Papers by Keyword: Two-Phase Flow

Abstract: Rain-wind induced vibration (RWIV) is a large amplitude and low frequency vibration of stay cables under wind and rain. The formation and oscillation of rivulets on stay cable surface plays an important role in RWIV, and it is also the symbolic characteristics of RWIV. In this paper, a numerical simulation approach of the formation process of rivulets around stay cable is presented by combining gas-liquid two-phase theory and volume of fluid method (VOF method) for the first time. The effect of gravity and air flow on morphology of rivulets is analysed by numerical simulation using computational fluid dynamics (CFD) software-CFX. The veracity and rationality of this approach is verifed by comparing with existing experimental data.

Abstract: To study the dispersion of fuel droplets in the supersonic flow and reveal the momentum and heat exchanges between two phases, a large eddy simulation (LES) and particle Lagrangian tracking model were employed to numerically simulate two-phase mixing layer flows, using the one-way coupling method. The velocity fluctuation disturbances were added to inspire the flow instabilities. The motions of droplets in different diameters and droplets’ response to the large scale eddies were analyzed. The results indicated that droplets of 1micro diameter below are corresponded with the motions of coherent vortexes in the mixing layer. The more intense momentum and heat exchange are performed with decreasing the droplet’s diameter. The well mixing of fuel droplets in turbulence would make the combustion preparedness more sufficient. The research conclusions are of important academic value for further analyzing the two-phase dynamics in the scramjet.

Abstract: A laboratory scale jet flotation column system was designed and air inflation for flotation column was provided by jet aerator with a chamber. In order to understand interior flow field distribution of jet aerator and flotation column, two-phase turbulent flow model was established by use of commercial computational fluid dynamics (CFD) software FLUENT 6.3.26. Modeling of the flow field was firstly established with GAMBIT 2.3.16; standard k-ε turbulence model and multiphase flow model MIXTURE were adopted for gas-liquid two-phase numerical simulation about jet aerator and flotation column. The simulation results show that gas-liquid two-phase mixing have been established by the cavity entrainment vortex flow in jet aerator with a chamber, and the distortion was really occurred although the reversed cone feed inlet have been designed, at the same time non-uniform distribution of air-bubble was also simulated. Simulation results can help to optimize the structure of the jet flotation column.

Abstract: The paper focuses on the interphase force of the gas-liquid two-phase flow in the horizontal pipe design and designs a new interpahse force quantitative detection devices. On the basis of analyzing the physical models and the mathematical models, the devices got the more accurate differential pressure and the two-phase flow phase holdup, avoiding many factors by using the capacitance sensor which is made up of the complete closure outer electrode and flow media as the inner electrode. Finally, the devices achieved the quantitative detection of the interphase force through the differential pressure and the phase holdup. The experiments proved that the devices can better reflect the interphase force changes of the gas-liquid two-phase flow in the horizontal tube and reached the design goal very well.

Abstract: Monitoring the flow behaviour on the micro-scale is very important in many industrial and biochemical process, the multiphase coexistence in microchannel provide many attractive characteristics compared to a single-phase flow. The precise flow rate control and well-defined channel geometries make it possible for us to make detailed investigation on multiphase flow phenomena. This paper aims at the measurement of resistance distribution in the cross-section of a novel microchannel based on the Agilent measuring instruments. Experimental results verified the possibility of estimation on particle concentration in the solid-liquid two-phase flow by the measurement of resistance distribution in the microchannel.

Abstract: We have studied the mechanism of interaction of shock waves with dust bulk, and built the model of stripping of boundary layer of dust entrained by shock waves, and calculated out the maximum uprising velocity of dust particle, and built the equation of dust outline with the equation of relaxation movement of a dust particle behind shock waves. The result is identical with that of experiments.

Abstract: According to the development of a new type of oil purifier——HIGEE rotating oil purifier, this paper has carried out related numerical simulations. The two-phase porous medium flow model in the rotating packed bed (RPB) was built, and by using CFD software, the distribution of the phases in the RPB which is on the condition of high gravity (HIGEE) field and the porous media has been simulated. The paper has developed the influencing rule of key technologies parameters which affect the separating efficiency of the rotating packed bed.

Abstract: This paper presents a study on an oil-water two-phase flow model in a downhole Venturi meter by theoretical calculation, numerical simulation and experimental testing. The flow field and pressure characteristics with different flow and oil-water ratios in Venturi tube are investigated. It is found that the flow is stratified in the Venturi tube, the water phase accumulates in the tube center and the oil phase concentrates on the wall; the pressure drop is increased with flow; theoretical and numerical results are verified by experimental data.

Abstract: The pressure drop in a helical-coil heat exchanger is studied. The helically coiled tube with a coil pitch of 1080 mm and coil diameter of 950 mm is fabricated by bending a stainless steel tube of 8m length and 15.6 mm inner diameter. The total height of the helix tube is 2.8 m. The concerned range of mass flow rate for two-phase flow is 25-100 kg/m2s. Computational fluid dynamics (CFD) simulation analysis of pressure drop in the vertical helical-coil heat exchanger is carried out.

Abstract: A T-junction with a horizontal main pipe and a vertically downward branch was employed to investigate phase separation phenomenon of oil-water two-phase flows at two segregated flow patterns. Water and kerosene (density of 796 kg/m³) were chosen as the working fluids. The effects of inlet flow pattern, mixture velocity, and water cut on the phase separation were examined. The results show that the variation of the mixture velocity in the same inlet flow pattern has little influence on the phase split and the phase separation highly depends upon the inlet flow pattern. The lower the mixedness of the inlet flow, the higher the separation efficiency can be achieved. The higher the water cut, the lower the separation efficiency peak can reach.