Hybrid RANS-LES Simulations of F-16XL Aircraft in Low-speed High-alpha Flight

Abstract

This article presents the comparisons of the results of the CFD study around the F-16XL CAWAPI configuration for flight condition FC25: M∞ = 0:24, α = 19:8°, β = 0°, Re = 32:2M. Previous work has established this case of high angle of attack flight as an outlier in the sense that the computed pressure distributions compared less favorably with those measured in flight tests than did similar comparisons for cases at lower angle of attack. One reason suggested for the discrepancy was that the flow over the outer wing panel was unsteady, possibly including vortex breakdown. This paper presents results computed time accurately with physical modeling that can capture such unsteady flow phenomena. The physical modeling employed is an innovative hybrid RANS-LES model termed HYB0. The simulations obtained are compared with those measured during flight testing of the vehicle as well as with results computed with RANS and URANS physical modeling. Although differences are found among all the results compared, they are not exceeding large. Further analysis of the results are presented, and conclusions are drawn.