摘要:

Laser Doppler anemometry, spectral extinction-absorption, and flame chemiluminescence measurements were carried out to characterize the fluid flow and to analyze the temporal and spatial distribution of liquid, vapor and some pollutant species in an optically accessed high swirl combustion chamber

ISSN:0010-2202    

DOI:10.1080/00102209908935769

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

In the present work a simple and inexpensive device for continuous generation of emulsified liquid fuels has been developed, which can for instance be used for NO-reduction in gas turbine application. The emulsification process was based on liquid-in-liquid atomization, hence water and oil were injected into a cell by means of pressure-swirl nozzles. The use of a nozzles for each stream ensured, in contrary to just one nozzle for one of them, fine emulsification in wide control ranges. The emulsions were sufficiently stable so that no surfactant was required. Jets of water-in-oil emulsions disintegrated easily and significantly faster than the pure substances or oil-in-water emulsions. This property of water-in-oil emulsions leads to significantly finer air-assist atomization.

ISSN:0010-2202    

DOI:10.1080/00102209908935770

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The sensitization of ethane oxidation by NO above 800  K and the oxidation of HCN-natural gas blend (CH4-C2H6, 10:1) mixtures at 1050 to 1450  K, with and without NO, have been studied in a fused silica jet-stirred reactor (JSR) at 1 atm. A detailed chemical kinetic model developed for NO-reburning by natural gas (754 reactions and 102 species), including a low-temperature reaction sub-mechanism, was used to simulate the present experiments. A good agreement between the experimental results and the modeling was generally obtained. According to the proposed kinetic mechanism, in the present conditions, the mutual sensitization of the oxidation of ethane and NO proceeds through the following sequence: C2H6+ OH → C2H5+ H2O; C2H5+ O2→ C2H4+ HO2followed by the oxidation of NO and production of OH sustaining ethane oxidation, NO + H02 -> N02 + OH. Other reactions yield mutual sensitization of the oxidation of ethane and NO: C2H5O2+ NO → C2H50 + N02 and CH302 + NO -> CH3O + N02 followed by thermal decomposition of alkoxy radicals (C2H50 -> CH3HCO + H, CH3O -* CH20 + H) and production of H02, H + 02 -> H02. The present modeling also shows that the oxidation of HCN-natural gas blend proceeds through the following routes: HCN + O -" NCO + H followed by NCO + CH4 -> HNCO + CH3. NCO + C2H6 -> HNCO + C2H5 and HNCO + H -" NH2+ CO. NO addition yields a strong sensitization of the oxidation process. The proposed kinetic model indicates that the reaction path is: HCN + O -> NCO + H followed by NCO + NO -> N20, CO, C02, and N2. N20 is mostly converted to N2through reaction with H and CO. In the NO-seeded experiments, the NCO + NO reactions dominate resulting in an increased production of N20 and a reduction of HNCO yield.

ISSN:0010-2202    

DOI:10.1080/00102209908935771

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The impact of the inlet conditions on particle dispersion in a post-transitional shear layer is investigated using two-dimensional simulations. The flow inlet conditions are varied between a monotonically changing inlet velocity profile (error-function) and one that exhibits a wake deficit. The particle field inlet conditions are varied by altering the particle inlet location. Monodisperse, dilute particle fields are considered. The numerical models for both the flow and particle fields are unsteady and Lagrangian. The applicability of a simplified form of the equation of particle motion is verified by comparing its solutions with those of a more comprehensive form. The maximization of dispersion for particles with intermediate Stokes numbers documented in previous studies is reproduced. So is the fact that increased proximity of particle introduction to the shear flow leads to enhanced dispersion. For the error-function flow, particles introduced close enough to the shear flow so that they get entrained into the vorticity region, disperse more if they originate from the fast stream. Particles introduced further away from the shear flow, on the other hand, disperse more if they originate from the slow stream. These results persist for all Stokes numbers and are related to the flow dynamics. They also help reconcile the contradictory results of previous studies. The impact of introducing the particles from either of the two streams is much more significant when a wake-modified inlet velocity profile is used. Dispersion patterns show a strong asymmetry in favor of the fast stream. This is attributed to the presence of positive vorticity on the slow speed side of the shear layer. This vorticity has its origin in the upstream boundary layer and tends to weaken the local particle entrainment. Overall, the results of this study suggest that the optimal location of particle introduction is on the fast stream side and close to the splitter plate. These results also imply that simulations that ignore the wake component of the inlet velocity profile may yield misleading results.

ISSN:0010-2202    

DOI:10.1080/00102209908935772

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Reduced chemical kinetic models have been developed to describe the combustion fundamentals for practical high hydrocarbons fuels over a wide range of experimental conditions. The fuels include n-Butane, Benzene. n-Heptane. Gasoline, Kerosene (JP-8), and n-Hexadecane. The mechanism for each fuel includes a single reaction expression for fuel and oxygen to form formaldehyde (CH2O) and hydrogen (H2) or carbon monoxide (CO)together with a detailed reaction mechanism for CH2O-CHO-CO-H2-O2oxidation. These kinetic mechanisms will be as generally applicable as possible and can be used in 2-D or 3-D combustion models to understand the practical combustion and emission problems in engines and furnaces. Each mechanism consists of 13 chemical species with 22 elementary reactions

ISSN:0010-2202    

DOI:10.1080/00102209908935773

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor