Experimental study on oscillation characteristics of natural gas blended with hydrogen in heavy-duty gas turbine central staged combustor

Natural gas combustion blended with hydrogen is one of the key technologies for reducing carbon emissions in gas turbines. However， changes in fuel composition can lead to combustion instability. This paper established a large-scale full-load combustion experiment to investigate the thermoacoustic oscillation characteristics of hydrogen-blended combustion in the central staged combustor of an actual heavy-duty gas turbine. The experiment reveals the variation rules of pressure pulsation parameters， flame structure， and performance parameters with the pilot hydrogen ratio （Rv）. Experimental results show that hydrogen blending of the fuel at the pilot stage can induce the independence of the two flame structures， resulting in a 79% reduction in the pressure pulsation amplitude. When Rv less than 30%， combustion oscillations are dominated by axial periodic pulsations of the global flame. However， when Rv exceeds 30%， the axial pulsations of the flame disappear with the change of the flame structure， and the combustion stability is significantly enhanced. Additionally， although the increase in the hydrogen ratio initially resulted in a 67% increase in NO emissions， with the improvement in combustion stability， NO emissions decreased to 69% compared to natural gas combustion.