Wake control using synthetic jets

Paper presented at the 9th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Malta, 16-18 July, 2012.The interactions of wake of an elongated bluff body and the periodic flow emanating from a pair of synthetic jets placed symmetrically at the trailing edge, spanning the width of the plate, were experimentally studied for the purpose of quantifying the flow physics that led to wake drag reduction. The experiments were carried out in a low turbulence wind tunnel at Reynolds number, Reh based on the flat plate thickness h, of about 7200. The synthetic jet actuators, providing a global momentum addition of Cμ=24%, were positioned symmetrically at the model base at a distance of ± 0.27 h from the base centerline to introduce perturbations at early stages of the shear layers’ development. The synthetic jet actuation frequency was selected to be about 75% the vortex shedding frequency of the natural wake. Two-component velocity measurements were acquired using Particle Image Velocimetry (PIV) and reported for natural wake and controlled wake using symmetric synchronous actuation and out-of-phase actuation. In this work, mean velocity profiles, Reynolds stresses and coherent structures and their dynamics in the wake of a bluff body were evaluated as the initial conditions (injection configurations) were changed. Furthermore, phaseaveraged velocity fields through the vorticity contours were determined to provide insights into the actuation mechanisms namely, the role of the synthetic jet vortex structures on the flow dynamics.dc201

Anti-Heparanase Aptamers as Potential Diagnostic and Therapeutic Agents for Oral Cancer

Peer reviewe

Application du contrôle actif aux instabilités aérodynamiques

This paper describes experimental investigations in which adaptive methods are applied to various structures of active control of flow instabilities : flow excited cavity oscillations, compressor surge, and bursting phenomena in laminar boundary layer. The main results are as follows : the adaptive controller manages to automatically find its optimal characteristics in order to cancel the instability in the three experiments under consideration. In the boundary layer case, despite the non linear behaviour of the bursting process, a periodic train of artificially generated burst is significantly reduced downstream the cancelling source

Lift improvement usign piezoelectric actuator

This paper deals with the determination of the lift improvement of plane winy using pulsed jets generated by piezoelectric actuators. This actuator is constituted by a large bimorph constituted by piezoelectric patches cemented on a brass plate. The bimorph is inserted into a rigid case and one of the long edge plate is clamped the other is free. An alternating voltage is applied to the piezoelectric patches inducing the bending of the brass plate which opens and closes a 100 x 1 mm2 slit. Due to the internal static pressure pulsated jets arc formed and escape the slit. This actuator is inserted into a particular wing profile in order to measure the pressure modifications induced by the jets and the corresponding lift improvements are deduced. The best functioning conditions of the actuator and the lift improvement are determined and discusse

POD analysis of momentumless trailing edge wake using synthetic jet actuation

International audienc

Advanced beamforming techniques for passive imaging of stable and inertial cavitation

International audienc

Synthetic jet actuation strategies for momentumless trailing edge wake

International audienc