Analysis of Fuel Vaporization, Fuel-Air Mixing, and Combustion in Integrated Mixer-Flame Holders PDF Download
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Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781726208970
Category :
Languages : en
Pages : 40
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Book Description
Requirements to limit pollutant emissions from the gas turbine engines for the future High-Speed Civil Transport (HSCT) have led to consideration of various low-emission combustor concepts. One such concept is the Integrated Mixer-Flame Holder (IMFH). This report describes a series of IMFH analyses performed with KIVA-II, a multi-dimensional CFD code for problems involving sprays, turbulence, and combustion. To meet the needs of this study, KIVA-II's boundary condition and chemistry treatments are modified. The study itself examines the relationships between fuel vaporization, fuel-air mixing, and combustion. Parameters being considered include: mixer tube diameter, mixer tube length, mixer tube geometry (converging-diverging versus straight walls), air inlet velocity, air inlet swirl angle, secondary air injection (dilution holes), fuel injection velocity, fuel injection angle, number of fuel injection ports, fuel spray cone angle, and fuel droplet size. Cases are run with and without combustion to examine the variations in fuel-air mixing and potential for flashback due to the above parameters. The degree of fuel-air mixing is judged by comparing average, minimum, and maximum fuel/air ratios at the exit of the mixer tube, while flame stability is monitored by following the location of the flame front as the solution progresses from ignition to steady state. Results indicate that fuel-air mixing can be enhanced by a variety of means, the best being a combination of air inlet swirl and a converging-diverging mixer tube geometry. With the IMFH configuration utilized in the present study, flashback becomes more common as the mixer tube diameter is increased and is instigated by disturbances associated with the dilution hole flow.Deur, J. M. and Cline, M. C.Glenn Research CenterGAS TURBINE ENGINES; FLAME HOLDERS; VAPORIZING; COMBUSTION; COMPUTATIONAL FLUID DYNAMICS; MIXERS; FUEL INJECTION; CONVERGENT-DIVERGENT NOZZLES; COMBUSTION CHAMBERS; FLAME PROPAGATION; FUEL SPRAY...
Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781726208970
Category :
Languages : en
Pages : 40
Get Book Here
Book Description
Requirements to limit pollutant emissions from the gas turbine engines for the future High-Speed Civil Transport (HSCT) have led to consideration of various low-emission combustor concepts. One such concept is the Integrated Mixer-Flame Holder (IMFH). This report describes a series of IMFH analyses performed with KIVA-II, a multi-dimensional CFD code for problems involving sprays, turbulence, and combustion. To meet the needs of this study, KIVA-II's boundary condition and chemistry treatments are modified. The study itself examines the relationships between fuel vaporization, fuel-air mixing, and combustion. Parameters being considered include: mixer tube diameter, mixer tube length, mixer tube geometry (converging-diverging versus straight walls), air inlet velocity, air inlet swirl angle, secondary air injection (dilution holes), fuel injection velocity, fuel injection angle, number of fuel injection ports, fuel spray cone angle, and fuel droplet size. Cases are run with and without combustion to examine the variations in fuel-air mixing and potential for flashback due to the above parameters. The degree of fuel-air mixing is judged by comparing average, minimum, and maximum fuel/air ratios at the exit of the mixer tube, while flame stability is monitored by following the location of the flame front as the solution progresses from ignition to steady state. Results indicate that fuel-air mixing can be enhanced by a variety of means, the best being a combination of air inlet swirl and a converging-diverging mixer tube geometry. With the IMFH configuration utilized in the present study, flashback becomes more common as the mixer tube diameter is increased and is instigated by disturbances associated with the dilution hole flow.Deur, J. M. and Cline, M. C.Glenn Research CenterGAS TURBINE ENGINES; FLAME HOLDERS; VAPORIZING; COMBUSTION; COMPUTATIONAL FLUID DYNAMICS; MIXERS; FUEL INJECTION; CONVERGENT-DIVERGENT NOZZLES; COMBUSTION CHAMBERS; FLAME PROPAGATION; FUEL SPRAY...
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 20
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Requirements to reduce pollutant emissions from gas turbines used in aircraft propulsion and ground-based power generation have led to consideration of lean premixed/prevaporized (LPP) combustion concepts. This paper describes a series of the LPP combustor analyses performed with KIVA-II, a multi-dimensional CFD code for problems involving sprays, turbulence, and combustion. Modifications to KIVA-II's boundary condition and chemistry treatments have been made to meet the needs of the present study. The study examines the relationships between fuel vaporization, fuel/air mixing, and combustion in a generic LPP combustor. Parameters considered include: mixer tube diameter, mixer tube length, mixer tube configuration (straight versus converging/diverging tubes), air inlet velocity, air inlet swirl angle, secondary air injection (dilution holes), fuel injection velocity, fuel injection angle, number of fuel injection ports, fuel spray cone angle, and fuel droplet size. Cases have been run with and without combustion to examine the variations in fuel/air mixing and potential for flashback due to the above parameters. The degree of fuel/air mixing is judged by comparing average, minimum, and maximum fuel/air ratios at the exit of the mixer tube, while flame stability is monitored by following the location of the flame front as the solution progresses from ignition to steady state.
Author: J. M. Deur
Publisher:
ISBN:
Category : Air
Languages : en
Pages : 18
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Author: Larry Philip Cooper
Publisher:
ISBN:
Category : Combustion
Languages : en
Pages : 24
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Book Description
Author: Dan Brasoveanu
Publisher:
ISBN:
Category : Combustion
Languages : en
Pages : 400
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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
The development of a residential size vaporizing oil burner is presented along with its operational and performance characteristics. The vaporization scheme consists of spraying No. 2 oil onto a regeneratively heated surface at a temperature above the oil vaporization temperature (650°F). The vaporized oil mixes with a preheated air (T = 250°F) stream to produce a uniform fuel air mixture. The premixed vaporized fuel/air stream produces short blue flamelets anchored to a steel screen flame holder. The operational and performance characteristics of this burner are presented for a range of the air and oil flow parameters around the stoichiometric condition, and for a nominal firing rate of less than or equal to 1.2 gph. Operation with less than 3% excess air is demonstrated with very little soot formation. The combustion quality of the vaporizing oil burner is substantially improved compared to conventional spray combustion and recirculation type blue flame burners. The vaporizing oil burner was adapted to a conventional boiler and the thermal efficiency was determined by a calorimeter technique and compared to the stack method. The thermal efficiency with the vaporized combustion mode is about 4% greater than conventional spray combustion burners. The increase is realized through the reduced excess air requirements. The increased efficiency can result in reduced oil consumption from 12% to 20% depending on the location and usage of the burner unit.
Author:
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ISBN:
Category :
Languages : en
Pages : 24
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Author: Sergeĭ Mikhaĭlovich Ilʹi︠a︡shenko
Publisher:
ISBN:
Category : Airplanes
Languages : en
Pages : 316
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Book Description
Contents: Discharge and atomization of liquid fuel; Ballistics of nonvaporizing drops; Evaporation of drops; Calculation of fields of concentrations of a fuel-air mixture; The theory of turbulent combustion of a homogenous mixture; Experimental investigations of burning in a turbulent flow of homogeneous mixture; Position of the flame in the combustion chamber; Flame stabilization; Burning of two-phase mixtures.
Author: Larry P. Cooper
Publisher:
ISBN:
Category :
Languages : en
Pages : 32
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Author: Wessam Estefanos
Publisher:
ISBN:
Category :
Languages : en
Pages : 205
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Book Description
An experimental study was conducted to investigate the effects of the fuel-air mixing on combustion instabilities and NO x emissions in lean premixed combustion. High speed PIV measurements in water were conducted to capture the mean and dynamic behavior of the cold flow generated by a 3X model of the tested premixer. High speed PLIF in water measurements were conducted to quantify the mean and unsteady fuel-air mixing at different momentum flux ratios. Atmospheric combustion tests using the original premixer, were conducted using natural gas and propane at the same momentum flux ratios of the PLIF mixing tests. An emissions analyzer was used to measure the emissions from combustion tests. Dynamic pressure transducers were used to measure the amplitude and the frequency of the dynamic pressure oscillations associated with the combustion instabilities. CHEMKIN-PRO was used to model the atmospheric combustion and predict NO x emissions at different conditions. Results showed that unsteady fuel-air mixing was concentrated at the center and near the outer edges of the premixer. These regions were characterized by high fuel concentration gradients. With the increase in the momentum flux ratio, the concentration gradient and the level of unsteady mixing increased, indicating that the fuel-air spatial unmixedness was the source of the unsteady mixing. It was found that local flow turbulence tended to decrease the concentration gradient through enhancing the fuel-air mixing, which resulted in decreasing the level of unsteady mixing. NO x emissions from atmospheric combustion increased with the increase in the momentum flux ratio due to the increase in the flame temperature and the fuel-air spatial and temporal unmixedness. The intensity of the combustion dynamics increased with the increase in the level of unsteady mixing. Axial injection of the fuel into the regions of strong unsteady mixing eliminated the combustion dynamics through damping the unsteady mixing. Results of CHEMKIN-PRO agreed very well with the experimental results and showed that the spatial and temporal unmixedness have a significant effect on NO x emissions for very lean combustion (F = 0.4). With the increase in the equivalence ratio, their relative contribution decreased.
