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

Abstract

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.