导流器对射流式自吸离心泵自吸性能的影响

Effects of Diffuser on Self-priming Performance of Flow-ejecting Self-priming Centrifugal Pump

在射流式自吸离心泵的叶轮出口处增设新型导流器,该导流器具有两个不对称出口及隔流板,隔流板与叶轮间隙为1.0 mm。基于Fluent软件提供的Mixture多相流模型、标准k-ε湍流模型及SIMPLE算法,对该泵的自吸过程进行了非定常数值模拟,得到了泵内压力、速度和气液两相分布及导流器两个出口的压力、气相体积流率和液相质量流率随时间步长的变化规律。结果表明:导流器内压力沿流体流动方向逐渐增大,并出现较大的变化梯度,叶轮各流道内的压力近似对称分布;导流器两个不对称出口气液混合物的各个流动参数呈规律的周期性变化;导流器上的隔流板与叶轮的间隙在泵自吸过程中不仅能阻止液体环流,减少水力损失,而且使泵加速气液的混合及分离,从而缩短泵的自吸时间。

A type of diffuser which had two asymmetrical exits and a separating flow board was placed at the inlet of the impeller of flow-ejecting self-priming centrifugal pump. The gap between the separating flow board and the impeller was 1.0 mm. Based on Mixture muhiphase flow model, the standard κ-ε turbulence model and SIMPLE algorithm, unsteady numerical simulation of the self-priming process was carried out by using Fluent software. The distributions of pressure, velocity and gas-liquid phases field inside the pump, and also the changing regularity of pressure, gas phase volume flow rate and liquid mass flow rate on the two exits of the diffuser with the change of timestep were obtained. The results show that the pressure in the diffuser gradually increases along the direction of flow and appears larger change gradient, the pressure inside the each runner of the impeller approximate symmetric distribution. The flow parameters appear periodic change on the two asymmetrical exits of the diffuser. The gap between the separating flow board and impeller have not only prevented the formation of circulation of the fluid, reducing hydraulic loss and improving the efficiency of the pump, but also quicken the mixing of the gas- liquid near the gap, shortening the self-priming time of the pump.