Jet installation noise reduction using porous treatments

Modeling of Wedge-Shaped Porous Flaps for Jet Noise Reduction

This article presents experimental and computational analyses of the flow field associated with porous wedge-shaped deflectors used for jet noise reduction in turbofan engines. The goal is to characterize the key parameters affecting the flow field in order to construct a macroscopic computational model of the deflector that obviates resolution of its detailed perforations. The model simulates ...

The Reduction of Supersonic Jet Noise Using Pulsed

Fluidic Chevrons for Jet Noise Reduction

Chevron mixing devices are used to reduce noise from commercial separate-flow turbofan engines. Mechanical chevron serrations at the nozzle trailing edge generate axial vorticity that enhances jet plume mixing and consequently reduces far-field noise. “Fluidic chevrons” generated with air injected near the nozzle trailing edge create a vorticity field similar to that of the mechanical chevrons ...

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...

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....