Suppression Effect of Upstream Installed Ring-Shaped Obstacle Plate on Cavitation Surge in Pump Inducers

Abstract

The attachment of an inducer upstream of a main impeller is a powerful method to improve the suction performance. It is known, however, that the cavitation surge oscillation, which is focused in the present paper, occurs under the operation condition with partial flow rate and low suction pressure. The attempts to suppress the cavitation surge have been made by installing a ring-shaped obstacle plate just upstream of inducer. The ring-shaped inlet plates with various blockage rates of 14%, 27% and 39% have been tested to examine the effect of blockage rates on the suppression of cavitation surge for two kinds of inducers having two blades with the solidity of 2.0 and the different blade angles of 8° and 14° at the blade tip. In the present paper, the changes of the onset region of cavitation surge are clarified and the mechanism of cavitation surge suppression is discussed with the measured casing wall pressure distribution and inlet velocity distribution.

Keywords

• turbomachinery
• inducer
• cavitation surge suppression
• obstacle plate