水平固液两相管流平衡砂床高度计算的概率模型

A new probability model for predication of equilibrium sand-bed height for liquid-solid two-phase flow in horizontal pipe

根据水流紊动理论 ,将砂床表面流体瞬时流速视为正态分布的随机变量 ,将颗粒运动状态转换视为随机事件 ,分析了状态转换事件概率及最终状态概率的数字特征。根据最终状态概率代表颗粒运动趋势的原理 ,砂床高度的变化应是床层表面颗粒运动状态转换的结果。根据平衡砂床高度与摩阻流速和平均流速的关系 ,建立了计算水平固液两相管流平衡砂床高度的概率模型。该模型的计算结果表明 ,砂床高度随排量变化的曲线在管子中心点位置处均出现明显的拐点。将计算结果与实验结果进行了对比 ,平均相对误差为 8.4 8% ,能够满足工程计算要求。

According to the turbulent flow theory, the instantaneous flow velocity on the sand-bed surface was regarded as a random variable subject to normal distribution, and the grain movement behavior was transferred into a random event. The probability of transformation process was then analyzed. The probability of the final movement of grain can indicate its movement tendency, and the change of the sand-bed height can reflect the transformation status of grain movement. After giving the relationship of equilibrium sand-bed height and average flow velocity, a new probability model for predicting the equilibrium height of sand-bed was built up. The calculated results of this model indicate that there are the clear breakdown points at the point of pipe center on the relation curves of sand-bed height and pump rate. The average relative error between theoretical and experimental results is 8.48 percent, which fits to the requirement of engineering calculation accuracy.