The Research Of Pulse Characteristic And Cutting Test Of Self-excited Pulse Abrasive Water Jet In Submerge Environment

Self-excited Pulse Abrasive Water Jet (SPAWJ for short) is applied to cutting holes on sunken ship under deep-sea environment in this thesis. This technology has great significance for promoting the level of Marine salvage equipment. SPAWJ is on the basis of Self-excited Pulse Jet and Abrasive Water Jet, which has the pulse characteristics of Pulse Jet and the destructive of Abrasive Water Jet.In this thesis, the pulsation of Self-excited Pulse Jet is explained by water hammer phenomenon, which is due to periodic pressure disturbance waves caused by external excitation; The relation between Helmholtz cavity structure parameters and self-excited frequency is put forward by the theory of fluid network; FLUENT is used to simulate deep sea environment’s influence on Self-excited Pulse Jet flow field; Dynamic pressure of self-excited pulse jet measurement bench was set up to analyze the effect on dynamic pressure of jet caused by self-excited pulse nozzle structure parameters and hydraulic parameters; In addition, Self-excited Pulse Abrasive Water Jet Cutting System was also set up to test the cutting ability of SPAWJ.Through theoretical research, simulation analysis and experiment, this paper comes up with the following conclusion:(1) Helmholtz oscillator’s natural frequency is associated with cavity structure parameters. If disturbance wave’s frequency in the cavity is same with oscillators’ natural frequency, large vortex ring can be generated, and resulting in the self-excited pulse jet.(2) The exit velocity of each phase in the SPAWJ decreases with the increasing of environment pressure by the depth, it is also found that the velocity of the water phase is larger than the velocity of abrasive phase.(3) The dynamic pressure of water jet product by the combined self-excited pulse nozzle has a periodic change with time, and the combined self-excited pulse nozzle has optimal structure parameters:the nozzle diameter ratio of up and down is 1-1.33, the length to diameter ratio of self-excited cavity is 0.66.(4) Through comparative cutting experiments, it is found that abrasive particle plays a major role in the target body grinding, and wears the self-excited pulse nozzle seriously. Therefore the nozzle material needs to be improved.