台阶式泄洪排沙隧洞掺气浓度分析

ANALYSIS OF AERATION CONCENTRATION IN STEPPED FLOOD DISCHARGE AND SEDIMENT DISCHARGE TUNNEL

台阶对与泄洪排沙洞的消能具有重要作用,其中水流掺气是台阶水流流动复杂性的重要特征,由于水流的复杂性,目前有很少的数值模拟方法可以模拟出水流的掺气效果。本文采用了五种不同水位条件下模拟三种不同台阶的掺气浓度,分析得泄洪洞的水流流速、初始掺气位置、流态特点。研究结果表明:(1)当水流较深时,空气与水的接触效率变低,导致水流的掺气浓度下降,初始掺气位置随之降低;(2)同一台阶其上部与空气接触面较大,因此台阶上半部分与空气接接触面积增多,并且随着台阶的掺气浓度增大,台阶断面的掺气量随之增高。

Steps play an important role in energy dissipation of flood discharge and sediment discharge tunnel,and flow aeration is an important feature of the complexity of step flow.Due to the complexity of flow,there are few numerical simulation methods to simulate the aeration effect of flow.In this paper,the aeration concentration of three different steps under five different water level conditions is simulated,and the flow velocity,initial aeration position and flow pattern characteristics of the spillway tunnel are analyzed.The results show that:(1)when the water flow is deep,the contact efficiency between air and water becomes low,resulting in the decrease of aeration concentration and the initial aeration position;(2)the upper part of the same step has a large contact surface with the air,so the contact area between the upper part of the step and the air increases,and with the increase of the aeration concentration of the step,the aeration of the step section increases.