Experimental and modeling study on the geometric characteristics of inclined hydrogen-blending natural gas jet flames

The geometry and size of hydrogen-blended natural gas (HBNG) jet flames are key parameters that determine their potential to trigger a series of accidental events, such as domino effects. This study experimentally investigated HBNG jet flames with hydrogen ratios of 0∼30%, inclination angles of −30° to 30°, and volume flow rates of 10∼40 L/min. A MATLAB code was used to extract the trajectory, projection distance, flame envelope boundary (side view), and flame widths of 50% intermittency flame. The results show that the flame-envelope boundary, horizontal projection distance, vertical projection distance, maximum flame width, and trajectory length decrease with increasing hydrogen blending ratio. As the jet inclination angle varies from negative to positive, the curvature of the flame trajectory gradually decreases, whereas the flame trajectory length increases. The effect of volume flow rate on the vertical projection distance becomes more pronounced at larger positive or negative inclination angles. Furthermore, a predictive method was established to determine the trajectory and envelope boundary of inclined HBNG jet flames. The flame trajectory was obtained by solving an integral model, the flame length was obtained by a correlation based on the flame Froude number, and the flame envelope boundary was calculated using a two-stage approach.