Simulation method for anisotropic power spectrum and wave structure function characteristic in hypersonic turbulent flow
A hypersonic and anisotropic technology, applied in the field of electromagnetic waves, can solve problems such as not being obtained, wave propagation theory cannot be applied, and staying in electromagnetic wave propagation
Inactive Publication Date: 2017-10-17
XIDIAN UNIV
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However, the mathematical theoretical model of the power spectrum of the refractive index fluctuation in hypersonic turbulent flow has not been obtained, so the theory of wave propagation in random media cannot be applied to hypersonic turbulent flow, and has been stuck in the research field of solving the problem of electromagnetic wave propagation in atmospheric turbulent flow
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[0024] refer to Figure 9 , the specific implementation steps of the present invention are as follows:
[0025] Step 1: According to the experimental image of the hypersonic turbulent mixed layer obtained by the nano-planar laser scattering technology, the power spectral density data of the spatial variation of the hypersonic turbulent refractive index is obtained.
[0026] (1.a) Convert the experimental image of the hypersonic turbulent mixed layer obtained by the nano-planar laser scattering technology into a two-dimensional grayscale matrix;
[0027] (1.b) Perform Fourier transform on each row of the two-dimensional grayscale matrix, and then take the average value to obtain the spatial variation spectral density data of the refractive index in the direction of the hypersonic turbulent flow field;
[0028] (1.c) Repeat the above two steps to obtain four sets of spectral density data, such as figure 1 shown.
[0029] Step 2: Correct the von Karman power spectrum by observ...
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The invention discloses a simulation method for an anisotropic power spectrum and a wave structure function characteristic in hypersonic turbulent flow, and mainly solves the problem that radio wave propagation cannot be simulated due to the fact that the anisotropic power spectrum of refractive index fluctuation in the hypersonic turbulent flow cannot be obtained in the prior art. The method comprises the steps of performing Fourier transform according to a hypersonic turbulent mixing layer experiment image to obtain power spectrum density data of refractive index space change; correcting a von Karman power spectrum to enable the von Karman power spectrum to better match with power spectrum density data of the hypersonic turbulent flow; based on this, introducing anisotropic parameters zeta x and zeta y, and building an anisotropic power spectrum model of the hypersonic turbulent flow; and finally performing simulative calculation on characteristics of change, with a refractive index fluctuation variance, an external dimension and the anisotropic parameters, of a wave structure function and a spatial coherence radius of an electromagnetic beam in the hypersonic turbulent flow by utilizing a wave propagation theory in a random medium. According to the method, the blank of the power spectrum of the refractive index fluctuation in the hypersonic turbulent flow is made up for, so that the wave propagation theory in the random medium is no longer limited to the field of atmospheric turbulence research and can be used for researching electromagnetic wave propagation characteristics in the hypersonic turbulent flow.
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technical field [0001] The invention belongs to the technical field of electromagnetic waves, and in particular relates to a numerical simulation method of radio wave propagation characteristics, which is used for obtaining anisotropic power spectrum of refractive index fluctuation in hypersonic turbulent flow. Background technique [0002] When the hypersonic vehicle re-enters the atmosphere, there will be severe friction with the surrounding atmosphere, resulting in the formation of a hypersonic flow field around the vehicle. The speed and altitude of the aircraft are constantly changing, resulting in drastic changes in the internal temperature of the hypersonic flow. Coupled with the effect of the internal shear force of the fluid, there is a severe turbulent effect in the flow field. Turbulent irregularities make electromagnetic waves reflect, refract and scatter, and absorb electromagnetic wave energy at the same time, resulting in random fluctuations in the wave front ...
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Login to View More IPC IPC(8): G06F17/50
CPCG06F30/20
Inventor 李江挺宫腾郭立新杨少飞程明建
Owner XIDIAN UNIV