Film heating heat transfer and effectiveness measurements for mainstream flow over a conical surface

Abstract

Adiabatic effectiveness and heat transfer coefficient measurements for fluid injection into the mainstream over a conical surface have been presented in this article. The axis-symmetric nature of the flow over the cone makes the heat transfer behaviour different from that observed for a flat surface, and dependent on the cone apex angles which were kept constant at 30° and 70° in the study. The injection angle was kept equal to 30° and 50° with respect to the surface of the cone and the blowing rate was varied between 0.3 and 2.5. The spatially resolved surface temperature measurements over the cone using an IR thermal camera were used to obtain the adiabatic effectiveness and heat transfer coefficient ratio values. The maximum values of the effectiveness for the 30° and 70° cones with 30° injection angle at locations along the centreline and in between the holes were 0.34, 0.22 and 0.24, 0.22 respectively at X/d = 5.5 for the lowest blowing ratio M = 0.3. The maximum increase in the heat transfer coefficient ratio was nearly equal to 30 % for both cones at 30° injection angle at the hole centreline at X/d =5.5 at the highest blowing rate M = 2.5. The effectiveness and heat transfer coefficient ratio experienced a reduced cross stream variation, compared to the flat surface case, for all cases studied.