| Summary: | In 2020, energy-related CO<sub>2</sub> emissions reached 31.5 Gt, leading to an unprecedented atmospheric CO<sub>2</sub> level of 412.5 ppm. Hydrogen blending in natural gas (NG) is a solution for maximizing clean energy utilization and enabling long-distance H<sub>2</sub> transport through pipelines. However, insufficient comprehension concerning the combustion characteristics of NG, specifically when blended with a high proportion of hydrogen up to 80%, particularly with minority species, persists. Utilizing the heat flux method at room temperature and 1 atm, this experiment investigated the laminar burning velocities of CH<sub>4</sub>/NG/H<sub>2</sub>/air/He flames incorporating minority species, specifically C<sub>2</sub>H<sub>6</sub> and C<sub>3</sub>H<sub>8,</sub> within NG. The results point out the regularity of <i>S<sub>L</sub></i> enhancement, reaching its maximum at an equivalence ratio of 1.4. Furthermore, the propensity for the enhancement of laminar burning velocity aligned with the observed thermoacoustic oscillation instability during fuel-rich regimes. The experimental findings were contrasted with kinetic simulations, utilizing the GRI 3.0 and San Diego mechanisms to facilitate analysis. The inclusion of H<sub>2</sub> augments the chemical reactions within the preheating zone, while the thermal effect from temperature is negligible. Both experimental and simulated results revealed that CH<sub>4</sub> and NG with a large proportion of H<sub>2</sub> had no difference, no matter whether from a laminar burning velocity or a kinetic analysis aspect.
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