Simulation of shock wave buffet and its suppression on an OAT15A supercritical airfoil by IDDES

Abstract

In the present paper, extremely unsteady shock wave buffet induced by strong shock wave/boundary-layer interactions (SWBLI) on the upper surface of an OAT15A supercritical airfoil at Mach number of 0.73 and angle of attack of 3.5 degrees is first numerically simulated by IDDES, one of the most advanced RANS/LES hybrid methods. The results imply that conventional URANS methods are unable to effectively predict the buffet phenomenon on the wing surface; IDDES, which involves more flow physics, predicted buffet phenomenon. Some complex flow phenomena are predicted and demonstrated, such as periodical oscillations of shock wave in the streamwise direction, strong shear layer detached from the shock wave due to SWBLI and plenty of small scale structures broken down by the shear layer instability and in the wake. The root mean square (RMS) of fluctuating pressure coefficients and streamwise range of shock wave oscillation reasonably agree with experimental data. Then, two vortex generators (VG) both with an inclination angle of 30 degrees to the main flow directions are mounted in front of the shock wave region on the upper surface to suppress shock wave buffet. The results show that shock wave buffet can be significantly suppressed by VGs, the RMS level of pressure in the buffet region is effectively reduced, and averaged shock wave position is obviously pushed downstream, resulting in increased total lift. supercritical airfoil, vortex generator, shock wave buffet PACS number(s): 47.20.lb, 47.40.Hg, 47.85.L- Citation:Huang J B, Xiao Z X, Liu J, et al. Simulation of shock wave buffet and its suppression on an OAT15A supercritical airfoil by IDDES.

Unsteady shock front waviness in shock-buffet of transonic aircraft

“…Secondly, the unsteadiness captured in Fig. 5a is not harmonic as previously seen for the RBC12 aircraft [19] or in 2D studies for the OAT15A aerofoil [9][10][11][12][13][14][15][16]. Although not shown here, the drag coefficient, C D , and pitching moment coefficient, C M , exhibit similar patterns.…”

“…With advancing technology, the use of Computational Fluid Dynamics (CFD) in shock-buffet prediction has increased substantially in the last two decades. The 2D experimental results for the OAT15A aerofoil [8] have been used for validation in a series of CFD studies in which the Unsteady Reynolds-averagedNavier-Stokes (URANS), Large Eddy Simulations (LES), and hybrid RANS-LES approaches have been applied [9][10][11][12][13][14][15][16]. The variation in results presented revealed that there is still an uncertainty in prediction of shock-buffet by means of URANS, particularly when closed with eddyviscosity-based turbulence models.…”

Direct numerical simulation of hypersonic transition induced by an isolated cylindrical roughness element

“…It is mainly developed to resolve the unsteady flows accurately, and has been applied in the incompressible [25,26] and transonic turbulent flows [27] successfully. To simulate the hypersonic RIT, the inviscid fluxes are solved using typical Roe Riemann solver, through 4th order MDCD-WENO reconstruction for the original variables.…”

Postponing the Onset and Alleviating the Load of Transonic Buffet by Using Steady and Periodic Tangential Slot Blowing

“…To save time and energy, high-speed flights are usually done by modern, large commercial aircraft, which always cruise between Mach 0.7 and 0.9 by employing supercritical wings [1][2][3]. These Mach numbers fall in the typical transonic flow range; consequently, unsteady shockwave/boundary layer interactions could induce intensive, large-scale, unsteady lift, and transonic buffet will be the result [4][5][6][7][8][9][10].…”

“…They pointed out that by introducing streamwise vortices, streamwise slot control may help delay or prevent downstream separation. By solving Navier-Stokes equations enclosed by an IDDES turbulence model, Huang et al [1] investigated the influence of vortex generators with inclined angles on the transonic buffet of an OAT15A airfoil. They found that the time-averaged location of the shockwave was pushed downstream; thus, the root-mean-square of the oscillating force in the buffeting zone decreases, and the total lift is enhanced.…”