离心泵自吸过程的气液两相流非稳态数值模拟

 选取一种常用的立式外混式自吸离心泵作为研究对象,运用非稳态数值模拟手段,探索自吸离心泵起动后气液两相流动的瞬态过程.研究采用了接近真实自吸情形的设置,选取一段吸入管路充满空气作为模拟计算的初始条件.计算得到了自吸泵内气液两相分布、压力分布和速度分布与时间的关系,叶轮入口和泵出口处气液相流量随时间的变化规律,由此可估算自吸时间.计算发现泵吸入和排出气量的时间主要集中在泵起动的初期,叶轮入口和泵出口处的瞬时含气率分别可达到30.9%和20.2%.此外,蜗壳开孔起到分流排气的显著作用,孔口排气量占整个蜗壳排气量的20%～25%.本文所采用的模拟方法和结果对于研究自吸泵自吸过程和自吸性能,具有一定的理论和工程价值.

Unsteady Numerical Simulation for Gas-liquid Two-phase Flow in the Self-priming Process of Centrifugal Pump

A common vertical self-priming centrifugal pump was selected as the research object. By using unsteady numerical simulation, the transient gas-liquid two-phase flow in the self-priming centrifugal pump during the self-priming process is explored. The main innovation in the simulation is that a section of the suction pipe filled with air is chosen as the initial condition, consisting with the actual self-priming conditions. The gas-liquid two-phase distribution as well as the pressure and velocity in relation to the time are computed and analyzed. The flow rates of both phases with time at the pump inlet and outlet are obtained based on the simulation, which could be used to estimate the self-priming time and other performance parameters. It is found that most of the gas are inhaled into and exhausted out of the pump during the early stage of the self-priming process. The air void fraction could reach at 30.9% and 20.2%, respectively at the impeller inlet and the pump outlet at some moments. The hole on the volute plays a significant role for gas exhaustion during the self-priming process. The air flow rate of the orifice accounts for 20%-25% of the entire air flow rate. The simulation method and results proposed have certain theoretical and engineering values for analyzing self-priming process and performance of self-priming pump.