椭圆截面形状大回转消防水炮炮管内流数值模拟

Numerical simulation of internal flow in large-turning fire water cannon barrel with elliptical cross-sectional shapes

以大回转型大流量消防水炮炮管为研究对象,对3种流量工况下圆截面和不同离心率椭圆截面消防水炮炮管内三维定常流动进行数值计算,分析不同截面炮管内流体水力损失和出口流态,得到截面变化对消防水炮炮管内部流动的影响规律,结果表明:在3种流量工况下,圆截面炮管与非圆截面炮管水力损失Δp差异较小,变化范围在2.7%以内;出口湍动能随着炮管截面的椭圆离心率增大而增大,从云图分布中可看出峰值且逐渐偏离管道的中心轴线;出口涡通量J随着椭圆离心率的增大而减小,可达到小于圆截面J值的情况,说明压扁管道可减小出口截面上旋涡强度;竖向椭圆截面炮管平均出口速度偏差Δu小于圆截面炮管出口值,且随椭圆离心率的增大而减小,表明竖向压扁管道带来更好的速度均匀分布.相同离心率的竖向椭圆截面炮管比横向的椭圆截面炮管的平均出口速度偏差值低21%,竖向压扁的方式优于横向压扁方式.大回转水炮炮管数值模拟对比后的结果表明,改变流道截面将改善出口流态.

Taking the large-turning and large-flow fire water cannon barrel as the research object,the computational fluid dynamics software Fluent was used to numerically calculate the three-dimensional steady flow in the fire water cannon barrel with circular cross-section and elliptical cross-section under three flow conditions.By analyzing the hydraulic loss of the fluid in the barrel of different cross-sections and the flow pattern of the outlet,the influence rule of the cross-section change on the internal flow of the fire water cannon barrel was obtained.The results show that under the three flow conditions,the difference of hydraulic loss between the circular cross-section barrel and the non-circular cross-section barrel is small,and the variation range is within 2.7%;the turbulent kinetic energy of the outlet increases with the increase of the elliptical eccentricity of the barrel section,and gradually deviates from the center axis of the pipe;At the exit of the circular barrel and non-circular barrel,the positive and negative vortices offset the reduction of vortex flux,the streamline density of the outlet of the circular cross-section barrel and the outlet of the vertical ellipse cross-section barrel is more uniform than that of the horizontal ellipse cross-section barrel,and the vertical ellipse cross-section barrel with the same eccentricity is 21%lower than the average exit velocity deviation of the transverse elliptical barrel.