Abstract
The interrelationship was experimentally studied between the performance of a centrifugal pump with an air-water two-phase inlet flow and the distribution of void fractions in the impeller. Void fraction was measured by the electric resistivity probe method at twenty-four locations in the impeller, i.e., eight needle tip void probes adjustable in their positions from the boss to the shroud-side were introduced. The distribution of void fractions is closely related with the pump performance, especially with the transition process to a 'breakdown', under which the performance drastically degrades. The slip ratio estimated from the information on void fraction decreases to less than unity with increasing volumetric inlet quality, which implies not only an increase of the amount of air dwelling near the inlet of the impeller, but also is an indication of breakdown. A possibility is suggested that parameters linked with void fraction will be effective as a quantitative tool for analyzing the pump performance.
