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Combustion Noise at Elevated Pressures in a Liquid-Fueled Premixed CombustorNoise generated in gas turbine combustors can exist in several forms-broadband noise, sharp resonant peaks, and regular or intermittent nonlinear pulsing. In the present study, dynamic pressure measurements were made in several JP-5-fueled combustor configurations, at various mean pressures and temperatures. The fluctuating pressure was measured at mean pressures from 6 to 14 atm and inlet temperatures from 550 K to 850 K. The goal of the present work was to study the effect of changes in mean flow conditions on combustor noise: both broadband noise and sharp tones were considered. In general, the shape of the broadband noise spectrum was consistent from one configuration to another. The shape of the spectrum was influenced by the acoustic filtering of the combustion zone. This filtering ensured the basic consistency of the spectra. In general, the trends in broadband noise observed at low mean pressures were also seen at high mean pressures; that is, the total sound level decreased with both increasing equivalence ratio and increasing inlet temperature. The combustor configurations without a central pilot experienced higher broadband noise levels and were more susceptible to narrow peak resonances than configurations with a central pilot. The sharp peaks were more sensitive to the mean flow than was the broadband noise, and the effects were not always the same. In some situations, increasing the equivalence ratio made the sharp peaks grow, while at other conditions, increasing the equivalence ratio made the sharp peaks shrink. Thus, it was difficult to predict when resonances would occur; however, they were reproducible. Acoustic coupling between the upstream and downstream regions of the combustor may play a role in the sharp-peaked oscillations. Noise was also observed near lean blow out. As with other types of noise, lean blow out noise was affected by the combustion chamber acoustics, which apparently maintains the fluctuations at a uniform frequency. However, the actual conditions when this type of noise was experienced appeared to simply follow the lean blow out limit as it varied with mean temperature and pressure.
Document ID
19970025576
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Darling, Douglas (NASA Lewis Research Center Cleveland, OH United States)
Radhakrishnan, Krishnan (NYMA, Inc. Brook Park, OH United States)
Oyediran, Ayo (AYT Corp. Brook Park, OH United States)
Date Acquired
September 6, 2013
Publication Date
June 1, 1997
Subject Category
Aircraft Propulsion And Power
Report/Patent Number
ASME-97-GT-308
NASA-TM-107481
E-10773
NAS 1.15:107481
Report Number: ASME-97-GT-308
Report Number: NASA-TM-107481
Report Number: E-10773
Report Number: NAS 1.15:107481
Meeting Information
Meeting: Turbo-Expo 1997
Location: Orlando, FL
Country: United States
Start Date: June 2, 1997
End Date: June 5, 1997
Sponsors: American Society of Mechanical Engineers
Accession Number
97N25072
Funding Number(s)
PROJECT: RTOP 537-02-21
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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