Experimental study on the heat transfer enhancement of the effect of teardrop protrusion-to-protrusion spacing

Abstract

An experimental analysis was presented for heat transfer on the surface of teardrop protrusions with an inline arrangement. The air flow was passed through perpendicularly over the single row of 5 protrusions in the rectangular wind tunnel. The protrusion height from the bottom of wind tunnel was H/D = 0.2 and the spacing of teardrop protrusion-to-protrusion was adjusted by four different spacing cases such as S/D = 1.125, 1.25, 1.5 and 2. The spacing can affect heat transfer enhancement and flow characteristics. Therefore, the spacing which was analysed in this study considered four cases because of experimental limitations. The temperature distributions of surface with protrusions was detected by using the thermochromic liquid crystal sheet (TLC) at ReH = 20,000. Image processing was used to evaluate distribution of Nusselt number. The result shows that the highest average Nusselt number was found in S/D = 1.125D case.