This content is not included in
your SAE MOBILUS subscription, or you are not logged in.
Assessing the Effects of Shear and Turbulence During the Dynamic Testing of the Crosswind Sensitivity of Road Vehicles
Annotation ability available
Sector:
Language:
English
Abstract
With increasing speeds and the anticipated reduction in weight of modern cars, the issue of crosswind sensitivity is becoming increasingly important. In a previous paper by the same authors, the normal method of testing such aerodynamic characteristics at model scale, using static models at yaw to the freestream, was compared with dynamic testing, in which the model is propelled across a ‘gust’ simulated by a wind tunnel. A direct comparison using a similar gust profile for both static and dynamic tests was made with the conclusion that the simple static test technique was underestimating the true transient loads.
Further tests have been carried out, on a generic squareback (or estate) model, during which the effect of varying both the vertical velocity profile and the turbulence intensity within the gust was considered. Although these gust characteristics were not necessarily representative of an atmospheric boundary layer they give a good indication of the differences that might be expected between tests done using a static model at yaw and the more accurate dynamic simulation.
The data show a considerable variation in aerodynamic load on the model as the vertical velocity profile was altered but less variation with turbulence intensity. An attempt is made to determine, a simple relationship between a reference velocity, representative of the shape of the gust profile and the resultant forces and moments.
Recommended Content
Journal Article | The Effect of High Turbulence Intensities on Surface Pressure Fluctuations and Wake Structures of a Vehicle Model |
Journal Article | The Decay of Bluff Body Wakes |
Topic
Citation
Macklin, R., Garry, K., and Howell, J., "Assessing the Effects of Shear and Turbulence During the Dynamic Testing of the Crosswind Sensitivity of Road Vehicles," SAE Technical Paper 970135, 1997, https://doi.org/10.4271/970135.Also In
References
- Macklin A R Garry K P Howell J P Comparing Static and Dynamic Testing Techniques for the Crosswind Sensitivity of Road Vehicles SAE SP-1145/960674 1996
- Bearman P W Morel T Effect of Freestream Turbulence on the Flow around Bluff Bodies Prog Aero, Sci. 20 97 123 1983
- Bearman P W An Investigation of the Forces on Flat Plates in Turbulent Flow NPL Aero 1296 1969
- Baker C J Ground Vehicles in High Cross Winds Part 2: Unsteady Aerodynamic Forces Jn of Fluids and Structures 5 90 111 1991
- Coleman S A The Aerodynamics of Ground Vehicles in Cross Winds University of Nottingham UK 1990
- Wacker J Friedrich R Plate E J Darsch F Drag and Lift on Rectangular Bluff Bodies Immersed in Deep Boundary Layer Flow over Rough Surfaces Int. Colloquium on Bluff Bodies and its Applications Kyoto Japan 113 123 1988
- Macklin A R Measuring the effects of crosswinds on cars Cranfield University UK 1996