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Communication Dans Un Congrès Année : 2006

Closed loop control experiments on a simplified car model using vortex generators and wall pressure measurements

Résumé

A control device is generally designed to operate a system in a desired manner. In case of automotive flows one often aims at reducing the drag force by creating small disturbances into the boundary layer. We choose to study the flow around a modified Ahmed body with a curved rear part (Re = 2.106) and first propose to use a line of vortex generators (fig. 1) that are shown to trigger separation on the one hand, but strongly reduce the tip vortices intensity on the other hand, so that the global effect on the drag is favorable. Next by varying the angle of the VG we observe that the drag reduction is minimum for an optimal value of α. As this optimum value is shown to be Reynolds dependant we use an extremum control strategy1 to make our system able to identify and reach its optimal set point in real time, and to fit to mean flow velocity modifications. In this set of feedback control experiments, the angle of the VG is a slowly variable function of time that is adjusted thanks to a wall pressure measurement located in the recirculation part of the rear of the model. The feedback law is built using the sinusoidal perturbations method1. It consists in a synchronous detection of the response measured in the pressure signal to a modulation of the angle of the VG. It is finally demonstrated that the closed-loop system is robust and reacts successfully to unpredictable changes in the external flow conditions.
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Dates et versions

hal-00174536 , version 1 (24-09-2007)

Identifiants

  • HAL Id : hal-00174536 , version 1

Citer

Jean-François Beaudoin, Olivier Cadot, Jean-Luc Aider, Jose Eduardo Wesfreid. Closed loop control experiments on a simplified car model using vortex generators and wall pressure measurements. Euromech Fluid Mechanics Conference – 6 (EFMC6), Jun 2006, Stockholm, Sweden. pp.376. ⟨hal-00174536⟩
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