ACERC
Abstracts - 1994 |
ACERC
Abstracts - 1994 |
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Thrust Area 6: Model Evaluation Data and Process Strategies |
Denison, M.K.
Spectral-Line Based WSGG Model for Arbitrary RTE Solvers, Ph.D./BYU, August
1994. Advisor: Webb
Rink, K.K.
Design, Construction and Operation of a FBC, Ph.D./U of U, December 1994.
Advisor: Lighty
Hedman, P.O.; Sturgess,
G.J.; Warren, D.L.; Goss, L.P. and Shouse, D.T.
Transactions of the ASME, 1994 (in press). (Also presented at the ASME
International Gas Turbine and Aeroengine Congress and Exposition, The Hague,
Netherlands, June 1994. Funded by ACERC, Wright Patterson Air Force Base and
Air Force Office of Scientific Research.
This paper presents results from an Air Force program being conducted by researchers at Brigham Young University (BYU), Wright-Patterson Air Force Base (WPAFB), and Pratt and Whitney Aircraft Co. (P&W). This study is part of a comprehensive effort being supported by the Aero Propulsion and Power Laboratory at Wright-Patterson Air Force Base, and Pratt and Whitney, Inc. in which simple and complex diffusion flames are being studied to better understand the fundamentals of gas turbine combustion near lean blowout. The program's long-term goal is to improve the design methodology of gas turbine combustors.
This paper focuses on four areas of investigation: 1) digitized images from still film photographs to document the observed flame structures as fuel equivalence ratio was varied, 2) sets of LDA data to quantify the velocity flow fields existing in the burner, 3) CARS measurements of gas temperature to determine the temperature field in the combustion zone, and to evaluate the magnitude of peak temperature, and 4) two-dimensional images of OH radical concentrations using PLIF to document the instantaneous location of the flame reaction zones.
Sturgess, G.J.; Hedman,
P.O.; Sloan, D.G. and Shouse, D.T.
Transactions of the ASME, 1994 (in press). (Also presented at the ASME
International Gas Turbine and Aeroengine Congress and Exposition, The Hague,
Netherlands, June 1994. Funded by ACERC, Wright Patterson Air Force Base and
Air Force Office of Scientific Research.
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 be 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.
Hedman, P.O. and Warren,
D.L.
Combustion and Flame, 1994 (in press). (Presented at the 25th Symposium
[International] on Combustion, University of California at Irvine, Irvine,
California. Funded by ACERC, Wright Patterson Air Force Base and Air Force Office
of Scientific Research.
Combustion characteristics of a propane-fueled, practical injector operating in a burner that closely reproduce the flow patterns of a gas turbine combustor have been investigated. The practical injector converges co-swirling airsheets on either side of a coannular fuel sheet into the central air passage. Instantaneous planar laser induced fluorescence (PLIF) images of OH radical, laser Doppler anemometer (LDA) measurements of mean and rms velocity, and coherent anti-Stokes Raman spectroscopic (CARS) measurements of mean and rms temperatures in the same burner at the same operating conditions have provided improved understanding of the complicated processes in a gas turbine combustor. The PLIF images of the OH radical have confirmed the vortex characteristics of the swirling flames and the highly variable nature of the flame shape as ø must lie between the lean and rich flammability limits for a flame to be locally present. Three recirculation zones were identified from LDA measurements. The highest axial velocity region is about 75 mm downstream for the fuel lean case, but is near the injector for the fuel rich case. The highest tangential velocities are located near the injector for both lean and rich cases. The effects of the injector on velocity were dissipated by one combustor diameter downstream. Large rms velocities occurred in areas where significant velocity gradients exist. The high temperatures changed location as the fuel equivilence ratio was varied from fuel lean (over the injector) to fuel rich (near the outer recirculation zone). The high temperature regions are consistent with the PLIF images of OH radical, and become relative uniform by about one combustor diameter downstream. Measured temperatures never exceeded the peak theoretical adiabatic flame temperature.
Cope, R.F.; Monson, C.R.;
Germane, G.J. and Hecker, W.C.
Energy & Fuels, 8(4):925-931, 1994. Funded by ACERC, Advanced Fuel Research
and US Department of Energy.
Coal combustion researchers have typically used the average temperature and residence time of a burning particle cloud to determine the high-temperature reactivity of coals and chars. These average values, however, cannot account for particle-to-particle variations or their possible causes. Researchers at Sandia National Laboratories developed a pyrometry technique to simultaneously measure the temperature, velocity, and diameter of individual char particles burning in a transparent-wall flat-flame facility. This work reports two significant advances relative to the optical pyrometry technique. First, pyrometer modifications together with a new analysis technique now permit the particle properties to be measured for smaller/cooler particles. Second, the modified pyrometer has been implemented in two heated-wall drop-tube reactors, rather than transparent-wall, flat-flame burners. This is significant because drop-tube reactors allow greater flexibility/control of gas environments and operating pressures during char oxidation. Glowing reactor walls, however, present some unique challenges for these optical measurements. Means of overcoming these challenges are discussed, and reliable in situ measurement of particle temperatures, velocities, and diameters is verified. The results of measurements made in these drop-tube reactors, both for calibration tests and actual oxidation tests with Spherocarb and a Utah bituminous coal char, are also presented.
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