A New Approach of Gas Turbine Component Matching for Electrical Power Generation

Abstract

Gas turbines are often required to operate at different power levels and under varying environmental conditions. But by the nature of the thermodynamic processes in the engine, it is not possible to obtain the same level of efficiency within the entire range of operation. Therefore, depending on the particular application, for example for power generation, the rotational speed would be constant and dictated by the electrical generating machine. Gas turbine engine consists of various components which are linked together in such a way that there exists a mechanical and thermodynamic interdependence among some components. This means that some operational compatibility (matching) between components will be required for a steady state or equilibrium operation. The steady state of gas turbine engine for power generation can be achieved by the matching of its compressor and turbine. The usual approach of matching the compressor and the turbine is usually based on using an iterative procedure to determine the turbine operating points which are then plotted on the compressor characteristics. The draw back of this process is being laborious and time consuming. The new approach developed overcomes this by superimposing the turbine performance characteristics on the compressor performance characteristics while meeting the components matching conditions. This can be done by introducing a new mass flow dimensionless parameter. Superimposing the turbine map on the compressor map cannot be totally accepted until both maps axes (the abscissa and the ordinate) are identical. This paper explains the new approach adopted to a single shaft gas turbine engine. Theoretically, the developed techniques can be applied to other gas turbine engines.