Aerostructural optimization of the Common Research Model configuration

Abstract

The NASA Common Research Model (CRM) has become a standard test case for verification and validation of Reynolds averaged Navier-Stokes computational fluid dynamics codes. In this paper we evaluate the suitability of the CRM for aerostructural and aeroelastic optimization studies. Since the CRM was originally intended for aerodynamic studies only, the undeformed geometry is not available. To address this issue, we designed a jig shape and the corresponding wingbox structure for the CRM using an inverse design procedure. The results are verified by computing the drag coefficient of the aerostructural solution with the jig shape at the nominal CRM operating conditions. The drag differs by less than one drag count relative to the CRM original shape. Using the CRM jig geometry, a sample high-fidelity aerostructural optimization is performed to determine the potential decrease in fuel burn for a long-range design mission when varying wing planform and airfoil shapes. The optimization increases the aspect ratio of the wing from 9.0 to 12.6 and reduces the fuel burn by 8.8%. We also perform a series of gust load analysis on both the initial and optimized designs and determine that the optimized structure is critical under gust loads. The aerostructural optimization produces a high aspect ratio wing with effective passive aeroelastic tailoring, but additional load cases with cruise-like lift distributions are required to produce a more realistic wing design.

Aeroelastic Tailoring of a Representative Wing Box Using Tow-Steered Composites

“…However, these studies did not consider dynamic gust loads or control effectiveness constraints. Indeed, Kenway et al [23] showed that the dynamic gust loads may become critical if the design is only optimized for maneuver cases. Up until the present time, mainly one-dimensional (spanwise) tow-steering have been considered.…”

Aerostructural Design Optimization of an Adaptive Morphing Trailing Edge Wing

“…This framework has been used previously to perform aerostructural optimization of the uCRM geometry [7], as well as other investigations [9,10,11].…”

“…However, the undeformed jig shape is required for aerostructural optimization. To address this issue, Kenway et al [7] developed the uCRM using an inverse design procedure that minimized the L 2 norm of the geometric differences between the CRM and 1-g deflected uCRM. The wingbox used for the internal structure of the uCRM was designed with the intent to closely represent the analogous structure in a Boeing 777.…”

“…and Table 1: Summary of baseline uCRM parameters based on the uCRM development [7] and publicly available Boeing 777-200ER data [23] where C L and C D are the approximate trimmed full configuration cruise lift and drag coefficients, C L wb and C D wb are the computed lift and drag coefficients on the wing-body configuration, and C Lt and C Dt are the lift and drag coefficient contributions produced by the horizontal tail. In this way, we account for the negative lift and positive drag produced by the trimming tail.…”

“…To investigate the effectiveness of morphing trailing edge devices, we perform a series of aerostructural optimizations on the uCRM geometry [7]. This geometry was developed to closely match the undeflected geometry of the CRM case, for which the only provided geometry represents the deflected 1-g shape.…”