The Lindbergh Foundation Believes that Innovative Science and Technology Hold the Key to Addressing Humanity’s Environmental and Productivity Challenges

Dr. Ganesh Raman

Dr. Ganesh Raman, Illinois Institute of Technology, Chicago, IL

“Using High Frequency Sound Waves from Ultrasonic Actuators to Reduce Noise from Commercial Aircraft"

Category: Aviation: 2008

The adverse effect of noise has been the subject of extensive research for many years. Repeated exposure to intense noise can cause permanent hearing impairment, sleep loss, increased stress, and other maladies. Aircraft noise is a problem that affects millions of people who live near airports worldwide. Noise also restricts the maximum utilization of airports and air transportation, which could hamper the economic development of the region. Current noise abatement techniques typically result in the loss of payload capacity and fuel efficiencies, making them undesirable.


Dr. Ganesh Raman proposes a paradigm shift to deal with this issue. Instead of the current passive flow control techniques, like lobed nozzles and chevrons, which are unable to adapt to changing working loads of the aircraft, he plans to develop an active High Frequency Flow Control (HFFC). Large air vortices produced by the engine are responsible for a significant percentage of total jet noise. Powered Resonance Tubes (PRTs) produce a high intensity acoustic tone that disrupts the air vortices, reducing the jet noise; however, they create their own noise. Dr. Raman plans to make the PRT produce high frequency sound instead, which is inaudible to the human ear, but still interferes with the air vortices to reduce the engine noise. An added benefit to this technique is that the HFFC can be turned on during take-offs and landings, when aircraft are noisiest, and off during cruising time, to retain maximum fuel economy. In addition, the high frequency PRT has no moving parts, making the operation simple and highly reliable.


Project Update

Dr. Raman has has some very good results from his research project.  He made a presentation about this work at the American Institute of Aeronautics and Astronautics at the 2010 Aerospace Sciences Conference in January in Orlando, Florida.  Click here to download a PDF of his paper.

Dr. Ganesh Raman

This aviation grant is sponsored by Lycoming Engines.

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