Numerical Study on Film Hole Outflow Effects on Flow and Heat Transfer in Rotating Turbine Blade Cooling Channels

Efficient cooling of turbine blades is one of the key technologies for enhancing the performance and service life of aero engines. The turbine blade cooling structure consists of interconnected external film holes and internal cooling passages, which jointly cool and protect the blades. In previous studies on turbine blade internal cooling channels, the film hole outflow effect on flow dynamics and heat transfer has often been overlooked. This study employs numerical simulation to investigate how film hole outflow affects flow heat transfer within an internal cooling channel under both static and rotating conditions. The internal cooling channel is simplified as a square cross-section straight duct with outflow holes located only on the trailing and leading walls. The investigated Reynolds numbers are 15,000 and 30,000, the rotation number ranges from 0 to 0.44, the film hole outflow ratios vary between 0 and 1. The results indicate that the presence of film hole outflow disrupts the boundary layer on the downstream wall of the film holes, thus enhancing heat transfer significantly within the channel. The outflow from the film holes causes a gradual decrease in flow rate along the channel, resulting in low heat transfer regions downstream. Rotation weakens the impact of film hole outflow. The Coriolis force induced by rotation causes main stream to shift toward channel trailing wall, enhancing heat transfer while reducing spread difference of wall temperature caused by film hole outflow. For the leading wall, the deviation of main stream weakens the destructive effect of film hole outflow on boundary layer, thereby diminishing heat transfer. The results presented in this study reveal the mechanisms by which film hole outflow affects flow heat transfer within an internal cooling channel, providing valuable insights for optimizing turbine blade cooling structures.