Combustion performance, fluid behaviors, and reaction mechanism of a disk-type planar swirl micro-combustor with dual tangential inlets

This study proposes a planar swirl micro-combustor with dual tangential inlets, distinguished by its novel disk-type structure—a key departure from traditional cylindrical micro-combustors—to enhance combustion stability and thermal efficiency in micro-scale energy systems. The combustor features a compact circular chamber (10 mm diameter, 0.5 mm height), where hydrogen/air mixtures generate a swirling flow, improving reactant mixing, extending residence time, and promoting heat recirculation. This 2D disk-type design offers superior adaptability for portable power and micro-thermophotovoltaic applications, boasting better prospects than traditional 3D cylindrical counterparts. Naturally, flames exhibit an ellipsoidal morphology, and this inherent structure becomes unstable when the transition from 3D to 2D combustion hinders the formation of the natural flame structure—particularly the recirculation zone—thus necessitating the deliberate design and artificial construction of a 2D flame structure. Moreover, inherent micro-scale challenges, such as the high surface-to-volume ratio, excessive wall heat loss, and radical quenching, are further amplified, rendering its combustion mechanism far more complex than that of traditional 3D counterparts. Experimental results show notable performance advantages: as the total flow rate increases from 0.20 L/min to 0.40 L/min, the stability limit (equivalence ratio range) expands from 0.404 to 2.60 to 0.095–3.73; peak temperatures reach 728 K (surface) and 1826 K (simulated core); relative heat loss drops from 95.4% to 49.6%. Numerical simulations reveal a fully developed swirl field at high flows, forming a unique “annular anchoring–radial diffusion” flame structure (anchored along the chamber’s edge arc) that avoids central overheating and uneven temperature distribution plaguing cylindrical combustors. Bayesian network data mining identifies a “Velocity → H₂→Structure → Homogeneous/Heterogenous” causal chain (test-set precision: 0.7187), underscoring the need for multi-physical field analysis. This disk-type design overcomes cylindrical limitations, providing a scalable, vane-free solution for high-efficiency micro-combustion.