This content is not included in
your SAE MOBILUS subscription, or you are not logged in.
Development of Aerodynamic Drag Reduction around Rear Wheel
Technical Paper
2021-01-0962
ISSN: 0148-7191, e-ISSN: 2688-3627
Annotation ability available
Sector:
Event:
SAE WCX Digital Summit
Language:
English
Abstract
Due to new CO2 regulations and increasing demand for improved fuel economy, reducing aerodynamic drag has become more critical. Aerodynamic drag at the rear of the vehicle accounts for approximately 40% of overall aerodynamic drag due to low base pressure in the wake region. Many studies have focused on the wake region structure and shown that drag reduction modifications such as boattailing the rear end and sharpening the rear edges of the vehicle are effective. Despite optimization using such modifications, recent improvements in the aerodynamic drag coefficient (Cd) seem to have plateaued. One reason for this is the fact that vehicle design is oriented toward style and practicality. Hence, maintaining flexibility of design is crucial to the development of further drag reduction modifications.
The purpose of this study was to devise a modification to reduce rear drag without imposing additional design restrictions on the upper body. First, the modification concept was devised using CFD analysis focusing on the air flow around the rear wheel. The concept is to guide the underfloor flow toward the rear wheel inboard side to reduce the size of the vehicle wake region from the underfloor center region. Then, a production Prius was modified to verify the actual modification developed from the concept in the wind tunnel. The air flow channel toward the rear wheel inboard region was expanded by adding a cut-out to the undercover at the side of fuel tank to derive the desired flow. The force and total pressure distribution of the underfloor region behind the vehicle were measured in a wind tunnel for cases with and without the modification applied to verify its effect. The modification exhibited the desired effect of expanding the high total pressure region at the underfloor center, and a reduction in drag was confirmed.
Recommended Content
Technical Paper | Aerodynamic Shape Optimization of a Container-Truck's Wind Deflector Using Approximate Model |
Technical Paper | A CFD Validation Study for Automotive Aerodynamics |
Technical Paper | Further Investigations on Gradient Effects |
Authors
Topic
Citation
Higuchi, H., Hirabayashi, H., and Kondo, T., "Development of Aerodynamic Drag Reduction around Rear Wheel," SAE Technical Paper 2021-01-0962, 2021, https://doi.org/10.4271/2021-01-0962.Also In
References
- Littlewood , R. , Passmore , M. , and Wood , D. An Investigation into the Wake Structure of Square Back Vehicles and the Effect of Structure Modification on Resultant Vehicle Forces SAE Technical Paper 2011-37-0015 2011 https://doi.org/10.4271/2011-37-0015
- Sterken , L. , Sebben , S. , Walker , T. , and Lofdahl , L. Experimental and Numerical Investigations of the Base Wake on an SUV SAE Technical Paper 2013-01-0464 2013 https://doi.org/10.4271/2013-01-0464
- Bajpai , D. and Regin , F. Aerodynamic Design Optimization in Rear End of a Hatchback Passenger Vehicle SAE Technical Paper 2019-01-1430 2019 https://doi.org/10.4271/2019-01-1430
- Tadatsu , M. , Yamamura , J. , Tanaka , H. , Yasuki , T. et al. A Study on Aerodynamic Drag Reduction of Two-Box Car Transactions of JSAE 43 4 935 942 2012 10.11351/jsaeronbun.43.935
- Terakado , S. , Makihara , T. , and Maeda , K. A Study of Vehicle Wake Structure for Drag Reduction Proceedings of 2015 JSAE Spring Convention 5349 78-15S 1860 1865 2015
- Hucho , W. Aerodynamics of Road Vehicles Warrendale, PA SAE International 1998 978-0-7680-0029-0
- Tadakuma , K. , Sugiyama , T. , Maeda , K. , and Iyota , M. Development of Full-Scale Wind Tunnel for Enhancement of Vehicle Aerodynamic and Aero-Acoustic Performance SAE Int. J. Passeng. Cars - Mech. Syst. 7 2 603 616 2014 https://doi.org/10.4271/2014-01-0598