Comparison of Jet Plume Shape Predictions and Plume Influence on Sonic Boom Signature

Abstract

An Euler shock- tting marching code yields good agreement with semiempirically determined plume shapes, although the agreement decreases somewhat with increasing nozzle angle and the attendant increase in the nonisentropic nature of the ow. Some calculations for a low-boom con guration with a sample engine indicated that, for ight at altitudes above 60 000 ft, the plume e ect is dominant. This negates the advantages of a low-boom design. At lower altitudes, plume e ects are signi cant but of the order that can be incorporated into the low-boom design process