Abstract:
Abstract: In order to obtain more information about the clearance flow in a centrifugal pump and provide further reference for the design of centrifugal pumps, this paper researched and analyzed the distribution of radial force and pressure fluctuation of the impeller in a centrifugal pump via using the methods of the numerical simulation and the verification of experiment. Numerical calculations and experiments were carried out with different seal ring clearances which were respectively 0.25, 0.5 and 0.75 mm. The special speed of model pump was 69. On the one hand, after numerical simulation the influence of different seal ring clearances on the impeller radial force was obtained by calculating and analyzing the pressure of outer surface of impeller. On the other hand, the pressure pulsation signals were obtained by experimental measuring at monitoring points that included 8 locations. Of those, 6 monitoring points were arranged at the seal ring and volute, and 2 monitoring points were arranged at the impeller inlet. According to the clearance size of model pump seal ring (0.25, 0.5 and 0.75 mm), there were 3 cases. The comparison of 2 head curves from the numerical calculation and the experiment showed they had good agreement. The influence of the seal ring clearance on the pressure pulsation of the model pump could be changed obviously with the changing of the condition and the location of the monitoring points. And there was an optimum size of the seal ring clearance with which the pressure pulsation amplitude under the design condition was the smallest. At the inlet of the front cavity, the pressure pulsation amplitude of the case of 0.25 mm was about 3.1 times that of the case of 0.5 mm, and about 1.3 times at the impeller outlet. When the seal ring clearance was 0.25 mm, the mean pressure pulsation amplitude of the wear-ring was the minimum. At this time the pressure pulsation amplitude of the case of 0.75 mm was about 1.24 times that of the case of 0.5 mm. At the impeller inlet and its upstream, the pressure pulsation amplitude of the case of 0.75 mm was about 0.67 times that of the case of 0.25 and 0.5 mm. The radial force of the impeller was changed by the changing of the seal ring clearance. With the increasing of the seal ring clearance, the leakage of the fluid flow increased, which not only changed the pressure fluctuation at the impeller inlet and outlet, but also induced the pressure fluctuation at the inlet of the front cavity. For the pressure fluctuation under the design condition, there was an optimum value of the seal ring clearance, with which the pressure fluctuation amplitude was the minimum. At the same time, the radial force of the impeller changed with the changing of the pressure along the outer surface of the impeller, and the total radial force changed nonlinearly. The traditional design of the centrifugal pump has been carried out by studying the pressure fluctuation and the radial force induced by different seal ring clearances. By studying the changing of pressure pulsation signals and radial forces, this paper provides the reference for the traditional design of centrifugal pumps.