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为解决大型水电站地下洞室空间密集等问题,输水系统通常采用尾水洞和部分导流洞相结合的布置方式,致使低尾水位发电时尾导结合段水深较浅和流速较大。当机组甩负荷后,尾导结合点处有可能发生“水流中断”的水力学现象。本文通过一维及三维数值模拟,分析了水流中断的机理,所得主要结论是:在非恒定流过程中尾导结合段(尤其是尾导结合点)的Fr数从起始值逐渐接近1再大于1,形成断波,阻滞了反向流量的补充。故其Fr 1是发生水流中断的内因。而尾水调压室的水位上升会进一步降低尾导结合段的水深,因此水流中断必然发生在调压室水位上升的时段。
In order to solve the problem of space-intensive underground caverns in large-scale hydropower stations, the water delivery system usually adopts a combination of a tailwater tunnel and a part of diversion tunnel, resulting in a shallow water depth and a large flow velocity at the tail-tail combined stage when the tail water level is generated. When the unit load rejection, the lead junction junction may occur “hydraulic flow interruption ” of the hydraulic phenomenon. In this paper, through one-dimensional and three-dimensional numerical simulation, the mechanism of water flow interruption is analyzed. The main conclusion is: The Fr number of the lead junction (especially the lead junction) in the unsteady flow gradually increases from the initial value 1, forming a broken wave, blocking the addition of reverse flow. So Fr 1 is the internal cause of water flow interruption. The tail water surge chamber water level rise will further reduce the lead tail section of the water depth, so the water flow interruption must occur in the surge chamber water level rise period.