Exhaust Plume Thermodynamic Effects on Nonaxisymmetric Nozzle Afterbody Performance in Transonic Flow

Book excerpt: An experimental investigation was conducted to determine the effect of exhaust plume thermodynamic properties on a nonaxisymmetric nozzle afterbody. The model consisted of a strut-mounted cone-cylinder with an isolated nozzle afterbody. The shape of the nozzle afterbody was generally based on the early configurations of the ADEN design. An ethylene/air combustor was used to vary the thermodynamic properties by varying fuel-to-air ratio. Data were obtained at four fuel-to-air ratios representing exhaust plume temperatures of approximately 500 F (cold flow, fuel-to-air = 0), 1,200, 1,500, and 1,900 R. Pressure measurements of the nozzle afterbody surface were obtained from which drag coefficients along the rows of pressure orifices were calculated. The investigation was conducted over a range of Mach numbers from 0.6 to 1.4 at a Reynolds number per foot of 2.5 million. Generally, the nozzle afterbody drag decreased with increasing exhaust plume temperature over the entire Mach number range.