摘要:

Burning rate data for single, mm sized, pine and oak cubes in a convective flow furnace are presented. The gas temperature was varied from 900 to 1200 K, the oxygen concentration from 0 to 21 percent, the particle Reynolds number from 60 to 240, the moisture content from 0 to 200 percent, and the size from 5 to 20 mm. The devolatilization stage accounts for 80-90 percent of the mass loss and 50 percent of the total burn time. The devolatilization rate of a given particle is influenced by a furnace temperature, Reynolds number and oxygen concentration. The implications of the experiments for modeling of wood particle combustion are discussed.

ISSN:0010-2202    

DOI:10.1080/00102208608959788

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The combustion of sodium pools in air or in mixtures of N2/O2with low oxygen contents has been studied for initial metal temperatures ranging from 365 to 620°C. The analysis of the combustion products, sodium monoxide (Na2O), sodium peroxide (Na2O2) in the residues and aerosols of Na2O2, and unburned sodium has shown that three successive stages are occurring. During the first stage, the whole surface of sodium pool burns. The only products are thus Na2O in the crust and the aerosols of Na2O2. The combustion rate has been measured for different temperatures, with an initial oxygen ratio of 20, 15 or 10 percent in nitrogen mixture and for three different flow rates of the combustible mixture. During the second stage, burning and extinguished zones coexist. In the latter the formation of aerosols ceases arid the crust monoxide is progressively oxidized into peroxide. This oxidation is the only phenomenon still observed during the last stage. In all cases, some sodium remains unburned, probably due to a progressive blocking of the capillary rising of the metallic sodium towards the surface during the second stage

ISSN:0010-2202    

DOI:10.1080/00102208608959789

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

In some turbulent flows involving premixed turbulent combustion either heat transfer or nonuniformity of the mixture leads to variations of the enthalpy. Here we extend the Bray-Moss model for the thermochemistry of such combustion to include nonisenthalpic flows. Applications are identified to boundary layers with reactants injected through a porous surface involving heat transfer, to channel flows with product streams serving as flameholders and to open flames discharging into quiescent air

ISSN:0010-2202    

DOI:10.1080/00102208608959790

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Two-color laser Doppler velocimetry has been used to measure two velocity components simultaneously in a turbulent diffusion flame jet of carbon monoxide in coflowing air. The Reynolds number of the jet was 1.14 × 104for all the measurements reported here. Statistical quantities which have been derived from the instantaneous velocity measurements include mean velocities, turbulence intensities, Reynolds stress and correlation coefficient. Comparison of the results to those of nonreacting jets showed several similar features of turbulence properties The reactions, however, influence the level of turbulence and the velocity decay characteristics of the jet

ISSN:0010-2202    

DOI:10.1080/00102208608959791

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

A comparison of the efficiency of several recently developed numerical techniques for solving chemical kinetic rate equations is presented. The solution procedures examined include two general-purpose codes, EPISODE and LSODE, developed as multipurpose differential equation solvers, and three specialized codes, CHEMEQ, CREK1D, and GCKP84, developed specifically for chemical kinetics. The efficiency comparison is made by applying these codes to two practical combustion kinetics problems. Both problems describe adiabatic, constant-pressure, gas-phase chemical reactions and include all three combustion regimes: induction, heat release, and equilibration. The comparison shows that LSODE is the fastest routine currently available for solving chemical kinetic rate equations. An important finding is that an iterative solution of the algebraic enthalpy conservation equation for temperature can be significantly faster than evaluation of the temperature by integration of its time derivative. Significant increases in computational speed are realized by updating the reaction rate constants [k=ATNexp(—E/RT)] only when the temperature change exceeds an amount AT that is problem dependent. Δh approximate expression for the automatic evaluation of ΔT is presented and is shown to result in increased computational speed

ISSN:0010-2202    

DOI:10.1080/00102208608959792

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

X-ray small angle scattering from flames has been reported for the first time. A butadiene/air slot burner and a liquid-fuelled wick burner have been studied using a synchrotron radiation source and exposures of less than 15 minutes. Data analysis assumed the presence of a distribution of spherical soot particle diameters; the following most probable diameters were obtained: butadiene/air slot burner 210 Ȧ allyl alcohol wick burner, 250 Ȧ Diesel-fuelled wick burner, 310 Ȧ. Possible improvements to the technique, its relation to optical Mie scattering, and future directions are also discussed

ISSN:0010-2202    

DOI:10.1080/00102208608959793

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

A time-dependent flame code designed for the evaluation of experimental premixed laminar flames is described. Measured values of temperature profile and mass flow are used. The calculations start from a kinetic approximation on a coarse grid, which is successively refined, A local implicit chemistry and explicit transport approach, incorporating a multi-component diffusion model, is used. Compared to our simpler earlier code, based on a trace diffusion model, the execution time is reduced by at least a factor of 10. Characteristic features in this new code are use of a time-independent approximation of the transport coefficients, automatic selection of the time-step, and a fast linear equation solver. For two test flames the execution times were a factor 2-3 shorter than the corresponding execution times published using a fast implementation of the steady state method

ISSN:0010-2202    

DOI:10.1080/00102208608959794

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

ISSN:0010-2202    

DOI:10.1080/00102208608959795

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor