给水管网球阀局部阻力系数计算研究

为确定给水管网阀门的局部阻力系数,提出了一种基于几何计算和现场试验的局部阻力系数公式的构建方法。先通过几何计算建立球阀通流面积与阀芯旋转角度的关系,并以某转角下和全开时的通流面积之比作为球阀的面积开度,指出了传统的以阀芯旋转角度与全行程所需旋转角度之比作为球阀开度定义的缺陷。然后以DN20球阀作为试验对象,通过现场试验,采集各开度下的压差和流量值并计算出相应的局部阻力系数,经曲线拟合,建立了面积开度与球阀局部阻力系数之间的关系。另一组面积开度和球阀局部阻力系数的试验数据表明,该计算公式能有效地应用于球阀局部阻力系数计算。

Calculation of local resistance coefficient of ball valve in water supply network

In order to determine the local resistance coefficient of valves in water supply network,a method of establishing local resistance coefficient formula was proposed based on the geometric calculation and field experiments.At first,the relationship between flow area of ball valve and rotation angle of spool was built by geometric calculation.The area opening degree of ball valve was defined as the ratio between flow area at a rotation angle and flow area in the fully open condition.The defect of traditional definition about the ratio between spool rotation angle and rotation angle in whole process as ball valve opening degree was put forward.Taking ball valves with the diameter of DN20 as the experimental object,the pressure differences and flow values at different opening degrees were collected and the relative local resistance coefficients were calculated by field experiments.The relationship between area opening degrees and local resistance coefficient of ball valves was established by curve fitting method.Another experimental data of area opening degree and local resistance coefficient of ball valves indicated that this calculation formula could be applied effectively in the calculation of ball valves local resistance coefficient.