Experimental and Numerical Investigations of Profile and Secondary Aerodynamic Losses in High Pressure Axial Turbines

A series of experimental studies were conducted in order to investigate the generation and growth of A series of experimental studies were conducted in order to investigate the generation and growth of aerodynamic losses in high pressure axial turbine stages. A two-dimensional linear blade cascade facility was utilized with two sets of blade designs to examine the effects of varying the flow incidence angle as well as the cascade stagger angle on the profile loss component and the blade loading. Experimental findings were compared to CFD results and empirical correlations from literature. A two-stage research axial turbine was assembled with a set of bowed stator and twisted rotor blades to study the three-dimensional aerodynamic losses at design and off-design operations. Extensive performance tests were carried out to create the full efficiency map of the turbine, while detailed interstage measurements resolved the complete flow field of the second stage. The radial distribution of the various flow parameters within the stator and rotor rows enabled accurately calculating the losses, which were compared to steady and transient CFD results. Findings from these experimental investigations were implemented into a generic streamline curvature method solver that inviscidly solves the radial equilibrium equations, and provides additional corrections for profile, secondary, trailing edge and seal leakage aerodynamic losses using empirical correlations to help predict the overall performance of axial turbines at various operating conditions