DESIGN, CFD ANALYSIS & MANUFACTURE OF GAS TURBINE STATOR VANE WITH IMPROVED COOLING SYSTEM
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With the rising need to increase gas turbine firing temperatures, rotor blades and stator vanes must be cooled to avoid engine failure1; this is done internally and externally, Han et al. (2000). However, conventional manufacturing methods (casting, stamping etc.) present numerous limitations, which restrict the design of blade and vane internal and external cooling structures. Additive Layer Manufacturing (ALM) offers significantly more design freedom, and as a result it is possible to manufacture parts that would have been otherwise impossible.The aim of this project was to design, analyse (using CFD), manufacture, and test a gas turbine stator vane with improved cooling system that would require the smallest change to a gas turbine engine, and thus cost less (financially, time wise etc.), to implement. This project uses computational fluid dynamics (CFD) to design a gas turbine engine first stage vane with film cooling holes from leading to trailing edge, and optimise it (the vane) to accommodate 2000°Κ firing temperature and 0.6MPa pressure under normal (steady state) conditions.Isolated studies on one film-cooling hole showed that 0.8mm was the most efficient radius for the holes, but given small enough separation distances, holes as small as 0.1mm could achieve sufficient cooling2. The effect of the coolant inlet angle on cooling was also investigated, and 90° was found to be the most efficient angle to supply cooling air to the vane surface. Also, cooling passage size was simulated in ANSYS Fluent, and Abaqus CAE was used the simulate gas pressure on stator walls of different thicknesses; the final stator had 2mm thick walls as this offered the largest cooling air passages possible while maintaining acceptable maximum and average deflections. A prototype of the final vane was manufactured in plastic via 3D printing technology, and the final design was to be manufactured in metal, using Laser Engineered Net Shaping (LENS), and tested in a wind tunnel, but was not feasibly, due to high manufacturing costs. It was concluded that it is possible to increase firing temperature significantly beyond current standards by implementing small film cooling holes across the stator vane surface from leading edge to trailing edge.