Abstract
Experiments are conducted to study turbulent steady state heat transfer and friction for airflow in a wide rectangular channel with periodic longitudinal deflector plates that are affixed to the two primary walls. The deflector plates are staggered and are oriented such that they deflect the flow of air toward the top and bottom primary walls alternately. The bottom wall of the channel is heated by passing electrical current through a thin Inconel foil that is attached to the inner surface. The temperature at the surface of the foil heater is indicated with thermochromic liquid crystals, which change color over a specific temperature range. Experimental results are obtained for two fin pitches, three angles-of-attack of 15', 30', and 45', and five flow rates. Results show that the deflector plate array with a smaller pitch is superior to that with a larger pitch. The smaller pitch array with the deflector plates at 45' angle-of-attack enhance heat transfer the most at all tested mass flow rates. The smaller pitch array with the deflector plates at 15' angle-of-attack gives the best thermal performance at the lower mass flow rates, while the same array at 45' fin angle-of-attack produces the best thermal performance at the higher mass flow rates. The array with the larger pitch causes lower pressure drop but does not increase heat transfer as much as the array with the small pitch.
Valant, Michael Eric (1995). An experimental investigation of a periodic impingement technique for heat transfer enhancement. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -1995 -THESIS -V345.