The Estimation of the Unsteady Aerodynamic Force Applied to a Turret in Flight

Lucca, Nicholas De; Gordeyev, Stanislav; Jumper, Eric J.; Hird, Kyle; Juliano, Thomas J.; Gregory, James W.; Thordahl, James; Wittich, Donald J.; Afb, Kirtland

doi:10.2514/6.2013-3136

Cited by 14 publications

(14 citation statements)

References 14 publications

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“…For both window geometries, first two modes had a peak around St D = 0.2 and a smaller, sharper peak around St D = 0.5. The first peak was related to the unsteady flow separation over the turret; similar values of the unsteady-pressure spectral peak were observed in other unsteady pressure measurements on the downstream portion of the turret [22,23]. The origin of the second peak was not quite clear and possibly was related to the blade passing frequency of the tunnel-driving fan.…”

Section: Local Increase Due To An Unsteady Local Vortexsupporting

confidence: 71%

“…All presented measurements were performed at a relatively-low Mach number of 0.33, and small transition effects for the flow around the turret were found to be present at this speed [1,23]. Thus, in order to find a Machnumber-independent POD modes, it is necessary to repeat PSP experiments at a higher Mach number of at least 0.4.…”

Section: Conclusion and Discussionmentioning

confidence: 96%

“…In the companion paper [23], POD pressure modes were used to study unsteady forces acting on the turret for different turret geometries and it was found that only first five modes are needed to correctly predict unsteady forces. So, a sparse unsteady pressure array can be properly placed using POD analysis to correctly measure unsteady forces acting on the turret.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

See 2 more Smart Citations

The Comparison of Unsteady Pressure Field over Flat- and Conformal-Window Turrets using Pressure Sensitive Paint

Gordeyev

Lucca

Jumper

et al. 2013

44th AIAA Plasmadynamics and Lasers Conference

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Spatially-temporally-resolved unsteady pressure fields on a surface of a hemisphere-oncylinder turret with either a flat-or a conformal-window were characterized using fastresponse pressure sensitive paint at M = 0.33 for several window viewing angles. Various statistical properties of pressure fields were computed and geometry effects on unsteady pressure, including an effect of either flat-or conformal-window, were analyzed and discussed. Proper orthogonal decomposition were also used to extract dominant pressure modes and corresponding temporal coefficients and to analyze and compare instantaneous pressure structures for different turret geometries and viewing angles. In addition, the effects of gaps and 'smile' cut-outs present on the turret were investigated.

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Section: Local Increase Due To An Unsteady Local Vortexsupporting

confidence: 71%

Section: Conclusion and Discussionmentioning

confidence: 96%

Section: Conclusion and Discussionmentioning

confidence: 99%

See 1 more Smart Citation

The Comparison of Unsteady Pressure Field over Flat- and Conformal-Window Turrets using Pressure Sensitive Paint

Gordeyev

Lucca

Jumper

et al. 2013

44th AIAA Plasmadynamics and Lasers Conference

Self Cite

View full text Add to dashboard Cite

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“…Another approach is to obtain the loads by integrating the measured surface pressure using pressure sensitive paint [5] and piezoelectric sensors for high frequency local information for both surface shear stress and surface pressure [18,1,4]. In some specific cases, more complex techniques can be applied.…”

Section: Introductionmentioning

confidence: 99%

Unsteady aerodynamics of single and tandem wheels

Spagnolo

Zhang

et al. 2017

Journal of Fluids and Structures

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The major unsteady aerodynamic forces and major physics of a generic single wheel and tandem wheels are studied for the first time using wind tunnel tests. The wind-tunnel tests are performed in the 2.1 m × 1.5 m wind tunnel at the University of Southampton. The tandem-wheel configuration consists of two in-line wheels that can be tested at different inter-axis distances and various installation angles. A vibration test is performed in situ on the model assembly to validate the unsteady-load measurements. Mean and unsteady aerodynamic loads and on-surface pressures are measured. Particle Image Velocimetry is used to acquire the velocity fields in the wake downstream of the model and surface oil-flow technique is used to identify the flow features on the surface of the wheels. Proper Orthogonal Decomposition is also used to characterise the wake in terms of unsteady fluctuations. The results of the experiments on the tandem wheels show that higher values of inter-axis distance correspond to slightly higher total mean drag coefficients and remarkably lower drag coefficient RMS values. Higher installation angles are associated with higher mean drag coefficients but generally lower fluctuations of the force coefficients. Non-zero mean lift coefficients are found for low inter-axis distance configurations at zero installation angle. The flow on the single wheel and on the front wheel of the tandem wheels is affected by laminar-turbulent transitional features. The vortical structures past the tandem wheels consist of four vortices that detach from the tyre shoulders of the front wheel and interact with the rear wheel. The study and obtained databases contribute to the general understanding of the complex flow and help to improve engineering predication of the gear aerodynamic loads.

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“…Another approach is the use of pressure sensitive paint to obtain the loads by integrating the measured surface pressure 20 and piezoelectric sensors for high frequency local information for both surface shear stress and surface pressure 21,22,23 . In some specific cases, more complex techniques can be applied.…”

mentioning

confidence: 99%

Unsteady Force and Flow Features of Single and Tandem Wheels

Spagnolo

Zhang

et al. 2015

53rd AIAA Aerospace Sciences Meeting

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Wind-tunnel experiments are presented in this paper for two different models, single wheel and tandem wheels. The tests are performed in the 2.1 m × 1.5 m wind tunnel at the University of Southampton. The aims of the experiment are to gain a better understanding of the flow past simple landing-gear components and to generate a CFD validation database. Since the model is designed to study basic landing-gear components, the wheel geometry is simplified, with no detailed elements in the assembly. The tandem-wheel configuration is formed of two in-line wheels that can be tested at different inter-axis distances and various angles of attack. Mean and unsteady data of aerodynamic loads and on-surface pressures are measured. A vibration test is performed in situ on the model assembly to validate the unsteady-load measurements. Particle Image Velocimetry (PIV) is used to acquire the velocity fields in the wake downstream of the model. The results highlight the low sensitivity of the measured quantities to the three versions of the wheel hub on the single wheel. The mean drag coefficients of the tandem wheels show a low sensitivity to the inter-axis distance, which has stronger effects on the mean lift coefficients and the unsteady aerodynamic loads. The angle of attack determines relevant changes in both mean and unsteady quantities. The pressures on the wheel surface are used for gaining a better understanding of the flow regimes and the effect of tripping the flow. Additionally, the PIV data are used to compare the velocity profiles in the wake and identify the wake vortical structures.

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The Estimation of the Unsteady Aerodynamic Force Applied to a Turret in Flight

Cited by 14 publications

References 14 publications

The Comparison of Unsteady Pressure Field over Flat- and Conformal-Window Turrets using Pressure Sensitive Paint

The Comparison of Unsteady Pressure Field over Flat- and Conformal-Window Turrets using Pressure Sensitive Paint

Unsteady aerodynamics of single and tandem wheels

Unsteady Force and Flow Features of Single and Tandem Wheels

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