COMPUTATIONAL INVESTIGATION OF JET IMPINGEMENT ON TURBINE BLADE LEADING EDGE COOLING WITH ENGINE-LIKE TEMPERATURES

A numerical investigation of leading edge impingement is completed in this study. Impingement onto a half cylinder, concave surface is used to model the leading edge of a modem gas turbine airfoil. The temperature difference between the impinging jet and the target surface is varied from Delta T = 60 degrees F (33.3 degrees C) (typical of traditional laboratory experiments) to Delta T = 1000 degrees F (555.6 degrees C) (representative of temperature differences encountered in modem engines). Over this range of temperatures, the simulations are validated against experimental data and extended to engine-like conditions. In addition to the varying temperatures, the effect of jet Reynolds number is also investigated (Re-jet = 5000 - 25000). The jet geometry is also varied in this investigation to model the effect of jet-to-jet spacing (s/d = 2-8), the effect of jet to target surface distance (l/d = 2-8.5), and the effect of target surface diameter (D/d = 3.6 and 5.5). For all simulations the k-omega.), Shear Stress Transport (SST) turbulence model is used to simulate the impingement flows. Over the range of flow conditions and geometry variations, the SST model is proven to be effective in predicting leading edge heat transfer coefficients. With multiple direct comparisons between the numerical simulations and existing experimental data, the simulations predict the surface Nusselt numbers within an average of 11% of the experimental data. Furthermore, the predictions indicate the existing correlations developed in low temperature laboratory experiments are sufficient for calculating stagnation region Nusselt numbers under engine-like temperatures.