Structure of the refractive index distribution of the supersonic turbulent boundary layer

Gao, Qiong; Yi, Shihe; Jiang, Zongfu; He, Lin; Wang, Xiaohu

doi:10.1016/j.optlaseng.2013.03.016

Cited by 28 publications

(11 citation statements)

References 25 publications

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“…In Figure 9 , the streamwise density field is the expected layered-ellipse shape, and the size of the density structure increases with the wall height, which is consistent with current research conclusions [ 10 , 30 ]. Since the spanwise density field is composed of many two-dimensional density fields, it has no specific shape.…”

Section: Resultssupporting

confidence: 89%

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A New Method for Analyzing Aero-Optical Effects with Transient Simulation

Yang

Zhang

et al. 2021

Sensors

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Aero-optical effects reduce the accuracy of optical sensors on high-speed aircraft. Current research usually focuses on light refraction caused by large-scale density structures in turbulence. A method for analyzing photon energy scattering caused by micro-scale structures is proposed in this paper, which can explain the macro image distortion caused by moving molecules in inhomogeneous airflow. Quantitative analysis of the propagation equation indicates that micro-scale structures may contribute more to the wavefront distortion than the widely considered large-scale structures. To analyze the micro mechanism of aero-optical effects, a transient simulator is designed based on the scaling model of transient distorted wavefronts and the artificial vortex structure. The simulation results demonstrate that correct aero-optical phenomena can be obtained from the micro mechanism of photon energy scattering. Examples of using the transient simulator to optimize the parameters of the star sensor on a hypersonic vehicle are provided. The proposed analysis method for micro-scale structures provides a new idea for studying the aero-optical effects.

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Section: Resultssupporting

confidence: 89%

“…OPD h (x, y) is the blurring component. Substituting Equation (30) into Equation (29) and using the phase shift properties of the Fourier transform, the total light field can be represented by the light field of the blurring component…”

Section: Applying Tsao To Analyzing the Aperture Effects Of A Star Sementioning

confidence: 99%

A New Method for Analyzing Aero-Optical Effects with Transient Simulation

Yang

Zhang

et al. 2021

Sensors

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“…The model reasonably predicts all the important aero-optical characteristics of non-adiabaticwall subsonic boundary layers; it also correctly predicts OPD rms for supersonic adiabatic boundary layers. 23 Because the density correlation lengths 42 and normalized pressure variations 43 are similar for subsonic and supersonic speeds, the model predictions can be extended to the supersonic non-adiabatic regime. Results of the predicted levels of OPD rms at different Mach numbers and temperature differences, adjusted to match experimental results at subsonic speeds, are shown in Figure 10.…”

Section: Extension To Supersonic Speedsmentioning

confidence: 94%

Aero-optical measurements in a subsonic, turbulent boundary layer with non-adiabatic walls

et al. 2015

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This paper presents experimental studies of aero-optical distortions due to a turbulent boundary layer over a range of subsonic speeds with the underlying wall both heated above and cooled below the adiabatic wall temperature. A statistical scaling model, based on extended strong Reynolds analogy is derived and shown to correctly predict experimentally observed results. The temperature mismatch between the flow and the wall was shown to have a profound effect on the level aero-optical aberrations, as the heated wall amplifies them and the cooled wall significantly reduces distortions. The importance of an inclusion of the pressure term in explaining the boundary-layer density fluctuations with the cooled wall is also discussed.

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“…In the longitudinal direction they are much greater than in the transverse one. In the latter case, as follows from [26], the scale of correlation of inhomogeneities L K is equal to tenth fractions of the cross dimensions of the flow. The shock wave cross section along the beam propagation direction (transverse to the flow) equals 0.55 m [ Figs.…”

Section: Calculation Of the Phase Screens Parametersmentioning

confidence: 97%

“…The outer scale L 0 for each screen was specified by the boundaries of the computational grid, since the scales of variation of the mean density In simulation of laser beam propagation through the shock wave we set 9 and 10 independent random phase screens. As it follows from [4,6,26], density inhomogeneities in the near-wall turbulent supersonic flow are characterized by anisotropy in the directions longitudinal and transverse to the flow. In the longitudinal direction they are much greater than in the transverse one.…”

Section: Calculation Of the Phase Screens Parametersmentioning

confidence: 99%

Optical beam distortions induced by a shock wave

2015

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The mean intensity and the displacement from the initially given propagation direction of the optical beam passed through the shock wave have been calculated. It has been shown that the spatial inhomogeneity of the refractive index of air caused by the shock wave arising in supersonic flow flowing a conical body can cause the focusing of the beam and strong anisotropic distortions of the intensity distribution in its cross section. The angular displacement of the optical beam from the initially given propagation direction owing to the shock wave depends only on the height above the Earth's surface at which the shock wave is formed. As the height increases, the influence of the shock wave on the optical beam propagating through it decreases.

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Structure of the refractive index distribution of the supersonic turbulent boundary layer

Cited by 28 publications

References 25 publications

A New Method for Analyzing Aero-Optical Effects with Transient Simulation

A New Method for Analyzing Aero-Optical Effects with Transient Simulation

Aero-optical measurements in a subsonic, turbulent boundary layer with non-adiabatic walls

Optical beam distortions induced by a shock wave

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