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Abstract The paper discusses a new two-phase flow simulation scheme used to simulate unsteady cavitating flows. For each phase of six conservation equations, the code solves the ensemble-averaged equations of mass, momentum, and electricity conservation for each phase. The equations system requires closure guidelines for the interfacial terms that represent the mass, speed, and energy exchanges between the liquid and vapor phases. Simulations are carried out for a NACA 65222012 hydrofoil with an angle of attack of 6 u00b0, a diameter of 60% of the hydrofoil chord, and various flow velocities are carried out for a NACA 65212012 hydrofoil with an angle of attack of 6u00b0, a cavity length of 60% of the hydrofoil chord, and various flow velocities.
Source link: https://doi.org/10.1088/1755-1315/1079/1/012045
One of the most promising research areas in cavitating flow is the mechanism of flow instability, which involves complicated gas-u2013liquid interactions and multiscale vortical structures. The role of turbulence modeling is vital in the numerical analysis of unsteady flow characteristics. To improve the prediction capability for the cloud cavitation flow, we used a hybrid Reynolds-averaged Navier u2013Stokes and LES model, namely, stress-blended eddy simulation. The SBES model's lift/drag coefficients, streamwise velocity profiles, and cavity diagrams were in better agreement with the experimental results than those obtained by the modified RANS model. The stretching and dilation terms dominated the formation of vorticity around the hydrofoil, according to a subsequent review of vorticity transportation. In conclusion, the SBES model can be used to predict turbulent flows in actual engineering applications.
Source link: https://doi.org/10.1177/09544089211025119
This gives LES a greater degree of accuracy over RANS than that for LES, although averaging time means the required computational time for RANS is much shorter than for LES. The results of this research reveal that the qualitative comparisons with earlier preliminary results and the simulated general cavitation behaviour match well with experimental findings, and that the simulations have the ability to predict the cavitation cycle in more detail.
Source link: https://doi.org/10.1243/09544062jmes2036
Purpose – u2013 The present study aims to solve the calibration problem of cavitation bubble number density in simulations of the cavitating flows within the diesel injection nozzle holes using a two-fluid cavitation scheme. In addition, a phenomenological model for the number density of cavitation bubbles that factorizes the hydrodynamic effect has been developed, as a result of combined analysis of cavitation bubble dynamics and internal flow characteristics of diesel injection nozzle holes. The two-fluid cavitation model together with this latest cavitation bubble number density model predicts well both the cavitation content inside the diesel nozzle hole and the relationship between discharge coefficient and cavitation number, according to the validation results, and the new cavitation bubble number density model has the ability to extend the application range of the two-fluid cavitation model.
Source link: https://doi.org/10.1108/hff-09-2011-0174
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