空气的压缩性对湍流边界层流场时均量的影响

为研究空气的压缩性对湍流边界层流场时均量的影响,对来流Mach数(Ma)分别为0.058、0.233、0.466、0.874和1.457的二维、定常边界层湍流流场进行了数值模拟计算。结果表明:空气的压缩性对速度边界层和温度边界层粘性底层区速度和温度分布影响较小,但会使完全湍流区速度和速度梯度、温度和温度梯度变大;对分子扩散过程影响极小,而对湍流扩散过程影响较大;当局部Reynolds数大于1×106且来流Ma大于0.466时,使得平板局部摩擦阻力系数较不可压缩态变小,而局部传热系数较不可压缩态变大。比较模拟计算结果和不可压缩态下经验公式的计算结果表明,模拟计算结果真实可靠。

INFLUENCE OF AIR COMPRESSIBILITY UPON TIME- AVERAGED QUANTITIES IN FLOW FIELD OF TURBULENT BOUNDARY LAYER

In order to study the influence of air compressibility upon the time-averaged quantities in flow field of turbulent boundary layer,a numerical simulation and calculation of 2D flow field in steady turbulent boundary layer with inlet Mach number of 0.058,0.233,0.446,0.872,and 1.457 respectively has been carried out.The results show that the compressibility of air has little influence upon the velocity and temperature distribution in the viscous sublayer zone of the velocity boundary layer and temperature boundary layer,but it can make the velocity and velocity gradient,as well as the temperature and temperature gradient,to be enlarged;the influence of air compressibility upon molecules’ diffusion process is utmost small,but has larger influence upon the diffusion process of turbulent flow.When the local Reynolds number is greater than 1×106,and the inlet Mach unmber is larger than 0.466,the local frictional resistance coefficient on the plate will be smaller than that in non-compressible state.Whereas the