Abstract
The cavitation phenomenon of the self-resonating waterjet for the modulation of erosion characteristics is investigated in this paper. A three-dimensional computational fluid dynamics (CFD) model was developed to analyze the unsteady characteristics of the self-resonating jet. The numerical model employs the mixture two-phase model, coupling the realizable turbulence model and Schnerr–Sauer cavitation model. Collected data from experimental tests were used to validate the model. Results of numerical simulations and experimental data frequency bands obtained by the Fast Fourier transform (FFT) method were in very good agreement. For better understanding the physical phenomena, the velocity, the pressure distributions, and the cavitation characteristics were investigated. The obtained results show that the sudden change of the flow velocity at the outlet of the nozzle leads to the forms of the low-pressure zone. When the pressure at the low-pressure zone is lower than the vapor pressure, the cavitation occurs. The flow field structure of the waterjet can be directly perceived through simulation, which can provide theoretical support for realizing the modulation of the erosion characteristics, optimizing nozzle structure.
Highlights
Submerged self-resonating waterjet is a simple means with strong self-oscillating cavitation characteristics [1,2], which have been widely applied in the industries of cutting of solid materials, cleaning and burry removal of complicated mechanical products [3,4,5]
For the sudden change of the nozzle geometry as shown in Figure 4, the high-speed flow passes through the nozzle, which would lead to the rapid fluid changes, and forms velocity vortexes in the direction of the flow
The sudden change of the flow velocity for the geometry of the nozzle formation the velocity vortexes consists of two shear zones
Summary
Submerged self-resonating waterjet is a simple means with strong self-oscillating cavitation characteristics [1,2], which have been widely applied in the industries of cutting of solid materials, cleaning and burry removal of complicated mechanical products [3,4,5]. Over the past few years, deep-sea resources have attracted worldwide attention, and selfresonating waterjet has broad applications in the exploitation of deep-sea mineral resources. The deep-sea environment is so complex, and the mineral resources have a changeable outlook when facing different erosion materials and cavitation behaviors, the confining pressure and the velocity of the flow decision on the oscillation characteristics of self-resonating waterjet. The modulation mechanisms of oscillation characteristics are a key technology in a complex deep-sea environment, it still not perfect
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