The Flow and Film Cooling Effectiveness Following Injection through a Row of Holes

Using a mass transfer technique, detailed studies have been made of the effectiveness and flow downstream of a row of holes in the flat floor of a wind tunnel. The effects of variation of injection angle, upstream boundary layer, and hole spacing are described, and an assessment of the relative aerodynamic penalties is made. A small injection angle is shown to give the best cooling effectiveness at low blowing ratio while large injection angles are best at high blowing rates. Increasing the upstream boundary layer thickness reduces the effectiveness due to enhanced lateral mixing and film dilution. Small hole spacings give improved lateral coverage and alleviate jet lift-off effects.