A parametric approach to turbine tip leakage aerodynamic investigation for axial flow turbine

This current paper deals with the development of a computational system dealing with parametric assessment of aerodynamic losses near the tip region of a high pressure turbine blade. Performance of an axial flow turbine is strongly related to the flow structure in the tip gap between blade tip and casing. Flow structure in the tip gap is a significant source of inefficiency. Special emphasis is paid to developing a sufficiently accurate 3D RANS based loss estimation system for the optimization of tip section geometry. An HP turbine tip section will be optimized for minimum aerodynamic losses and also for minimized heat loss. The present study deals with a preliminary study of effective parametric grid generation and turbulent flow model implementation and assessment under realistically simulated turbine flow conditions. Initial development of this computational model is performed in a linear turbine cascade arrangement. Numerical experiments with parametrically generated multizone structured grid topologies and unstructured grids pave the way for the 3D optimization of the HP turbine blade tip region. The future efforts will include modified squealer tips, tip trenches and tip carving investigations in an effort to obtain optimal 3D tip shapes as far as aerodynamic losses and heat losses are concerned.