Transient Simulations of Valve Motion in Cryogenic Systems

Abstract

Valve systems in rocket propulsion systems and testing facilities are constantly subject to dynamic events resulting from the timing of valve motion leading to unsteady fluctuations in pressure and mass flow. Such events can also be accompanied by cavitation, resonance, system vibration leading to catastrophic failure. High-fidelity dynamic computational simulations of valve operation can yield important information of valve response to varying flow conditions. Prediction of transient behavior related to valve motion can serve as guidelines for valve scheduling, which is of crucial importance in engine operation and testing. In this paper, we present simulations of valve motion utilizing a multi-element unstructured computational approach that permits the use of variable grid topologies, thereby permitting solution accuracy and resolving important flow physics in the seat region of the valve. The approach is based on a mesh library strategy in which generalized mesh movement is applied between a sequence of meshes and the solution is transferred between meshes at specific valve positions pre-defined in the library. We discuss important valve flow characteristics such as valve response to variable plug control speeds as part of our simulations. Furthermore, we present an alternative methodology that utilizes a single grid that deforms and adapts during valve motion.