充水速度对空气阀驼峰管段水力特性的影响

The Influence of Filling Flow Discharge on Hydraulic Performance of Hump Pipe with Air Valve

常规操作规程建议长距离管道系统的初始充水速度应小于0.3 m/s,但该方案偏于保守和低效。对比若干种速度较大的空管充水方案,分析其对装有空气阀的驼峰管段(简化模型)水力特性的影响,同时考虑两相流动和空气阀浮球的刚体运动特性。应用格子玻尔兹曼方法进行各充水方案的数值模拟,分析了驼峰管及空气阀的瞬态流动特性,包括流速分布、关阀残余气团分布、空气阀排气速度对比、空气阀浮球位移变化过程等。结果表明,随着充水速度增加,空气阀快速关闭产生的二次水锤压力近似线性地增大,而残余气团体积分数则呈近似抛物线的增长趋势。该研究结果对输水工程的空管充水操作具有参考意义。

Conventional operational protocol suggests that large-scale pipeline system should be initially filled with a low flow discharge equivalent to a full-pipe velocity limit of 0.3 m/s, which may be conservative and inefficient. In this research, higher filling flow discharges are considered to investigate their influences on pipeline hydraulic performance, in which two-phase flow transients and rigid body motion of the air valve float are involved. A simplified hump pipe model with an air valve installed on the top is established and lattice Boltzmann method is applied for the numerical simulation. Based on different flow discharges, the transient characteristics of flow field are analyzed, including the velocity distribution, vertical displacement of the valve float, residual air distribution, and air release velocity through the air valve. Results indicate that the induced water hammer pressure will increase with an approximate linear trend as the filling flow discharge is getting higher, while the volume fraction of residual air pocket will increase with similar parabolic growth. This investigation is of guiding significance to water conveyance projects in regard to pipeline filling.