Internal Cooling Using Porous Turbulators: Heat Transfer and Pressure Drop Measurements

Heat transfer and pressure drop characteristics were studied in a low aspect ratio channel with high temperature carbon foams. The convoluted fluid flow path that significantly increases the surface area is a primary reason for the high heat transfer augmentation. The experiment provided module-averaged heat transfer coefficients on the heated wall, from which the Nusselt number was calculated. Increasing the channel blockage increased the heat transfer coefficient due to the amplification in the surface area. On the contrary, the pressure drop was also high for a high channel blockage. By using a corrugated foam arrangement, heat transfer remained relatively high with a pressure drop reduction by a factor of four. The staggered arrangement of the porous foam continuously perturbs the thermal boundary layer, which helps to sustain a high thermal gradient between the hot wall and the fluid. Increased Reynolds numbers resulted in a corresponding rise in the heat transfer rate while the roughened to smooth wall heat transfer ratio decreased.