Impact of the underside velocity on the drag reduction of a trailer model using a passive control system

International audienceThe effect of passive control (inclined boat-tails) on the flow in the wake of a 1:43 scale simplified trailer model is experimentally studied for various underside flow conditions. Base pressure measurements show that the boat-tails allows increasing the base pressure whatever are underside flow velocities studied and the base pressure distribution is always symmetric in the vertical mid plane. In addition, according to the underside flow velocity, the near-wake flow structure consists of a recirculating area attached or completely detached from the ground

EXPERIMENTAL STUDY OF THE WAKE OF A SIMPLIFIED TRUCK MODEL IN GROUND PROXIMITY IN VIEW OF DEFINING A CONTROL STRATEGY FOR DRAG REDUCTION

International audienceNear wake study of a simplified truck model is presented for various underbody velocity. The mean base pressure evolution and the near wake structure evolution for a change of the underbody velocity lead to the identification of four classes of flow. The wake of class (I), for un-derbody velocities below 15% of the free stream velocity U ∞ looks like a 3D backward facing step. Then for higher underbody velocities, until typically 0.4U ∞ , the wakes of classes (II) and (III) are associated to a back-flow impag-ing the rear base. This back-flow is responsible for a low pressure area on the bottom of the rear base. It would then be interesting to limit the curvature of the back-flow in order to limit the low pressure. The last class is identified for an underbody velocity above 0.6U ∞ and the wake looks like an Ahmed body wake. For all classes, turbulence is mainly localized in the upper and lateral shear layers. Flow control on these sides would be useful to attenuate these velocity fluctuations for stabilizing the near wake

Experimental application of active flow control on a 1:8 scale, simplified truck model

International audienceThe effect of active flow control combining synthetic jets and inclined flaps on the flow behind a 1:8 scale simplified truck model is experimentally studied. Aerodynamic drag and base pressure measurements show that forcing the flow within a given range of actuation frequencies allows reducing the drag. However, results also show that such drag reductions greatly depend on the underside flow velocity

Impact of the underside velocity on the drag reduction of a trailer model using a passive control system

International audienceThe effect of passive control (inclined boat-tails) on the flow in the wake of a 1:43 scale simplified trailer model is experimentally studied for various underside flow conditions. Base pressure measurements show that the boat-tails allows increasing the base pressure whatever are underside flow velocities studied and the base pressure distribution is always symmetric in the vertical mid plane. In addition, according to the underside flow velocity, the near-wake flow structure consists of a recirculating area attached or completely detached from the ground