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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

THERMAL STRATIFICATION AND FLOW STABILITY IN FILM COOLING WITH CURVED COOLANT INJECTION

Get access (open in a dialog) DOI: 10.1615/IHTC11.1290
pages 547-552

Sinopsis

A flow visualization study is performed, in a subsonic wind tunnel with a curved test section, on a flow layer formed on a flat plate resulting from a smoke injection through a curved slot into the mainstream. The blowing ratio (mass flux ratio based on inlet gas mass flux) is varied from 0.25 to 3.0. The flow and heat transfer characteristics are numerically simulated using a RNG k-ε turbulence model Navier-Stokes analysis with the aid of FLUENT software. Numerical results are obtained for the distributions of the static and total pressure, velocity vector, streamline, kinetic energy of turbulence, eddy dissipation, and temperature in both the main and coolant streams. It is disclosed that high static pressures are concentrated at the slant widened inlet region and low static pressures at the widened, curvy exit region of the coolant inlet slot. As a result, the velocity profile is uniform across the flow passage and the streamlines are parallel to the walls throughout the coolant injection slot. Accordingly, both the kinetic energy of turbulence and eddy dissipation diminish orderly along the slot passage. Most important is that thermal stratification in the coolant film over the plate becomes nearly parallel to the plate surface. However, when the blowing ratio is less then unity, the points of inflexion and convex curvatures appear on the velocity profiles inside coolant film at a certain distance downstream from the slot. This phenomenon is very special and occurs only when the blowing ratio is less than unity and in the region when a surge in the kinetic energy of turbulence takes places. Theoretical predictions are confirmed by flow visualization results.