Abstract：A series of experiments on underwater self-excited pulse jet are made by using a self-developed test platform and the axial and radial distributions of pressure around an underwater self-excited pulse jet are obtained. Then, the flow fields inside and outside the jet are simulated, the corresponding velocity and pressure distributions are acquired and compared with the experimental data. The results show that obvious low frequency pulses can occur for the self-excited pulse jet under non-submerged condition. Under submerged condition, however, because part of the jet energy is consumed in the submerged water body so much that it is hard for cavitation to form in the chamber and to generate obvious pulse, further the stagnation pressure is reduced significantly. The radial pressure distribution is basically the same in different depths of the water, approximately yields the Gaussian distribution. The axial stagnation pressure is decreased with the increasing distance to the target, and its attenuation characteristic is similar to that for continuous jet and under non-submerged condition, just the decay rate is even faster. A low pressure zone in the jet core, two symmetrical negative pressure zones and a high pressure impinging zone exist in the flow field in the chamber of the underwater self-excited pulse jet device. Vortexes are generated near the bottom casing, and the flow field is similar to the jet flow in the chamber, but without a core.
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