HEAT TRANSFER AND FLOW CHARACTERISTICS OF A LEADING EDGE IMPINGEMENT COOLING SYSTEM FOR LOW PRESSURE TURBINE VANES

An impingement cooling system for the leading edge of a contra-rotating Power Turbine (PT) representative of a small turboshaft engine was investigated experimentally as well as numerically. The PT vane features a very thin leading edge with high curvature and side channels rapidly facing backwards. Constraints on cooling flow consumption and distribution led to a leading edge (LE) configuration with two rows of staggered jets. This particular configuration was experimentally investigated for three different Reynolds numbers around the design point by using a transient liquid crystal technique. Heat transfer results are presented in terms of surface distributions, impingement rows stagnation line local distributions, streamwise distributions along planes over the impingement stagnation points, span averaged streamwise local distributions and surface averaged values, and then compared to available correlations from existing literature. In order to investigate the flow features of this kind of configuration in more detail, a CFD investigation was also conducted. Results from CFD simulations were compared to the experimental data and then used to discuss in detail the main flow features driving the surface heat transfer.