Computational study of afterbody effects for the joint direct attack munition (JDAM)

摘要

Computational analysis of a JDAM in the flow regime of freestream Mach number = 0.9-1.4 determined the effect of changes to the store afterbody and support sting on store loads. ^The computational results compared well to three sets of wind tunnel data. ^Accuracy requirements necessitated both that the store geometry be modeled with exceptional detail, and that the Navier-Stokes equations with the Nichols' k-epsilon turbulence model be employed. ^Comparisons to measured data showed excellent agreement with aerodynamic load increments and also with the absolute values of the loads. ^Analysis using a wall function model for the boundary layer also compared well with data. ^The comparisons established a sufficient level of confidence in the numerical model as to allow its use in determining the forces and moments free of support effects at the flight Reynolds number. ^(Author)