特集—多様化する燃料
可燃性ガスハイドレートの燃焼特性
2011 年 53 巻 164 号 p. 69-77
詳細
2011 年 53 巻 164 号 p. 69-77
Characteristics of flame propagation over combustible hydrates, methane hydrate and natural gas hydrate, in a laminar flat plate boundary layer has been investigated experimentally. The fine powder hydrate is packed in an insulated container and set flush with the bottom wall of the wind tunnel. The free stream velocity (U∞) is varied from 0.4m/s to 1.1m/s. The hydrate is ignited at the downstream end of the container when the surface temperature at the center of the hydrate surface reaches that at the igniton (Ts,ig). Ts,ig is varied from -80℃ to -20℃. The motion of the flame propagation is recorded by a digital video camera. The location of the leading flame edge is measured by using the image of the video camera. Two types of flame propagation are observed. When Ts,ig is low, the flame propagates almost linearly with time with the velocity around 3-4mm/s. In this case, the flame propagation velocity is determined by the dissociation rate of the hydrate. When Ts,ig is relatively high, the periodic flame propagation is observed. The maximum flame propagation velocity reaches around 800mm/s. In this case, the premixed mixture is formed over the hydrate surface because the hydrate can dissociate in the atmospheric condition and the flame propagates in the premixed mixture.
