Abstract: The change of instantaneous vortex of the jet shear layer has an important effect on pulsation process of the vortex ring. Based on the energy storage and release status of the vortex, the boosting effect of the self-excited oscillation pulsed vortex is analyzed. The large eddy simulation method is used, the disturbance of self-oscillation instantaneous vorticity changes in the primary time, the instantaneous flow vorticity changes in a pulsating cycle and the change of downstream flow of self-excited oscillation chamber rate are analyzed when the inlet pressure is at 1 MPa. The results show that the shear layer and the initial large vortex are formed for airflow in the self-excited oscillation chamber. When the initial large vortex is separated by the angle of the chamber collision, the shear layer produces a reverse disturbance wave, and the discrete vortex is fed back in the separation zone and forms the primary flow vortex. When the energy of the large vortex in last oscillation period is completely released, the axial flow rate reaches the maximum pulsation. When the discrete vortices in the shear layer converge into new large vortices, the axial velocity reaches the lowest pulsation. When the large vortex begins to not completely fall off, the axial flow rate reached the average pulse; As the inlet pressure increases, the velocity of the fluid increases first and then decreases, and when the inlet pressure is 1.2 MPa, the maximum pulse rate is up to 22.53%.

Key words: axial velocity, instantaneous vortex, large structure vortex ring, pulse rate, self-excited oscillation chamber