Design of Thermal Barrier Coatings Thickness for Gas Turbine Blade Based on Finite Element Analysis

Abstract

Thermal barrier coatings (TBCs) are deposited on the turbine blade to reduce the temperature of underlying substrate, as well as providing protection against the oxidation and hot corrosion from high temperature gas. Optimal ceramic top-coat thickness distribution on the blade can improve the performance and efficiency of the coatings. Design of the coatings thickness is a multiobjective optimization problem due to the conflicts among objectives of high thermal insulation performance, long operation durability, and low fabrication cost. This work developed a procedure for designing the TBCs thickness distribution for the gas turbine blade. Three-dimensional finite element models were built and analyzed, and weighted-sum approach was employed to solve the multiobjective optimization problem herein. Suitable multiregion top-coat thickness distribution scheme was designed with the considerations of manufacturing accuracy, productivity, and fabrication cost.

Effect of Thermal Barrier Coating on the Thermal Stress of Gas Microturbine Blades and Nozzles

“…The TBC properties used to predict heat transfer by CFD are indicated in Table 1, which also contains substrate (nozzles and blades) properties [23]. Coating thickness is considered uniform and constant for the whole cases with a value of 550 µm based on some investigations [6] and [12], and it is added as a virtual layer into the CFD software. This virtual technique uses the TBC properties (thermal conductivity, specific heat, density and thickness) to compute heat transfer to the blades.…”

“…The design of proper TBC plays a key role in the operating life of turbine blades; as a consequence, several studies are focused on the study of TBC characteristics. Li et al [12] studied the thickness of TBC for a gas turbine blade. The materials used were ZrO 2 -8 wt% Y 2 O 3 (8YSZ) as a TC layer, -Al 2 O 3 as TGO layer and NiCrAlY as a BC layer.…”

“…The k-є realizable offered the most accurate results when modelling blades with one-layer TBC. Li et al [12] employed the FEM to design the TBC for a gas turbine blade. They found that thermal insulation was enhanced with the increase of the TC.…”

“…However, their model was restricted to a 2D model. In other works [12] and [21], the uniform temperature on blade surfaces and static blade boundary conditions were used. However, these simplified conditions could drive to imprecise results since temperature fields on blade surfaces, induced by high-temperature combustion gases and the blade, are highly three dimensional and non-uniform.…”

Design of Microstructure by Evaluating the Effect of Thermal Barrier Coating’s Microstructure on TGO Interface Stress

“…그러나 열차폐코팅이 고온에서 장시간 노출되거나 열적 부하 변동을 받으 면 Top 코팅과 TGO의 열팽창계수 차이와 온도 구배 로 인해 TGO 계면에서 열응력이 발생한다. 이 열응력 은 열차폐코팅 파손을 유발하는 주요 원인 [2,3] [4,5] 또한 TGO가 굴곡지게 형성될수 록 열팽창량 차이가 큰 TGO의 peak 부분에서 열응력 이 크게 발생하기 때문에 TGO의 형상도 열응력에 미 치는 주요 미세구조이다 [3] . [3] .…”