Experimental and numerical aspects of simulating unsteady flows around the X-31 configuration

Abstract

The procedure of realizing aerodynamic aspects of experimental and numerical manoeuvre simulations of a fighter aircraft will be presented. The work is part of the DLR (Deutsches Zentrum für Luft- und Raumfahrt, German Aerospace Center) Project SikMa-‘Simulation of Complex Maneuvers’. In this project the X-31 configuration is used as a target configuration for numerical and experimental manoeuvre simulations. The numerical aerodynamic investigations using the DLR TAU-Code are part of an objective to develop and validate a numerical tool for simulating the unsteady aerodynamics of a free flying aeroelastic combat aircraft, by use of coupled aerodynamic, flight mechanics, and aeroelastic computations. In order to obtain a database for validation of the aerodynamic methods within the project, ground-based simulations of complex manoeuvres of a model of the X-31 aircraft have been performed in the low-speed wind tunnel NWB of the German-DutchWind Tunnels DNW. In the wind tunnel tests a newly installed, novel test rig with six degrees of freedom (DOF) was used for the first time. The focus of the article is on the validation process of steady and unsteady guided manoeuvre simulations of the X-31 configuration. Experimental and numerical requirements are discussed based on experimental and numerical results. Lessons learned and directions for future investigations are provided.