开放剪切流空间全局动力学与空间相位斑图间的关系

开放流动空间动力学可基于两类全局能量关系式进行研究；而空间相位斑图则可通过互谱空间演化加以测定。全局能量关系式以时间Fourier系数的形式建立流场任意两点问速度脉动能量间的关系，籍此可定义全局意义上的线性、非线性和线性一非线性机制。基于轴对称剪切流、变密度轴对称圆射流以及平面对称剪切流的实验发现：轴对称旋涡结构的配对由线性、线性一非线性机制表征，对应有序空间相位斑图；并且能量可通过线性一非线性机制在具有相同相速度的扰动间传递。螺旋结构由线性机制表征，对应有序相位斑图。全局自激励振荡由非线性的能量共振表征，对应无序相位斑图。籍此，有序空间相位斑图对应线性和线性一非线性机制；而混沌相位斑图则对应非线性机制。

Relations between Spatial Global Dynamics and Phase-Patterns of Open Shear Flows

Spatial global dynamics of open flows can be studied experimentally based on two kinds of global energy relations and spatial phase patterns can be detected through spatial evolution of cross spectrum. The relations of fluctuation velocity energies in temporal Fourier forms corresponding to two arbitrary positions in a flow field can be set up through global energy relations. Subsequently, global linear, linearnonlinear and nonlinear mechanisms can be defined. Base on the experimental studies of axisymmetric shear flows, variable density round jets and planar-symmetric shear flows, it was discovered as follows. Pairing of axisymmetric vortical structure repressented by linear and linear-nonlinear mechanisms corresponds to ordered spatial phase-pattern. In addition, energy transfer can take place between some disturbances with the same phase speeds. Helical structure is represented by linear mechanism corresponds to ordered phase-pattern. Global self-excited oscillation is represented by nonlinear energy resonance corresponds to chaotic phase-pattern, It is implied that ordered phase-patterns correspond to linear and linearnonlinear mechanisms, but chaotic ones are related to nonlinear mechanism.