Numerical Research of the Submerged High‐Pressure Cavitation Water Jet Based on the RANS‐LES Hybrid Model

Abstract

The submerged high-pressure water jet has the characteristics of high velocity, strong turbulence, and severe cavitation. In order to reveal the formation mechanism of shear cavitation in the submerged high-pressure water jet and to grasp the turbulent structure and velocity distribution characteristics in the jet, the prediction ability of different turbulence models is studied first. The models represent the RANS model and RANS-LES hybrid model which are used to simulate the same cavitation jet, and the results are compared with the experimental results. The most reasonable model is then used to investigate the submerged high-pressure cavitation jet with different cavitation numbers. It is found that the calculation accuracy for small-scale vortexes has a great influence on the prediction accuracy of cavitation in the submerged jet. Both the DDES model and the SBES model can effectively capture the vortexes in the shear layer, and the SBES model can obtain more turbulence details. The result of the simulation under different cavitation numbers using the SBES model agrees well with the experimental result. Under the condition with low cavitation number, an intensive shear layer is formed at the exit of the nozzle, and small-scale vortexes are distributed along the shear layer. Mass transfer rate is relatively high in the region with a stronger vortex, which confirms that the low pressure in the vortex center is the main reason for the generation of cavitation in the shear layer. With the decrease of the cavitation number, the cavitation intensity increases obviously, while the nondimensional velocity along the radial direction changes little, which follows an exponential function.

A Study of Cavitation Erosion in Artificial Submerged Water Jets

“…ANSYS Fluent has a proven track record of success in cavitation analysis, including applications related to water jet pump tip leakage vortex and water jet phenomena [26][27][28]. The Stress-Blended Eddy Simulation (SBES) model employed in this study is chosen based on the SST k-ω model, as it has demonstrated its capability to simulate the super-cavitation flow generated by high-speed water jets within the injection pressure range of 5-25 MPa [29]. The SBES turbulence model is specifically developed to capture the dynamic behavior of turbulence in distinct flow regions.…”

Numerical Investigation on Cavitation Jet in Circular Arc Curve Chamber Self-Excited Oscillation Nozzle

“…The high computational cost limits the wide application of the LES. To solve the problems of these two models, the stress-blended eddy simulation (SBES) was adopted, which not only guaranteed the calculation accuracy but also saved the calculation time [26]. The SBES achieves stress mixing between RANS and LES through the following equation:…”

Optimization of Composite Cavitation Nozzle Parameters Based on the Response Surface Methodology

“…The results showed significant differences in the formation and development of intercepted surges, with the elliptical jet having the slowest penetration rate. Yang et al [27] used the RANS method, LES method, and the RANS-LES hybrid method to simulate the fluid field of submerged cavitation water jets and analyzed the accuracy of different turbulence models in predicting jet cavitation. The results showed significant deviations in RANS, while RANS-LES and LES models showed higher precision.…”