Fluid dynamics and aero-optics of turrets

Gordeyev, Stanislav; Jumper, Eric J.

doi:10.1016/j.paerosci.2010.06.001

Cited by 189 publications

(111 citation statements)

References 45 publications

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“…These modifications can result in the addition of a components to the outside of the airframe such as a boom, or a turret (10,11) . In some cases, more substantial external modifications to the airframe many be required such as a pod, turret or blister (12,13) . These changes to the airframe can significantly alter the aerodynamics in terms of the lift and the drag characteristics, which will result in a performance penalty.…”

Section: Introductionmentioning

confidence: 99%

Comparison of flight test data with a computational fluid dynamics model of a Scottish Aviation Bulldog aircraft

Lawson

Salmon

Gautrey

et al. 2013

Aeronaut. j. (1968)

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The following paper presents detailed aerodynamic data of a Scottish Aviation Bulldog light aircraft. The data is taken from the pre-stall region of the aircraft flight envelope through two flight test methods and from a geometrically accurate computational fluid dynamics (CFD) model of the full scale aircraft, which was meshed in Ansys ICEM CFD and solved in Ansys Fluent. The fidelity of the CFD model was achieved by development of a CATIA solid model with surfaces matching a spatial point cloud of the aircraft taken using a 3D laser scanner. Following a CFD verification process, a 3·4m hybrid mesh with a Spalart-Allmaras (SA) turbulence model was found to give the best overall lift and drag characteristics. Further detailed comparisons with the glide flight test data showed the CFD drag polar to have 63% lower zero lift drag, although this discrepancy was related to the simplification of the original CATIA surface model, which excluded the undercarriage, aerials and other protuberance drags. Inclusion of estimates of these sources of drag resulted in a match in zero lift drag to within 15% and a maximum lift to drag of 10:1 which was within 11% of the glide flight test result. The remaining drag discrepancy is attributed to other effects including trim drag and the surface finish of the actual aircraft.

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Section: Introductionmentioning

confidence: 99%

Comparison of flight test data with a computational fluid dynamics model of a Scottish Aviation Bulldog aircraft

Lawson

Salmon

Gautrey

et al. 2013

Aeronaut. j. (1968)

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show abstract

“…18 The original aero-optical wavefronts were produced by turbulence over a flat-windowed turret 18,[27][28][29] during a flight test in which a continuous-wave laser was transmitted between two planes flying in a constant formation at an altitude of 4570 m. The planes were separated by approximately 50 m to ensure aero-optical turbulence was the primary source of wavefront aberrations. Other significant parameters for the flight test are give in Table 1.…”

Section: Aero-optical Wavefront Disturbances In the Ao Experimentsmentioning

confidence: 99%

Receding-horizon adaptive control of aero-optical wavefronts

2013

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Abstract. A new method for adaptive prediction and correction of wavefront errors in adaptive optics (AO) is introduced. The new method is based on receding-horizon control design and an adaptive lattice filter. Experimental results presented illustrate the capability of the new adaptive controller to predict and correct aero-optical wavefronts derived from recent flight-test data. The experimental results compare the performance of the new adaptive controller the performance of a minimum-variance adaptive controller previously used in AO. These results demonstrate the reduced sensitivity of the receding-horizon adaptive controller to high-frequency sensor noise.

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“…In the AO system, Cz is a diagonal MIMO transfer function with each diagonal element equal to the scalar transfer function in Eq. (22). The controller Uz in Fig.…”

Section: Classical Ao Control Loop and Associated Transfer Functionsmentioning

confidence: 99%

“…However, AO applications frequently involve nonstationary wavefront statistics due to changing flow velocities, turbulence strength, and changing the optical paths. For instance, results in [16,[22][23][24] reveal a strong relationship between the spatial statistics of aero-optical wavefronts and the turret viewing angle. Thus, a slew maneuver to track a moving target in the AAOL experiment or similar application should produce time-varying wavefront statistics.…”

Section: Introductionmentioning

confidence: 99%

Optimal and adaptive control of aero-optical wavefronts for adaptive optics

Tesch

Gibson

2012

J. Opt. Soc. Am. A

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This paper compares two control methods to predict and correct aero-optical wavefronts derived from recent flight-test data. The first is an optimal linear time-invariant controller constructed from an identified state-space model of the turbulence flow. The second control method is an adaptive controller based on a recursive least-squares lattice filter. The performance of these control schemes versus classical integrator methods is investigated in an adaptive optics experiment that reproduces the aberrations from in-flight measurements of aero-optical turbulence. Experimental results show the improvement in wavefront correction achieved by both prediction methods. Altering the flow characteristics of the disturbance wavefront during the control process illustrates the ability of the adaptive controller to track changes in the aberration statistics.

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Fluid dynamics and aero-optics of turrets

Cited by 189 publications

References 45 publications

Comparison of flight test data with a computational fluid dynamics model of a Scottish Aviation Bulldog aircraft

Comparison of flight test data with a computational fluid dynamics model of a Scottish Aviation Bulldog aircraft

Receding-horizon adaptive control of aero-optical wavefronts

Optimal and adaptive control of aero-optical wavefronts for adaptive optics

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