Investigations into film cooling and unsteady flow characteristics in a blade trailing-edge cutback region

Unsteady flow characteristic and film cooling effect in the blade trailing edge cutback region are numerically investigated using DES (detached eddy simulation) method at three blowing ratios, four lip thickness ratios and three rib geometries. With the experimental data, reliability and accuracy of the numerical methods are validated. The results indicate that, compared with RANS (Reynolds-averaged Navier-Stokes) equations solutions, the DES method has a superior accuracy in predicting the film cooling effectiveness on trailing-edge cutback. The lip thickness has a pronounced effect on shedding vortex scale downstream the slot. As the lip thickness ratio decreases, the film cooling effect on trailing edge cutback is improved. Compared with the line ribs, the arrangement of pin fin ribs enhances the uniformity of coolant coverage on trailing edge cutback along lateral direction. However, with different types of rib, the film cooling effectiveness on the trailing edge cutback is mainly determined by the stable cooling flow structures and mixing effect between mainstream and coolant. The development of vortex system downstream the slot is significantly affected by the blowing ratio, which in turn influences the film cooling effect on trailing edge cutback.