Development, Verification, and Validation of a Fluid-Structure Interaction Capability and Evaluation of Temporal Coupling Strategies

The objective of this work is the development of computational models and analysis of the coupled fluid-structure response of a slat gap filler (SGF) noise treatment applied to the leading-edge slat component of a high-lift system typical of modern transport aircraft. The representative airframe chosen for this work is the NASA-Boeing High-Lift Common Research Model (CRM-HL) in a baseline high-lift configuration. Superelastic shape memory alloys (SMAs) have been identified as enabling materials for these structural treatments. Since the technology elements rely upon having a highly reconfigurable structure, designs must be assessed for static aeroelastic deflection as well as dynamic aeroelastic stability using coupled computational fluid dynamics (CFD) and nonlinear computational structural dynamics (NL-CSD) tools. The technical approach consists of solving for the flow field around the entire vehicle using a global CFD model, followed by extraction of relevant local subdomain data for CFD and NL-CSD cosimulations. The SGF design is assessed using both 2D and 3D co-simulations to predict quasi-static aeroelastic deformations and to assess dynamic aeroelastic stability. 

Fully-coupled, Aeroelastic Stability Analysis of Adaptive, Shape Memory Alloy Structural Technologies for Airframe Noise Reduction

Recent Developments in Fun3D and LoCi/CHEM CFD Codes Towards Multiphysics Modeling

Aeroelastic analysis of an idealized landing gear door in subsonic potential flow

Incorporation of static equilibrium aereoelastic deformations into the design phase of a vehicle platform would result in a final design that is holistically closer to optimal from a weight and performance perspective than neglecting these effects and potentially correcting problems with a patchwork of solutions. Today, accurate analysis of fluid structure interaction (FSI) is readily achieved by coupling computational fluid dynamics (CFD) solvers to finite element analysis (FEA) tools. Unfortunately, due to the high computational cost associated with CFD-based FSI analysis, the consideration of aeroelastic solutions in trade studies and design optimizations are typically infeasible. The desire to account for these aeroelastic effects in the design phase has led researchers to develop alternative means of obtaining the equilibrium aeroelastic solution. One such scheme, known as the uncoupled static aeroelastic analysis (SAA) method, removes the standard iterative approach of exchanging field information between the structure and fluid domains across a model interface, and instead replaces it with independently generated fluid and structural databases. Generation of these databases is trivially parallelizable and obtained by performing many separate structure and fluid analyses. By generating response surfaces from these solution databases, the equilibrium solution between the structure and fluid domains can be analytically obtained without additional assumptions. Previous work has shown this scheme is capable of significantly reducing computational expense as compared to traditional coupled FSI analyses when many static solutions are required. However, prior work has been limited to 2D and simple 3D problems with easily parameterized geometry. This work extends the approach to arbitrarily complex 3D geometries by utilizing mode shapes and corresponding generalized forces as fitting parameters. Application of this new approach is demonstrated on a high-altitude long endurance (HALE) wing utilizing both linear and nonlinear finite element models. The uncoupled approach is shown to accurately reproduce the equilibrium solution obtained by classic coupled approaches. Furthermore, the incremental computational costs associated with obtaining subsequent aeroelastic solutions is substantially reduced as compared to the traditional coupled FSI scheme. 

A Generalized Methodology for a Highly Parallelizable Uncoupled Method for Static Aeroelastic Analysis in Support of Design Optimization

During flight testing for a business jet, an aeroelastic instability was observed in the landing gear door at certain airspeed and side-slip conditions. Because the flow over the landing gear door begins to separate, traditional linear flutter analysis methods were not able to accurately predict the instability, and high-fidelity fluid-structure interaction (FSI) simulations utilizing a Navier-Stokes computational fluid dynamics solver were necessary. An aeroelastic stability analysis was performed to predict the flutter boundary of the landing gear door at multiple airspeeds and side-slip angles, and the results were compared to flight test data.

Azariah Cornish

Papers

Aeroelastic Stability Predictions of a Business Jet Landing Gear Door using High Fidelity Fluid-Structure Interaction Tools

Development, Verification, and Validation of a Fluid-Structure Interaction Capability and Evaluation of Temporal Coupling Strategies