New Method for Jet Noise Reduction in Turbofan Engines

New Method for Jet Noise Reduction in Turbofan Engines

A new method for reducing large-scale mixing noise from dual-stream jets is presented. The principle is reduction of the convective Mach number of turbulent eddies that produce intense downward sound radiation. In a jet representing the coaxial exhaust of a turbofan engine, this is achieved by tilting downward, by a few degrees, the bypass (secondary) plume relative to the core (primary) plume....

AIAA 2003-1059 A New Method for Jet Noise Reduction in Turbofan Engines

Noise Reduction Technologies for Turbofan Engines

Significant progress continues to be made with noise reduction for turbofan engines. NASA has conducted and sponsored research aimed at reducing noise from commercial aircraft. Since it takes many years for technologies to be developed and implemented, it is important to have aggressive technology goals that lead the target entry into service dates. Engine noise is one of the major contributors...

Passive Techniques for Fan Noise Reduction in New Turbofan Engines : Review

Among the various environmental concerns, the aircraft noise item has been constantly growing in importance over the past years. Measures for its reduction at the source as well its mitigation around airports must take into account aspects of medicine and technical design as well as legal and land use planning aspects. Fan noise is one of the principal noise sources in turbofan aero-engines. In...

Turbofan Jet Noise Reduction via Deflection of the Bypass Stream

We describe a parametric experimental study of noise reduction via de ection of the secondary stream in dual-stream jets. The jets simulated the exhaust of turbofan engines with bypass ratios 4.5 and 6.0. The secondary (bypass) stream was de ected downward by means of vanes installed inside the bypass duct. Variables included the number of vanes, vane angle of attack, azimuthal placement, and a...