基于VOF方法的尾水隧洞过渡过程明满流水力特性研究

针对尾水隧洞结合导流隧洞布置时过渡过程中的明满流问题,采用VOF气液两相流模型对尾水系统的三维流场进行计算和分析.计算了尾水隧洞过渡过程中满流至明流和明流至满流两种典型工况,通过模型试验中尾水隧洞监测点的数据验证了数值模拟的可靠性和准确性.在此基础上,对明满流的水力特性进行了深入的分析和研究.结果表明:尾水隧洞发生明满...

VOF-based study on hydraulic characteristics of free surface-pressurized flow in hydraulic transient process of tailrace tunnel

Aiming at the problem of the free surface-pressurized flow in the hydraulic transition process of the tailrace tunnel arranged in combination with diversion tunnel，the VOF air-water two-phase flow model is adopted to calculate and analyze the 3-D flow field of the tailrace system，from which the two typical conditions in the hydraulic transition process of the tailrace tunnel，i． e． pressure-flow to open-flow and open-flow to pressure-flow，are calculated，and then the reliability and accuracy of the numerical simulation are verified through the data obtained from the tailrace tunnel monitoring points during the model experiment． On the basis of this，the hydraulic characteristics of the free surface-pressurized flow is deeply analyzed and studied． The study result shows that the pressure changing amplitude at the tunnel bottom monitoring point is relatively large with a longer duration when the tailrace tunnel is full of open flow，while the wind speed ( plus or minus) of vent-hole is related to the fluctuation of water level and then all the air-out wind speeds are larger than all the air-in wind speeds under the conditions of both load rejection and load increase． The changing process of the free-water surface in the tailrace tunnel is captured with VOF method，thus the effect of the vent-hole to retard the free surface-pressurized flow is verified，from which it is proved that the vent-hole with the diameter of 2 m is more suitable to be selected through the comparison made among the effects of the vent-holes with different diameters．