Thermodynamic Performance of Heavy-Duty Gas Turbines with Hydrogen–Ammonia Co-Fuel by Inlet Guide Vane Variations

When methane (natural gas) fuel gas turbines switch to hydrogen–ammonia co-fuel, their thermodynamic performance undergoes significant changes. To expand the operating range of heavy-duty gas turbines when using hydrogen–ammonia co-fuel and to improve their thermodynamic performance, based on the 255.6 MW heavy-duty gas turbine at the Banshan Power Plant in Hangzhou, China, a simulation model was established. A strategy based on changing the angle of the compressor inlet guide vanes (IGVs) was proposed. The thermodynamic performance, turbine stage supercritical flow velocity, and flow matching characteristics of gas turbines were studied under different hydrogen–ammonia mixing ratios. The results indicate that the developed model can accurately predict the performance of the gas turbine under rated operating conditions, yielding a rated output power of 254.59 MW and an efficiency of 36.33%, with relative errors of −0.4% and −1.54% compared with the design values, respectively. When hydrogen–ammonia blended fuel is employed, the outlet Mach numbers of the second- and third-stage turbine stators exceed the safety limit unity. Reducing the IGV angle effectively decreases the turbine stator outlet Mach number and improves operational safety, although a slight reduction in gas turbine efficiency is observed. As the ammonia volumetric fraction in the blended fuel increases, the gas turbine output power increases while the efficiency decreases slightly, accompanied by a reduction in turbine stator outlet pressure and an increase in outlet temperature. Further investigation shows that, after IGV regulation, the combustor outlet pressure, gas turbine power output, and efficiency all increase. Under a fixed IGV opening condition, the gas turbine efficiency gradually decreases with increasing ammonia volumetric fraction. Under off-design fuel flow conditions, increasing the relative fuel flow leads to higher combustor outlet pressure and temperature, whereas increasing the ammonia volumetric fraction causes a slight reduction in these parameters. This research can provide theoretical support for the optimal design and operation of gas turbines using hydrogen–ammonia mixed fuel.