To supply cooling air which delivered from turbine stationary parts to the rotational parts, pre-swirl system have been widely used in gas turbines with various shapes and types. The key functions of pre-swirl system is to provide turbine cooling temperature lower than pre-swirl system inlet within required pressure drop target. In modern gas turbine system, pre-swirl system is a key component in the turbine cooling system because first rotor entering flow qualities were defined by pre-swirl system. Especially most of modern blade cooling system were required adequate coolant pressure level to meet film cooling conditions and also need to keep lower level of temperature condition to improve cooling effectiveness in their cooling circuit.
To meet the design target, cooling system designer should built effective pre-swirl system by increase swirl ratio within required pressure margin. When the design results of pre-swirler system was satisfied initial design requirements, designer should select best pre-swirler system based on its discharge coefficient characteristics. To verify analytic methodologies, to compare main design parameters of this research and former studies which reference data already validated analytically and experimentally.
To find best pre-swirl nozzles shape, total 15 kinds of airfoil was selected for detail investigation. Best available was selected by pre-swirl performance comparing. Also shape optimization was applied to improve pre-swirl performance within minor geometrical changes within mechanical integration limit.
To verify inlet duct system effects, the effect of the inlet duct shape was added on to verify desired pre-swirl system. To find the best model, case study was conducted by CFD approaches to increase the discharge coefficient and the adiabatic effectiveness of the pre-swirl system.
New pre-swirl test rig was construct to verify pre-swirl characteristics and to find best pre-swirl nozzles shape. Discharge coefficients of the tested data was relatively higher than 3-D CFD results due to the pre-swirl inlet conditions was relatively fair in test rig compared with real gas turbine conditions.