Prediction of unsuppressed jet engine exhaust noise in flight from static data

Author:: Stone, J. R.
Published:: JAN 1, 1980.
Physical Description:: 1 electronic document

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Summary:

A methodology developed for predicting in-flight exhaust noise from static data is presented and compared with experimental data for several unsuppressed turbojet engines. For each engine, static data over a range of jet velocities are compared with the predicted jet mixing noise and shock-cell noise. The static engine noise over and above the jet and shock noises is identified as excess noise. The excess noise data are then empirically correlated to smooth the spectral and directivity relations and account for variations in test conditions. This excess noise is then projected to flight based on the assumption that the only effects of flight are a Doppler frequency shift and a level change given by 40 log (1 - m sub 0 cos theta), where M sub 0 is the flight Mach number and theta is the observer angle relative to the jet axis.

Other Subject(s):

ACOUSTICS

Collection:

NASA Technical Reports Server (NTRS) Collection.

Note:

Document ID: 19800020631.
Accession ID: 80N29132.
E-491.
NASA-TM-81537.
Aeroacoustics Conf.; 4-6 Jun. 1980; Hartford, CT; United States.

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