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ISSN Online: 2377-424X

ISBN Print: 1-56032-797-9

International Heat Transfer Conference 11
August, 23-28, 1998, Kyongju, Korea

PREDICTIVE METHODS FOR FRICTION AND HEAT TRANSFER CHARACTERISTICS OF CHANNELS WITH SWIRLERS

Get access (open in a dialog) DOI: 10.1615/IHTC11.1870
pages 303-308

Sinopsis

The brief description of a general modelling procedure, two predictive methods and some computational results for fluid flow and heat transfer simulations in annular channels and tubes with various swirl-flow devices (swirlers) are presented. Background of proposed methods consists in the combined consideration of the following modelling aspects: the application of averaging procedure to simplify the formulation of governing equations, the description of transport properties and boundary conditions for averaged swirled medium, and the formulation of the phenomenological relations for a mathematical model closure.
The predictive method for annular channels enables to compute the friction and heat transfer characteristics of lengthy channels with arbitrary diameter ratio and internal spiral swirlers. The influence of inner and outer surfaces curvature on flow transport properties in annular channels is taken into account. Different spiral elements can be considered as the swirlers: helical internal ribbing on one or both surfaces, helical wire inserts or spacers, helically coiled internal pipes, which are placed in the arbitrary part of the channel cross section and only partially block it, etc. The case of full blockage of annular gap with spiral elements was also examined to verify the proposed method.
Another presented method has been developed for tubes with interrupted swirlers to evaluate the pressure drop, intensity of flow swirling and heat transfer in the circular channels with discontinuous spiral devices or ribbing of various shapes. This method is based on the transformation vortex model and can be applied for pipes with full-length swirlers also, for example, multiple-helix internal ridged tubes.
The computing algorithm of each method is built on the finite-difference solution of governing equations and using the complicated iterative process. Computations have been fulfilled with the help of created FORTRAN computer codes. The comparison of computational and experimental results is adduced.