Sponsor:
NASA Glenn Research Center

Collaborators:
Michigan State University
Purdue University

Propulsion noise is a major contributor to the overall noise level near airports due to low flying aircraft in the takeoff or landing phase of flight. The identification of propulsion noise of turbofan engines plays an important role in the design. However, the noise generation mechanisms of a typical turbofan engine are very complicated.

In this project, a generalized acoustical holography (GAH) system that can handle aero-acoustic sources under stead-state and transient conditions is developed. Major accomplishments of the project include the development of efficient methods for the generation of transfer matrix that relates sources to sound pressure field measured using surface mounted microphones, application of innovative filtering techniques of measurement data using de-noising techniques, and the development of extensive regularization methods.