An Experimental Study on Heat Transfer and Flow Characteristics of a Circular Impinging Jet on a Flat Plate : Effects of Nozzle Wall Thickness and Nozzle Exit Pressure

원형 제트 충돌 열전달과 유동 특성에 관한 실험적 연구 : 노즐 벽 두께와 노즐 출구 압력의 영향

An experimental study on heat transfer and flow characteristics of a circular impinging jet on a flat plate has been carried out. Of particular interests are the effects of nozzle wall thickness and nozzle exit pressure. Experimental apparatus has been designed to view heating plate coated by TLC from the opposite side of the nozzle in order to measure heat transfer rates for cases of very small nozzle to plate spacings. A visualization study of jet flows has also been performed. As the nozzle wall thickness increases at small nozzle to plate spacings, the effect of mixing is inhibited due to the confinement caused by the finite nozzle wall, consequently, heat transfer rates have been decreased. At small nozzle to plate spacings, heat transfer rates and nozzle exit pressures are increased together, therefore, enhancement of heat transfer at small nozzle to plate spacings should be considered in conjunction with the need of more fan power to generate the same Reynolds numbers.