commercial vehicles (such as bus) is roughly bluff body and will produce high aerodynamic drag and aerodynamic lift at high speed. Among them, the wake structure contributes more to aerodynamic drag, and the bottom pressure distribution contributes more to aerodynamic lift. The installation of diffuser at the bottom of the vehicle can increase the speed of the airflow passing through the bottom of the vehicle, thereby reducing the pressure on the bottom of the vehicle body. Then the downforce will be increased the vehicle stability wil be improved. The diffuser was first used in racing cars and later gradually applied to passenger cars. In this paper, the CFD simulation method is used to study the aerodynamic characteristics of the bus under different diffuser inlet and outlet angles, and then an optimal inlet and outlet angle is determined based on the simulation results. Then, using this angle as a constant, the 2, 3, and 4 channel numbers were chosen as the diffuser channel variables to study the influence of the multiple-channel…

Fine tuning the SST k-ω turbulence model closure coefficients for improved NASCAR Cup racecar aerodynamic predictions

University of North Carolina-Chen Fu, Charles Bounds, Mesbah Uddin, Christian Selent
  • Technical Paper
  • 2019-01-0641
To be published on 2019-04-02 by SAE International in United States
Faster turn-around times and cost-effectiveness make the Reynolds Averaged Navier-Stokes (RANS) simulation approach still a widely utilized tool in racecar aerodynamic development where a large volume of simulations and short development cycles are constantly demanded. However, a well-known flaw of the RANS methodology, its inability to properly characterize the separated and wake flow associated with complex automotive geometries using the existing turbulence models, is still the root cause of this method’s poor of prediction veracity; experience suggests that this limitation cannot be overcome by simply refining the meshing schemes alone. Some earlier researches have shown that the closure coefficients involved in the RANS turbulence model transport equations usually influences the simulation prediction results. The current study explores the possibility of improving the performance of the SST k-ω turbulence model, one of the most popular turbulence models in motorsports aerodynamic applications, by re-evaluating the values of certain model closure constants. A detailed full-scale current generation NASCAR Cup racecar was used for the investigation. The simulations were run using a commercial CFD package STAR-CCM+ (version 13.04.010). Five…

Safety and Lateral Dynamics Improvement of a Race Car Using Active Rear Wing Control

University of Ontario Institute of Technology-Mohammed Hammad, Khizar Qureshi, Yuping He
  • Technical Paper
  • 2019-01-0643
To be published on 2019-04-02 by SAE International in United States
As the forward speed of a race car increases, the safety of the vehicle and the driver becomes of a significant concern. Active aerodynamic control can effectively enhance the lateral stability of race cars over tight cornering maneuvers. A split rear wing has been proposed in this regard. By means of manipulating the attack angles for the right and left parts of the split rear wing, a favorable yaw moment may be achieved to ensure the lateral stability of the vehicle. However, active control of the split rear wing has not been adequately explored. This paper proposes a novel active split rear wing, which can improve the lateral stability over tight cornering maneuvers, and will not degrade the longitudinal dynamics of the vehicle. A LQR-based controller for the active split rear wing is designed using a linear vehicle model. In order to examine the performance of the active split rear wing, co-simulation is carried out by combining the LQR-based controller designed in Matlab and a high fidelity vehicle model generated in CarSim. The effectiveness of…

Design of High-Lift Airfoil for Formula Student Race Car

Ain Shams University, Egypt-Abdelrahman Ibrahim Mahgoub, Hashim El-Zaabalawy, Walid Aboelsoud, Mohamed Abdelaziz
  • Journal Article
  • 02-12-01-0002
Published 2018-12-05 by SAE International in United States
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…
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Methodical Selection of Sustainable Fuels for High Performance Racing Engines

Audi AG-Stefan Dreyer, Ulrich Baretzky, Wolfgang Kotauschek, Sebastian Wohlgemuth, Florian Bach
Universitat Stuttgart-Michael Bargende
Published 2018-09-10 by SAE International in United States
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…
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