跌流竖井结构优化及其气压特性数值模拟

Structure optimization and numerical simulation of air pressure characteristics of a plunging flow dropshaft

针对入流水舌引起的跌流竖井内负压过大问题,对前人研究中的原始竖井模型进行了结构优化设计。采用可实现的k-ε湍流模型以及VOF两相流模型研究了不同入流量下原始竖井模型和优化竖井模型中的流态分布规律及气压分布情况,建立了可用于确定优化竖井模型中通气管道底部安装高程的水舌撞击模型,探讨了通气管道相对进水管的位置对优化模型中气压分布的影响。结果表明:进水管附近的跌落水舌束窄了井内气体的正常流通通道,水舌上方形成了大面积气体回流区,水舌下方补气不足,进水管附近负压突增现象明显;建立的水舌撞击模型能够较准确地预测出水舌末端的撞击点位置,最大误差不超过10%;得到的通气管道底部安装高程为2.31 m,顶部高程略高于进水管上壁面;相比原始竖井模型,优化竖井模型能够使负压突增区的压差降低70%以上,并且当通气管道与进水管水平中心延长线之间的夹角为30°时,优化竖井模型所发挥的效果最好。

Aiming at the problem of excessive negative pressure in a dropshaft caused by the inflow water tongue,the structure optimization design for the original dropshaft model was carried out.The realizable k-εturbulence model and VOF two-phase flow model were used to study the flow regime and air pressure distribution in the original model and the optimized one under different inflow rates.A water tongue impact model was established to determine the installation elevation of the ventilation pipe bottom in the optimized model.The influence of the ventilation pipe position relative to the intake pipe on the air pressure distribution was discussed.The results show that the falling water tongue near the intake pipe blocks the normal air flow in the well,and large air recirculation zones are formed above the water tongue.The space below the water tongue cannot be replenished in time,and the sudden increase of negative pressure near the intake pipe is obvious.The established water tongue impact model can accurately predict the impact point position at the water tongue end,and the maximum error is within 10%.The installation elevation of the ventilation pipe bottom is 2.31 m,and the top elevation is slightly higher than the upper wall of the water inlet pipe.The optimized shaft model can reduce the pressure difference in the negative pressure surge zone by at least 70%,and when the angle between the ventilation pipe and the horizontal center extension line of the inlet pipe is 30°,the optimized dropshaft model has the best effect.