An open cavity flow is strongly dependant on its geometry and Reynolds number, yielding to development of different types of instabilities. The shear layer between the external and the inner cavity flow is able to give rise to a Kelvin-Helmholtz-like instability, coupled with the shear flow impingement on the downstream cavity wall. The velocity gradient, between external and internal flows and the wall confinement, induce a recirculation inside the cavity. A centrifugal Taylor-Görtler-like instability, originating from that flow curvature, is also subject to appear, for particular parameters. The aim of the study is to provide better understanding of the coupling between the shear-layer and the occurrence of centrifugal instabilities.