Flutter Analysis of the Benchmark Supercritical Wing at Moderate Angles of Attack

The paper presents flutter analyses of the Benchmark Supercritical Wing, at moderate angles of attack, performed as part of the Third Aeroelastic Prediction Workshop. Aeroelastic simulations of the pitch and plunge spring-suspended wing were performed using the EZAir flow solver at an ambient Mach number of 0.8, angles of attack ranging from one to five degrees, and various dynamic pressure values. Flutter onset was detected and compared with experimental data, where available. The focus of the study was threefold: 1) Predicting flutter in a computationally efficient manner by fitting a linear dynamic model to responses at pre-flutter conditions and extrapolating a stability parameter, 2) Studying the angle of attack effect on flutter onset and mechanism at this transonic Mach number, and 3) Studying the possible relation between shock buffet and flutter, and the fluid-structure interaction mechanism. Simulations indicate that as the angle of attack increases, shock buffet occurs, the flutter-onset dynamic pressure decreases significantly, and the flutter mechanism changes from two degrees of freedom to single-degree-of-freedom pitch oscillations

Transonic Shock Buffet on the Benchmark Supercritical Wing

The Benchmark Supercritical Wing (BSCW) is studied as part of the Third Aeroelastic Prediction Workshop (AePW-3). The BSCW was tested at the NASA Langley Transonic Dynamic Tunnel in two campaigns, one studying transonic unsteady aerodynamics, the other studying transonic flutter of the spring-suspended wing. The AePW-3 focuses on computational transonic fluid-structure interactions and flutter prediction with comparison to wind tunnel data. In the wind-tunnel test, shock wave unsteadiness was observed at a test point at Mach 0.8 and angle-of-attack of 5 deg, indicating the presence of transonic shock buffet. The goal of this paper is to study the rigid BSCW buffet characteristics. The results reported herein support the notion the shock buffet on the rigid BSCW is essentially two-dimensional in terms of frequency content, shock wave structure, and physical mechanism. The strong tip effects and considerable extent of flow separation behind the shock result in a reduced shock excursion distance, and a wavier shock front, compared to an infinite straight wing