长距离重力流输水系统的联合阀组水力控制研究

Study on hydraulic control of combined valve group in long-distance gravity flow water delivery system

针对长距离重力流输水工程中因调节阀的启闭操作产生的正、负水锤问题,本文利用特征线法和水锤波传播理论,结合工程实例,分别对采用末端阀控制、在线阀控制以及在线阀与末端阀联合控制等水力控制方案开展了数值模拟与对比分析。结果表明:采用在线阀与末端阀联合阀组控制方案可有效解决在线阀控制方案中下游管道的负压问题,同时相较于末端阀控制方案,在线阀下游近99km管道的最大正压降低了15.0~18.6mH_(2)O。基于联合阀组方案的控制优势,优化设计了调节阀的关闭时间与方式,提出在线阀的关闭时间宜适当小于末端阀,且宜采用线性或先快后慢的两阶段关阀方式;优化后的联合防护方案不仅保证了管道沿程无负压,而且进一步抑制了在线阀下游管段的水锤正压,极大地降低了管道投资,为类似工程的水力控制方案提供重要参考。

Aiming at the positive and negative water hammer problems caused by the opening and closing operation of the control valve in the long-distance gravity flow water delivery project,the numerical simulation and comparative analysis of multiple hydraulic control schemes such as end valve control,on-line valve control and combined valve group control are carried out in this paper using the method of characteristics and the water hammer wave propagation theory.The results show that the combined control scheme of the on-line valve and the end valve can effectively solve the negative pressure problem of the downstream pipeline in the on-line valve control scheme.In addition,compared with the end valve control scheme,the maximum positive pressure of the pipeline downstream of the on-line valve with a length of nearly 99 km is reduced by 15.0 to 18.6 meters.Based on the control advantages of the combined valve group scheme,the closing time and closing mode of the control valve are optimized.It is proposed that the closing time of the on-line valve should be appropriately shorter than that of the end valve,and the linear or first fast and then slow two-stage closing mode should be adopted.The optimized combined control scheme not only ensures no negative pressure along the pipeline,but also further inhibits the positive water hammer pressure in the downstream pipe of the on-line valve,which greatly reduces the pipeline investment and provides an important reference for the hydraulic control schemes of similar projects.