Improved Profile Loss and Deviation Correlations for Axial-Turbine Blade Rows

Abstract

Empirical correlations continue to play an important role in the early stages of turbine design and in the optimizing of the gas path. The recent development of highly-loaded low-pressure (LP) turbines has extended the design space beyond the range of geometric and aerodynamic parameters on which the existing correlations for profile losses and deviation are based. With the aid of a large database of measured profile losses, including in-house results and recent cases from the open literature, the profile loss predictions of Kacker and Okapuu have been reviewed. As a result, a revised correlation is proposed that appears to capture much better the loss behavior of axial-turbine airfoils of recent design, including very highly-loaded LP turbine airfoils. The opportunity was also taken to extend the range of applicability of the correlation for trailing-edge deviation originally proposed by Islam and Sjolander in 1999.