On The Two-phase Slip Flow With Condensation

The two-phase slip flow with the condensation of vapor is a common phenomenon in both natural and industrial applications,and it is closely related to society,economics,and daily life.The interphase slip of the two-phase slip flow with the condensation of vapor is mainly manifested in two aspects:one is the slip of velocity,the other one is the slip of temperature.For the former one,the density of droplets is much larger than the density of gas,which result in the hysteresis of movement between the droplets and the gas when the movement of the gas changes.For the latter one,the temperature of droplets is different from the temperature of gas.The latent heat released by the condensation of vapor will enlarge the slip of temperature and change the movement of the gas significantly.The process of the condensation of vapor is very rapid and the radii of droplets are in the order of micron and below.Therefore,neither theoretical research nor experimental research can carry out more detailed research.So numerical simulation is an effective way to solve this problem.The two-phase slip flow with the condensation of vapor is numerically investigated through the Method of Moments with interphase slip in the present work,which are briefly introduced as follows:Firstly,the Method of Moments with interphase slip is simplified.Instead of the nucleation of vapor,the droplets with the same size are added directly to the flow.As a result,the interphase slip,the growth of the droplets,and the latent heat released by the condensation of vapor will be decoupled,which ensures us to analyze the effect of interphase slip on the structure of flow better.In this paper,the process of the transfer of droplets from the core to the outside of the Rankine vortex is analyzed in detail.It is found that the droplets' distribution shows a " four arms " structure when the flow upsets.And furthermore,the mechanism of the flow instability is analyzed from the perspective of vorticity.Then,the condensation of vapor in Rankine vortex is numerically investigated.Because the droplets are very small and the interphase slip is also very weak,the la-tent heat released by the condensation of vapor becomes the main factor affecting the parameter of the flow field.From the point of droplet distribution,although the inter-phase slip is weak,the droplets will move outside the vortex and keep growing.From the point of the parameters of flow,the latent heat released by the condensation will induce an increase of the pressure and temperature of the vortex.Because the Rankine vortex's pressure and velocity is self-matching,the vortex velocity is reduced and the strength of the vortex is weakened during the condensation of vapor,which has an im-portant practical significance.The effect of the growth of droplets on interphase slip is also discussed.The results show that a part of momentum of the gas will be transferred to the droplets during the condensation.This additional momentum transfer makes the interphase slip relaxation process shorter,enhances the followability of the droplets,and weakens the interphase slip eventually.In the end,the Method of Moments with interphase slip is extended to deal with the problem of the heterogeneous condensation.The influence of the effect of het-erogeneous condensation and interphase slip on nozzle flow(Ma=2)is analyzed numerically under three flow conditions:(1)without heterogeneous condensation,(2)without interphase slip,(3)both heterogeneous condensation and interphase slip.It is found that the heterogeneous condensation occurs at the contraction section of the noz-zle,so that the pressure and Mach number of the nozzle flow increase.The interphase slip will hinder the expansion of the nozzle flow,so that the pressure of the nozzle flow will increase and the Mach number of the nozzle flow will decrease 5%.