Papers by Keyword: Two-Phase Flow

Abstract: Based on the principle of the attenuation of an acoustic wave propagating in a gas-liquid two-phase flow, an experiment has been designed to measure the void fraction. The experiment system is consisted of three segments which arepressure stabilizing control system, ultrasonic measurement system and bubble injection system. The measurement process is three steps. First, a reference experiment is performed to acquire the received signal amplitude in pure liquid. Then, measurement of the received signal amplitude in different void fraction is accomplished. Last, the relationship between void fraction and signal amplitude attenuation is given on which the void fraction of two-phase flow can be detected. It is confirmed that void fraction detection using the present method achieves successfully.

Abstract: Three-dimensional two-phase flow in the typical double downside 90°afterburning chamber of boron based ducted rocket is numerically simulated by means of Realizable turbulence model, one-step eddy-dissipation combustion mode1 and the ignition and combustion mode of boron particles of KING with considering the film moving effect in the high-speed flow. The results show that co-swirl and counter-swirl air in the double side of inlet enters into afterburning chamber to make mixture of air and gas more fully and combustion efficiency increases with the increase of swirl number. Boron particles and total combustion efficiency with co-swirl is higher than counter-swirl when the swirl number is less than 0.179. On the contrary, the counter-swirl is higher than co-swirl when the swirl number greater than 0.385, the co-swirl is balance to the counter-swirl when the swirl number is about 0.2; the ignition time of boron particles is reduced with swirling air, its minimum can be attained when swirl number is 0.385.

Abstract: For the internodal absolute permeabilities of flow in heterogeneous porous media, the most popular method is harmonic means, but it has been known that the harmonic mean method underestimate the flux of the single phase steady flow, especially for the strong heterogeneities. Based on the power-law behaviour of pressure, a finite analytic numerical method is proposed for two phase incompressible flow in 2D heterogeneous porous media. Numerical example shows that the finite can obtain more accurate value than traditional numerical methods such as the harmonic average method and so on, for different permeability distributions, only with or subdivisions can provide rather accurate solutions while traditional numerical methods need very small scale grids.

Abstract: Based on the PDF transport equation of particle, Using both non-isotropic correlation coefficient and isotropic correlation coefficient, the two-order moment trajectory model of particles (TOMTM) is used to simulate the backward-facing step two-phase flow. It is shown that the isotropic correlation coefficient of TOMTM can simulate the anisotropic turbulence of particle better.

Abstract: Based on the PDF transport equation of particle, a two-order moment trajectory model of particles (TOMTM) is proposed to obtain reasonable statistical characteristics of a two-phase flow. Using the method proposed by Risken, It is shown that TOMTM is just the solution of the particles PDF equation

Abstract: The bubbles in the liquid will scatter and absorb the ultrasound, therefore the existence of bubbles will seriously affect the ultrasound propagation in the liquid medium inside the pipeline. This paper analyzes the influence of bubbles in the liquid on the performance of the ultrasonic flow meter, and the gas-liquid two-phase flow rate measurement experiments are implemented. Experimental results show that with the increase of the bubble volume fraction in the liquid, the measurement error of the ultrasonic flow meter increases. When the bubble volume fraction exceeds 1%, the transit-time difference method of measuring the flow rate is nearly useless.

Abstract: Flashing is an important factor in the working process of hot water rocket motor. In order to deeply understand the performance characteristic of hot water rocket motor, a numerical simulation model of the flow field in the nozzle was established in this paper. According to the study of flow field in the nozzle of the motor,it is found that the phase change occurs at the position of the throat,and the flow reaches to supersonic after the throat because of the changing sound speed.The flow in the nozzle can be divided into three processes in this paper: single-phase flow process, flash process and expand-accelerating process.

Abstract: Three liquid-gas separator units were designed and manufactured from transparent acrylic resin based on the concept of a new kind of validated high performance condenser. The separator units had different spaces between baffle and outlet arm or different header diameters. A visualization cold state test system was set up to explore the basic principle of liquid-gas separation and liquid discharge process, using air and water as the working fluids. Four kinds of liquid flow patterns were observed by the liquid staining and high-speed photography at inlet air superficial velocities from 1m/s to 15m/s and water superficial velocities from 0.0015m/s to 0.06m/s. The effects of operation conditions and structure parameters on the separation efficiency of the liquid-gas separator units were investigated. The results showed that under the experimental conditions, the separation efficiency was more than 70%, the separation efficiency could be improved by increasing the space between baffle and outlet arm as well as the header diameter.

Abstract: In this paper, a two phase flow distribution in a horizontal pipe is numerically analyzed by solving one dimensional steady state momentum equation for predicting the pressure drop (∆P), quality of steam at outlet of the pipe (X), void fraction (α). The heat absorbed by the pipe (Q) and the mass flow rate (W) of water are varied over a wide range to investigate the above parameters. The locations of the two phase mixture are discussed. Pressure drop along the pipe is inconsistent for different flow rate so, the stable and unstable steady state solution is also carried out using Linear Stability analysis. The present numerical results are compared with the reported data from the literature and found that they are in good agreement. This study is used to calculate the pressure, temperature, hold up and quality within the horizontal pipe.

Abstract: The simulation of two-phase oil-water coupling flows in a low permeability reservoir with capillary pressure and start-up pressure gradient was carried out. First of all, the state equations with all the oil pressures at grid nodes were established based on lump-centre finite difference method. Secondly, the recurrence formulae of all the oil pressures and water saturations at grid nodes were built up according to IDPIM and an explicit difference method, respectively. Finally, the simulation of two-phase oil-water coupling flows for a typical five point area water injection as an example was carried out. Simulating results show that capillary pressure has a little effect on moisture rate and oil production, but startup pressure gradients have an outstanding effect on them. Therefore the existence of startup pressure gradients will enhance the difficulty of oil development.