中心正交旋转管道内流动沸腾特性的数值研究

Numerical Study on Characteristic of Flow Boiling in Center Orthogonally Rotating Tube

采用数值方法研究管轴与转轴正交的、匀角速度旋转管道内流动沸腾的流动和传热过程,建立物理模型和数学模型,基于流体体积多相流模型和Realizable k-ε(RKE)湍流模型,结合用户定义函数(user defined function,UDF)添加汽、液质能源项,求解汽液相变过程中的传热传质。结果显示,旋转管道内核态沸腾开始点(onset of nucleate boiling,ONB)发生时的壁面过热度与静止管道差别显著。随着管道转速的提高,ONB分布逐渐远离管道入口端。管道流动沸腾汽液两相流型受热载荷与旋转载荷的耦合影响,任意载荷的增强都会使流型向紊乱趋势发展。根据汽液两相流动及传热特性,分析了发生以上现象的原因。

Transient numerical analysis on process of flow and heat transfer of flow boiling in rotating tube with rotating axis vertical to the tube axis at constant angular speed was performed.The numerical model and physical model were developed.Employing realizable k-ε(RKE)turbulence model to calculate vapor liquid two phase turbulent flow.The multiphase model volume of fluid(VOF)was used to predict heat and mass transfer combining with user defined function(UDF)to add source terms of vapor and liquid.On the basis of transient numerical results,the difference of wall superheat between rotating channel and static channel is significant at onset of nucleate boiling(ONB)condition.Location of ONB shift to exit with increase of rotation speed.Flow pattern of vapor liquid two phase flow in duct affected by coupling effect of thermal load and rotating load.Either enhanced could make the stability of flow pattern tending toward to disorder.Basing on vapor-liquid two phase flow and heat transfer theory,analyses of the phenomenon appeared were given.