高扬程超长距离供水工程中的水锤防护研究

Research on water hammer protection in high-lift and long distance water supply project

基于特征线法进行数值仿真计算,建立了空气罐节点控制方程、超压泄压阀边界条件以及计算模型,探讨了空气罐及泄压阀联合在高扬程小流量供水工程中的研究及应用。首先对比分析了无防护措施、空气罐及泄压阀联合防护对停泵水锤的影响;接着,针对控制工况,比较了空气罐体积60 m^(3)-无泄压阀,空气罐体积80 m^(3)-无泄压阀以及计算空气罐体积60 m^(3)-有泄压阀3种防护方案。结果表明:空气罐及安全阀联合防护对抑制正负水锤的影响是有利的。然后,优化选择了空气罐的体型参数,分析得到泵后阀可采用10 s一段直线关闭的规律;最后,依据优化后空气罐的体型参数对特征点的压力进行复核计算,结果说明联合防护后的效果比较明显。

Based on the method of characteristic line,we established acalculation model containing control equation of air vessel node,boundary condition of overpressure relief valve,and then discussed the research and application of air vessel and overpressure relief valve in water supply project with high head and low flow.Firstly,we compared and analyzed the influence of the following two schemes on the water hammer during pump stopping period:no protective measures and combined protection of air vessel and overpressure relief valve.Then,for the control conditions,we compared and assessed three protection schemes,such as air vessel volume 60 m^(3) without pressure relief valve,air vessel volume 80 m^(3) without pressure relief valve,air vessel volume 60 m^(3) with pressure relief valve.The results showed that the combined protection of air vessel and pressure relief valve was beneficial to restrain the influence of positive and negative water hammer.Then,we optimized the shape parameters of air vessel and gaveaclosing law of the valve-behind pump that the valve could be closed in 10 seconds.Finally,according to the shape parameters of the optimized air vessel,we rechecked and calculated the pressure at characteristic points toverify effectiveness of combined protection.