Variation in Spanwise Direction of Transonic Buffet on a Three-dimensional Wing

Abstract

Transonic buffet is self-induced oscillation of shock waves appeared on a suction side of a wing. We simulated the transonic buffet over the NASA Common Research Model (CRM) wing, which is an open geometry, generic transport model, and characterized its variation in spanwise direction. The numerical method employed in this simulation was a zonal detached eddy simulation (ZDES), which is a RANS/LES hybrid method. The numerical results indicate that the frequency spectra of oscillation on the surface pressure were varied in spanwise direction and were categorized into three patterns. In the inboard region, buffet exhibits a periodical oscillation having a single dominant frequency equivalent to the 2D wing. At the mid-span of the wing, the wavefront of shock moves due to the existence of the angle of sweepback. In the outboard, the spectrum exhibits multiple dominant modes due to superposition of two difference sources. One is a periodical oscillation similar to the 2D wing. The other is pressure oscillation propagating from the inboard region.