Dynamic response of the cavitating LE-7 LOX pump

The dynamic response of the LE-7 engine LOX pump under cavitating conditions was investigated by perturbation tests using cryogenic fluid in order to obtain data for the analysis of the H-II rocket POGO phenomena. Mass flow gain factor, Mb, and cavitation compliance, Cb, were determined by pressure data using resonant frequency. Mb and Cb show cavity volume change rates due to flow fluctuation and pressure fluctuation, respectively. A large accumulator was installed in the vicinity of the pump inlet in order to eliminate the upstream effects. The test results of Mb agreed well with the values calculated by equations presented in the literature. However, the test results of Cb were quite different from the calculated values.