| The self-excited pulsed jet is formed by the modulating effects of theself-excited pulsed nozzle. Since the pulsed jet device has the advantagesof small volume, simple structure, well tightness, high reliability and noextra power source, it can effectively improve equipment reliability,reduce maintenance costs, and is widely used in crushing, cleaning andcutting of materials.This paper describes various high efficient jet, such as abrasive jet,cavitation jet, air-water jet and self-excited oscillation pulsed jet, etc. Theoccurrence mechanism of the self-excited oscillation pulsed jet isanalyzed, and its oscillation frequency and natural frequency models arededuced. The mathematical model of the testing system is alsoestablished. The present research focuses on the dynamic characteristicsand erosion capability of the self-excited pulsed water jet under thesubmerged conditions.Under submerged conditions,the dynamic characteristics signal ofthe self-excited oscillation pulse jet impact cantilever beam is collectedby the vibration signal analyzer (model is QLVC-ZSA1).Theexperimental results show that the peak frequency of the self-excitedpulse jet decreases with increasing pump pressure, and graduallydecreases with increasing chamber length; the peak frequency of theself-excited pulsed jet under the submerged conditions is smaller than thenon-submerged conditions.With chamber length of pulsed nozzle as main experimentalparameters, the experiment on eroding sand brick block (compressivestrength7.0MPa) is carried out. The evaluation parameters are the erosionvolume and erosion length. The experimental results show that theself-excited oscillation nozzle existed a optimal chamber length toachieve the best pulsed effect; the erosion volume of pulsed jet increaseby about37.1-52.3%larger than the continuous jet. The erosionappearance under the submerged conditions is much regular than the non-submerged conditions. |
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