Influence of turbulence structure with different scale on aero-optics induced by supersonic turbulent boundary layer

Abstract

Studying the effects of turbulent structure with different scale on aero-optics is of great significance to improve the accuracy of wavefront measurement and simulation, and to guide the suppression of aero-optics through large eddy breakup. Based on the high-spatial resolution (11.4 μm/pixel) density field of the supersonic (M∞ = 3.0) turbulent boundary layer (SPTBL) obtained by Nano-tracer-based planar laser scattering (NPLS) technique, the curvelet transformation is used to extract the density field at a specific turbulence scale. The statistical results of the propagation of Gaussian plane light wave in the corresponding density field at different turbulence scales are calculated. The smaller the scale of turbulence structure is, the less contribution it makes to aero-optical distortion. The fully developed SPTBL has less effect on the beam center offset (x¯), but more obvious effect on the beam spread about the center (x'2¯). x¯ is mainly caused by the turbulent structure with relatively large scale (turbulence characteristic length scale Lj>δ), while the contribution of large-scale structure to the x'2¯ is not significant. The x'2¯ is mainly caused by the turbulent structure with relatively small size (Lj≈0.13δ) in the flow field. The smaller scale (Lj<0.94θ) turbulence structure has less influence on the x¯ and x'2¯. θ can be also used as a validation index of aero-optical effective scale.