水力输送管道中粗颗粒运动状态变化及其判别

Movement Status Change of Coarse Particlesand it's Discriminant Parameter in Hydraulic Transporting Pipeline

粗颗粒运动形态变化规律是管道安全输送的关键问题.针对这一问题,利用粗颗粒管道输送试验系统,通过高速摄影技术和粒子图像测速法记录粗颗粒的运动状态及其速度变化,分析了不同粒径、不同体积浓度、不同输送速度条件下粗颗粒在管道中的水力学特性,并拟合得到粗颗粒运动状态的判定参数.研究结果显示,粗颗粒在管道中随着流体平均流速的增加依次出现扬动状态、间歇式推移状态、连续式推移状态和悬移状态,并通过不同运动状态的力学机制和能量损失分析提出了不同运动状态的变化规律;从粗颗粒安全输送的角度,提出连续式推移状态是粗颗粒在较广输送速度范围内,能够实现连续有效输送的一种运动形式,是管道运输中的颗粒物主要运动状态;从分析结果可知,粗颗粒的运动状态与流速、颗粒粒径以及颗粒浓度有关,通过引入管径和重力加速度两个参数,采用量纲分析法得到无量纲数φ为颗粒运动状态判别参数,并以此作为判定粗颗粒不同运动状态,该参数可以在工程中预测粗颗粒的运动状态.

The change rule of coarse particles movement status is the essential problem to pipeline safe operation. To solve this problem,the hydraulic characteristic of coarse particles was studied by high speed photography and particle image velocimetry under different particle size,concentration and velocity condition in pipeline hydraulic transportation system,and judgment parameter of coarse particles movement status was fitted. The result indicates that coarse particles appear starting,discontinuous movement as bedload,continuous movement as bedload,and suspension in order with mean velocity of fluid media increase; the variational laws of different movement status are proposed by mechanism and energy loss; from safety transportation of coarse particles standpoint,continuous movement is the mainly movement status which can realize continuous transmission effectively; In analysis result,we can find out that coarse particles movement status is mainly concerned with velocity,particle size and concentration,by the introduction of pipe diameter and acceleration of gravity,we get dimensionless number φ as discriminant parameter by the method of dimensionless parameter,and it could divide and forecast coarse particles movement status in the practical engineering.