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This paper aims to present an experimental investigation of an active flow control solution mounted at rear of a sport utility vehicle (SUV) with the objective of drag reduction, thanks to a selection of flow control parameters leading to a pressure increase on the tailgate.

A flow control design of experiments was conducted with a pulsed jet system mounted on the top and sides of the rear window of the vehicle. The wall pressure, instantaneous velocity and drag were measured with this prototype in a wind tunnel. A dynamic modal decomposition (DMD) analysis of the pressure enables to describe the pressure fluctuations. Fluid dynamic computations show relation between pressure and velocity fields.

Measurements with this prototype in the wind tunnel revealed small improvements in drag for the best flow control configurations. This small benefit is because of the core of the upper span wise vortex further away from the rear window than the lower span wise vortex. These small improvements in drag were confirmed with pressure measurements on the rear window and tailgate. The DMD analysis of the surface pressure showed a low frequency pendulum oscillation on the lower area of the tailgate, linked with low velocity frequencies in the shear layers near the tailgate.

Experimental and numerical results show interest to increase pressure at bottom of the rear end of this SUV prototype. The dynamic description of the wall pressure shows importance of flow control solutions reducing pressure fluctuations at low frequencies in the lower area of the tailgate.

The purpose of this paper is to study pressure measurement correlations, as the location of the pressure sensors should enable to capture variation of the drag force depending on the yaw angle and some geometrical modifications.

The present aerodynamical study, performed on a reduced scale mock-up representing a sport utility vehicle, involves both numerical and experimental investigations. Experiments performed in a wind tunnel facility deal with drag and pressure measurements related to the side wind variation. The pressure sensor locations are deduced from wall streamlines computed from large eddy simulation results on the external surfaces of the mock-up.

After validation of the drag coefficient (Cd) values computed with an aerodynamic balance, measurements should only imply pressure tap mounted on the vehicle to perform real driving emission (RDE) tests.

Relation presented in this paper between pressure coefficients measured on a side sensor and the drag coefficient data must enable to better quantify the drag force contribution of a ground vehicle in RDE tests.