Evaluation of Suction Performance of Inducer with Splitter Blade

Abstract

For general-use turbopumps with inducer, instability-free operation is required as well as high suction performance in a wide operating range from shut-off to over flow rates. Among the instabilities, the cavitation surge at low flow rates is a very vital phenomenon that is known to be strongly associated with the occurrence of inlet back flow. The low inlet blade angle would be favorable for the suppression of inlet backflow through the reduction of blade loading at the inlet, while the inlet throat area should be kept large for better suction performance to minimize the flow blockage due to cavitation. In the present study, a splitter blade inducer is designed on the basis of the knowledge acquired by our previous CFD study conducted for the 2-D cascade and 3-D straight-hub inducer. Then the effectiveness of the splitter inducer is investigated by experiments and CFD. As a result, the inlet backflow and the cavitation surge are found to be suppressed in the splitter inducer, which is achieved by reducing the blade loading with low inlet blade angle. The suction performance is improved at high flow rates by relaxing the low pressure region with high relative velocity.