Effect of viscosity on the external characteristics and flow field of a molten salt pump in the view of energy loss

Abstract

The performance of molten salt pump is affected by its geometrical structure and the physical properties of delivered fluids. In order to reveal the effects of these factors on pump performance, the performance curves were analyzed theoretically, the flow field was measured accurately by using high-speed photography, and the external characteristics were tested by using water as test medium. The numerical model was verified by the path lines, absolute velocity and performance curves obtained by experiment. Based on the verified model, the relationship among the fluid viscosity, external characteristics and flow field was investigated in the view of energy loss. The results show that reducing the blade outlet angle and outlet width as well as increasing the blade outlet thickness can avoid the unstable running. When delivering low viscosity fluids, since the impact loss is relatively large at low flow rate, the hump is easy to appear in the Head-Flow rate curve. When delivering high viscosity fluids, the opposite happens. With the increase of viscosity, the head and efficiency decrease monotonously, and the maximum efficiency point moves towards low flow rate. At the low flow rate, the shaft power decreases as the viscosity increases, while at the high flow rate, the shaft power increases as the viscosity increases. Compared with delivering water, when the viscosity is lower than 0.01453Pa⋅s, the drop of head and efficiency is less than 5%. The results of the study have reference significance on the development of high-performance molten salt pump and stable operation.