Time-Domain Aeroelastic Simulation by a coupled Euler and Integral Boundary-Layer Method

Abstract

An interactive boundary-layer method that solves the unsteady Euler equations coupled with Green’s lag entrainment integral boundary-layer equations is presented for time domain aeroelastic computation. The three-dimensional unsteady Euler equations are solved on stationary body-fltted curvilinear grids. Unsteady boundary conditions on moving surfaces in an aeroelastic problem are accounted for by using approximate small-perturbation method without moving the computational grid. A semi-inverse method is used to couple the Euler and the boundary-layer solutions in order to compute ∞ows with strong inviscid and viscous interactions. The method is tested on standard steady transonic ∞ow computations for the NACA0012 and RAE2822 airfoils and computations of three-dimensional steady and unsteady ∞ows of the LANN Wing. Comparisons with Navier-Stokes results and available experimental data show that the interactive-boundary-layer method provides signiflcant improvement over inviscid calculations by the Euler equations alone. The proposed method is used to predict the ∞utter boundary for the Isogai wing test case through time domain simulations. The interactive boundary-layer result agrees with that by a Navier-Stokes solver and indicates fundamental difierences between the viscous and inviscid solutions in the transonic range.