VOLUMETRIC 3-COMPONENT VELOCIMETRY MEASUREMENTS OF THE FLOW FIELD ON THE REAR WINDOW OF A GENERIC CAR MODEL

Abstract

Volumetric 3-component Velocimetry measurements are carried out in the low field around the rear window of a generic car model, the so-called hmed body. This particular flow field is known to be highly unsteady, three imensional and characterized by strong vortices. The volumetric velocity easurements from the present experiments provide the most comprehensive data for this flow field to date. The present study focuses on the wake flow modifications which result from using a simple flow control device, such as the one recently employed by Fourrié et al. [1]. The mean data clearly show the structure of this complex flow and confirm the drag reduction mechanism suggested by Fourrié et al. The results show that strengthening the separated flow leads to weakening the longitudinal vortices and vice versa. The present paper shows that the Volumetric 3-component Velocimetry technique is a powerful tool used for a better understanding of a threedimensional unsteady complex flow such that developing around a bluffbody.

Keywords

Dates

  • Submission Date2011-12-20
  • Revision Date2011-12-20
  • Acceptance Date2012-02-10

DOI Reference

10.2298/TSCI111220036T

References

  1. Fourrié, G., et al., Bluff-body drag reduction using a deflector, Experiments in Fluids, 50 (2011), 2, pp. 385-395
  2. Manojlović, A. V., et al., Fleet renewal: an approach to achieve sustainable road transport. Thermal science, online first, 2011
  3. Petersen, M.S., et al., Report on Transport Scenarios with a 20 and 40 year Horizon, Final report, Funded by DG TREN, Copenhagen, Denmark, 2009
  4. Ahmed, S. R., Ramm, G., Faltin, G., Some salient features of the time-averaged ground vehicle wake, SAE Paper 840300, 1984
  5. Spohn, A., Gilliéron, P., Flow separations generated by a simplified geometry of an automotive vehicle, Proceedings, UTAM Symposium on unsteady separated flows, Toulouse, France, 2002
  6. Aider, J. L., Beaudoin, J. F., Wesfreid, J. E., Drag and lift reduction of a 3d bluff-body using active vortex generators, Experiments in Fluids, 48 (2010), 5, pp. 771-789
  7. Gilliéron, P., Kourta, A., Aerodynamic drag reduction by vertical splitter plates, Experiments in Fluids, 48 (2010), 1, pp.1-16
  8. Brunn, A., et al., Active drag control for a generic car model, Notes on Numerical Fluid Mechanics and Multidisciplinary Design, 95 (2007), pp. 247-259
  9. Willert, C. E., Gharib, M., Three-dimensional particle imaging with a single camera, Experiments in Fluids, 12 (1992), 6, pp. 353-358
  10. Pereira, F., et al., Defocusing digital particle image velocimetry: a 3-component 3-dimensional DPIV measurement technique. Application to bubbly flows, Experiments in Fluids, 29 (2000), suppl 1, pp. S078-S084
  11. Pereira, F., et al., Two-frame 3D particle tracking, Measurement Science and Technology, 17 (2006), 7, pp. 1680-1692
  12. Sims-Williams, D. B., Duncan, B.D, The Ahmed model unsteady wake: Experimental and computational analyses, SAE Paper 2002-01-1315, 2002.
  13. Minguez, M., Pasquetti, R., Serre, E., High-order large-eddy simulation of flow over the "ahmed body" car model, Physics of Fluids, 20 (2008), 9, pp.095101.1-095101.17
  14. Thacker, A., Experimental contribution to the steady and unsteady anlysis of the flow behind a bluff body (in french), Ph. D. thesis, Université d'Orléans, Orléans, France, 2010
  15. Kiya, M., Sasaki, K., Structure of large-scale vortices and unsteady reverse flow in the reattaching zone of a turbulent separation bubble, Journal of Fluid Mechanics, 154 (1985), pp. 463-491
  16. Hudy, L. M., Naguib, A. M., Humphreys, W. M., Wall-pressure-array measurements beneath a separating/reattaching flow region, Physics of Fluids, 15 (2003), pp. 706-717
Volume 16, Issue 1, Pages313 -320