Large Eddy Simulation of Cavitating Throttle Flow

The Reynolds averaged Navier-Stokes equation model (RANS) is state-of-the-art for numerical simulations of cavitating throttle and injector flows. RANS models are based on time-averaged Navier-Stokes equations, and the computational costs are much lower than those for the more advanced Large Eddy Simulations (LES). The principle of LES is low-pass filtering of the Navier-Stokes equations to eliminate the small scales of the solution. In general LES requires higher numerical resolution in space and time, and higher order discretization schemes. In the recent years, clustered processing units provide increased computational resources, and therefore LES simulations became, also for two-phase flows, more and more interesting. The current paper presents Large Eddy Simulations of the cavitating two-phase flow in a rectangular micro-scale throttle operated with Diesel fuel and compares them with RANS simulations. The LES shows interesting new details which cannot be resolved by RANS simulations in general, such as the transition from laminar to turbulent flow in the channel or the phase change caused by turbulent pressure fluctuations in the shear layer. A cavitation erosion model predicts the zones with highest damage probability. All simulations are performed with the commercial CFD code AVL FIRE^®. Time-averaged results of the numerically predicted velocity profiles and the liquid–vapor distributions are compared with already published optical measurements performed with the Laser-Induced Fluorescence (LIF) and the light transmission techniques.