CFD-based computer simulation of optical turbulence through aircraft flowfields and wakes

Jones, Mike I; Bender, Erich

doi:10.2514/6.2001-2798

Cited by 41 publications

(17 citation statements)

References 4 publications

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“…The flows of interest include boundary layers, wakes and cavity flows, typically associated with flight through the atmosphere. Although the depth of turbulence in a typical aerooptical field is not more than a few optical aperture diameters, density fluctuations in these flows can cause wavefront distortions of the order of a few optical wavelengths [2,3]. Such initial distortions reduce the coherence of the beams, so that by the time they arrive at the receivers, they have much lower intensities and are more dispersed compared to undistorted beams.…”

Section: Aero-optical Frameworkmentioning

confidence: 98%

“…LES is capable of capturing a range of flow structures, from large-scale motions down to the scale comparable to the mesh spacing, while the effect of unresolved features is modeled. LES has been used for aero-optical computations in various flow configurations, from simple shear [4,12,13] and wake [3] flows to flows around complex objects, such as the fuselage of an aircraft [2].…”

Section: Computational Approaches To Aero-opticsmentioning

confidence: 99%

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Resolution requirements for aero-optical simulations

Mani

Wang

Moin

2008

Journal of Computational Physics

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Section: Aero-optical Frameworkmentioning

confidence: 98%

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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“…For example, as shown in Figure 3, if a hemispherical dome is installed on an aircraft the region in front of the dome experiences a relatively static pressure build-up while the region aft of the dome can experience dynamic turbulence including vortex eddies in the air flow. This is a well-known result and visualizations have been provided in many forums (e.g., see [7,8]). The result of this varying nature is that the effects of the boundary layer have a strong spatial and view angle dependence.…”

Section: Boundary Layer Turbulencementioning

confidence: 68%

Airborne Laser Communications: the Challenges of the Propagation Medium

2006

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As is widely known one ofthe great promises of laser-based communications is the potential to achieve free-space communications with data rates in the Gbps. There could be a utility to the United States Air Force by teaming this potential communication capability with advanced sensors that generate large volumes of data. In this paper this potential is explored with a particular focus on issues unique to applying lasers to communications in an airborne environment.

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“…Jones et al [20] pointed out that ray-tracing was sufficient for near-field aero-optical aberration measurement, so the ray-tracing method is adopted to analyze the wavefront propagating in supersonic flows.…”

Section: Ray-tracing Theorymentioning

confidence: 99%

Aero-optical aberration measuring method based on NPLS and its application

Tian

Zhao

et al. 2010

Chin. Sci. Bull.

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The existing methods for measuring aero-optical aberration suffer from several problems, such as low spatiotemporal resolution, sensitivity to environment, and integral effects. A new method for measuring aero-optical aberration of supersonic flow is proposed. Based on the self-developed measuring method of supersonic density field, the wavefront aberration induced by a cross-section of supersonic flow field could be measured by ray-tracing. Compared with other methods, the present one has three significant innovations: (1) high spatiotemporal resolution. Its time resolution is 6 ns, and the spatial resolution can reach up to micrometers; (2) it can avoid the integral effects and study the wavefront aberration induced by the flow field of interest locally;(3) it can also avoid the influence from the test section wall boundary layers and environmental disturbances. The present method was applied to supersonic flow around an optical bow cap. The results of high spatiotemporal resolution reveal fine wavefront structures, and show that shock waves, expansion waves and turbulent boundary layers have different impacts on the wavefront aberration. NPLS, supersonic flow field, aero-optics Citation:Yi S H, Tian L F, Zhao Y X, et al. Aero-optical aberration measuring method based on NPLS and its application.There are many methods for measuring aero-optical aberration induced by supersonic flow, such as Shack-Hartmann wavefront sensor (SHWS), small-aperture beam technique (SABT) and interferometry. SHWS is not sensitive to the vibration of equipments, and its dynamic measurement range is more than a hundred times or even thousands of times of traditional interferometry [1]. Its resolution is related to the size and spacing of small lens [2], and can reach up to 100-500 μm. Its temporal response frequency is not generally higher than 2500 Hz [3], and can be improved by reducing its spatial resolution [2]. In 1992, Jumper and Hugo [4] described SABT in detail, and studied the optical phase aberration caused by turbulent flow. The frequency of SABT is up to 100 kHz [5], which is the highest among numbers of wavefront sensors nowadays, and its spatial resolution is lower than that of SHWS by one or two orders *Corresponding author (email: zhaixing_nomin@sohu.com)[5]. SABT has been successfully used in various flow fields [6,7]. Interferometry is commonly used when the wavefront aberration is relatively weak [8]. By comparing the disturbed wavefront and the reference one, the interferometry can directly measure the wavefront phase aberration. The interferogram is recorded on CCD, and the brightness at each pixel is proportional to the local disturbed wavefront phase [9]. The time-response frequency of interferometry is related to the CCD record out time and the spatial resolution. Based on the background oriented schlieren (BOS), Zhao et al.[10] proposed a technique to measure the aero-optical aberration and jitter of supersonic mixing layer. The time resolution of the technique based on BOS is 6 ns, the highest time correlation...

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CFD-based computer simulation of optical turbulence through aircraft flowfields and wakes

Cited by 41 publications

References 4 publications

Resolution requirements for aero-optical simulations

Resolution requirements for aero-optical simulations

Airborne Laser Communications: the Challenges of the Propagation Medium

Aero-optical aberration measuring method based on NPLS and its application

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