Study on Pressure Oscillation Characteristics of Methane Mixed With Hydrogen in Long Straight Tubes
This paper investigates the combustion and pressure oscillation characteristics of CH4-H2/air.Flame development images and pressure oscillation data were measured on a long straight tube combustion platform with initial pressures of 0.15 and 0.1 MPa,initial temperatures of 298 K,hydrogen mixing ratio range of 0 to 100％,equivalence ratio range of 0.8 to 1.5,and tube length-diameter ratios of 1.43,1.86,and 2.29.There are single point and double point ignition modes.The results indicate that the finger shaped flame stage is an important stage for the formation of strong compression waves,and the flame acceleration time and propagation speed are both factors that affect the intensity of compression waves.As the hydrogen mixing ratio increases,the overall trend of pressure oscillation intensity increases,with the main frequency distribution ranging from 3080 Hz to 3470 Hz.Under dual ignition conditions,the pressure peak,rise rate,and oscillation intensity at various aspect ratios are higher than those of single ignition,and the main frequency distribution of oscillation is the same as that of single ignition.
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