Abstract
Turbulent flow and heat transfer in a channel with a detached rib array have been simulated. The computations are based on the finite volume method with the SIMPLE algorithm. The forms of ribs considered in this study were rib with rectangular cross section, rib with groove, broken rib, and V-shaped rib. The ribs were deployed transverse or aligned $60^{\circ}$ to the main direction of the flow. Local heat transfer coefficients were obtained at various Reynolds numbers within the turbulent flow regime. Area-averaged data were calculated in order to compare the overall performance of the tested ribbed surfaces and to evaluate the degree of heat transfer enhancement induced by the ribs with respect to the smooth channel. The highest heat transfer occurred for the rib with groove which was aligned $60^{\circ}$ to the main flow direction. Performance factor was decreased with the increase of velocity, and it was found that the best performance factor was obtained in the low velocity region.
열전달 향상을 위하여 이차유동을 발생시켜 열전달을 증가시키는 방법에는 여러 가지가 있다. 본 연구에서는 수평채널에 다양한 형태의 립을 설치하여 유속을 변화시켰을 때의 열전달 및 압력강하 특성을 수치해석을 통하여 고찰하였다. 립은 수평채널의 아랫면에 설치하였고, 립의 높이는 5mm이다. 립이 $60^{\circ}$ 기울어지고 그루브도 설치된 경우 열전달 특성이 가장 우수하게 나타났는데, 이는 주유동이 립을 따라 흘러가면서도 유속이 어느 정도 유지되기 때문이다. 끊어진 립에서 주유동이 립의 저항을 적게 받으면서 압력강하가 가장 작게 나타났다. 모든 립의 형태에서 유속이 증가함에 따라 열전달이 향상되는 경향을 보였지만 성능계수는 감소하였다.
