Abstract:

ESDU 82018 provides pressure distribution data for the flow of air over four families of blunt forebodies at zero incidence. The families chosen are ellipsoidal (subsonic or supersonic freestream), spherically-curved nose with radiused shoulder (supersonic freestream only), spherically-blunted cone (supersonic freestream only) and spherically-blunted tangent ogive (subsonic freestream up to Mach 1). The ranges of geometry and Mach number covered for each family are as wide as possible dependent on the availability of data. The pressure distribution data were largely derived either from theoretical methods involving inviscid finite-difference techniques or the method of characteristics or from experimental data. The pressure distribution data are used as a means of estimating, for inviscid flow, the surface Mach number distribution and the temperature distribution with no heat transfer. For real, viscous, flows with heat transfer to or from the body the values of local Mach number and temperature obtained are good approximations to the values at the edge of the boundary layer and may be used as input to ESDU 69012 to determine the equilibrium surface temperature distribution if required. Data derived from use of ESDU 82018 would typically be used as input data for structural strength calculations in missiles or other externally carried aircraft stores and an example illustrating this is given. The geometrical relationships, including surface length, defining the forebody shapes used are summarised, and the flow development over a typical blunt body is described as the freestream Mach number traverses the full range from low subsonic to high supersonic.