Tailored Nozzles for Jet Plume Control and Noise Reduction

• Published in: AIAA journal 2012-10, Vol.50 (10), p.2115-2134
• Main Authors: Viswanathan, K, Spalart, P. R, Czech, M. J, Garbaruk, A, Shur, M
• Format: Article
• Language: English
• Subjects: Aerodynamics; Aircraft; Bevels; Computer simulation; Deflection; Emissions control; Noise control; Noise reduction; Nozzle geometry; Nozzles; Plumes; Reduction; Simulation; Thrust
• ISSN: 0001-1452; 1533-385X
• DOI: 10.2514/1.J051436

A synergistic utilization of computational simulations with experimental measurements is employed to develop dual-stream nozzle geometries that provide jet-noise reduction with the concurrent ability to control the orientation of the jet plumes, so as to minimize the thrust degradation associated with low-noise designs. The geometries consist of round primary and secondary nozzles, beveled primary nozzles, modified secondary nozzles, and combinations thereof. Specifically, the secondary nozzle is altered internally to provide the same deflection as a beveled primary in dual-stream exhaust geometry. The cross-sectional profiles are similar, but the bevel deflects the jet toward the short lip, whereas the modified secondary deflects the jet in the opposite direction. It is possible to eliminate/minimize the deflection of the total thrust vector through a judicious combination of the bevel and the modified secondary; numerical simulations facilitate this objective. The magnitude of the noise reduction increases with increasing primary jet velocity, and decreases with increasing flight Mach number. There is a gradual erosion of noise benefit as the azimuthal angle is increased from 0 deg (below the long lip of bevel). There is a benefit in effective perceived noise level for all the nozzle geometries evaluated in this investigation. The combinations of modified secondary nozzles with bevel 24 and bevel 30 provide the largest reduction in effective perceived noise level over a wide range of freestream Mach number, with a small thrust penalty. The design approach developed and evaluated here seems promising vis-a-vis practical applications, requiring only relatively limited modifications to an existing design. In addition, the modified secondary nozzle provides the ability to deflect the plume away from the underside of the wing and the flap, thereby reducing the jet-flap interaction noise.