Prediction of optical phase degradation using a turbulent transport equation for the variance of index-of-refraction fluctuations

Smith, R. M.; Truman, C. Randall; Masson, Bruce S.

doi:10.2514/6.1990-250

Cited by 21 publications

(9 citation statements)

References 15 publications

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“…Due to lack of computational power, earlier computations were typically based on Reynolds-averaged Navier-Stokes (RANS) calculations with a turbulence model, such as the k-e model [8,9]. However, since aero-optics is highly dependent on fluctuations in the turbulent density field, an accurate representation of aero-optical distortions with a RANS simulation alone is not possible.…”

Section: Computational Approaches To Aero-opticsmentioning

confidence: 99%

Resolution requirements for aero-optical simulations

Mani

Wang

Moin

2008

Journal of Computational Physics

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Section: Computational Approaches To Aero-opticsmentioning

confidence: 99%

Resolution requirements for aero-optical simulations

Mani

Wang

Moin

2008

Journal of Computational Physics

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“…This provides a practical approach for high-Reynolds-number flows in realistic configurations that is not currently affordable with more accurate techniques. Smith et al (1990) proposed a transport equation for the variance of index-of-refraction fluctuations and solved it along with compressible turbulent boundary-layer equations with a k − ε model for a plane mixing layer. The computed refractive-index variance, together with the turbulence length scale estimated based on k and ε solutions, allowed the linking equation to predict the wave-front error for a beam passing the mixing layer and its impact on target intensity.…”

Section: Computation Of Aberrating Flowsmentioning

confidence: 99%

“…Using the same methodology, Pond & Sutton (2006) performed an aero-optic analysis of a nose-mounted optical turret on an aircraft. Their solutions are based on three-dimensional RANS equations, the k − ε model, and the transport equation for the refractive-index variance proposed by Smith et al (1990).…”

Section: Computation Of Aberrating Flowsmentioning

confidence: 99%

Physics and Computation of Aero-Optics

Wang

Mani

Gordeyev

2012

Annu. Rev. Fluid Mech.

190

104

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This article provides a critical review of aero-optics with an emphasis on recent developments in computational predictions and the physical mechanisms of flow-induced optical distortions. Following a brief introduction of the fundamental theory and key concepts, computational techniques for aberrating flow fields and optical propagation are discussed along with a brief survey of wave-front sensors used in experimental measurements. New physical understanding generated through numerical and experimental investigations is highlighted for a number of important aero-optical flows, including turbulent boundary layers, separated shear layers, and flow over optical turrets. Approaches for mitigating aero-optical effects are briefly discussed.

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“…There are several approaches to accomplish this including equations for the density or index-of-refraction fluctuation 16 or from some other combination of the K-e equations. We have chosen a simpler method to obtain the turbulence parameter from the mean (time-averaged) flow.…”

Section: Computational Aerodynamicsmentioning

confidence: 99%

Hypersonic interceptor aero-optics performance predictions

Sutton

Pond

Snow

et al. 1994

Journal of Spacecraft and Rockets

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This paper describes hypersonic interceptor aero-optics performance predictions. It includes code results for three-dimensional shapes and comparisons to initial experiments. It covers the aerothermal, aerodynamic computational codes that are capable of covering the entire flight regime from subsonic to hypersonic flow and includes chemical reactions and turbulence. Heat transfer to the various surfaces is calculated as an input to cooling and ablation processes. The aero-optics codes determine the effect of the mean flowfield and turbulence on the tracking and imaging capability of on-board optical sensors. This paper concentrates on the latter aspects.Nomenclature area, m 2 speed of sound, m/s tip correlation function speed of light, m/s aperture (lens) diameter tilt compressibility correction term focus correction, m~! intensity at focal plane, w/cm 2 wave number 2ir/X, m~' path length, m turbulence scale length, m Mach number index of refraction pressure, N/m 2 distance, m temperature, K time, s velocity, m/s scalar electric field, V/m coordinates, m Gladstone-Dale constant, m 3 /g rate of turbulence dissipation, j/kg-s coordinates of ray pierce point of a CFD cell, m orthogonal separation distances at the aperture turbulent kinetic energy, j/kg wavelength, m density, kg/m 3 ; dimensionless distance between rays at the aperture angle from centerline of focal plane optical path length, m modulation transfer function z dummy variable Subscripts 2 = on surface of cone A = aperture c -coolant at exit FF = flow field Presented as Paper 93-2675 at the 2nd AIAA/

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Prediction of optical phase degradation using a turbulent transport equation for the variance of index-of-refraction fluctuations

Cited by 21 publications

References 15 publications

Resolution requirements for aero-optical simulations

Resolution requirements for aero-optical simulations

Physics and Computation of Aero-Optics

Hypersonic interceptor aero-optics performance predictions

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