The letdown back-pressure regulating valve maintains pressure in the section of letdown upstream or the letdown heat exchanger to prevent the letdown liquid flashing to steam.

下泄背压控制阀维持下泄流上游段或下泄热交换器处的压力，防止压力过低引起流体汽化。

The non-symmetric refracted flow is possible to correspond to the non-symmetric entrance condition of upstream cross before sudden expansion section, and also to the symmetric entrance condition.

这种非对称折冲流动可能与上游突扩前断面非对称入口条件相对应，也可能与上游突扩前断面对称入口条件相对应。

Along with the increase of the secondary flow pressure ratio, the shock move toward upstream divergent section and the thrust vector angle gradually increases;

次流压比的增加将导致激波向扩张段上游移动，且喷管矢量角不断增加；

The purpose of this research is to establish a simple and practical mathematical model for the water retention curve in unsaturated section of upstream embankment constructed tailings dam.

本研究的目的是建立一种简单实用的上游式尾矿坝非饱和带滞水曲线的数学模型。