NASA LogoNTRSNTRS - NASA Technical Reports ServerSearchmore_vertCollectionsAboutNewsHelpLogin Back to ResultsCombustion 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 ID19970025576Acquisition SourceLegacy CDMSDocument TypeConference PaperAuthorsDarling, 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 AcquiredSeptember 6, 2013Publication DateJune 1, 1997Subject CategoryAircraft Propulsion And PowerReport/Patent NumberASME-97-GT-308NASA-TM-107481E-10773NAS 1.15:107481Meeting InformationMeeting: Turbo-Expo 1997Location: Orlando, FLCountry: United StatesStart Date: June 2, 1997End Date: June 5, 1997Sponsors:American Society of Mechanical EngineersAccession Number97N25072Funding Number(s)PROJECT: RTOP 537-02-21Distribution LimitsPublicCopyrightWork of the US Gov. Public Use Permitted.Available DownloadsNameType19970025576.pdfSTIcloud_downloadcontent_copyvisibilityRelated RecordsThere are no records associated with this record.visibility_offNo Preview Available
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