As part of the PARTNER noise research program, the Source Emission and Propagation project has the goals to provide a better understanding of aviation noise problems and to contribute to the development of improved noise impact prediction tools that lead to developing solutions. Project 2 is primarily concerned with the radiation (emission) of sound from aviation noise sources and how that sound is transmitted (propagated) from noise source to receiver. Thus, the results of Project 2 feed into many of the other PARTNER noise projects. Several tasks are underway or have been recently studied in Project 2. One task has been to assess thrust reverser noise for aircraft landing operations. Another task has been to try to understand the effects of terrain on the sounds of supersonic aircraft sonic booms heard near buildings and other natural ground topography. Included with this task is an investigation of the cause of sonic boom postboom noise — the rumbling heard after the passage of a sonic boom. The effect of weather on sonic boom and subsonic aircraft noise is also of interest. Recently, PARTNER Project 2 began work related to high altitude enroute aircraft noise, and noise of proposed open rotor aircraft. High altitude aircraft (altitudes greater than 10,000 ft.) enroute noise is important for assessing the noise in National Parks and other areas of low background noise. Since the integrated noise model has primarily been concerned with aviation noise around airports, our ability to predict this type of enroute noise is quite limited at present. In addition, aircraft using open rotors (also known as unducted fans, propfans, or ultra-high bypass engines) seem poised to re-emerge as viable alternatives for civil aviation propulsion systems. Compared to traditional turbofan engines, open rotors can have substantially decreased emissions due to a reduced fuel burn. However, the cost of this reduced emissions impact could be an increase in radiated noise. The noise impact is greater not only because the fans are outside the engine nacelles, but also open rotor aircraft fly more slowly than conventional jets so the aircraft spends more time over populations living around airports. Current research is focusing on developing a roadmap to address the gaps and research needs for predicting the noise from open rotor aircraft.

ANTICIPATED OUTCOMES

Improved understanding and tools for predicting the noise of aircraft during all phases of operation, from takeoff to landing

PARTICIPATING UNIVERSITIES

Pennsylvania State University

LEAD INVESTIGATOR

Victor W. Sparrow, Professor of Acoustics, Graduate Program in Acoustics. Pennsylvania State University, vws1@psu.edu

PROJECT MANAGER

Hua He, hua.he@faa.gov