The hybrid noise numerical simulation method of nonlinear harmonic method coupled with FW-H equation was used to study the aerodynamic force and noise of a 11×9 counter-rotating propeller model.The results of the study showed that:during the takeoff phase,the main noise source of the counter-rotating propeller was the interference noise generated by the interaction of the vortex systems such as the blade tip vortex,leading edge vortex and trailing vortex generated by the front propeller with the rear propeller,and the non-constant pressure fluctuation on the rear propeller was the main contributor to the interference noise.At the frequencies where interference noise appeared,the noise of the front propeller radiated mainly downstream,and the noise of the rear propeller radiated mainly upstream.Compared with the solid FW-H surface,the calculation results of the porous FW-H surface were closer to the experimental data.Different integration surfaces had little effect on the noise of the counter-rotating propeller,but the variation of the downstream integration surface had a greater effect on the interference noise.
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