Integrated design and thermo-mechanical assessment of a hydrogen-fueled microscale combustion system for micro gas turbines

Achieving Net Zero energy targets requires the development of efficient hydrogen-fueled power generation technologies for applications where electrification remains technically or economically challenging. Hydrogen offers a carbon-free energy carrier with a wide flammability range and high energy density; however, its application in microscale gas turbine combustors is challenged by high flame speeds, elevated operating temperatures, thermo-diffusive instabilities, and severe thermo-mechanical loading. This study presents the design and integrated numerical assessment of a high power-to-weight hydrogen-fueled microscale combustion system incorporating compact swirling combustion chambers for a micro gas turbine. The proposed methodology combines 0-D thermodynamic analysis, computational fluid dynamics (CFD), and coupled thermo-mechanical finite element analysis to evaluate combustion performance, thermo-fluid behavior, thermal loading, structural integrity, and material selection under high-pressure operating conditions. The numerical results demonstrate stable lean hydrogen combustion at an operating pressure of 35 bar. A hydrogen combustion efficiency exceeding 99%, calculated from the hydrogen mass flow rates entering and leaving the combustor, indicates nearly complete fuel conversion. Based on the increase in the internal energy of the working fluid, the combustor subsystem achieved a thermal efficiency exceeding 95%, together with acceptable pressure losses and turbine inlet temperatures approaching 1850 K. Thermo-mechanical analysis identified thermal loading as the dominant factor governing the structural response, whereas pressure loading had only a minor influence. A comparative material investigation involving Inconel 718, UDIMET 700, silicon carbide (SiC), and silicon nitride (Si 3 N 4 ) demonstrated that material properties significantly influence structural behavior. Silicon nitride exhibited the lowest thermal deformation and superior dimensional stability, whereas nickel-based superalloys provided lower stress levels and greater fracture tolerance under high-temperature operating conditions. Overall, the proposed integrated numerical methodology provides a practical framework for the design, thermo-mechanical optimization, and preliminary material selection of compact hydrogen-fueled combustion systems for next-generation micro gas turbine applications.