F-16XL Hybrid Reynolds-Averaged Navier–Stokes/Large-Eddy Simulation on Unstructured Grids

Abstract

The Cranked Arrow Wing Aerodynamics Program, International (CAWAPI) investigation is continued with the FUN3D and USM3D flow solvers to fuse flight test, wind tunnel test, and simulation of swept wing aerodynamic features. Simulations of a low speed, high angle of attack condition are compared. Detached Eddy Simulation (DES), Modified Delayed Detached Eddy Simulation (MDDES), and the Spalart-Allmaras (SA) RANS model. Isosurfaces of Q criterion show the development of coherent primary and secondary vortices on the upper surface of the wing that spiral, burst, and commingle. Mean DES and MDDES pressures better predict the flight test measurements than SA model predictions, especially on the outer wing section. The USM3D simulations predicted many sharp tones in volume point pressure spectra with low broadband noise and The FUN3D simulations predicted more broadband noise with weaker tones. Spectra of the volume points near the outer wing leading-edge was primarily broadband for both codes. Time-averaged forces are very similar between FUN3D simulations and and similar between USM3D simulations, but FUN3D predicts slightly higher lift and lower drag than USM3D. There is more variation in the pitching moment predictions. Spectra of the unsteady forces and moment are mostly broadband for FUN3D and tonal for USM3D simulations.

A Synthesis of Hybrid CFD Results for F-16XL Aircraft Aerodynamics

“…All of these codes are well vetted with established user communities, although the hybrid RANS/LES capability is relatively new to EDGE and USM3D. Additional details of the codes can be found among the individual application papers [6][7][8][9][10][11] of this study. As part of the approach to this study, all partners followed their internal best-practice guidelines.…”

“…This particular case, identified as FC-25, has M = 0.242, Rcref = 32.22 x 10 6 , and  = 19.84°. Five studies [6][7][8][9][10] were published in this special session entitled "Hybrid CFD Method Assessments for F-16XL Aircraft Aerodynamics," and five numerical formulations were used. This paper presents a synthesis of those individual findings.…”