Abstract
This paper presents a numerical investigation on the combined influences of film cooling and thermal barrier coatings (TBCs) on the cooling performances of a NASA C3X guide vane. The results show that: (1) film cooling on the pressure side is more effective than suction side, especially on the trailing edge where multiple cooling and thermal protection techniques include internal cooling and TBCs are necessary. (2) TBCs show positive and negative roles in improving cooling performance at the same time for the coated vane with or without film cooling. Without film cooling, TBCs show negative roles on the regions with lower temperature external hot gas, which is caused by flow acceleration from the stagnation line of the suction side. (3) Internal cooling improvement caused by coolant introduction leads to a larger cooling effectiveness inclement due to TBCs near coolant plenums and film cooling holes. However, the influence of TBCs on cooling effectiveness increment goes down and even shows negative roles on the regions away from coolant plenums and under the effective coverage of the film cooling. (4) Improving the convective heat transfer of coolant with the wall of coolant plenums and film cooling holes is the guarantee of improving the cooling performance of a coated vane.
Highlights
Because of the continuing demand for the increment of thermal efficiency and the decline of fuel consumption, the inlet temperature of gas turbines has far exceeded the normal material temperature limits of the vane over the previous century [1,2]
(3) Internal cooling improvement caused by coolant introduction leads to a larger cooling effectiveness inclement due to thermal barrier coatings (TBCs) near coolant plenums and film cooling holes
Multiple cooling and thermal protection techniques have applied to ensure gas turbine working within safety margins, which include internal cooling and film cooling, as well as thermal barrier coatings (TBCs) [3,4]
Summary
Because of the continuing demand for the increment of thermal efficiency and the decline of fuel consumption, the inlet temperature of gas turbines has far exceeded the normal material temperature limits of the vane over the previous century [1,2]. Liu et al [13] studied the coating insulation of an internally cooled vane coated with multilayered TBCs. Their work showed that inlet flow condition exerted a greater influence on the coating insulation [13]. Building the precise geometry of multilayered TBCs for a specific film cooled vane is still necessary for studying the heat transfer, thermal load, and cooling performances, as well as the TBCs stresses of a coated vane. The performance of various film cooling ejections on the cooling performances and temperature distributions of the C3X vane with and without the inclusion of external multilayered layers of TBCs have been studied to provide reference for the design of coated vane or blade with film and internal cooling
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