阀门小开度对突扩管流下游脉动压力特性的影响

Influence of valve small opening on pulsating pressure characteristicsof pipe flow downstream sudden expansion section

为了分析阀门开度对变截面管流下游脉动压力特性的影响,提高管路水流的稳定性和输送效率,进行了不同阀门开度对突变截面圆管下游流动的脉动压力特性试验.以清水为流体,并以不同阀门开度和距突扩距离的长短为变量,测试了突扩管流不同位置的脉动压力幅值.研究结果表明:变截面管流下游流体脉动压力过程曲线具有随机平稳特性,使用阀门调节流速会使各点脉动压力周期变长;阀门会使变截面管流下游产生50 Hz左右的脉动压力,流体脉动压力幅值与阀门开度正相关;随着距突扩距离的增加,流体压力脉动强度先增大后减小;随着阀门开度的增加,脉动压力能量分布频域逐渐变宽,流体流过突扩后的脉动压力恢复长度变长.

In order to analyze the effect of valve opening on pulsating pressure characteristics of pressure downstream and improve the stability of pipe flow and transport efficiency,experiments were performed to measure the pulsating pressure characteristics in downstream flow of the pipe with sudden expansion section at different valve openings.In the experiments,tap water was the working fluid,the valve opening and the length between the valve and the sudden expansion section were varied,and the amplitude of pulsating pressure at different positions along the pipe downstream the sudden expansion section was measured.Furthermore,the influence of different valve openings on the pulsating pressure characteristics of variable cross-section pipe flow was analyzed.It is found that the pulsating pressure curve of the downstream pipe with variable cross section has random but steady characteristics.Using a valve to adjust flow rate can lengthen the pulsating pressure period at each point.The valve can cause an about 50 Hz pulsating pressure downstream the variable cross-section pipe,and the amplitude of the pressure is positively correlated with valve opening.As the distance to the sudden expansion section increases,the standard deviation of fluid pressure first rises and then decreases.As the valve opening increases,the frequency domain of the pulsating pressure energy is widened gradually,and the turbulent intensity of the flow is intensified step by step.Thus,the length of the pressure recovery behind the sudden expansion section becomes longer.