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ISSN Online: 2377-424X

ISBN Print: 0-89116-130-9

International Heat Transfer Conference 6
August, 7-11, 1978, Toronto, Canada

AERODYNAMIC AND HEAT TRANSFER CHARACTERISTICS OF AXISYMMETRIC CONFINED GASEOUS FLAMES

Get access (open in a dialog) DOI: 10.1615/IHTC6.1970
pages 25-31

要約

A general computer programme was developed to calculate the local flow properties in turbulent recirculating compressible flows in axisymmetric geometries; these calculations were obtained by solving the appropriate conservation equations of mass, three components of momentum, species and energy in a finite difference iterative scheme. The present paper made use of the two equation turbulence model, (k−ε), which is based on the solution of transport equations for the turbulence kinetic energy and its dissipation rate. The validity of this model was assessed by comparison test cases with experimental data in a wide range of geometric and flow configurations.
The calculation procedure embodies a combustion model which calculates the rate of reaction which appears as a sink term in the fuel conservation equation. The modelling of chemical reaction rates with their exponential temperature dependencies and associated closure problems in terms of high turbulence levels in species and temperature is considered and the time average value of the rate of reaction; Rfu is calculated as;
Rfu = ∫RfuP(Yfu)dyfu
and the mean and variance of the probability distribution P(Yfu) are obtained from the solution of conservation equations for mean mass fraction of fuel and the square of its fluctuation. The validity of these assumptions is assessed by comparisons with experiments and the prognosis for improving and extending the method to three dimensional geometries is discussed. The radiative heat flux, which appears in the energy conservation equation is obtained from a four flux representation, by expressing the radiant intensity in a Taylor series expansion and integrating the radiation transfer equation over the solid angle. Comparisons between calculations and the corresponding measurements in a range of geometries are provided and quantify the advantage and limitations of the method.
The agreement obtained with this numerical solution is satisfactory and suggests the use of such procedure for design purposes.