Assessment of Sting Effect on X-31 Aircraft Model Using CFD

Jirasek, Adam; Cummings, Russell M.

doi:10.2514/6.2010-1040

Cited by 7 publications

(4 citation statements)

References 23 publications

(18 reference statements)

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“…Previous results have shown an offset in the experimental pitch moment due to the wake formed behind the belly mounted sting. 15 Thus, for validation purposes the sting geometry has been added to CFD models.…”

Section: Test Casementioning

confidence: 99%

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Validation of Unsteady Aerodynamic Models of a Generic UCAV Using Overset Grids

Ghoreyshi

Jirasek

Cummings

et al. 2014

32nd AIAA Applied Aerodynamics Conference

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This work is part of the NATO STO Task Group AVT-201 Special Sessions being organized by the AIAA Applied Aerodynamics Technical Committee. Reduced-OrderModeling techniques based on response functions are presented and validated for unsteady aerodynamic prediction of a generic unmanned combat air vehicle with trailing edge flaps. The overset grid approach was used to move these control surfaces and simulate the flow fields around the vehicle in static and dynamic conditions and with different control surface deflections. Single meshes were also generated to study the effects of gaps present in the overset mesh and the sting geometry available in the experimental model. The Reynoldsaveraged Navier Stokes predictions were first validated by wind-tunnel static and dynamic case measurements. The flow topology over the configuration was then described for a range of angles of attack and control surface deflections. The response functions with respect to angle of attack and pitch rate were directly calculated from step motion simulations in CFD and a grid motion approach. An aerodynamic model was then created from these functions and used to predict the vehicle aerodynamic responses obtained from pitching oscillations at different amplitudes and frequencies. The results show that predictions from a linear model are only in good agreement with time-accurate simulations of small amplitude motions. A model that has response dependence on the angle of attack match quite well with CFD data of large amplitude motions within the range of data used for model generation, however, small discrepancies can also be seen in pitch moment plots. The results show that model predictions get worsen with including sting geometry in simulations because of the nonlinear hysteretic behavior of a wake formed behind the sting. Nomenclatureroll moment coefficient in wind axes Downloaded by CORNELL UNIVERSITY on July 30, 2015 | http://arc.aiaa.org |

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Section: Test Casementioning

confidence: 99%

“…9 However, an offset can be seen in the experimental pitch moment due to the wake formed behind the belly mounted sting. 15 The sting geometry is therefore included in the CFD models of this work.…”

Section: Introductionmentioning

confidence: 99%

Validation of Unsteady Aerodynamic Models of a Generic UCAV Using Overset Grids

Ghoreyshi

Jirasek

Cummings

et al. 2014

32nd AIAA Applied Aerodynamics Conference

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“…However, most of the research is devoted to the assessment of sting interference rather than to the optimal design of the sting. Jirasek and Russell described the computational evaluation of the effect for a belly mounted sting on the aerodynamic characteristics of an X-31 wind tunnel model, which included the results of steady and time-dependent CFD analysis of the X-31 model with and without a sting [9]. L.A. Schiavetta and O.J.…”

Section: Introductionmentioning

confidence: 99%

The Optimal Design of a Wind Tunnel Model Sting System Based on the CFD Method

Li¹,

Liu²,

Li³

2015

IJHT

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This paper aims to design a sting support system for a transonic wind tunnel test for a commercial wide-bodied aircraft, which includes a single sting and a blade support. Parameters of the sting support system have been analyzed and three key parameters are selected for optimization. A RANS solver has been developed to investigate the effects of key parameters on the sting support interference. Influences of four incidence angles and five locations of an expanding point on the single sting interference are studied, and also the effects of six vane leading edge sweep angles on the blade support interference are investigated. The optimal key parameters are determined, based on numerical results and structural rigidity. Structural intensity verification of the optimized support system has been performed under the estimated aerodynamic loading by commercial software. Results indicate that a 6° incidence angle and 03 expanding point are the optimal parameters for a single sting and a 50° leading edge sweep angle of the vane is optimal for blade support. The optimized sting system with sufficient safety factors is suitable for commercial wide-bodied aircraft wind tunnel tests, which implies the method in this paper can be used to optimize the sting support system of other vehicles.

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“…It also can affect the noise in the solution. 41 Meanwhile the average values of pitching moment can be corrected by subtracting the offset due to belly mounted sting, the noise in both normal force (see figure 9) and pitching moment caused by the sting has a detrimental effect on the assumption of fading memory. Unlike a model with the sting, the model without the sting shows steady values of both normal force and pitching moment without any excessive noise.…”

Section: X-31 Pitching Motionmentioning

confidence: 99%

Application of Volterra Functions to X-31 Aircraft Model Motion

Cummings

2009

27th AIAA Applied Aerodynamics Conference

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Recent advances towards an efficient computational method for accurately determining the stability and control characteristics of an aircraft are discussed and critiqued. The present approach with greatest promise is to reduce the number of high-fidelity CFD sim ulations by using Volterra functions Reduced Order Modeling. This type of reduced order model is a predictive model which has a unique training maneuver -a unit impulse. The advantage of such an approach is the fast prediction of the aerodynamic characteristics of an aircraft. This article presents the results of application of the Volterra functions ROM for prediction of linear movement of a 2D airfoil and of an X-31 aircraft model. The Volterra ROM predicted well normal and axial force which are linear or weakly non-linear and was in a fairly good agreement with pitching moment as long as the pitching moment predictions were weakly non-linear.

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Assessment of Sting Effect on X-31 Aircraft Model Using CFD

Cited by 7 publications

References 23 publications

Validation of Unsteady Aerodynamic Models of a Generic UCAV Using Overset Grids

Validation of Unsteady Aerodynamic Models of a Generic UCAV Using Overset Grids

The Optimal Design of a Wind Tunnel Model Sting System Based on the CFD Method

Application of Volterra Functions to X-31 Aircraft Model Motion

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