A Pressure-Base One-Fluid Compressible Formulation for High Speed Two-Phase Flows With Heat and Mass Transfer

2018 ◽  
Vol 140 (8) ◽  
Author(s):  
Yan Luo ◽  
Jianqiu Zhou ◽  
Xia Yang ◽  
Zhanxiang Jiang

This paper presents a numerical method for high-speed compressible cavitating flows. The method is derived from one-fluid formulation in a sense that the two phases are well mixed and the mixture is considered as a locally homogeneous media. Energy equation is solved to predict the temperature evolution which is then used together with pressure to update the density field. A volume of fluid (VOF) phase-fraction based interface capturing approach is used to capture the phase front between the two immiscible fluids. The derived formulations have been implemented into a pressure-based, segregated algebraic semi-implicit compressible solver in Openfoam, which can be used to solve for high-speed compressible two-phase flows involving phase changing. Numerical examples include the cavitating flows induced by an ultrasonic oscillating horn with and without a counter sample. The numerical results by the proposed method are validated against the published experimental data as well as numerical results and good agreements have been obtained. Our calculation demonstrates that the proposed numerical method is applicable to the study of high-speed two phase flows with phase transition and wave propagation, such as shock waves induced by the collapse of the cavitation bubbles.

2004 ◽  
Vol 126 (3) ◽  
pp. 419-429 ◽  
Author(s):  
Yuka Iga ◽  
Motohiko Nohml ◽  
Akira Goto ◽  
Toshiaki Ikohagi

Three types of cavitation instabilities through flat plate cascades, which are similar to “forward rotating cavitation,” “rotating-stall cavitation” and “cavitation surge” occurring in high-speed rotating fluid machinery, are represented numerically under the three-blade cyclic condition. A numerical method employing a locally homogeneous model of compressible gas-liquid two-phase medium is applied to solve the above flow fields, because this permits the entire flow field inside and outside the cavity to be treated through only one system of governing equations. In addition, the numerical method suites to analyze unsteady cavitating flow with a long time evolution. From the calculated results of the present numerical simulation with wide range of cavitation number and flow rate, we obtain a cavitation performance curve of the present three-blade cyclic cascade, analyze the aspects of unsteady cavitation, and discuss the characteristics and mechanisms of cavitation.


2012 ◽  
Vol 219 (1) ◽  
pp. 320-344 ◽  
Author(s):  
Mai Duc Thanh ◽  
Dietmar Kröner ◽  
Christophe Chalons

Author(s):  
Miguel Xavier Diaz-Lopez ◽  
Juan Sebastian Rubio ◽  
Rui Ni

The objective of this study is to understand the dynamics of a high-speed particle-laden under-expanded jet, motivated by landings on extraterrestrial bodies. In this setup, inertial particles are entrained and accelerated by an under-expanded jet. But, due to their inertia, the particle velocity is significantly lower than that of the surrounding gas close to the nozzle, so the two phases are coupled through aerodynamic drag. Sub-micron oil droplets are dispensed upstream to serve as tracers, whose velocity is determined through a PIV system; inertial particles, after image segmenting is performed to separate them from PIV data, will be tracked over time with a PTV system. This was accomplished with a single laser pulse and the camera straddle time to produce image pairs and shorten the pulse width. The results will help to understand particle-laden flow in a new regime where the background flow is compressible and the Mach number based on the slip velocity is not negligible, which may help to pave a foundation for future studies in compressible multiphase flows.


2021 ◽  
Vol 409 ◽  
pp. 39-48
Author(s):  
S. Gourari ◽  
Fateh Mebarek-Oudina ◽  
Oluwole Daniel Makinde ◽  
M. Rabhi

Two-phase flows are widely encountered in many natural phenomena and industrial processes. The presence of one or more interfaces between the two phases presents a major difficulty which makes the modeling and the simulation of this type of flow complex. This work consists in performing a three-dimensional numerical simulation of a two-phase Hydrogen-Water flow inside a horizontal cylindrical channel. The results are obtained in the form of velocity contours, enthalpy and pressures.


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