CENTRIFUGAL PUMP PERFORMANCE ENHANCEMENT BY BLADE SHAPE MODIFICATION

摘要

The effect of impeller blades shape modification on the centrifugal pump performance has been investigated numerically. Impeller blades' shape have been modified by new technique called "bladelet". This technique has been called the "bladelet" after the name of the aeroplane winglet because of the great similarity between them in shape and function. The shapes of the blade trailing edge greatly affect the performance of the turbomachines. So, the purpose of the blade tilting (bladelet) is to decrease the recirculating flow at the pump trailing edge due to the high pressure difference and enhance the hydraulic performance of the centrifugal pump. The bladelet technique has two main geometrical parameters: radial position R_(BL) and bladelet inclination angle θ_(BL). 3-D validated numerical simulation model has been carried out using commercial software, ANSYS® CFX, to study the effect of the bladelet technique and its different parameters on the pump performance at different flow rates. In this study nine cases with different bladelet parameters have been numerically simulated in order to check its effect on the centrifugal pump performance. These nine cases have been chosen by considering the geometrical constrain of the bladelet parameters. The results of these nine cases have been compared with the basic impeller (the same impeller but without bladelet) at the same operating condition in order to discuss the effect of the bladelet parameters variation on the centrifugal pump performance. It was found that the use of the bladelet technique decrease the pressure difference between the pressure and the suction side at the blade trailing edge. This decrease in pressure difference at the blade trailing edge decreases the flow recirculation at the impeller outlet from pressure side to suction side. Also, bladelet technique improves the hydraulic efficiency at the part-load operating zone. In addition, the bladelet has a regression effect on the pump head for some cases with high inclination angle and low radial position. However, the bladelet technique increases the impeller blades' overlap.