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Active Aeroelastic Technology Applied to a Joined Wing Concept with Model Complexity

Ned J Lindsley1 Air Force Research Laboratory, Wright-Patterson AFB, OH, 45433

A Joined Wing Concept (JWC) is investigated for active aeroelastic technology application and model complexity quantification.

I. Model Definitions, Investigation and Results he JWC is represented by a highly detailed, stress-level finite element model, as shown in Figure 1. The JWC structural model considered here is for the 100% (full) fuel configuration. There are three models used for the

aeroelastic analyses. The Doublet Lattice Aeroelastic (DLA) model (Figure 2) couples with the finite element model directly for trim analysis, and uses its modal basis representation for gust analysis. The Low Definition Geometry Aeroelastic (LDG) model (Figure 3) performs both trim and gust analyses using the modal basis, as does the High Definition Geometry Aeroelastic (HDG) model (Figures 4 and 5). The HDG model is an outer moldline of the structural model, and uses triangular panels to account for control surfaces not aligned with the streamwise axis (Figure 5). The input required to generate the HDG model (95%) can also be coupled with automatic grid generation (5%) input to generate a skewed-Cartesian grid for trimmed, unsteady Euler aeroelastic analysis.

All contours for Pressure Coefficient, Cp and deflection, dZ are to the same scale for comparison purposes

(Figures 6 to 23). Similarly, all gust load monitor plots on the same page are to the same scale (Figures 24-38). All steady state symmetric trim and discrete gust results presented (Figures 6-35) are for critical gust flight condition (M=0.255, altitude=0 feet, gust velocity=62.4 fps). This critical flight condition for the 100% fuel configuration was identified by all 3 aeroelastic models (e.g. Figures 36-38), but the HDG aeroelastic model produced distinctly different force magnitudes and distributions.

Figures 6-23 present trim results for 1g level flight (6-11), a 2g pullup (12-17) and a 1g pushover (18-23). The

top figure on each page is a trim result using the HDG model by solving a 2-dof determined trim system, while the middle figure presents results for the LDG model. The bottom figure on each page is a trim result using the HDG model and solving an indeterminate 2-dof trim system by optimizing independent control surface psotitions to minimize wing root bending. All pages of Figures show nearly identical results for the 2-dof determined trim system (top vs. middle), while pressure distribution and wing deflection which are less severe and more evenly dispersed (bottom) when all the forward and aft wing control surfaces are utilized independently. This results in a much less stressed configuration, especially for the 1g level flight (Figures 6-11), which is the initial stress state prior to gust analysis.

Model Equivalence Verification between the DLA and LDG models was accomplished for both trim and gust

analysis. This was essential to maintain confidence in the measure of Model Complexity Quantification and Active Aeroelastic Technology benefit when comparing the LDG and HDG models.

Figures 23-35 present discrete gust results for 1g level flight. Comparison of he top (DLA) and middle (LDG) figures verify model equivalence for internal loads due to critical gust. The bottom (HDG) and middle (LDG) figures show how the model complexity affects the internal load magnitudes and distribution. All three models were simulated under gust profile generated using Matched Filter Theory, which will generate a critical gust profile for a given critical load or measure (e.g. wing root bending here).

1 Research Aerospace Engineer, Department Name, Address/Mail Stop, AIAA Member

T

AIAA Atmospheric Flight Mechanics Conference10 - 13 August 2009, Chicago, Illinois

AIAA 2009-5710

This material is declared a work of the U.S. Government and is not subject to copyright protection in the United States.

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Figure 1: Joined Wing Concept (JWC) Structural Model

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Figure 2: JWC Doublet Lattice Aero Model

Figure 3: JWC Low Definition Geometry Aero Model

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Figure 4: JWC High Definition Geometry Aero Model

Figure 5: JWC HDG Aero Model, Wing & Control Surface Section

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Figure 6: hdg m255 h00 1g dZ

Figure 7: ldg same

Figure 8: hdg, using trim objective function

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Figure 9: hdg m255 h00 1g Cp

Figure 10: ldg same

Figure 11: hdg, using trim objective function

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Figure 12: hdg m255 h00 2g dZ

Figure 13: ldg same

Figure 14: hdg, using trim objective function

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Figure 15: hdg m255 h00 2g Cp

Figure 16: ldg same

Figure 17: hdg, using trim objective function

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Figure 18: hdg m255 h00 -1g dZ

Figure 19: ldg same

Figure 20: hdg, using trim objective function

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Figure 21: hdg m255 h00 -1g Cp

Figure 22: ldg same

Figure 23: hdg, using trim objective function

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Figure 24: Rod Forces, M=0.255, H=00k, HDG MFT gust profile, on DLA model

Figure 25: same, on LDG

Figure 26: same, on HDG

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Figure 27: Qxx Forces, M=0.255, H=00k, HDG MFT gust profile, on DLA model

Figure 28: same, on LGD

Figure 29: same, on HGD

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Figure 30: Qyy Forces, M=0.255, H=00k, HDG MFT gust profile, on DLA model

Figure 31: same, on LGD

Figure 32: same, on HGD

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Figure 33: Qxy Forces, M=0.255, H=00k, HDG MFT gust profile, on DLA model

Figure 34: same, LDG

Figure 35: same, on HDG

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Figure 36: Rod Forces, M=0.850, H=55k, HDG MFT gust profile, on HDG model

Figure 37: HDG MFT gust profiles, a) M=0.850, H=55k, vs. b) M=0.255, H=00k

Figure 38: Rod Forces, M=0.255, H=00k, HDG MFT gust profile, on HDG model