New Method for Cycle Performance Prediction Based on Detailed Compressor and Gas Turbine Flow Calculations

Abstract

Gas turbines have made significant progress in recent years. The efficiencies of the compressor and turbine were improved based on achievements in aerodynamics, i.e., on the introduction of numerical flow simulation. The introduction of massive cooling and thermal barrier coating permitted a considerable increase in the turbine inlet temperature. These developments led to a significant increase in the thermal efficiency of gas turbines. However, most of the existing tools for predicting cycle performance are based on 0D compressor and turbine maps for the efficiency and pressure ratio as a function of the mass flow. Such tools cannot simulate all new trends in gas turbines in the most efficient way. The new method proposed here is a 2D method based on detailed flow calculations in the compressor and the gas turbine. Previously developed through-flow tools for compressor/turbine flow simulation and performance prediction were applied for this purpose. The processes in the compressor and the turbine are connected by calculation of the processes in the combustion chamber and the secondary and cooling air system. The turbine inlet temperature is determined by an iterative procedure. The method allows the accurate prediction of performance at every operating point. Air cooling bleeds in the compressor and its injections in the turbine blades can be simulated precisely. Also, adjustments of the inlet guide and stator vanes and their influence on compressor behavior can be accurately taken into account at every operating point. Finally, calculation of the combustion and the flow in the compressor and the turbine allows a simulation with correct gas composition and humidity of the air. The method is demonstrated on a case of an industrial gas turbine. The numerical results were compared with experimental data and showed very good agreement. The procedure is rapid and robust and permits optimization of the different solutions during the design phase.