In view of the short water hammer control distance of a single air valve in long-distance and low lift water delivery projects, which can not effectively suppress the vacuum in the pipe, a new water hammer control scheme of combined protection of air-valve surge tank and air valve was proposed. Taking a practical project as an example, a comparative analysis of the hydraulic transient process was carried out for the air valve protection and the combined protection scheme of air-valve surge tank and air valve. The results show that the water column separation occurs in the main pipe when the air valve is used for protection, and a large impact water hammer is caused by the rapid exhaust. The combined protection scheme of air-valve surge tank and air valve can not only effectively suppress the vacuum in the main pipe, but also effectively alleviate the impact water hammer caused by exhaust. It is an economic and effective water hammer protection scheme, and can provide a reference for the water hammer protection of other long-distance and low-lift water delivery projects.

low lift  /  water hammer protection  /  air valve  /  air-valve surge tank  /  water column separation