旋转矩形通道内湍流流动与换热的直接数值模拟

Direct Numerical Simulation of Turbulent Flow and Heat Transfer in a Square Duct Rotating along Its Spanwise Direction

对旋转矩形通道内的湍流流动和换热进行了直接数值模拟.非稳态N-S方程的空间离散采用二阶中心差分法,时间推进采用二阶显式Adams-Bashforth格式.分析了旋转对通道截面上主流平均速度、截面流速以及截面平均温度的影响,结果表明:在不考虑离心力的作用时,随旋转数的增大,管道截面的平均速度减小,平均湍动能减小,与静止时相比,旋转数为1.5时平均湍动能减小了33%;在考虑离心力的影响时,对于径向旋转轴向出流,平均速度增大,平均湍动能增大,而对于径向旋转轴向入流,结果相反.在旋转数为1.5时,与不考虑浮升力相比,对于径向旋转轴向出流,平均湍动能增大了17%,而对于径向旋转轴向入流,平均湍动能减小了43%.

Turbulent flow and heat transfer in a square duct rotating along its spanwise direction is investigated by direct numerical simulation. The spatial terms in the governing equations are discretized by second-order central difference scheme and the time terms are discretized by the Adams-Bashforth scheme. The influence of rotation on the streamwise velocity, crosswise velocity and the mean temperature is analyzed. The results show that the mean velocity and the mean turbulent kinetic energy decreases with the increase of rotation number when the centrifugal buoyancy force is neglected. The mean turbulent kinetic energy of Rot=1.5 decreases by 15 percent compared with that of Rot-0. If the effect of the centrifugal buoyancy force is taken into account, for the radially outwards flow, the mean velocity and turbulent kinetic energy increase with rotation number compared with those without the effect of centrifugal force, and the results are converse for the flow radially inwards. It is found that the mean turbulent kinetic energy increases by 17 percent for the radially outwards flow at Rot = 1.5 compared with that of Grr, L=0, but it decreases by 43 percent for the flow radially inwards.