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Drag reduction on the 25° slant angle Ahmed reference body using pulsed jets

Abstract

This paper highlights steady and unsteady measurements and flow control results obtained on an Ahmed model with slant angle of 25° in wind tunnel. On this high-drag configuration characterized by a large separation bubble along with energetic streamwise vortices, time-averaged and time-dependent results without control are first presented. The influence of rear-end periodic forcing on the drag coefficient is then investigated using electrically operated magnetic valves in an open-loop control scheme. Four distinct configurations of flow control have been tested: rectangular pulsed jets aligned with the spanwise direction or in winglets configuration on the roof end and rectangular jets or a large open slot at the top of the rear slant. For each configuration, the influence of the forcing parameters (non-dimensional frequency, injected momentum) on the drag coefficient has been studied, along with their impact on the static pressure on both the rear slant and vertical base of the model. Depending on the type and location of pulsed jets actuation, the maximum drag reduction is obtained for increasing injected momentum or well-defined optimal pulsation frequencies.

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Acknowledgments

This work was carried out in the framework of the CARAVAJE project supported by the Agence pour le Développement Et la Maîtrise de l’Energie (ADEME). We thank the Renault SA and PSA Peugeot-Citroën Aerodynamics Research teams and the Plastic Omnium research team for fruitful discussions. Technical support by the S4 Wind Tunnel team is also gratefully acknowledged.

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Correspondence to Jean-Luc Aider.

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Joseph, P., Amandolèse, X. & Aider, JL. Drag reduction on the 25° slant angle Ahmed reference body using pulsed jets. Exp Fluids 52, 1169–1185 (2012). https://doi.org/10.1007/s00348-011-1245-5

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  • DOI: https://doi.org/10.1007/s00348-011-1245-5

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