ISSN Online: 2377-424X
International Heat Transfer Conference 4
THE EFFECT OF TURBULENCE PROMOTERS ON HEAT AND MOMENTUM TRANSFER FOR AIR FLOW IN AN ANNULUS
Sinopsis
Wire rings 2.54 mm. and 1.8 mm. in diameter are used as turbulence promoters on the inner tube of an annulus (76 mm I.D., 152 mm O.D.) which heats an air stream. Local heat transfer coefficients between promoters and pressure drops are measured with temperature and velocity profiles, for developed flow and thermal conditions at constant wall temperature. Maximum performance ratios (St/f) for both wires occur at a pitch to height ratio of about 7. Friction factors are independent of spacing and flow patterns correspond to local coefficient behaviour. Suggestions for a mathematical model are given.