Unsteady transonic flow calculations for wing/fuselage configurations

Abstract

Unsteady transonic flow calculations are presented for wing/fuselage configurations. Calculations are performed by extending the XTRAN3S (version 1.5) unsteady transonic small-disturbance code to allow the treatment of a fuselage. The research was conducted as part of a larger effort directed toward developing the capability to treat a complete flight vehicle. Details of the XTRAN3S fuselage modeling are discussed in the context of the small-disturbance equation. Transonic calculations are presented for two wing/fuselage configurations with leading-edge sweep angles of 0 and 36.65 deg, the results of which compare well with available experimental steady-pressure data. Unsteady calculations are performed for simple bending and torsion modal oscillations of the wing. Comparisons of sectional lift and moment coefficients for the wing-alone and wing/fuselage cases reveal effects of fuselage aerodynamic interference on the unsteady wing loading. Tabulated generalized aerodynamic forces, typically used in flutter analyses, indicate small changes in the real (in-phase) component and as much as a 30% change in the imaginary (out-of-phase) component when the fuselage is included in the calculation. These changes result in a 2-5% increase in total magnitude and a several degree increase in phase.