Numerical Study on the Impact of Air-Side Inflow Condition and Oil-Side Thermal Boundary Layer on a Cooling Performance of Surface Air Cooled Oil Cooler

Abstract

Surface Air Cooled Oil Cooler (SACOC) is a widely used oil cooler for turbofan engines. While SACOC has a simple configuration of air-cooling fins on oil passages, the cooling performance is not sufficiently clarified because the coolant air is of high-Reynolds number. In the present study, a numerical analysis was conducted to identify the impact of inflow swirl angle and inflow turbulence intensity on the cooling performance of SACOC. From the results, it was found that the cooling performance was not sensitive to either swirl angle or turbulence intensity. A simple numerical method for a crossflow type heat exchanger was also developed in this study to avoid simulating several hundreds of air-side and oil-side passages. With the developed method, the thermal resistance of the oil passage of SACOC was investigated, which was usually ignored in industrial investigations, and a possibility of improving the cooling performance was found in oil-side devices.