叶片开槽对低比转数离心泵内部流动的影响

Effects of slotted blades on internal flow in centrifugal pump of low specific speed

基于Fluent泵内流场数值模拟及性能预测,针对低比转数离心泵在小流量范围内叶轮内部流动的不稳定性,对低比转数离心泵进行了叶片改型尝试,分析了在改型前后叶轮内部流场流动情况及离心泵性能的变化规律,发现在叶片单开槽后离心泵的扬程在小流量范围内较未开槽前有所上升,效率有所提高;但在大流量范围内离心泵的扬程较未开槽前呈下降趋势,并且效率也随之降低,因此,低比转速离心泵在小流量情况下表现出来的流动不稳定性可以通过叶片单开槽的方法来进行抑制.为了研究叶片开槽数目对其影响,将开槽数目增加至2个,研究其内部流场流动情况和性能变化规律,发现叶片双开槽在抑制叶轮流道流动不稳定性及效率的提高上不及叶片单开槽情况.研究结果表明:在小流量工况下,叶片开槽对离心泵内部流动紊流情况会有一定的改善作用,而开槽数目是否合理也将影响离心泵的性能.

To remedy the instability of internal flow in the impeller of a centrifugal pump of low specif- ic speed at low flow rates, the impeller was redesigned to have slotted, then the flows in the pump with this kind of impeller and the original one were analyzed by using CFD code-Fluent to identify effects of such blades on the internal flow and performance. It was shown that the pump head and total efficiency are a little increased at a lower flow rate as one slot was presented on every blade blades compared with the pump with the original impeller, but they are declined at a higher flow rate, suggesting the blade with one slot on it can improve the instability of internal flow in the impeller passages of centrifugal pumps of low specific speed at partial flow rates. In order to clarify influence of number of slots on the internal flow and the performance, an additional slot was made on every blade as well, and it was found that the instability of flow and efficiency are poorer against the case with one slot. It was con- firmed that the slots on blades do improve the turbulence of flow in the impeller of a centrifugal pump of low specific speed at lower flow rates point in some degree, however, that number of slots will affect the performance of the pump.