The flame propagation in a half-open tube was investigated experimentally. The experiment was done in various shaped tubes.(A straight tube, converging tubes and straight tubes with orifice) The images of flame propagation were pictured with HICCD(High speed intensified CCD) and the dynamic pressure of flame were measured by piezo pressure sensor.
By analyzing the images of the flame propagation, we found the features of flame propagation in various tubes. When the flame propagated in the converging area, the area of flame becomes larger and the velocity becomes faster. When the diameters of holes in open-side of tubes are equal, the flames propagate similarly in the early stage of flame propagation regardless of shapes of tubes.
By analyzing the images of the flame propagation, we found the time and distance of tulip-inversion. Regardless of the shapes of tubes, time of tulip-inversion is inversely proportional to the burning velocity and not affected by the shapes of tubes. But the distances of tulip-inversion have different tendency. When the diameter of a hole in open-side of tube was small, the distance of tulip-inversion was much smaller than that of straight tube. This fact caused by the deceleration of a flame when the diameter of a hole in open-side of a tube is small. The deceleration causes little effect on the time of tulip-inversion. The fact means that the process of tulip-inversion is dominated by the radial propagation of a flame.
