Abstract: In order to build a more accurate performance prediction model of centrifugal pump under cavitation condition,the flow in the pump under cavitation condition is divided into inlet region and outlet region, and the volume of cavitation in the pump is determined by the difference of two-stage flow so that the relative reduction coefficient of cavitation head is determined. The simulation results of five types of pumps are compared with the hydraulic test results to verify the universality and accuracy of the modeling method. The maximum calculation deviation occurs near the second critical point, which is about 1%. The simulation results of cavitation fault in hot test are compared with the results of hot test to verify the effectiveness of the modeling method. On this basis, the injection and simulation of the cavitation fault of the oxidant pump in the staged combustion cycle liquid oxygen kerosene engine are carried out. The results show that the reduction of the inlet pressure of the pre-pressure pump can lead to the cavitation of the oxidizer pump; under the cavitation condition, the head of the oxidant main pump decreases, the mass flow rate decreases and the revolution increases; and therefore, the mixture ratio of the gas generator tends to the equivalent ratio and the temperature increases. The results are consistent with the theoretical analysis and hot test, as well as the fault in launch. Minimum allowable boost pump inlet pressure is 53% rated inlet pressure, so reducing the pressure continually will cause the gas generator temperature exceed the critical temperature, which may lead to devastating consequences.

Key words: staged combustion cycle, gas generator, cavitation fault, LOX/kerosene engine, system simulation