Unsteady numerical investigation of back‐step three‐dimensional slots on film cooling effectiveness

A numerical investigation was carried out to study the aerodynamics and cooling effects of a trailing edge. For a greater understanding and to learn more details, an unsteady numerical model has been proposed based on a steady model. The unsteady numerical simulation was conducted under different blowing ratios (0.5, 2.0) to show their effects on film cooling effectiveness. The computational results show that the turbulence intensity downstream of a trailing edge outlet tends to be enhanced by the unsteady flow effect. Film cooling effectiveness of an unsteady model is weaker than that obtained by a steady model. When the blowing ratio is 0.5, the mixing and intersecting of the main flow and secondary flow is rapid and fierce; with the increase of blowing ratio up to 2.0, the secondary flow plays a dominant role on the flow characteristics near the outlet of the trailing edge. The mixing and intersecting of the main flow and secondary flow become smooth. The unsteady computational results agree better with the experiment results than those of steady computation. © 2008 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20236