This 3D numerical study investigates the combustion characteristics of methane-hydrogen blends in a high-pressure swirl burner for gas turbine applications. Hydrogen concentration is varied from 0% to 50% in steps of 5 % by volume for four thermal power levels (42KW, 84 KW, 126 KW, and 168 kW). The other parameters such as the inlet temperature as well as the fuel-air ratio were kept constant in order to analyze only the effect of the H2 addition and the power variation. Results demonstrate hydrogen enrichment mildly increases flame temperature and stabilizes the reaction zone without significantly disturbing the flow field. All cases exhibit coherent temperature evolution and steady flame fronts. NOx production shows an acceptable rise with hydrogen addition peaking at 6.2 ppm for 168 KW power and 50 % of H2. Results suggest this burner geometry can stably operate on methane-hydrogen mixtures up to 50% by volume hydrogen across a wide power band, offering promising prospects for gas turbine fuel flexibility.