D\'eveloppement d'instabilit\'es dans un \'ecoulement subsonique se d\'eveloppant au-dessus d'une cavit\'e : mesures synchronis\'ees PIV-LDV

TL;DR

This study experimentally investigates the instabilities in a subsonic flow over a cavity using synchronized PIV and LDV measurements to analyze shear layer interactions and vortex formations at medium Reynolds numbers.

Contribution

It introduces synchronized PIV-LDV measurement techniques to analyze flow instabilities and vortex dynamics in cavity flows at medium Reynolds numbers.

Findings

Identification of shear layer instabilities and vortex interactions.

Phase-averaged velocity fields reveal flow structures.

Insights into flow behavior relevant for environmental and aeronautical applications.

Abstract

A boundary layer interacting with a cavity is a benchmark case that is present in environmental applications, aeronautics, automobile aerodynamics or industrial applications, where the velocity over a rectangular cavity is relatively low. In the present investigation, the interaction between a laminar boundary layer with external velocity Ue and an open cavity is investigated experimentally for medium range Reynolds numbers (between 4600 and 18500) with flow diagnostics optical methods, for a cavity aspect ratio (length over depth) of two. A shear layer induces a main vortex and a counter-rotating secondary vortex inside the cavity. The shear layer also develops instabilities interacting with the downstream cavity edge. Particle image velocimetry (PIV) and laser Doppler velocimetry (LDV) measurements are synchronized in order to get global information of both spatial velocity fields and time-resolved signals in a particular position situated downstream of the development of the shear layer above the cavity. The PIV velocity fields are phase-averaged with a singular value decomposition of the LDV signal.