The Numerical Simulation Of Two-stage Liquid Ring Vacuum Pump

Liquid ring vacuum pump has no metal friction surfaces inside the pump and doesn't need to be lubricated. It has many advantages such as less precision parts, easy to manufacture, low cost, simple structure, reliable operation, easy maintenance, less prone to failure, etc. Water is the most common type of ring liquid and seal for these machines, hence it's suitable for pumping hazardous, toxic gases. Gas is isothermal compression which means the gas temperature changed slightly during the compression. Therefore it's particularly suitable for compressing and pumping flammable and combustible gas as well as vapor, liquid and dirt particles. It has a wide range of applications in the metallurgical, power, petrochemical, light industry, food and other industries and it can't be replaced.Compared with single-stage liquid ring pump, two-stage liquid ring pump has higher efficiency, higher vacuum degree, more stable gas flow rate and higher cavitation safety, but related researches are still less. Through the exploration of the design and simulation methods, this paper is an attempt in this field using CFD tools. Pump flow rules, including cloud images and curves of the two-phase distribution, static pressure distribution, dynamic pressure distribution, total pressure distribution, velocity distribution and temperature distribution, etc. are analyzed, and the conclusion can be drawn:(1) The numerical simulation is consistent with the theory and practice in the prediction of the mechanical energy of the blades translate into internal energy of fluids. Therefore, this method has a high degree of confidence in the analysis of three-dimensional flow field distribution in the two stage liquid ring pump, including the pressure field, velocity field, and two-phase distribution.(2) In the simulation of two-phase flow, the VOF model is accurate for the prediction of the gas liquid interface. But, there are still problems to be solved when used in the simulation of the two stage liquid ring vacuum pump.(3) The influence of inlet and outlet on the gas-liquid interface of two stage liquid ring vacuum pump is not obvious, but the calculation time is one of the important factors that affect the calculation results.This paper is a pioneer to explore the numerical simulation of the two stage liquid ring vacuum pump. It has reference value in the follow-up study and the design of the two stage liquid ring vacuum pump.