Acoustic characteristics of a research step combustor

Shouse

1993

Volume 3B: General

The U.S. Air Force is conducting a comprehensive research program aimed at improving the design and analysis capabilities for flame stability and lean blowout in the combustors of aircraft gas turbine engines. As part of this program, a simplified version of a generic gas turbine combustor is used. The intent is to provide an experimental data base against which lean blowout modeling might be evaluated and calibrated. The design features of the combustor and its instrumentation are highlighted, and the test facility is described. Lean blowout results for gaseous propane fuel are presented over a range of operating conditions at three different dome flow splits. Comparison of results with those of a simplified research combustor is also made. Lean blowout behavior is complex, so that simple phenomenological correlations of experimental data will not be general enough for use as design tools.

Section: Wcooiingmentioning

confidence: 99%

Lean Blowout Research in a Generic Gas Turbine Combustor With High Optical Access

Shouse

1993

Volume 3B: General

“…This device and the redesign of the annular air passage, reduced pressure fluctuations in the combustor significantly. These developments are fully described by Heneghan et al (1989).…”

Section: Combustion Characteristicsmentioning

confidence: 97%

Design and Development of a Research Combustor for Lean Blowout Studies

Volume 3: Coal, Biomass and Alternative Fuels; Combustion and Fuels; Oil and Gas Applications; Cycle Innovations

Sloan

Lesmerises

et al. 1990

In a modern annular aircraft gas turbine combustor, the phenomenon of lean blow out (LBO) is of major concern. To understand the physical processes involved in LBO, a research combustor was designed and developed to specifically reproduce recirculation patterns and LBO processes that occur in a real gas turbine combustor. A total of eight leading design criteria were established for the research combustor. This paper discusses the combustor design constraints, aerothermochemical design, choice of combustor configurations, combustor sizing, mechanical design, combustor light-off, and combustor acoustic considerations that went into the final design and fabrication. Tests on this combustor reveal a complex sequence of events such as flame lift-off, intermittency, and onset of axial flame instability leading to lean blowout. The combustor operates satisfactorily and is yielding benchmark quality data for validating and refining computer models for predicting LBO in real engine combustors.

“…The combustor has been subject to considerable development work to ensure that spurious acoustic effects were minimized (Heneghan et al, 1990). To this end a baffle is installed in the fuel tube to acoustically isolate the fuel supply system from the combustor.…”

Section: Research Combustor Descriptionmentioning

confidence: 99%

Aspects of Flame Stability in a Research Dump Combustor

Volume 3: Coal, Biomass and Alternative Fuels; Combustion and Fuels; Oil and Gas Applications; Cycle Innovations

Hedman

Sloan

et al. 1994

The lean blowout process is studied in a simplified, nominally diffusion flame research combustor that incorporates the essential features of the combustor primary zone for an aircraft gas turbine engine. The research combustor is provided with extensive optical access. To investigate the blowout, a variety of diagnostic techniques are employed, including direct flame observation, laser-Doppler anemometry, spontaneous OH-imaging, thin-filament pyrometry, laser-induced fluorescence OH-imaging, coherent anti-Stokes Raman spectroscopy, and computational fluid dynamics. Lean blowouts in the research combustor are related to well-stirred reactor blowout. A blowout sequence is found to initiated by the loss of a key flame structure in the form of an attached pilot flame. The behavior of this attached flame is investigated. It is concluded that a major contribution to the existence of the attached flame is near-field, non-stationary radial transport of reactants directly into the recirculation zone, rather than by mean flow recirculation of hot products. “Lift” of the attached flame is the reason that lean blowout in the research combustor is related to well-stirred reactor blowout since it allows at least partial premixing of reactants to take place.