Form 9.B Project Summary

Chron: 972262

Proposal Number: 03.01-3400

Project Title: Autonomous Far-Field Cancellation of Broadband Noise from Ducted Fans

Technical Abstract (Limit 200 words)

We propose to show that two new active control algorithms can reduce the noise radiated from a ducted fan by more than 10 dB in the far-field. This demonstration will provide strong evidence that the difficult noise standards of FAR 36, Stage 3 will be attainable, at least in part, with active control, at substantially reduced cost and performance when compared with passive methods alone. The two new algorithms we propose to apply have the following features, which together constitute a new, enabling capability for the control of broadband and tonal fan noise in the far field: they automatically account for feedback from the control actuators to the disturbance reference microphones; they control multiple duct modes in a coordinated fashion; they adapt on-line to changes in the system dynamics over flight conditions; and they perform their computations in a particularly efficient manner due to the small number of parameters required by their system representations. The existence of two highly relevant, already funded efforts makes it possible to demonstrate feasibility within the funding and time constraints of Phase I: one which makes key measurements on a NASA noise control testbed, and another which develops the theory for the algorithms.

Potential Commercial Applications (Limit 200 words)

The specific product that will be developed with this SBIR effort is a fully adaptive, autonomous controller for multiple-input, multiple-output systems in which there is significant feedback from the actuators to the disturbance sensors. This product can be applied to many different structural or acoustic control problems, including: ducted fans for aircraft transport propulsions, low-noise propulsors for submersible vehicles, commercial and industrial cooling and ventilation fans and ducts, and almost any lightly damped structure in which motion can be sensed for later cancellation. Initial development will focus on high-valued systems, such as aircraft engines and submarines, where there is a large financial incentive for noise reduction.

Name and Address of Principal Investigator (Name,

Organization Name, Mail Address, City/State/Zip)

Larry Davis

Planning Systems Incorporated

7923 Jones Branch Drive

McLean , VA 22102

Name and Address of Offeror (Firm Name, Mail Address,


Alan Friedman

Planning Systems Incorporated

7923 Jones Branch Drive

McLean , VA 22102