The Effects of Blade Loading in Radial and Mixed Flow Turbines

Abstract

Understanding of the effects of blade loading and blade number in radial and mixed flow turbines is often based on analogies with axial turbine cascade tests or centrifugal compressors rather than direct measurement. In this paper test results from a series of similar mixed flow turbines are described. The turbine rotors differ only in blade number or inlet incidence variation. The results comprise performance data and hub and shroud pressure measurements, from which it is possible to deduce parameters such as incidence angle with good accuracy. In addition, predictions of blade loading using three-dimensional computations are shown. The results are correlated against a loading coefficient and a slip factor, both derived for the general case of a mixed flow turbine. The influence of these parameters on the performance of the tested turbines, and for comparison of other radial turbines, is shown.