Transonic Compressor Development for Large Industrial Gas Turbines

Abstract

With increasing mass flow and constant rotational speed of the single shaft gas turbine, the diameters and tip speeds of compressor and turbine blading have to be enlarged. A significant further increase in mass flow can be achieved with transonic compressor stages, as they have been in service in aero gas turbines for many years. For industrial applications, weight and stage pressure ratio are not nearly as important as efficiency. Therefore, different design criteria had to be applied, which led to a moderate front stage pressure ratio of 1.5 with a rotor tip inlet Mach number of 1.37 and a high solidity blading. In order to simulate the first three stages of a 200-MW gas turbine, a test compressor scaled by 1:5.4 was built and tested. These measurements confirmed the aerodynamic performance in the design point very well. The compressor map showed a satisfactory part speed behavior. These results prove that the single-shaft industrial gas turbine still has a high development potential with respect to power increase. Additionally, with the higher pressure ratio, the cycle efficiency will be improved considerably.