Simulations of Mach 0.8 Transonic Truss-Braced Wing Aircraft Aerodynamics at High Angles of Attack

Abstract

This paper presents numerical simulations of the Mach 0.8 Transonic Truss-BracedWing (TTBW) aircraft at high angle of attack using CFD solver FUN3D. Three different approaches steady Reynolds Averaged Navier-Stokes (RANS), Unsteady Reynolds Averaged Navier-Stokes (URANS), and Delayed Detached Eddy Simulation (DDES) are used to simulation the TTBW aircraft at Mach number 0.8 and altitude 40, 000 ft. The pitch break phenomenon is observed at this flight condition. The simulation results show that the pitch break angle of attack occurs at 2.75◦ by DDES, 2.81◦ by URANS, and 2.89◦ by RANS. The DDES unsteady pressure begins to grow at angle of attack of 3.5◦, which might indicate the buffet onset, and rise one order of magnitude larger at angle of attack of 4.0◦. However the URANS unsteady pressure begins to grow at angle of attack of 4.0◦. Both unsteady simulation results show the pitch break occurs before buffet onset.