物理学报2017，Vol.66Issue(2)：217-228,12.DOI:10.7498/aps.66.024701
超声速湍流边界层密度场特性
Experimental study on the density characteristics of a supersonic turbulent boundary layer
摘要
Abstract
An experimental study on the density characteristics of a zero-pressure-gradient flat plate turbulent boundary layer at Ma =3.0 is performed by the density field measurement method based on Nano-tracer planar laser scattering (NPLS) technology.The mean and the fluctuating characteristics of the density field of the boundary layer are analyzed.And the spectrum analyses of density fluctuations are performed by utilizing Taylor's hypothesis to convert spatial measurements into pseudo-temporal measurements.The mean density profile increases away from the wall,which accords well with the density profile deduced from the mean velocity distribution by using the adiabatic Crocco-Busemann relation.The root mean square (RMS) of the density fluctuations increases in the logarithmic region with a peak value of 0.2ρ∞,and its probability density distribution follows a normal distribution.However,the RMS of density fluctuations decreases in the outer region of the boundary layer.According to the spectrum analysis,the density fluctuations are characterized in a wide range of frequencies throughout the boundary layer,with the maximum frequency on the order of 1 MHz.The low frequency fluctuations are predominant near the wall and in the outer region of the turbulent boundary layer.However,the proportion of high-frequency fluctuations is nearly equal to that of low-frequency fluctuations in the logarithmic region.The combined NPLS and PIV technique provide a simultaneous density and velocity measurements of the present turbulent boundary layer.The high frequency fluctuations in the supersonic turbulent boundary layer may be induced by the density fluctuations,which are caused by the convection of the turbulent structures with nonuniform density distributions.And the contribution of the velocity fluctuations only to the low frequency fluctuations is observed.There are good similarities between the density fluctuations and the mass flux fluctuations for both the probability density distribution and the spectrum characteristics.On the contrary,a large difference between the fluctuations of velocity and density is identified.Therefore,the strong density fluctuations inside supersonic turbulent boundary layers,as well as its difference between the velocity fluctuations,should be one of the most important differences between compressible and incompressible turbulent boundary layers.关键词
超声速/湍流边界层/密度场/频谱分析Key words
supersonic/turbulent boundary layer/density field/spectrum analysis引用本文复制引用
何霖,易仕和,陆小革..超声速湍流边界层密度场特性[J].物理学报,2017,66(2):217-228,12.基金项目
国家自然科学基金(批准号:11302256)资助的课题.Project supported by the National Natural Science Foundation of China (Grant No.11302256). （批准号:11302256）
