An influence of novel upstream steps on film cooling performance

摘要

In this study, computational simulations were made using ANSYS CFX to predict the improvements in film cooling performance by using novel upstream steps. These steps are curved shapes instead of the normal shapes. The film cooling effectiveness (η), the heat transfer coefficient (h) and the net heat flux reduction (NHFR) over flat plate were investigated and compared with experiments. The width of the curved steps was changed from (W) to (W/8). Blowing ratios in the range (0.5,1,1.5 and 2) were investigated. Results show that the curved step with less width (W/8) gives higher laterally film cooling effectiveness, lower heat transfer coefficient and higher NHFR comparing with normal step, rectangular and circular film holes without step at all blowing ratios. Interpretation of the low and high heat transfer coefficient regions for curved step (W/8) depending on the flow structures was explained in detail.