Unsteady subsonic aerodynamics for bodies and wings with external stores including wake effect

Abstract

An unsteady subsonic method has been developed for aerodynamic computations of any elastic or rigid aricraft with external stores. The method consists of two integral parts: a body surface panel method (SPM) and a constant-pressure lifting surface method, which is the subsonic parallel of the HGM (or the ZONA51 code) for unsteady supersonics. The body considered can be flat-based or close-ended and its geometry input is amenable to any given fuselage or store configuration. The present method is considered an advancement over the past development at least in three aspects: (1) correct unsteady boundary condition on body, (2) a new wake model to account for the body/wake effect and (3) improved accuracy in wingbody interference. Various AGARD iifting surfaces, truncated blunt and pointed bodies and a number of NLR wing-storetiptank combinations were studied for method validation. The present method has shown substantial improvement in the pressures, stability derivatives and airloads on these configurations. For all cases considered, the present results, with or without the wake model, have consistently shown closest agreement with all measured data among existing methods. Therefore, we believe that an accurate and effective method is finally at hand for subsonic aeroelastic applications.