Experimental analysis on flow regulation and operation scheme of forebay of Dazhaihe-Banzha main canal pumping station

Abstract

[Purpose] In order to clarify the flow characteristics of the lateral inflow forebay of Dazhaihe-Banzha main canal pumping station at different characteristic water levels, and to put forward the control measures of the flow field of the forebay and the operation scheme of the unit at the lowest water level, so as to provide technical reference for the safe, efficient and stable operation of the pumping station unit. [Methods] The method of hydraulic physical model test was used to carry out hydraulic physical model test on the diversion river, forebay and open inlet pool of pumping station. The flow field of forebay with or without flow control measures was analyzed, and the flow field characteristics of forebay with different start-up schemes at the lowest water level were analyzed. [Results] The result showed that after adopting the rectification measures of non-equal gradient arc-shaped diversion piers, the average velocity distribution uniformity of the surface layer of the forebay with the full opening of the unit at the design water level was 85.86%, the average velocity distribution uniformity of the middle layer was 88.75%, and the average velocity distribution uniformity of the bottom layer was 85.42%. The high-speed area became smaller and the flow pattern improved better. At the lowest water level, if the unit is fully started, the flow pattern of the forebay is further deteriorated, and the unit vibrates. The flow field of the 1 ~# unit deteriorates most significantly and the vortex band inside the intake pool. [Conclusion] At the lowest water level, it is recommended to open 3~# unit when the pump station is 0.2 times the load flow. When the pump station is 0.4 times the load flow, it is recommended to open 3~# and 4~# units, and the pump station is 0.6 times the load.

Keywords

pumping station / lateral inflow forebay / flow field / model test / operational scheme