ALGEBRAIC TURBULENCE MODEL SIMULATIONS OF SUPERSONIC OPEN-CAVITY FLOWPHYSICS

A time-accurate double thin-layer Navier-Stokes computation is perform ed for an unsteady supersonic open cavity with a length-to-depth ratio of 2. The results are used to determine the how-physics mechanisms re sponsible for the cavity oscillation cycle, A new cycle is described a nd compared to previous descriptions. It is found that a shed vortex i mpinges on the cavity aft lip and forms a pressure pulse that augments or forces, at the vortex shedding frequency, an internal upstream mov ing wave that has been reflected from the aft corner. This upstream mo ving wave eventually reflects off the cavity forward wall and forces t he shedding of a new vortex. It was found, however, that the reflected wave dissipates before it reaches the aft wall. Instead, a second wav e forms beneath the shed vortex and eventually reflects from the aft c orner and is forced at the shedding frequency by the shed vortex wave, completing the cycle.