Active Control of Rotor-Lock Noise in Turbofan Engines

The proposed innovation is the design of an active control system to reduce aircraft turbofan engine rotor-lock inlet noise generated when rotor tip speeds become transonic. The system design for this program would be tailored to the requirements of the NASA GRC 22-inch diameter Source Diagnostic Fan. The proposed Phase I research program consists of (1) a conceptual design of a prototype active control sound source and (2) a MatLab based design of an active control system. The concept is an innovation because it uses an active/passive segmented liner noise cancellation concept, developed at Hersh Acoustical Engineering, Inc. (HAE) to cancel rotor-lock noise. A successful Phase I research program will establish the feasibility of developing an active control system capable of efficiently suppressing rotor-lock noise.