消防水炮主体弯管的绕转结构出口流态分析

采用标准k-ε湍流模型对180 mm管内径的3种绕转结构(传统回转、半回转、大回转)内部流动进行了数值模拟,对比和分析了水力损失和出口流态,其中出口流态参数包括平均湍动能、速度分布曲线和迪恩涡.结果表明:随着弯管曲率R/d的增大,3种形式的水炮主体的水力损失均减小,相同的R/d=1.4情况下传统回转结构具有最小的水力损失,半回转结构水力损失最大;绕转结构的出口速度分布曲线显示,管轴线附近速度低而速度峰值出现在靠近管壁附近,表明出口处流体带有旋转的特点;在R/d=1.4情况下,大回转结构形式的出口具有最小的平均湍动能值,出口流线具有一个顺时针方向的基本涡,与传统回转结构出口涡形态一致,涡量积分后得到的旋涡强度小于传统回转结构.大回转的绕转结构形式有利于后续水炮炮管和喷嘴内部流动.

Analysis of outlet flow state of firefighting monitor rotary main structure

Numerical simulations were done with standard k-εturbulence model for inner flow of three kinds of rotary structure,which diameter was 180 mm.Three rotary structures were named traditional rotary,half rotary and large rotary respectively.The outlet flow state flow state and hydraulic losses were compared and analyzed.The outlet flow state parameters include the average turbulence kinetic energy,velocity distribution curves and Dean vortex.The results show that the hydraulic loss of three types of rotary structure are reduced with the curvature R/d increasing.As the R/d is 1.4,the traditional rotary has the smallest hydraulic loss and the half rotary is the largest.The outlet velocity curves show that the largest velocity occurs near the wall not near the center of pipes,which means that the flow has swirl characteristic at the outlet.When the R/d is 1.4,the large rotary structure has the smallest average turbulence kinetic energy at the outlet,and its streamline has one clockwise basic vortex which is consistent with the vortex state of traditional rotary structure,but the vortex intensity which is obtained after integral the outlet vorticity is smaller.The format of large rotary structure is beneficial for subsequent flow in tube and nozzle of firefighting monitor.