Project Title:
Noise Reduction by the Dynamical Entrainment of Aircraft Engine Acoustics
02.10-2585
910289
Noise Reduction by the Dynamical Entrainment of Aircraft Engine Acoustics
Advanced Projects Research, Inc.
5301 North Commerce Avenue, Suite A
Moorpark
CA
93021
James D.
Sterling
805-523-2585
LeRC
NAS3-26326
026
02.10-2585
910289
Abstract:
Noise Reduction by the Dynamical Entrainment of Aircraft Engine Acoustics
A novel method for the reduction of noise in propulsion systems will be developed.
Pressure oscillations associated with engine internal flow dynamics will be analyzed
using nonlinear dynamical systems theory to determine the effective number of degrees
of freedom that participate in the oscillations. Reduction of this dimension can
be achieved by nonlinear forcing of the system to achieve "mode-locking" or "entrainment"
of the oscillations so that low-dimensional deterministic dynamics are obtained.
Both linear and nonlinear control techniques may then be applied to the system to
reduce or modify the attractor. Phase I will demonstrate the entrainment of high-dimensional
dynamics onto low-dimensional attractors for known mathematical constructs; apply
dimension-determination techniques to the results of acoustic models to characterize
"noisy" data; and investigate the application of dimension reduction techniques to
acoustic oscillations associated with rotor-stator interactions, nozzle acoustic-entropy
interactions, combustion chamber acoustic modes, and compressor surge.
The reduction of noise by nonlinear entrainment of the high-dimensional dynamics
may prove beneficial for many engineering systems. Application to propulsion systems
requires hardware that can influence the fluid flow to reduce noise. It is anticipated
that commercial implementation of the methods will first be applied to minimize pressure
oscillations in combustors of aircraft engines.
noise, acoustics, dynamical systems, fluid mechanics, propulsion