叶片数变化对轴流泵流体激励力影响

Fluid Excitation Forces of Axial Flow Pumps with Different Number of Blades

泵的振动有一部分是由泵内的非稳定流动引起的,叶片数的改变会引起泵内非稳态流场的变化,从而对泵的振动特性产生影响。通过流体力学计算软件FLUENT对某台立式轴流泵内流场进行仿真计算,先通过定常计算得出泵的性能与叶片数的关系,并以定常计算结果为初场进行非定常计算,得出分别在3、4、5叶片下,作用在泵壳及叶轮上的流体激励力的变化情况。结果表明额定工况下4叶片设计的扬程和效率最高,随着叶片数减少,1倍叶频处的压强系数峰值逐渐增大,泵内流体激励力脉动变强,会使流动诱导的振动增加。

Vibration of pumps is partially induced by the pressure pulsation of the unsteady flow in the pumps, while the change of the number of blades can alter the unsteady flow field within the pumps and influence the vibration of the pumps. In this paper, numerical simulation of the internal flow field of an axial flow pump was carried out by means of FLUENT software. At first, the relation between the pump performance and the number of the blades was determined through the steady-flow calculation. Then, taking the steady-flow field as the initial field, the unsteady-flow field in the pump was calculated. Finally, the flow excitation forces applied to the shell and impeller of the pump with 3, 4 and 5 blades were obtained respectively. The results show that the lift and efficiency of the pump with 4 blades is the highest under the rated condition. With the reduction of the number of blades, the peak of pressure coefficient increases gradually, and the pulsation of the flow-excitation force becomes stronger, which will increase the vibration of the pump.