基于PANS模型的湍流Taylor-Couette流及其换热特性

以同轴圆筒环隙内流体为研究对象,通过多种湍流模型计算结果与PIV测试结果的对比分析,建立了基于局部时均化模型(PANS)的环隙内湍流流场的数值模拟方法,在此基础上重点研究了沟槽模型内湍流流场分布与换热特性,获得不同旋转雷诺数、内外壁面温度梯度对流场分布及其换热性能的影响规律,同时研究了沟槽内涡流的形成机理及沟槽区域流体速度、剪切力及热流密度分布.结果表明:当流场转捩为湍流Taylor-Couette流时,泰勒涡沿轴向呈现无规则波动运动,并且泰勒涡轴向尺寸随雷诺数及内外壁面温度梯度增加而增加,径向速度与内壁面热流密度沿轴向的变化趋势表明:径向速度引起的射流作用对内外壁面间热量交换有直接影响;环隙内流体经过沟槽区域时撞击沟槽壁面,在惯性力、黏性力及壁面剪切力相互影响下形成涡流;沟槽区域的速度与壁面剪切力的变化呈现一致性,热流密度的变化与之相反.

Turbulent Taylor-Couette flow and its heat transfer characteristic based on PANS model

The flow field in the annulus of two coaxial cylinders was studied.The turbulent flow simulation method based on partially-averaged Navier-Stokes method(PANS)was established by comparing various turbulent model results with PIV experimental results.The flow field distribution and heat transfer characteristics of slit model were mainly analyzed in turbulent Taylor-Couette flow regime.The influences of Reynolds number,and temperature gradient between inner and outer cylinders on the flow distribution and heat transfer characteristics were investigated.In addition,the formation mechanism of smaller vortices and the distributions of heat flux,velocity and wall shear stress in the slit region were analyzed.The results show that the axial motion of turbulent Taylor-Couette vortices appears aperiodical when the flow regime turns into turbulent Taylor-Couette flow.The axial sizes of Taylor vortices increase with the increase of Reynolds number,and temperature gradient between inner and outer walls.The change of radial velocity and inner wall heat flux along the axial direction shows that the out jet caused by radial velocity has a direct influence on heat exchange between inner and outer walls.When the fluid in the annulus flow goes through the groove area,it impacts on the groove wall surface and forms vortices under the influence of inertia force,viscous force and wall shear force.The velocity in the groove area is consistent with the change of wall shear force,but the change of heat flux is opposite.