Simulations of Cavitation in Orifice and Venturis

Computational simulations can play an integral role in supporting testing and developmental activities by identifying and characterizing flow instabilities. However, the diversity of flow regimes and instability mechanisms place very stringent requirements on any computational framework that could be used for such analyses. For example, the identification of dominant frequencies associated with flow instabilities in such systems requires high order numerics, advanced turbulence modeling capabilities, sophisticated grid topologies to resolve local physics in complex geometries, embedded models for unsteady cavitation, capture thermal effects in cryogenic fluids, and dynamic motion of feed system components such as valves. In this paper, we discuss simulations of cavitating instabilities in feed system components and control elements used in the E-1 test facility at NASA Stennis Space Center (SSC). The two different feed system components considered here are: (a) orifice and (b) flow control venturi that is attached to a 90 degree turning duct. These two components represent the two disparate regimes of cavitating flows: the orifice is representative of traveling cavitation class of flows commonly observed in tip vortices of propeller blades, whereas the venturi represents a sheet cavitation type problem with periodic shedding of vaporous clouds from this well developed cavity. The simulations are performed with a well validated cryogenic cavitation model that takes into account evaporative cooling and other associated thermal effects.