Flutter analysis for the second aeroelastic prediction workshop

The paper presents flutter prediction and simulations that were performed with the EZNSS flow solver for the second Aeroelastic Prediction Workshop (AePW). The reference test cases for the AePW are based on two wind tunnel experiments of the Benchmark Supercritical Wing (BSCW). Two cases are addressed, at different transonic flow conditions: One case at lower Mach numbers of 0.74, 0^◦angle of attack (AoA), and one more physically complex case at Mach 0.85, 5^◦AoA. The cases were analyzed with the EZNSS code, using several computational setups and turbulence models. The simulations at Mach 0.74 0^◦AoA were able to predict accurately the flutter response. A reduced-order model (ROM) for the unsteady aerodynamic forces was constructed and used to predict the flutter point. The ROM was shown to be an accurate and computationally efficient tool for flutter prediction. The higher Mach number case, at Mach 0.85, 5^◦AoA, which involves a strong shock, separated flow behind the shock, and some flow unsteadiness, was more challenging. In the static analysis, different turbulence models yielded different upper-surface shock positions, and none of the models was able to capture accurately the pressure recovery behind the shock. Flutter was computed via an aerodynamic ROM, and since there is no reference flutter point from wind tunnel tests, the flutter point was validated with full aeroelastic simulation.