Investigation of supersonic projectile drag reduction using base injection and free stream combustion
investigationof00horn.pdf (2.958Mb)Abstract
Base drag accounts for nearly half the total drag of a supersonic
projectile. A review is presented of early base flow studies. By relating
rate of entropy generation to projectile drag, it is demonstrated
that the trailing shock dominates "base drag. Base injection was selected
as the means of weakening this shock. Base pressure, as a function
of injectant flow rate, was obtained by means of a free jet wind tunnel
with a coaxial, Mach 2.0 nozzle. Base pressure ratio (P(β)/P ͚) increases
of 13 percent at an effective I(SP) of 465 seconds were achieved with cold
nitrogen. Free stream combustion was simulated by nozzle contour. Base
pressure increases due to free stream combustion and base injection were
shown not to be additive effects.