Algebraic turbulence model simulations of supersonic open-cavity flow physics

Abstract

A time-accurate double thin-layer Navier-Stokes computation is performed for an unsteady supersonic open cavity with a length-to-depth ratio of 2. The results are used to determine the flow-physics mechanisms responsible for the cavity oscillation cycle. A new cycle is described and compared to previous descriptions. It is found that a shed vortex impinges on the cavity aft lip and forms a pressure pulse that augments or forces, at the vortex shedding frequency, an internal upstream moving wave that has been reflected from the aft corner. This upstream moving wave eventually reflects off the cavity forward wall and forces the shedding of a new vortex. It was found, however, that the reflected wave dissipates before it reaches the aft wall. Instead, a second wave forms beneath the shed vortex and eventually reflects from the aft corner and is forced at the shedding frequency by the shed vortex wave, completing the cycle.