F/A-18 Twin-Tail Buffet Modeling Using Nonlinear Eddy Viscosity Models

Abstract

Several fighters suffer from tail buffet problems. The buffet phenomenon is the oscillation of aircraft surface components excited as a result of the interaction between the differential pressures associated with turbulent airflow, aircraft structures, and control surfaces. This paper presents the modeling and simulation of a steady-state one-way and two-way fluid–structure interaction for the tail buffet problem of an F/A−18 fighter. The commercial software ANSYS is used to conduct the simulations. The unsteady Reynolds-averaged Navier–Stokes equations with four turbulent models are used to model the fluid domain. Simulation results of two nonlinear eddy viscosity turbulence models were compared with those of two linear viscosity turbulence models and the experimental data. The two linear turbulence models are standard linear Wilcox and Spalart–Allmaras. The two nonlinear eddy viscosity models are nonlinear eddy viscosity model and Spalart–Allmaras model with rotation and rotation/curvature corrections. The nonlinear eddy viscosity model is based on the standard linear Wilcox model and uses the formulation of an explicit algebraic Reynolds stress model. The Spalart–Allmaras model with rotation and rotation/curvature corrections turbulence model is the modified Spalart–Allmaras model with a strain-vorticity-based production and curvature treatment. The finite element analysis to model the structural components was conducted by using shell elements. Based on the simulation results, it is concluded that the buffet problem could be simulated as a two-way fluid–structure interaction and by using the nonlinear eddy viscosity model turbulence model as those give better results than the other considered models.