低温液体在水中快速相变过程流动与传热数值模拟

用试验和理论分析的方法对快速相变爆炸强度的预测缺乏定量模型,因此建立了一种欧拉-欧拉双流体多相流模型与传热模型相互耦合的数值模型,并通过与Clarke H将液氮喷射入水的快速相变试验数据对比来验证模型的可靠性和正确性。通过数值计算得出快速相变过程中流场、压力场、温度场随时间变化的情况,探讨了快速相变的传热机理。结果表明:快速相变是强制对流、膜态沸腾、爆发沸腾和核态沸腾之间的转换过程;相间换热系数随时间的无量纲变化关系可以用3个高斯分布的叠加来描述。

Numerical simulated model for heat transfer and the fluid flow of the rapid phase transition initiated by the cryogenic liquid injection in water

This article is inclined to provide a quantitative method to predict the explosion strength of RPT,a two-fluid Euler-Euler multiphase numerically simulated model for the cryogenic liquid to be injected into the liquid water,which may lead to the Rapid Phase Transition (RPT).In the said model,a single pressure can be shared with by all the phases whereas the momentum and continuity equations can be solved for each phase,in the condition when Lee model is adopted in case that the mass transfer and the custom coefficient is equal to 10.At the same time,it is necessary to apply Grace model for the interphase momentum exchange between the cryogenic liquid-gas and/or water-gas while Schiller-Naumann model can be used for the liquid cryogenic liquid-state water.What is more,higher-order discretization and the structural mesh generation can also be used in hoping to achieve accurate results.A typical rapid phase transition experiment conducted by Clarke H.is modeled and the simulation results perfectly match the experiment results.In doing so,we have found that it would be desirable to build up a simulation model to prove the availability of the accuracy within the proper marginal size of the error.And,then,we have taken into account the rapid phase transitions by analyzing the basic heat transfer theory,while studying the undergoing 4 stages involving the transmission of the boiling process from the forced convection,the film boiling,the explosive boiling and the nucleate boiling with all the interphase heating exchanging status-in-situ included.In doing so,we have identified and determined the interphase heat transfer coefficients based on the classical formulations and the relevant experiments.Thus,simulating the RPT in the enclosed space with the model and solving the conservation equations with the coupled method of pressure and velocity,we have worked out the pressure-time profile and the temperature-time profile.And,in turn,we have proposed a dimensionless model to describe the heat transfer with the time going on.Furthermore,we have disclosed the heat transfer regularity that the liquid tends to keep going on rise in temperature until its vapor film is broken and finally getting to be constant eventually on the basis of the simulation.From what has been stated above,a conclusion can be arrived at that it is for the RPT to go through 4 different stages before getting to the vapor,that is,the forced convection,the film boiling,the explosive boiling and the nucleate boiling.In addition,the RPT's dimensionless interphase heat transfer should follow the coefficients over time of 3 Gaussian distributions.Thus,it can be seen that the research results of this paper can be expected to provide a theoretical reference for the safety protection for the LNG water transportation and transfer.