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Abstract
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Gas turbine blades are the key parts of energy production units because they work in very tough conditions.
Therefore, it is important to increase their life to prevent extra expenses of repair and maintenance. There are several ways to increase gas turbine blades life such as using cooling lines to reduce the blade temperature, applying Thermal Barrier Coating (TBC) and using super alloys, which have high strength. TBCs usually apply on blade body with plasma spray coating systems and cover the whole body in order to protect it from high temperatures.
In this paper, we investigate the effects of TBC thickness on heat transfer between combustion gases and blade body. TBC acts like an insulation layer that increases the temperature gradient between the hot gases and blade body. For this purpose, a 3D model of the blade body and TBC have been created. Material properties are considered as temperature dependent and boundary conditions have been applied as heat transfer coefficient. The important point is that while the TBC thickness increases, the blade body geometry decreases respectively , so that total geometry of the whole blade remains constant in order to keep its aerodynamic behavior unchanged. Results show that increasing TBC thickness, affects significantly on temperature distribution of the blade as some regions
of blade surface experience a 100 °C collapse in temperature by increasing TBC thicknesses from 100 to 500 μm.
In addition, temperature of ejected coolant from blade top is affected by TBC thickness especially in microholes near leading and trailing edges.
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