Flow simulations for the first aeroelastic prediction workshop using the EZNSS code

This paper presents numerical simulations that were performed with the EZNSS flow solver for the first NASA Langley Aeroelastic Prediction Workshop. Two configura- tions were studied, the Benchmark Supercritical Wing (BSCW) and the High Reynolds Number Aerostructural Dynamics (HIRENASD) model. The BSCW wing is a rigid wing that was studied at transonic flow conditions, at a fixed angle of attack. Static as well as time-accurate simulations were performed, using several computational meshes and turbulence models, with the purpose of predicting the pressure coefficient dis- tribution at a wing section at 60% of the span, where pressure data was available from a wind tunnel experiment. All of the models predicted the shock location within 10% chords of its wind-tunnel location. None of the models predicted accurately the pressure recovery behind the shock on the upper and lower surfaces. While some tur- bulence models and computational setups resulted in a steady flow, some predicted flow unsteadiness, with fluctuations of the shock position and of the aerodynamic coef- ficient values. This may indicate that the case of the BSCW wing, at the studied flow conditions, is on the verge of buffet instability. The HIRENASD wing was studied for its elastic deformations and associated pressure coefficient distribution at three flow conditions. All of the studied flow conditions resulted in good correlation between the computed and experimental pressure coefficient data. The HIRENASD wing was also excited at its second-bending mode. The transfer function between the pressure coefficient distribution at different span-wise section and the amplitude of motion of a reference point was computed and compared to experimental data. A fair comparison was demonstrated. Overall, it appears that the numerical simulations predicted well the transonic static aeroelastic response and the response to forced excitation in cases of attached flows. The transonic cases of detached flows behind a shock were found to be highly sensitive to the numerical parameters of the simulation, especially the turbulence model used.