Aerodynamic and heat transfer optimization of one stage air-cooled turbine

摘要

In this paper, we present a study on the aerodynamic and heat transfer performance optimization of one stage air-cooled turbine. In order to tackle the high cost associated with both CFD simulations and the large number of design variables involved, 28 parameters are chosen as the optimization variables including the blade profiles and the direction of film cooling holes. Multiple Pareto Fronts are constructed using the optimization algorithm NSGA-Ⅱ. A new objective function is proposed to reflect the worst heat transfer condition of the blade except the objective function which is used to reflect the aerodynamic performance. Then three solutions are chosen according to design requirements to compare with the original scheme. The aerodynamic efficiency is improved by 1.5%, and the second objective function is improved by 110.48%. The maximum temperature and the area of the high temperature region is decreased significantly. The result shows that the shock loss is decreased in the stator passage, and the increase of the reaction degree increased the rotor load and changed the separation structure. All the reasons mentioned above can improve the aerodynamic efficiency. The heat transfer effect improvement mainly due to the direction change of the film holes. The direction change makes the coolant distribution more reasonable than the original scheme, so the coolant could cover the blade directly. Meanwhile, the double-jet ejection plays an important role in the improvement of film cooling.