考虑热交换的引水隧洞施工通风两相流模拟

Simulation for Construction Ventilation Two-Phase Flow in Diversion Tunnel Considering Heat Exchange

针对深埋引水隧洞的储热作用所导致的施工通风散烟困难问题,建立综合考虑气固热交换、尘粒间相互耦合作用的三维非稳态欧拉-拉格朗日两相流紊流模型.尘粒间相互耦合作用力包括相间曳力、浮力、热泳力、升力和虚拟质量力等.结合某大型水电站深埋长距离引水隧洞施工通风,探讨隧洞内含尘气流的对流热交换规律,研究隧洞内风流微观运动机理以及粉尘运移规律.模拟结果表明:风流在风管出口下侧形成涡流区,1号和2号引水隧洞风流分布基本一致;工作面附近通风降温效果明显,隧洞壁面的表面平均换热系数沿工作面到风管出口处呈先增大后减小的趋势,表面平均换热系数模拟值与经验公式计算结果基本吻合;施工通风1,350,s左右时,粉尘浓度满足规范要求.

Smoke extraction difficulties caused by storage heat effects exist in the construction ventilation of deep diversion tunnel. A three-dimensional unsteady Euler-Lagrange two-phase flow turbulence model considering the gas- solid heat exchange and the intercoupling between dust particles was proposed. The intercoupling between dust parti- cles included the effects of buoyancy, inter-phase drag, thermophoretic force, lift force and virtual mass force. The construction ventilation of a large-scale hydropower long-distance diversion tunnel was used as a case. The dusty air convection heat transfer law in the tunnel was discussed. The microscopic airflow movement mechanism and the dust migration law were analyzed. Results show that an eddy zone is formed under the duct outlet, and that the airflow distribution tendency of No.1 diversion tunnel is similar to that of No.2 diversion tunnel. With the ventilation time increasing, the temperature near the heading face apparently drops. The surface average heat transfer coefficients of the tunnel have a tendency to increase firstly and then diminish from the heading face to the duct outlet. The simula- tion values of heat transfer coefficients are in good agreement with the experiential values. Dust concentration meets the standard after about 1 350 s.