INVESTIGATION OF THE EFFECT OF SURFACE ROUGHNESS ON THE RANGE OF A 155mm BOAT TAIL PROJECTILE

Abstract

The surface roughness of a 155 mm artillery projectile is a controlled parameter during manufacturing, but not much data exists as to its influence on actual performance. It was decided to use practical empirical calculations as a first-order prediction of its effect on drag complemented with a CFD simulation and verified by actual firings of generic 155 mm BT projectiles with various surface roughness values. Practical empirical correlations for the effect of surface roughness on flat plates for compressible flow were used while the FloEFD solver was used for a CFD prediction of the effect of surface roughness on a standard 155 mm shell. For validation, a group of standard 155 mm projectiles with increasing surface roughness were fired. The drag curves obtained from the radar data showed a continuous increase from the baseline curve as the surface roughness increased, with the overall trend of the dynamic firings corresponding well with the CFD simulation.