变比热真实气体效应的高超声速槽道湍流直接数值模拟

Direct numerical simulation of hypersonic turbulent channel flow in thermally perfect gas

在高超速情况下,利用直接数值模拟方法,我们研究了真实气体效应(振动由度激发导致比热随温度变化)对槽道湍流影响,并与不考虑振动由度激发情况进行了比较.我们发现振动能激发对统计平均量影响主要体现在温度上,它能够抑制湍流场中平均温度升高;而对于密度,速度及压强影响很小.振动由度激发使原分运动更加剧烈,以致湍流场趋于"平坦",表现为脉动值、相关函数及互相关函数减小.同时,由于振动能激发过程是一个吸热过程,因此它对湍流有抑制作用,表现在减小涡量、抑制湍能成及耗散等方面.振动由度激发对于湍流两点相关量、偏斜因及平坦因影响很小.

In this paper,the effects of real gas,special heat is a function of temperature because of vibrational energy,on the statistics in hypersonic channel flow are investigated using direct numerical simulation（DNS）,and comparing with the perfect gas.To compare the perfect gas,vibrational energy can reduce the mean temperature,but has little effect on the mean density,velocity and pressure.Owe to vibrational energy excited,the turbulent flow is tending towards smooth in consequence of the diatomic molecule moved so quickly,for exmaple,the value of RMS and Renolds shear stress are minishing.Meanwhile,the process of vibrational energy excited（endothermic reactions） damps turbulence.However,it has a small effection on two-point correlations,skewness and flatness.