High-pressure micro-mix combustion characteristics of hydrogen–oxygen-steam with regenerative cooling

The hydrogen-oxygen-steam gas turbine system embodies a promising pathway toward zero-emission technology. The inherent challenges of flashback and ablation associated with hydrogen fuel and high-oxygen-concentration flames have steered current hydrogen turbine advancements toward micro-mix combustion technology. To meet the experimental demands for hydrogen-oxygen micro-mix high-pressure combustion under steam dilution, this study utilized 3D printing technology for the fabrication of the combustion chamber, and developed an innovative experimental technique utilizing throat pressure buildup and regenerative cooling for steam generation. The system is capable of accommodating hydrogen-oxygen-steam micro-mix high-pressure (0.3-1 MPa) combustion testing across a power spectrum of 5.40-10.80 kW, with pressure fluctuation below 0.01 MPa during stable combustion stage. Regenerative cooling and steam dilution can substantially lower the maximum temperature of hydrogen-oxygen flame even at high pressure near 1 MPa, thus offering a viable means to achieve hydrogen-oxygen combustion in gas turbines. By integrating wall-mounted temperature sensors, combustion chamber pressure monitoring, and infrared thermographic imaging, comprehensive data on combustion chamber wall temperatures, combustion pressures, and qualitative steam temperature fields at the outlet were systematically acquired. The combustion efficiency was evaluated through combustion temperature and pressure metrics. The findings demonstrate that the initial temperature within the combustion chamber and the structure of micro-mixing injection exert a considerable influence on combustion efficiency, whereas the impact of combustion chamber pressure is marginal. In particular, the cross-jet injection technique augments combustion efficiency by 6%-8% in contrast to the axial-tangential swirl approach. Moreover, an elevation in the initial temperature of the combustion chamber from 100 °C to 300 °C results in a 4% improvement in combustion efficiency. Thus, a novel integrated system combining 3D-printed combustion chambers with regenerative steam cooling for high-pressure hydrogen-oxygen combustion studies was developed. This technology may provide experimental validation and design guidelines for next-generation hydrogen gas turbine development.