Experimentally Determined External Heat Transfer Coefficient of a New Turbine Airfoil Design at Varying Incidence Angles

摘要

Predicting and measuring heat transfer coefficients of hot gas path turbine components are extremely important tools for gas turbine designers. Accurate prediction of heat transfer coefficients with CFD is strongly dependent upon calibration and validation using experimental measurements. Since turbine components often handle a range of inlet flow incidence angles during dynamic flight situations, understanding the sensitivity of heat transfer coefficients to a range of inlet conditions is important. In the past, researchers have performed CFD predictions for turbine airfoils and vanes at off-nominal incidence angles, but few researchers have directly measured the heat transfer coefficients, and then only at shallow, off-nominal angles. This research program filled a void by evaluating incompressible CFD predictions with direct measurements of heat transfer coefficients for appreciably off-nominal incidence angles at both high and low turbulence. Particle Image Velocimetry was used to verify the incident flow angle. The high turbulence condition was generated using a turbulence grid to produce Tu = 5% at the leading edge of the test article, whereas the low turbulence condition had Tu = 0.6%. The test facility was adjusted so that the pressure distribution around the model airfoil matched the pressure distribution predicted by an aerodynamic CFD model. IR thermography and an airfoil model equipped with a constant heat flux surface were used to measure the heat transfer coefficient. This process was repeated for each incidence angle measured. The results quantified the effects of inlet angle upon the heat transfer coefficient and the accuracy of the SST-kω, SST-Transition, and k-kl-ω models used to predict the experimental results.