视密度加权的时平均统一二阶矩两相湍流模型

A MASS-WEIGHED MERAGED SECOND-ORDER MOMENT TWO-PHASE TURBULENCE MODEL

在气粒两相湍流的双流体模型中，颗粒相的视（表观）密度是有脉动的，在时平均的统一 工阶矩（ＵＳＭ）模型中出现了和颗粒数密度或视密度脉动有关的项和方程；使模型方程比较复 杂．实际上，用ＬＤＶ或ＰＤＰＡ测量的流体（用小颗粒代表）和颗粒速度都是颗粒数加权平均 的结果．因此，在视密度加权平均基础上推导两相湍流模型更为合理．通过推导和封闭了视密 度加权平均的统一二阶矩模型（ＭＵＳＭ）方程组，改进了两相速度脉动关联的封闭，并引入了 颗粒遇到的气体脉动速度及其输运方程．ＭＵＳＭ模型可以减少所用方程数，节省计算量．视 密度加权平均的统一二阶矩两相湍流模型是一种对原有时间平均的统一二阶矩模型的改进和 发展．

There is particle apparent density or number density fluctuation in turbulent gas- particle flows. Hence, the time-averaged unified second-order moment (USM) two-phase turbulence model must include the terms and equations related to number density fluctuation, which makes the model more complex. Actually, the gas (tracked by small particles) and particle velocities measured by LDV or PDPA are the number-averaged ones. So, it is more reasonable to use mass-weighed averaging instead of time averaging. Furthermore, the mass-weighed averaging can reduce the number of equations, thus reduce the computation storage and time. In this paper, a mass-weighed averaged second-order moment (MUSM) two-phase turbulence model is derived and closed. This model includes an equation of gas fluctuation velocity seen by particles. Therefore, the MUSM model can be considered as the improvement and development of the original time-averaged USM model.