A new numerical solution method for the calculation of the thermal radiation transfer in combustors is described. It has been especially developed for incorporation in general combustor prediction procedures for the flow, and chemical reaction. It combines features and advantages of the zone, Monte Carlo, and flux model solution methods while avoiding their shortcomings. It is based on the solving of representatively directed beams of radiation within the enclosure between the known wall boundary conditions and on the subsequent computing of the radiation sources which arise within the finite difference control volumes of the flow procedure due to the passage of the beams. It is fast, exact applicable to complex geometries, and it retains in evidence the physics of the problem by avoiding complex mathematics.

A new radiation solution method for incorporation in general combustion prediction procedures

Consideration is given to the major features of the characterization of swirl flow combustion, with emphasis on application to practical combustors. Recent experimental work is surveyed first with special regard to the main effects of swirl on the performance, stability, and combustion intensity of flames in combustors. Since solution of the basic governing equations yields predictions that are realistic only if the physical processes are sufficiently well expressed in mathematical form and suitable computational methods of solution are employed, these details are discussed. The treatment is brief, since extensive reviews are available in the literature. It is possible to predict major features of these swirling flows and some solutions are exhibited. The achievements and current status of serial flow combustion are summarized.

Swirl Flows in Combustion: A Review

Basic Remarks on Modeling and Simulation Solid Fuels Equipment and Processes Basic Calculations Zero-Dimensional Models Introduction to One-Dimensional Steady-State Models Moving-Bed Combustion and Gasification Model Chemical Reactions Heterogeneous Reactions Drying and Devolatilization Auxiliary Equations and Basic Calculations Moving-Bed Simulation Programs and Results Bubbling Fluidized-Bed Combustion and Gasification Model Fluidization Dynamics Auxiliary Parameters Related to Fluidized-Bed Processes Bubbling Fluidized-Bed Simulation Program and Results Circulating Fluidized-Bed Combustion and Gasification Model Circulating Fluidized-Bed Simulation Program and Results Appendices Index

Solid Fuels Combustion and Gasification: Modeling, Simulation, and Equipment Operations

A novel coupled strategy is presented for predicting soot and gas species concentrations, and radiative exchange in turbulent combustion. The relatively slow processes governing soot formation are described by a model which accounts for radiative loss. In contrast to past studies, it is coupled here to the discrete transfer radiation model (DTRM) incorporating a weighted sum of gray gases (WSGG) solution to the radiative transfer equation, in an elliptic computational simulation. Incorporation of the WSGG solution in the DTRM provides a better representation of the non-gray radiative properties of combustion media than that offered by other more straightforward strategies, and without excessive computational expense. Combustion is modelled by an eddy breakup concept and the k-e turbulence model, with temperature evaluated from the solved enthalpy field. This complete strategy - the first reported of its kind - is applied to a confined turbulent jet diffusion flame burning methane in air. Confinement of the flame demands that account should be taken of the conjugate heat transfer at the boundaries. Numerical results are compared to experimental measurements of mixture fraction, temperature and soot volume fraction, and generally good agreement is achieved. Additionally, the computation of radiative exchange is considered in detail.

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F. C. Lockwood

Papers

An improved flux model for the calculation of radiation heat transfer in combustion chambers