Date of Award

1987

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Mechanical Engineering

First Advisor

Sumanta Acharya

Abstract

The objective of this dissertation study is to evaluate and improve the modeling of individual processes associated with single- and two-phase turbulent reaction processes. In particular, attention is focused on the pulverized coal combustion process, and a reliable comprehensive computer code for pulverized coal combustion systems is developed to assist in design developments. Primary emphasis in this work has been on the modeling of non-equilibrium turbulent reactions, turbulent particle dispersion, and pollutant species formation. In addition, contributions have been made towards improving the numerical algorithm for pressure-velocity linked system in swirling flows. Two turbulent reaction models are developed for resolving non-equilibrium effects. The first model is a modified perturbation model for the calculation of non-equilibrium effects in intensive turbulent combustion. This method appears to be well suited for application to single- and two-phase flame stability studies. The second model is a moment closure method for the simulation of a moderately fast or slow reactions. This method is applied to the modeling of fuel bound nitrogen oxide formation in pulverized coal combustion systems. A systematic performance evaluation of existing turbulent particle dispersion models such as the empirical gradient models and the stochastic method has been made. An improvement is made the stochastic method by incorporating the effects of the particle fluctuation velocities at the inlet stream. With this modification significant improvement in particle dispersion predictions are obtained compared to the predictions of the gradient models and the stochastic method without this modification. The comprehensive computer code developed in this study is validated by comparisons of the predictions with a series of experimental data in an IFRF furnace. Some deficiencies are noted in the prediction of minor species like carbon monoxide and in the prediction of flame lift-off. These topics are important future tasks to be undertaken.

Pages

219

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