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

Area of Science:

• Aerospace Engineering
• Computational Fluid Dynamics
• Fluid Mechanics

Background:

• The Cranked Arrow Wing Aerodynamics Program, International (CAWAPI) investigates swept wing aerodynamics.
• Understanding complex flow phenomena like vortex dynamics is crucial for aircraft design.

Purpose of the Study:

• To compare the predictive capabilities of different computational fluid dynamics (CFD) models for swept wing aerodynamics.
• To fuse flight test, wind tunnel, and simulation data for a comprehensive analysis.

Main Methods:

• Simulations were performed using FUN3D and USM3D flow solvers.
• Aerodynamic performance was analyzed using Detached Eddy Simulation (DES), Modified Delayed Detached Eddy Simulation (MDDES), and Spalart-Allmaras (SA) RANS models.
• Flow visualization utilized Q criterion isosurfaces to depict vortex structures.

Main Results:

• DES and MDDES models showed improved pressure prediction accuracy compared to the SA model, particularly on the outer wing sections.
• FUN3D simulations predicted more broadband noise, while USM3D simulations exhibited sharper tonal noise.
• Time-averaged forces were similar between solvers, with FUN3D predicting slightly higher lift and lower drag.

Conclusions:

• DES and MDDES are more effective than the SA model for simulating swept wing aerodynamics at high angles of attack.
• Differences in noise spectra between FUN3D and USM3D highlight distinct flow physics predictions.
• The study provides valuable data for validating and improving CFD tools for complex aerodynamic investigations.