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Unsteady flows around radial impellers are analyzed by the use of singularity methods. Unsteady torque is given for transient and/or sinusoidal flow rate and/or angular velocity fluctuation. It is shown that the unsteady torque can be divided into three components—quasisteady, apparent mass and wake—and the nature of each component is discussed. As a result of separating the torque into these three components, it is shown that the wake component is usually smaller than the others. A gross estimate of torque fluctuation can be made easily by using the apparent mass coefficient given in the paper for logarithmic impellers covering a wide range of blade angles, blade numbers and impeller diameter ratios.

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The test facility has been operated since 2003． Liquid nitrogen and liquid hydrogen are used as working fluid fbr the experiments of rocket engine turbopump inducers ， therefore the thermodynamic effcct on cavitation could be examined ． The faculty of CITF was verified f 沁 m 血 e elemental and comprehensive tests ． In this paper， the vilification tcst results and the future programs are presented ．