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Aerodynamic Load Maps of Vehicle Shapes at Arbitrary Attitude
Technical Paper
2015-01-2574
ISSN: 0148-7191, e-ISSN: 2688-3627
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English
Abstract
The interest in flying cars comes with the question of characterizing aerodynamic loads on shapes that go beyond traditional aircraft shapes. When carried as slung loads under aircraft, vehicles can encounter severe aerodynamic loads, which may also cause them to go into divergent oscillations that can threaten the vehicle and aircraft. Slung loads can encounter the wind at arbitrary attitudes. Flight test certification for every vehicle-aircraft combination is prohibitive. Characterizing the aerodynamic loads with sufficient resolution for use in dynamic simulation, has in the past been extremely arduous. Sharp changes that drive instabilities arise over small ranges of yaw and pitch. With the Continuous Rotation technique developed by our group, aerodynamic load characterization is viable and efficient. With two well-chosen attitude sweeps and appropriate transformations, the entire 6-DOF load map can be obtained, for several rates. The paper describes application of the method to scale models of various vehicles of interest, and the decomposition of the air load features into various fluid dynamic phenomena. Rate effects are also measured and investigated using both 6-DOF load measurements at varying rates of motion, and hot-wire anemometry data from the wake. Generalized aerodynamic load prediction by reference to canonical shapes, is explored. Unsteady effects are conclusively shown to be absent. Starting with generalized empirically-based load prediction for cylinders and rectangular shapes that we have already demonstrated, the uncertainty in load prediction for some vehicles of interest is examined. Models of a truck, a HumVee and a Sentinel vehicle reminiscent of a Tactical Response Vehicle, are used as examples.
Authors
Citation
Motahari, N., Turbeville, F., Hiremath, N., and Komerath, N., "Aerodynamic Load Maps of Vehicle Shapes at Arbitrary Attitude," SAE Technical Paper 2015-01-2574, 2015, https://doi.org/10.4271/2015-01-2574.Also In
References
- Hucho , Wolf-heinich , and Gino Sovran Aerodynamics of road vehicles Annual review of fluid mechanics 25 1 1993 485 537
- Hucho , Wolf-Heinrich Aerodynamics of road vehicles: from fluid mechanics to vehicle engineering Elsevier 2013
- Hucho , W. and Emmelmann , H. Theoretical Prediction of the Aerodynamic Derivatives of a Vehicle in Cross Wind Gusts SAE Technical Paper 730232 1973 10.4271/730232
- Sims-Williams , D. Cross Winds and Transients: Reality, Simulation and Effects SAE Int. J. Passeng. Cars - Mech. Syst. 4 1 172 183 2011 10.4271/2011-01-0172
- Coleman , SA T. , and Baker C. J. High sided road vehicles in cross winds Journal of wind engineering and industrial aerodynamics 36 1990 1383 1392
- Baker , C. J. Ground vehicles in high cross winds part I: Steady aerodynamic forces Journal of Fluids and Structures 5 1 1991 69 90
- Suzuki , Minoru , Katsuji Tanemoto , and Tatsuo Maeda Aerodynamic characteristics of train/vehicles under cross winds Journal of Wind Engineering and Industrial Aerodynamics 91 1 2003 209 218
- Baker , Chris , Federico Cheli , Alexander Orellano , Nicolas Paradot , Carsten Proppe , and Daniele Rocchi Cross-wind effects on road and rail vehicles Vehicle system dynamics 47 8 2009 983 1022
- Ahmed , S. , Ramm , G. , and Faltin , G. Some Salient Features Of The Time-Averaged Ground Vehicle Wake SAE Technical Paper 840300 1984 10.4271/840300
- Kobayashi , N. and Yamada , M. Stability of a One Box Type Vehicle in a Cross-Wind-An Analysis of Transient Aerodynamic Forces and Moments SAE Technical Paper 881878 1988 10.4271/881878
- Ryan , A. and Dominy , R. The Aerodynamic Forces Induced on a Passenger Vehicle in Response to a Transient Cross-Wind Gust at a Relative Incidence of 30° SAE Technical Paper 980392 1998 10.4271/980392
- Baker , Chris , Federico Cheli , Alexander Orellano , Nicolas Paradot , Carsten Proppe , and Daniele Rocchi Cross-wind effects on road and rail vehicles Vehicle system dynamics 47 8 2009 983 1022
- Tsubokura , Makoto , Toshio Kobayashi , Takuji Nakashima , Takahide Nouzawa , Takaki Nakamura , Huilai Zhang , Keiji Onishi , and Nobuyuki Oshima Computational visualization of unsteady flow around vehicles using high performance computing Computers & Fluids 38 5 2009 981 990
- Theissen , P. , Wojciak , J. , Heuler , K. , Demuth , R. et al. Experimental Investigation of Unsteady Vehicle Aerodynamics under Time-Dependent Flow Conditions - Part 1 SAE Technical Paper 2011-01-0177 2011 10.4271/2011-01-0177
- Cheng , S. Y. , Tsubokura , M. , Nakashima , T. Nouzawa , T. , and Okada Y. A numerical analysis of transient flow past road vehicles subjected to pitching oscillation Journal of Wind Engineering and Industrial Aerodynamics 99 5 2011 511 522
- Warner , and Norton , 1920 Wind Tunnel Balances Report 72, National Advisory Committee for Aeronautics
- Greenwell , D. 2011 Modelling of static aerodynamics of helicopter underslung loads Aeronautical Journal 115 1166 201 219
- Cicolani , L. , and Kanning , G. 1987 A Comprehensive Estimate of the Static Aerodynamic Forces and Moments of the 8- by 8- by 20-foot Cargo Container Technical Report 89433, NASA May
- Windsor , R. Wind tunnel tests of two models of rectangular containers Wind Tunnel Report 573, Glenn Martin Wind Tunnel University of Maryland College Park, MD January 1970
- Forbes , A. , Pirau , S. , Liberi , B. , Raghav , V. , and Komerath , N. Testing-based approach to determining the divergence speed of slung loads In Proceedings of the 70 th American Helicopter Society Forum Montreal, CA May 2014
- Pirau , Raghav , Forbes , Liberi , Komerath Efficient Aerodynamic load Determination For Bluff Body Aeromechanics. IMECE2014-37638 Montreal Nov. 2014
- Liberi , B. , Pirau , S. , Komerath , N. , Ton . C. Effects of Uncertainty on Slung Load Divergence Speed Determination Proceedings of the 71 st Forum American Helicopter Society Virginia Beach, VA May 2015
- Forbes , A. , Raghav , V. , and Komerath , N. Continuous Rotation Technique to Measure Aerodynamic Loads on a Bluff Body Data Report ADLP-2013090501, Experimental Aerodynamics and Concepts Group, School of AE, Georgia Institute of Technology September 2013
- Pirau , S. , Liberi , B. , Barbely , N. , Komerath , N. Generalizing Prediction Of Bluff Body Air Load Maps Proceedings of the ASME-JSME-KSME Joint Fluids Engineering Conference 2015 July 26 31 2015 Seoul, Korea