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Twin jet shieldingFor an over-the-wing/under-the-wing engine configuration on an airplane, the noise produced by the upper jet flow is partially reflected by the lower jet. An analysis has been performed which can be used to predict the distribution of perceived noise levels along the ground plane at take-off for an airplane which is designed to take advantage of the over/under shielding concept. Typical contours of PNL, the shielding benefit in the shadow zone, and the EPNL values at 3.5 nautical miles from brake release as well as EPNL values at sideline at 0.35 nautical miles have been calculated. This has been done for a range of flow parameters characteristic of engines producing inverted velocity profile jets suitable for use in a supersonic cruise vehicle. Reductions up to 6.0 EPNdB in community noise levels can be realized when the over engines are operated at higher thrust and the lower engines simultaneously operated with reduced thrust keeping the total thrust constant.
Document ID
19790042911
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Parthasarathy, S. P.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Cuffel, R. F.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Massier, P. F.
(California Institute of Technology, Jet Propulsion Laboratory, Pasadena Calif., United States)
Date Acquired
August 9, 2013
Publication Date
March 1, 1979
Subject Category
Aircraft Design, Testing And Performance
Report/Patent Number
AIAA PAPER 79-0671
Meeting Information
Meeting: American Institute of Aeronautics and Astronautics, Aeroacoustics Conference
Location: Seattle, WA
Start Date: March 12, 1979
End Date: March 14, 1979
Sponsors: American Institute of Aeronautics and Astronautics
Accession Number
79A26924
Distribution Limits
Public
Copyright
Other

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