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  • Open Daily: 10am - 10pm
    Alley-side Pickup: 10am - 7pm

    3038 Hennepin Ave Minneapolis, MN
    612-822-4611

Open Daily: 10am - 10pm | Alley-side Pickup: 10am - 7pm
3038 Hennepin Ave Minneapolis, MN
612-822-4611
Core Noise Diagnostics of Turbofan Engine Noise Using Correlation and Coherence Functions

Core Noise Diagnostics of Turbofan Engine Noise Using Correlation and Coherence Functions

Administration (Nasa), National Aeronaut

Paperback

General ReferenceAstronomy & Space

Currently unavailable to order

ISBN13: 9798672049267
Publisher: Independently Published
Published: Aug 10 2020
Pages: 40
Weight: 0.26
Height: 0.08 Width: 8.50 Depth: 11.02
Language: English
Cross-correlation and coherence functions are used to look for periodic acoustic components in turbofan engine combustor time histories, to investigate direct and indirect combustion noise source separation based on signal propagation time delays, and to provide information on combustor acoustics. Using the cross-correlation function, time delays were identified in all cases, clearly indicating the combustor is the source of the noise. In addition, unfiltered and low-pass filtered at 400 Hz signals had a cross-correlation time delay near 90 ms, while the low-pass filtered at less than 400 Hz signals had a cross-correlation time delay longer than 90 ms. Low-pass filtering at frequencies less than 400 Hz partially removes the direct combustion noise signals. The remainder includes the indirect combustion noise signal, which travels more slowly because of the dependence on the entropy convection velocity in the combustor. Source separation of direct and indirect combustion noise is demonstrated by proper use of low-pass filters with the cross-correlation function for a range of operating conditions. The results may lead to a better idea about the acoustics in the combustor and may help develop and validate improved reduced-order physics-based methods for predicting direct and indirect combustion noise. Miles, Jeffrey H. Glenn Research Center NASA/TM-2009-215609, AIAA Paper 2009-1237, E-16924 WBS: 561581.02.08.03.18.02 ACOUSTICS; COMBUSTION CHAMBERS; ENGINE NOISE; JET AIRCRAFT NOISE; TURBOFAN ENGINES; CORRELATION; LOW PASS FILTERS; COMBUSTION

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