Performance Simulation and Off-Design Performance Control of Reheat Gas Turbine Engines

A reheat gas turbine engine with a sequential combustion system has the potential to offer high cycle efficiency at moderate turbine entry temperatures. Consequently, it has one more degree of power setting control, which offers more flexible but also more complex control of engine off-design operations. An example of such a design with reheat is GT24/GT26 industrial gas turbine engines. In this paper, a novel simulation method for off-design thermodynamic performance of reheat gas turbines has been introduced and a novel performance control schedule for part-load operations at various ambient conditions have been proposed aiming to keep the relative workloads between the two turbine sections constant. The proposed control schedule is simple and can be adapted easily. By applying the off-design performance control schedule to a model reheat industrial gas turbine engine similar to GT24/GT26 gas turbine engines, the performance of the model engine is simulated at different part-load and at different ambient pressures and temperatures. The results show that by applying the proposed off-design performance control schedule, the model reheat gas turbine engine could operate effectively at different part-load operating conditions and at different ambient conditions with both turbine sections keeping nearly constant workload distributions.