Evaluation of different turbulence models on simulation of gas-liquid transient flow in a liquid-ring vacuum pump

Abstract

To analyze the prediction ability and applicability of different turbulence models to the complicated gas-liquid flow in the liquid-ring vacuum pump, three different turbulence models, namely RNG k-ε, SST k-ω and LES were respectively used to simulate the gas-liquid flow, and the numerical results were compared with the experimental results. The study shows that the trend of pump hydraulic performance with the flow rate and the shape of gas-liquid interface in pump calculated by the three turbulence models have a good agreement with the experimental results. The three models are difficult to capture the small-scale bubbles in liquid-ring, but LES model can capture larger scale bubbles near the gas-liquid interface. The prediction ability of RNG k-ε and SST k-ω models to the complex vortex structures is limited for the influence of Reynolds-averaged treatment, but the LES model can predict the complex channel vortices in impeller passage and the wake vortices of different scales at the impeller outlet. The computation cost of LES model is about three times of the other two models. The RNG k-ε and SST k-ω models have better applicability than LES model if we mainly focus on the distribution of phase and pressure fields in pump.