Thermomechanical Stress Distributions in a Gas Turbine Blade Under the Effect of Cooling Flow Variations

Thermomechanical stresses in gas turbine blades are investigated. Attention is focused on effects caused by varying the cooling airflow that runs through the blade interior, keeping constant a mainstream condition around the blade surface. Stress concentration was predicted numerically under engine real operating conditions. Temperature distributions in the metal blade surface produced by convective boundary conditions were linked with heat conduction within the blade using a conjugate solution. Results of stress concentration in the blade material for reduced cooling flow rate, blocked cooling ducts, and rotation rate were obtained. It is shown that temperature and stress distributions are a strong function of position in blade interior material and surface. Thermomechanical stress concentration was observed in the leading edge, with the endwall region affected by large stress concentration. Stress magnitude increments were found for combined cyclic thermal heating and sustained mechanical loads on specific planes of airfoil span for reduced cooling flow. Also, large stress gradients between leading and trailing regions of the blade were observed. The study reveals that blocking channels increase stresses in the central region of blade transversal cross section.