The Aerodynamic Characteristics of Steam Turbine Reaction Stages. (Aerodynamic Characteristics of Multistages).

Abstract

The aerodynamic characteristics of reaction stages of a large steam turbine have been studied for the purpose of performance improvement. For the second step, the characteristics of the multistage with typical reaction bladings were studied by two-dimensional low-speed cascade tests and three-stage air turbine tests. The principal results are as follows. (1) In stationary rows, profile losses are almost the same as the two-dimensional cascade test results in low-turbulence flow. (2) In rotating rows, profile losses are about double those of the stationary rows, which is the same phenomenon as observed in single-stage turbine tests. Secondary flow losses near base sections are fairly larger than the two-dimensional cascade data based on the estimated blade exit flow angles, sin-1λ. (3) Stage efficiency distributions along the blade height indicate the capability of performance improvement near the base diameters. (4) The internal efficiency of the tested multistage reaction turbine can be estimated by total-to-static efficiency for the last stage and total-to-total efficiency for the other stages.