A Comparison of Loss Models Using Different Radial Distribution of Loss in an Axial Turbine Streamline Curvature Program

The streamline computer codes published in the open literature and used to analyze the performance of axial flow turbines have employed a particular loss model chosen from a number of existing prediction methods. It is well known that the performance prediction methods developed for one-dimensional models concentrates the losses at the blade mid-height. When used in a streamline curvature model, however it is necessary to distribute these losses along the blade span. However the way to distribute the losses is not unique, as is clear from the open literature. Some methods seem to be an arbitrary procedure, with a shortcoming in representing the real flow behavior within the blade row. In this paper, two different loss distribution models were implemented in a streamline curvature program specially developed for the study of axial flow turbine performance. The study seeks to establish which one best represents the reality of the complex flow physics occurring within a blade row. Three different loss models were also implemented in the program to check their reliability and validity when combined with different loss distribution systems. Performance maps for a single-stage turbine were generated by means of different combinations of loss models and radial loss distributions. The computed result for each case was compared with available experimental data of a single-stage turbine.Copyright © 2007 by ASME