Analysis And Optimization Of Performance Of A Tandem Pump

A tandem pump consists of 3 main parts: a front impeller and a rear impeller connect directly with a guide vane following by. Because of the advantages such as short axial dimension, large flow coefficient, good cavitation performance and high efficiency, the investigation on tandem pump is of much engineering significance. A tandem pump’s inner flow field and performance are particular in some areas compared with a common 2-stage pump because of the absence of middle guide vane. while the research on this area is still not enough. For these reasons, tandem pump performance and its inner flow field was investigated in this thesis with CFD method and surrogate model method. The main contents and conclusions are as below:A CFD numerical simulation method was developed to calculate the tandem pump hydraulic performance based on standard k-ε turbulence model and homogeneous flow model. With this method certain knowledge about the tandem pump performance and the inner flow field has been got and both impellers’ interaction have been investigated.The influence of structure parameters on tandem pump hydraulic performance and inner flow field was investigated, and the front impeller’s outlet blade angle was considered as the key to both impellers’ external characteristics and cavitation characteristics. The rise of tandem pump external performance was found to rely on reasonable proportion between both impellers’ external characteristics. A way to optimize the tandem pump was developed, the relationship between external characteristic and cavitation characteristic was studied. A conclusion has been reached that both characteristics are difficult to obviously raise together because of the structural contradiction between them.A muti-objective parameters optimization method was developed based on the surrogate model method. 3 optimal tandem pump with different demand has been got. The optimization method’s feasibility was tested by numerical simulation. It is considered that the proportion between both impellers’ head in design condition can be the index to measure the balance between tandem pump’s external characteristic and cavitation characteristic, and the balance proportion should be 3:5.