The recent advances in numerical methods and the vast development of computers had directed the designers to better development and modifications to airflow pattern and heat transfer in combustion chambers. Extensive efforts are exerted to adequately predict the heat transfer characteristics in the combustor zones and to reduce the emitted pollution and noise abatement to ultimately produce quite and energy efficient combustor systems. The Present paper fosters mathematical modeling techniques to primarily predict what happens in cylindrical and three-dimensional combustion chambers simulating boiler and industrial furnaces in terms of heat transfer characteristics and interactions. The present work also demonstrates the effect of chamber design and operational parameters on performance under various operating parameters. The governing equations of mass, momentum and energy are commonly expressed in a preset form with source terms to represent effects of pressure gradients, turbulence and heat transfer. Fluid flow and heat transfer characteristics in combustors play an important role in the efficiency, thermal balance and performance. The present paper discusses the various combustion modeling assumptions and those of the heat transfer in furnaces. The results are obtained in this work with the aid of the three-dimensional program 3DCOMB; applied to axisymmetrical and three-dimensional complex geometry with and without swirl. The numerical grid comprises, typically, 288000-grid node covering the combustion chamber volume in the X, R or Y and Z coordinates directions. The numerical residual in the governing equations typically less than 0.001%. Examples of large industrial furnaces are shown and are in good agreement with available measurements in the open literature. One may conclude that heat transfer characteristics in combustors are strongly affected by the inlet swirl, inlet momentum ratios, combustor geometry; both micro and macro mixing levels are influential. Higher tangential velocities and turbulence characteristics are demonstrated in situations with higher swirl intensities. The present modeling capabilities can adequately predict the local flow pattern and turbulence kinetic energy levels in complex combustors.

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