圆管壁粗糙度对圆管内流态影响研究

基于尼古拉兹圆管实验思想,利用颗粒流程序中的流体计算模块,实现了对圆管壁粗糙度的模拟,进而分析了不同粗糙度对圆管断面流态分布的影响以及在不同压力差作用下平均流速与圆管壁粗糙度之间的关系。研究结果表明:圆管内流体流速受管壁的扰动影响,在横截面上呈U型分布,而非抛物线型分布;圆管壁对管内流体流态的影响范围随管壁粗糙度变化而变化,圆管管壁相对粗糙度越大,管内受扰动流体范围越大,即管内层流范围越小;在管壁粗糙度一定的情况下,圆管断面流量随上下端面压力差的增大而增大;在相同压力差作用下,圆管断面流量随管壁相对粗糙度增大而逐渐减小,颗粒的阻流作用明显;随着管壁粗糙度的增大,圆管上下端面受压力差作用的影响范围也随之增大,使管内流体流态变得更加复杂。

Effects of Pipe Roughness on Flow Pattern Within Circular Pipe

Based on the idea of Nikuradse’s experiment ,this paper simulated the roughness of pipes by using Particle Flow Code (PFC) FLUID SCHEME ,and analyzed the effects of different roughness of pipes to the flow pattern and the relationship between the mean velocity and roughness under different pressures .The results showed that flow velocity within pipe was influenced by pipe wall ,and presented U-shaped in cross-section profile ,rather than parabolic distribu-tion;The flow pattern was affected by the pipe roughness ,the larger relative roughness of the pipe ,the greater range flu-id was perturbed ,namely laminar flow range become smaller .Under certain circumstances of pipe roughness ,pipe flow increases with the increased pressure;while under the same pressure difference ,pipe flow decreases with the increased roughness of pipe and the particles damping action is significant .While increasing roughness ,the affected area within pipe also increased under different pressure ,which make fluid flow patterns within pipe become more complex .