Scaling of Guide Vane Coolant Profiles and the Reduction of a Simulated Hot Streak

The turbine section of a gas turbine engine is subjected to a non-uniform temperature distribution in the gas flow from the combustor. Regions of elevated temperatures, known as “hot streaks,” subject the turbine airfoil to high heat loads. In this study, the reduction of hot streaks by coolant from a film cooled nozzle guide vane was experimentally evaluated. Experiments were conducted with an approach mainstream turbulence level of 20% to simulate actual turbine conditions. The coolant distributions downstream of the vane were measured for varying blowing ratios and varying coolant density, and scaling methods were found for variations in both parameters. For this study, the hot streak peak was positioned to impact the vane at the stagnation line. Measurements of the hot streak strength with coolant blowing showed as much as a 55% decrease in peak temperature compared with no coolant.