Numerical Investigation of a High-Pressure Submerged Jet Using a Cavitation Model Considering Effects of Shear Stress

Abstract

In the current research, a high-pressure submerged cavitation jet is investigated numerically. A cavitation model is created considering the effect of shear stress on cavitation formation. As such, this model is developed to predict the cavitation jet, and then the numerical results are validated by high-speed photography experiment. The turbulence viscosity of the renormalization group (RNG) k-ε turbulence model is used to provide a flow field for the cavitation model. Furthermore, this model is modified using a filter-based density correction model (FBDCM). The characteristics of the convergent-divergent cavitation nozzle are investigated in detail using the current CFD simulation method. It is found that shear stress plays an important role in the cavitation formation in the high-pressure submerged jet. In the result predicted by the Zwart-Gerber-Belamri (ZGB) cavitation model, where critical static pressure is used for the threshold of cavitation inception, the cavitation bubble only appears at the nozzle outlet and the length of the cavity is much shorter than the actual length captured by the high-speed photography experiment. When the shear stress term is added to the critical pressure, the length of the predicted cavity is close to the experimental result and three phenomena of the jet are captured, namely, growth, shedding, and collapsing, which agrees well with the experimental high-speed image. According to the orthogonal analysis based on the simulation result, when the jet power is unchanged, the main geometry parameter of the divergent-convergent nozzle that affects the jet performance is the divergent angle. For the nozzle with three different divergent angles of 40°, 60°, and 80°, the one with the medium angle generates the most intensive cavitation cloud, while the small one shows the weakest cavitation performance. The obtained simulation result is confirmed by cavitation erosion tests of the Al1060 plate using these three nozzles.

Reduction of Energy Consumption for Water Wells Rehabilitation. Technology Optimization

“…It can be seen that in the first two cases, the cavitation zone propagated through the entire domain, and in the last case it propagated up to 87 mm; therefore, this nozzle can effectively produce cavitation in well depths up to 300 m. It is also shown that cavitation clouds are formed inside the nozzle; they continue developing downstream and then expand. The experimental results presented in [21] demonstrate that cavitation jets consist of three zones: growing, shedding and collapsing. When a cavitation cloud propagating from a nozzle reaches a specific location, the downstream part is shed from the initial cloud.…”

“…It was developed using re-normalization group (RNG) methods to re-normalize the Navier-Stokes equations in order to consider the effects of smaller scales in the flow [20]. Such a model was successfully used in [21] for the dynamic study of cavitation jets. The Autodesk CFD package was used for numerical modelling.…”

A Review on the Erosion Mechanism in Cavitating Jets and Their Industrial Applications

“…Recently, Yang et al [33] compared their numerical predictions of the cavitation cloud in a cavitating jet to their high-speed flow visualizations. They found almost zero vapor volume fraction in the central region of the jet near the nozzle exit and the presence of a ring-type cavitation zone in the high-speed shear layer, around the central zone.…”

“…Yang et al [33] also studied the effect of the diverging angle of the nozzle exit on the flow dynamics using the RANS RNG k-ε turbulence model. The vapor volume fraction distribution showed (Figure 4) that the cavitation cloud is larger for a 60 • angle than for 40 • and 80 • .…”

Experimental Study on Submerged High-Pressure Jet and Parameter Optimization for Cavitation Peening

“…Fig. 1 shows the high-pressure cavitation jet experiment system, which is mentioned in our former works [20]. The system uses an Italian ANNOVI REVERBERI SHP 15.50N high-pressure piston pump to provide high pressure for the jet.…”