충돌판(衝突板) 근방(近傍)에 배열(配列)된 2차원(次元) rod가 충돌분류(衝突噴流) 열전달(熱傳達)에 미치는 영향(影響)[3] : rod직경변화(直徑燮化)에 대한효과(效果)

Heat Transfer Augmentation on Flat Plate with Two-Dimensional Rods in Impinging Air Jet System [3] : Effect of Rod Diameter

The purpose of this study is augmentation of heat transfer without additional power in two-dimensional impinging air jet. The technique of heat transfer augmentation used in this experiment is to place rod bundles in front of the flat heated surface. The effects of rod diameter, nozzle-to-target plate distance and the nozzle exit velocity on heat transfer have been investigated. The main conclusions obtained from this experiment are as follows. High heat transfer augmentation is achieved by means of flow acceleration and thinning of boundary layer by placing rod bundles in front of the flat plate. Average heat transfer coefficient becomes maximum in the case of H/B=10,D=4mm. For H/B=2,D=4mm, maximum heat transfer augmentation has been determined to be about 1.5 times larger than that of the flat plate. Heat transfer augmentation by placing the rod bundles at 12m/s is to be about 2 times more than increasing nozzle exit velocity from 12m/s to 18m/s.