阀体间隙对球阀性能和内部流场分布的影响

为了研究阀体间隙对于管道球阀性能和内部流动特性的影响,基于有限体积法和标准k-ε湍流数值模型,对管道球阀含有间隙和不含有间隙的流道模型进行三维数值模拟计算. 结果表明:无论是含有间隙和不含有间隙的管道球阀流道模型,球阀的流量系数特性、阻力系数特性、空化系数特性,都是在球阀开启角度40°~50°时发生转变; 此时,截面YOZ压力存在压力局部位置较大的集中区域以及旋涡分离现象,会形成2个大小基本相同且对称分布的旋涡. 含有间隙的球阀模型,阀体间隙影响管道下游的流动分布(压力分布、速度分布以及涡分布),流动更加复杂. 同时,阀门开度对阀门过流截面上的压力分布也有一定的影响. 在进行球阀性能精确预测时,不可以进行简化处理,必须考虑间隙对球阀性能和内部流场分布的影响.

Effects of valve body clearance on valve performance and internal flow field distribution

Three-dimensional numerical simulations of the flow in a ball valve-pipe channel model with and without clearance were carried out based on the finite volume method and standard k-εturbulence model to study effects of valve body clearance on hydraulic performance and internal flow characteristics of ball valve.The results show that the flow coefficient,resistance coefficient,pressure reco-very coefficient and cavitation coefficient of ball valve are relevant to valve body clearance.Specially,all coefficients vary significantly with valve opening angle being over 40°-50°.This is because there is a large local pressure zone and two symmetrical,separated vortices downstream of the ball body.The ball body clearance influences the distributions of pressure,velocity and vortex downstream of the valve,and makes the flow pattern even more complicated.Moreover,the valve opening angle has a certain influence on the pressure distribution in a cross-section of the valve.In consequence,for accurately predicting the hydraulic performance of a ball valve the clearance should not be ignored by simplification treatment,instead the influence of the clearance on the performance and internal flow field must be taken into account.