振动对弯管减阻效果分析

Analysis of drag reduction effect of vibration on elbow

节能减阻是近年来亟待解决的问题,长距离管道输送系统中的应用尤为重要。与现有输送介质不同,将振动减阻技术用于气力输送气固两相流系统中。采用欧拉-欧拉双流体模型,用户自定义函数控制的单参考系模型,数值模拟不同振动参数对减阻率的影响,并考虑不同流速、固相体积分数的变化。模拟结果表明:剪切应力随振幅和频率的增加而减小,减阻率随振幅和频率的增加而增加,振动方向沿x轴时,减阻效果最佳,沿y轴次之,z轴最差;压差随流速的增加呈幂指函数增加,且振动不改变压差随流速的变化趋势,相同振动参数下流速越大减阻率越低;压差随固相体积分数的增加线性增加,且振动不改变压差随固相体积分数的变化趋势,相同振动参数下固相体积分数越大减阻率越低。其结论可为气固两相减阻技术提供参考。

Energy saving and drag reduction is an urgent problem to be solved in recent years,and the application of long-distance pipeline transportation system is particularly important.Different from the existing conveying medium,the vibration drag reduction technology was used in the gas-solid two-phase flow system of pneumatic conveying.The Euler-Euler two-fluid model and the single reference frame model controlled by user-defined function were used to numerically simulate the influence of different vibration parameters on drag reduction rate,and the changes of different flow rates and solid phase volume fraction were considered.The simulation results show that the shear stress decreases with the increase of amplitude and frequency,and the drag reduction rate increases with the increase of amplitude and frequency.When the vibration direction is along the x-axis,the drag reduction effect is the best,followed by the y-axis,and the z-axis is the worst.The pressure difference increases with the increase of the flow rate as a power exponential function,and the vibration does not change the trend of the pressure difference with the flow rate.The drag reduction rate decreases with the increase of the flow rate under the same vibration parameters.The pressure difference increases linearly with the increase of solid phase volume fraction,and vibration does not change the trend of pressure difference with the increase of solid phase volume fraction.The drag reduction rate decreases with the increase of solid phase volume fraction under the same vibration parameters.The conclusion can provide guidance for gas-solid two-phase drag reduction technology.