摘要:

Abstract-A model is presented by means of which the enthalpy (h) and density (p) of the products of hydrocarbonair combustion can be calculated as functions of pressure (P), temperature (T). and equivalence ratio (φ) for a given C: H ratio of the fuel, and N: 0 ratio of Ihe oxidizer. By direct differentiation, the partial derivatives of h and p with respect to P, T, and φ can also be calculated. Results of calculations using this model are compared with results from a detailed thermochemical equilibrium calculation incorporating over 40 species, and it is shown that accuracy of the approximate model is acceptable over most conditions of interest in typical combustion calculations for a range of practical fuels. The principal advantage of this method is computational speed; it thus has obvious utility in, for example, internal combustion engine performance calculations.

ISSN:0010-2202    

DOI:10.1080/00102207708946765

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Abstract-It has previously been demonstrated that free burning fires in solid fuels can be modeled by increasing the ambient air pressure while reducing all length scales with the two-thirds power of pressure. The modeling concept has been tested, up till now, for steady or quasi-steady aspects of fires in simple, isolated fuel elements of wood or solid plastic. The current study is concerned with testing the pressure modeling concept for the important transient processes of fire growth and decay in pine-wood cribs ignited at the center of the crib base. In addition, the validity of pressure modeling compartment fires is tested by burning cribs within simplified, vented enclosures. Measurements of crib burning rates for a ten to one range of length scale show that pressure modeling of portions of Ihe burning rate time history is indeed easible. While modeling of ventilation-controlled crib fires is highly successful, it appears that a lack of modeling of the rate of radial fire spread within the crib allows only peak burning rates and the fire decay process to be modeled in the fuel surface-controlled regime. For the specific crib geometries considered, the effect of an enclosure on fire intensity is measurable and can be pressure modeled.

ISSN:0010-2202    

DOI:10.1080/00102207708946766

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Abstract – An analysis of inviscid incompressible flow in a tube of sinusoidally perturbed circular cross section with wall injection has been made. The velocity and pressure fields have been obtained. Measurements of axial velocity profiles and pressure distribution have been made in a simulated star shaped tube with wall injection. The static pressure at the star recess is found to be more than that at the star point, this feature being in conformity with the analytical result. Flow visualisation by photography of injected smoke seems to show simple diffusion rather than strong vortices in the recess.

ISSN:0010-2202    

DOI:10.1080/00102207708946767

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Abstract — The gas phase reactions of NO-NO2and surface effects for oxygen atom recombination in a geometry typical of water-cooled stainless steel aerodynamic sampling probes are considered. The rate equations describing the system are summarized in a set of non-linear ordinary differential equations which are solved numerically. It is shown that the catalytic activity of the probe walls for atom recombination, the available surface to volume ratio, and the pressure are important parameters controlling the extent of NO2/NO reactions in the probe environment.

ISSN:0010-2202    

DOI:10.1080/00102207708946768

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Abstract – The surface temperature of a substrate at ignition is a sensitive measure of its ignitability and one which holds the promise of providing direct information about the fundamental chemistry and physics of ignition. We present measurements of the surface temperature of the substrate in the moving wire technique (MWT) for studying polymer combustion. In the MWT. the substrate is moved at a controlled speed through a stationary ignition source, with the result that combustion is held stationary in laboratory coordinates. The measurement of surface temperature is a vital part of the MWT and substantially clarifies the ignition process. The measurements were achieved by two methods. The first employs a null point method in which a thermocouple is in rubbing contact with the substrate; the thermocouple is surrounded by an oven whose temperature is adjusted to the null point. The second method makes use of thermal paints in the nonburning regimes. Our results for teflon indicate that the surface temperature at ignition in an O2-rich source flame is independent of the shape, temperature, flow speed and O2-level of the source flame. It is also independent of the size and probably the geometry of the substrate. Hence, ignition temperature appears to be invariant, and information of direct applicability to real practical systems can thus be gathered in the scientifically simpler moving wire system.

ISSN:0010-2202    

DOI:10.1080/00102207708946769

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Abstract-The opposed-jet diffusion flame has been considered with four step reaction kinetics for hydrogenoxygen system. The studies have revealed that the flame broadening reduces and maximum temperature increases as pressure increases. The relative importance of different reaction steps have been brought out in different regions (unstable, near extinction and equilibrium). The present studies have also led to the deduction of the oveall reaction rate constants of an equivalent single step reaction using matching of a certain overall set of parameters for four step reaction scheme and equivalent single step reaction.

ISSN:0010-2202    

DOI:10.1080/00102207708946770

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Abstract – Adiabatic spray vaporization is investigated by analyzing the coupled problem of the vaporization of an ensemble of droplets in a gaseous medium whose properties are continuously being modified by the vaporization process. A criterion on the mixture properties for achieving complete spray vaporization is established. By further showing that the droplet emperature rapidly approaches a constant, characteristic, value after vaporization is initiated, simplified solutions are obtained for the transport of monodisperse, as well as polydisperse, sprays in quasi-one-dimensional chambers.

ISSN:0010-2202    

DOI:10.1080/00102207708946771

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Abstract – Thermo-difTusive ignition of porous solid fuel constituting a semi-infinite slab in contact with a hot oxidizing gas is analysed. Heat and oxidant are considered to be supplied to the fuel convectively in accordance with the instantaneous temperature and oxidant concentration differences between the fuel surface and the gas phase. Governing equations of the mass and energy have been analyzed by employing the Laplace transformation and the Laplace asymptotic method. Surface temperature-time histories have been obtained for the zeroth, first, and second order reactions based on the gaseous oxidant concentration. Effects of various governing parameters on ignition delay times have been discussed.

ISSN:0010-2202    

DOI:10.1080/00102207708946772

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor