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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
Published 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, an industry where a large volume of simulations and short development cycles are constantly demanded. However, a well-known flaw of the RANS methodology is its inability to properly characterize the separated and wake flow associated with complex automotive geometries using the existing turbulence models. 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 modeling transport equations most times influence 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 different closure coefficients in the SST k − ω model,…
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Advanced Connector Technologies: From Aerospace to Racecars to Robots

  • Magazine Article
  • TBMG-33713
Published 2019-02-01 by Tech Briefs Media Group in United States

Different types of motion encountered in dynamic environments require designers to specify connectors for boards, wiring, and devices that can meet significant g-forces, vibrations, and weight challenges. Advanced connectors designed to handle dynamic forces were introduced in the 1970s to meet the needs of aerospace applications. In the early 1990s, the extreme speed and vibration in Formula One, NASCAR, Indycar, and Le Mans cars inspired the development of advanced interconnection solutions for autosports.


Mahle MJI technology sparking ignition advances

Automotive Engineering: July/August 2019

Stuart Birch
  • Magazine Article
  • 19AUTP08_07
Published 2019-01-01 by SAE International in United States

Engine-development supplier Mahle believes pre-chamber combustion technology for production gasoline engines has a promising future.

Any technology transfer between the racetrack and the road is usually a one-way street, with motor racing leading and humble production machinery way back on the innovative grid. But just occasionally, there is a role reversal-and Mahle Powertrain demonstrates it with its pre-chamber Jet Ignition (MJI) system.

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EDITORIAL: The future of motorsports is…quiet

Automotive Engineering: July/August 2019

Editor-in-Chief-Lindsay Brooke
  • Magazine Article
  • 19AUTP08_09
Published 2019-01-01 by SAE International in United States

Perched up on jackstands, its fat Michelin-shod wheels removed, the Audi e-tron FE05 looks like a multicolored shark out of water. Mechanics are swirling around this battery-electric race car, preparing it for a practice session during the Brooklyn E-Prix-the final race of the 2019 FIA Formula E championship season in New York.

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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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Prototype Powertrain in Motorsport Endurance Racing

West Virginia Univ.-Alberto Boretti
  • Progress In Technology (PT)
  • PT-185
Published 2018-08-01 by SAE International in United States
Racing continues to be the singular, preeminent source of powertrain development for automakers worldwide. Engineering teams rely on motorsports for the latest prototype testing and research. Endurance racing provides the harshest and most illuminating stage for system design validation of any motorsport competition. While advancements throughout the 20th Century brought about dramatic increases in engine power output, the latest developments from endurance racing may be more impactful for fuel efficiency improvements. Hybrid powertrains are a critical area of research for automakers and are being tested on the toughest of scales. Prototype Powertrain in Motorsport Endurance Racing brings together ten vital SAE technical papers and SAE Automotive Engineering magazine articles surrounding the advancements of hybrid powertrains in motorsports. The book also includes a history of endurance racing from the World Sports Car Championship through the 24 Hours of Le Mans to the World Endurance Championship written by the author. The goal is to provide the latest concepts being researched and tested on hybrid systems that will influence vehicles for years to come - appealing to engineers…
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Control Optimization of a Charge Sustaining Hybrid Powertrain for Motorsports

Clemson University-Qilun Zhu, Robert Prucka
Jilin Province Education Association-Xiaoping Tan
Published 2018-04-03 by SAE International in United States
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…
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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 Model

Cranfield University-Renan Francisco Soares, Andrew Knowles, Sergio Goñalons Olives, Kevin Garry, Jennifer Holt
Published 2018-04-03 by SAE International in United States
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…
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Computational Investigations on the Aerodynamics of a Generic Car Model in Proximity to a Side-Wall

UNC Charlotte Motorsports Engineering-Mesbah Uddin, Srivatsa Mallapragada, Adit Misar
Published 2018-04-03 by SAE International in United States
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…
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Light Reconnaissance Vehicle

  • Magazine Article
  • TBMG-28397
Published 2018-02-01 by Tech Briefs Media Group in United States

Supacat Honiton, Devon, UK 01 404 891 777