Heat transfer study of airfoil arrays in low Reynolds number gas flows

Abstract

In electronic components, pin fins arrays are commonly used to manage the thermal load. Even though several shape forms and configurations of the pin fins array are possible, cylindrical and airfoil shapes in staggered arrangements are chosen for this study to compare their heat transfer properties for Reynolds number range of 500 to 1000. A numerical investigation is started by taking a single cylinder case and moving up to 16-row staggered arrays and comparing it with available empirical correlation. For airfoil geometry, NACA 0012 has been considered in the study. The numerical methodology employed with cylinder arrays was then utilized with the airfoil array. Heat transfer characteristics of NACA airfoil for three different angles of attacks (0°, 5°, and 10°) have been observed. The effect of spanwise (ST) and streamwise (SL) separation in staggered arrangements for both cylindrical pin fins and NACA 0012 fins has been studied. A comparison is made based on the calculated Nusselt number. The study shows that, for the cylindrical case, numerical results are close to the empirical results, which validates the numerical analysis. The Nusselt number of cylindrical arrangements is 1.1 times higher than that of the NACA 0012 array with airfoils at a 5° angle of attack. However, the overall heat transfer rate is 1.2 times higher for the same airfoil array when the domain is identical to the cylindrical array, as more airfoils could be packed in the same domain size. Additionally, the pressure drops for airfoil arrays are 5-9 times lower than the cylindrical arrays, which denote less power required to pump the fluid.