Entropy generation of staggered short pin fin arrays

Abstract

Staggered short pin fins are usually used to increase the heat transfer in modern gas turbine blade mainly due to its function of increasing the level of turbulence in the cooling flow, which leads to both higher heat transfer and pressure drop. In order to decrease the energy loss of the cooling flow, an entropy generation analysis was carried out for a pin fin array. The entropy generation model was established based on the second-law analysis. Three types of pins with stepped diameter were studied. The distribution of the entropy generation due to heat transfer and fluid friction irreversibility respectively was analyzed. The entropy generation number component due to heat transfer decreased as Re d increased, while the component due to fluid friction increased with the increase of Re d . The entropy generation number took its minimum value when the two components met and the corresponding Reynolds number was optimal. Thermal diffusion of the fluid strongly influenced the entropy generation at small Reynolds number, while the effect of fluid friction on entropy generation became dominant at large Reynolds number. Keywords-heat transfer; pin fin array; entropy generation I.978-1-4244-9171-1/11/$26.00 ©2011 IEEE