Influence of Transonic Flutter on the Conceptual Design of Next-Generation Transport Aircraft

Abstract

Transonic aeroelasticity is an important consideration in the conceptual design of nextgeneration aircraft configurations. This paper develops a low-order physics-based flutter model for swept high-aspect-ratio wings. The approach builds upon a previously developed flutter model that uses the flowfield's lowest moments of vorticity and volume-source density perturbations as its states. The contribution of this paper is a new formulation of the model for swept high-aspect-ratio wings. The aerodynamic model is calibrated using off-line 2D unsteady transonic CFD simulations. Combining that aerodynamic model with a beam model results in a low-dimensional overall aeroelastic system. The low computational cost of the model permits its incorporation in a conceptual design tool for next-generation transport aircraft. The model's capabilities are demonstrated by finding transonic flutter boundaries for different clamped wing configurations, and investigating the influence of transonic flutter on the planform design of next-generation transport aircraft.

Design Methodology for Aeroelastic Tailoring of Additively Manufactured Lattice Structures Using Low-Order Methods

“…The complete aeroelastic tailoring approach can be summarized as follows. This work uses a previously-developed physics-based low-order model for transonic flutter [31,32]. The first step, therefore, is to calibrate the aerodynamic coefficients of that model using 2D unsteady Euler simulations for the airfoil family used in the wing design.…”

“…Second, the load distribution over the wing is computed to obtain the baseline lift coefficient c 0 at each beam section-which is needed to select the correct aerodynamic coefficients for the flutter model [32]-and to generate a pressure field over the wing that is subsequently used as input to the structural analysis of the wing internal structure. There are several ways of computing the flow over the wing, e.g., using a vortex-lattice method or a higher-fidelity Euler simulation.…”

“…At transonic Mach numbers, Theodorsen theory with compressibility corrections is no longer accurate. Instead, we employ a physics-based low-order model for transonic flutter [31,32]. This section briefly summarizes the physics-based model's formulation; for more details, see Ref.…”

“…This section briefly summarizes the physics-based model's formulation; for more details, see Ref. [31] and [32].…”

A Coupled Newton-Krylov Time Spectral Solver for Wing Flutter and LCO Prediction

“…This high computational cost makes the full time-accurate method ill-suited to optimization. Recently, various efforts use time-accurate results to train surrogate models on airfoils or flat plates and use the surrogate models to substitute high fidelity CFD in flutter simulation to reduce the computational cost [15,16,17,18]. But the surrogate may not be accurate to predict aerodynamics on a more complex geometry e.g.…”