带三维扰流元的方形通道内流动换热的数值模拟研究

Numerical Simulation on Flow and Heat Transfer in a Square Channel with Three-Dimensional Turbulator

关键词:  三维扰流元  数值模拟  换热特性  流动特性

Key words:  Three-dimension turbulator  Numerical simulation  Heat transfer character  Flow character

摘要:

在涡轮叶片内部冷却通道中一般都布置扰流结构以强化换热，带走传入的热量来保护叶片。针对一种三维扰流结构，在布置有该结构的方形通道内，研究了流动参数与结构参数对通道内流动与换热特性的影响。扰流元高为通道当量直径的1/8。雷诺数变化范围为1.5×104～8.0×104，扰流元流向间距变化范围为3～10倍扰流元高度。结果表明:针对该结构，雷诺数的变化只影响换热强度的大小，并不影响换热分布。同一换热面上扰流元顺排的换热效果比差排方式更好。随着扰流元流向间距的增大，通道换热面的平均努赛尔数比和通道流阻系数比不断下降，扰流元间距达到其8倍高度以上，下降速度减缓。扰流元张角在80°附近时，有最佳的换热强化效果。

Abstract:

In the internal cooling channels of turbine blade， the turbulators are usually employed to enhance the heat transfer and take away the heat conducted into the blade walls， therefore protect the blade. A kind of three dimension turbulaor is investigated in a square duct. The effects of the flow and structure parameters on the flow and heat transfer characters are studied. The height of the turbulator is 1/8 of the channel equivalent diameter. The Reynolds number is changed from 1.5×104 to 8.0×104. The pitches between turbulators in the flow direction are 3～10 times of the turbulator’s height. The results show that the change of the Reynolds number only affects the heat transfer intensity， and does not affect the heat transfer distribution character. The aligned arrangement of turbulator may cause higher heat transfer enhancement than the staggered arrangement. With the increase of pitch between the turbulators， the average Nusselt number ratio and the flow resistance coefficient ratio of the channel are decreasing. This decreasing trend slows down when the pitch is greater than 8 times of turbulator’s height. The best heat transfer enhancement can be achieved when the front angle of turbulators is about 80°.