Title: Characterisations of force and pressure fluctuations of real vehicles

Authors: O. Cadot; A. Courbois; D. Ricot; T. Ruiz; F. Harambat; V. Herbert; R. Vigneron; J. Délery

Addresses: ENSTA ParisTech, 828, Bd des Maréchaux, 91162 Palaiseau, France ' ENSTA ParisTech, 828, Bd des Maréchaux, 91162 Palaiseau, France ' Renault SAS, 13/15 Quai Alphonse le Gallo, Boulogne-Billancourt, France ' PSA Peugeot Citroën, Route de Gisy, 78140 Vélizy-Villacoublay, France ' PSA Peugeot Citroën, Route de Gisy, 78140 Vélizy-Villacoublay, France ' PSA Peugeot Citroën, Route de Gisy, 78140 Vélizy-Villacoublay, France ' GIE S2A, 2 Avenue Volta, 78180 Montigny-le-Bretonneux, France ' GIE S2A, 2 Avenue Volta, 78180 Montigny-le-Bretonneux, France

Abstract: Both the unsteady aerodynamics force and base pressure distributions are investigated for four model cars in real flow conditions. The low pass cut-off frequency of the measurements is about 5 Hz which is sufficient to consider the global fluctuations of drag, lift and side forces. The drag fluctuations are very low, they never exceed 1% of the mean drag. A clear correlation is found with the base pressure distribution fluctuations. It is found that the regions of smallest pressure fluctuations on the vehicle base are the most correlated to the drag fluctuations or in other words, the regions of largest pressure fluctuations on the base are not associated with the drag fluctuations. Sideslip effect is studied, and one of the models presented a clear bistable behaviour on the lift creating huge fluctuations as investigated in the academic experiment of Grandemange et al. (2013b).

Keywords: road vehicles; vehicle aerodynamics; separated flows; 3D wake dynamics; bistability; full-scale experiments; drag sources; force fluctuations; pressure fluctuations; drag fluctuations; lift fluctuations; side forces; vehicle base; sideslip effect; modelling.

DOI: 10.1504/IJESMS.2016.075529

International Journal of Engineering Systems Modelling and Simulation, 2016 Vol.8 No.2, pp.99 - 105

Received: 29 May 2014
Accepted: 25 Nov 2014
Published online: 28 Mar 2016 *

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