| High pressure water jet technology has gradually developed in recent decades. Self-excited oscillation pulsed jet as a new type, which is particularly outstanding. Because of its high efficiency, energy saving, easy to happen and environmental protection etc., it is widely used in many engineering fields, such as:rock crushing, oil drilling, mining, blanking, cutting, and building fire protection.The nozzle is the key to the high pressure water jet device. It is directly related to the working effect of water jet. Therefore, it is particularly important to study nozzle. And at present, most of the pulsed jet nozzle is studied on the basis of single nozzle chamber structure, in order to improve the work performance of the self-excited oscillation pulsed jet nozzle better, and improve the efficiency of the application of high pressure water jet in many industrial fields. Based on the theory of transient flow and on the basis of underwater acoustics, this paper proposes a dual chamber self-excited oscillation pulsed jet nozzle, for the development of the high pressure pulse water jet generator provides a new train of thought. The structure of the pulse jet generator is composed of two typical natural vibration chamber: the self-excited oscillation cavity and organ of Helmholtz resonator in series.This paper, through using CFD software Fluent to this new type of self-excited oscillation, double chamber structure on the numerical simulations of the flow field inside the nozzle.Studied the change of the device's internal structure parameters influence on jet characteristics, to explore the best chamber structure size parameters than the nozzle, the downstream side of the nozzle collision wall to the right cone shape the strongest fighting force, and the single chamber and double chamber which carries out a comparative analysis on the simulation results of the two kinds of nozzles.Simulation results show that there is a range of structural parameters than the water jet in the nozzle interior vibration effect is best; And a certain structure of double chamber structure compared with single chamber, the force is larger. And experiment shows that this experimental device was built dual chamber the accuracy of the numerical simulation of pulsed nozzle, and discussed the different organ chamber structure size of cavity pressure and the influence of the fluid pulsation, analyzes the different organ chamber structure size and shape of the downstream wall collision of self-excited oscillation pulsed jet erosion effect are studied. Experiments show that:there is a certain range of cavity length and cavity size range cavity fluid pulsation of maximum.The longer the cavity length, cavity pressure, the greater the cavity diameter of the size, the effect on cavity pressure is not bigger,there is a range of nozzle structure parameters than the water jet excitation and erosion effect is best,the downstream side of the nozzle collision wall to the right cone shape erosion effect is best,in double chamber when the pulse nozzle structural parameters of the two cavity reasonable matching, greatly enhance the jet pressure pulsation effect, increase the ability of jet erosion. Chamber under the same conditions, the double pulse nozzle is Helmholtz single chamber nozzle has a better effect of erosion and its erosion pit volume increased by about 14.5%, erosion depth increased by 12.6%, got the conclusion is consistent with the numerical simulation in this paper, and also explains the double chamber pulse nozzle is single cavity pulse nozzle has stronger erosion effect, for the development of pulse jet nozzle laid a certain foundation. |
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