抄録
The attachment of inducer in front of main impeller is a powerful method to improve cavitation performance. In operating condition at partial flow rate and extremely low suction pressure, however cavitation surge oscillation occurs. As the cavitation surge oscillation with low frequency occurs in a close relation between the inlet back-flow cavitation and the growth of blade cavity to the throat section of blade passage, one method of installing an axi-asymmetrical plate upstream of inducer is proposed to suppress the oscillation. It is considered as the suppression mechanism of oscillation conceptually to avoid making flow at all throat sections unstable simultaneously due to inlet flow distortion by suction axi-asymmetrical plate. In the present study, cavitation behaviors in the inducer is observed with distributing multi-cameras circumferentially, recording simultaneously and reconstructing multi-photos on one plane field as moving a linear cascade. Observed results are utilized for discussion with other measuring results as casing wall pressure distribution. Then the suppression mechanism of oscillation by installing axi-asymmetrical inlet plate will be clarified in more details.
