Abstract: Aiming at the low-frequency pressure fluctuation phenomena in certain liquid oxygen delivery systems during dual engine operation, a numerical study on the intrinsic frequency of the liquid oxygen delivery system was conducted by adopting an acoustic unit in Abaqus. Factors such as condensation characteristics of the oxygen-enriched gas gas in the liquid oxygen’s pipeline between pumps, flexibility of the accumulator, and cavitation flexibility of the engine were considered in the simulation models. The simulation results show that the second order frequency of the liquid oxygen delivery system is 8.77 Hz, and the phase difference of the corresponding acoustic modal is 180°, which is the liquid circuit frequency of the small loop between the two branches of the tee. This is consistent with the low-frequency fluctuation phenomenon during flight. Moreover, the simulation results were consistent with the liquid circuit frequency solved via the transfer matrix, which also verified the effectiveness of the frequency analysis method based on acoustic theory.

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