Turbulent combustion characteristics of premixed gases in a packed pebble bed at high pressure
Turbulent combustion characteristics of premixed gases in a packed pebble bed at high pressure
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DOI：
10.1016/j.proci.2010.05.071
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
Masaki Okuyama;Takuro Suzuki;Yasuhiro Ogami;M. Kumagami;Hideaki Kobayashi
中科院分区：
文献类型：
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作者：
Masaki Okuyama;Takuro Suzuki;Yasuhiro Ogami;M. Kumagami;Hideaki Kobayashi
为了研究高压下填充床内CH 4/空气传播火焰的燃烧特性，在较宽的环境压力和流速范围内对填充床内CH 4/空气传播火焰进行了实验研究。重点研究了在高压下火焰厚度小于填充床空隙尺度的情况下湍流火焰的传播。在压力为0.1-1.0MPa、流速为5- 130 cm/s的条件下，用高速摄像机成功地测量了火焰速度，并研究了火焰速度与压力、流速、卵石直径和卵石雷诺数Rep之间的关系。在高压下的湍流测量也进行了使用2-D的伪填充卵石床，以调查在流动通道中的湍流强度和估计的湍流火焰结构。火焰传播实验结果表明，填充床中的火焰速度在Re = 150时有一个极小值，并随着流速和压力的增加而迅速增大。湍流测量结果表明，火焰传播模式的这种变化是由压力增加时从层流到湍流的转变引起的。在高压下填充床中的火焰速度Sr与湍流燃烧速度ST之间存在显著的相关性，该湍流燃烧速度ST是根据湍流测量结果和小林等人先前对湍流预混本生火焰的研究估算的，表明在高压下具有和不具有填充卵石的湍流预混燃烧之间的相似性。在高压下传播过程中的火焰熄灭也被视为以及在常压下，熄灭机制被解释的基础上，在湍流火焰和湍流传热的卵石之间的热释放的竞争。
An experimental study on CH4/air propagating flames in a packed pebble bed was performed over a wide range of ambient pressures and flow velocities to clarify the combustion characteristics in a packed bed at high pressure. It focused on the turbulent flame propagation in cases that the flame thickness was sufficiently smaller than the void scale of the packed bed at high pressure. The flame speed was successfully measured at pressures of 0.1–1.0MPa and flow velocities of 5–130cm/s using a high-speed video camera, and then the relationships between the flame speed and pressure, flow velocity, pebble diameter and pebble Reynolds number, Rep, were examined. Turbulence measurements at high pressure were also conducted using a 2-D pseudo packed pebble bed to investigate the turbulence intensities in the flow channels and the estimated turbulent flame structure. Results of flame propagation experiments showed that the flame speed in a packed bed had a minimum value at Rep≅150 and rapidly increased with the increase of the flow velocity and pressure. Results obtained in the turbulence measurements indicated that this change of the flame propagation mode was caused by the transition from laminar to turbulent flow when the pressure increased. A significant correlation was seen between the flame speed in a packed bed, Sr, at high pressure and the turbulent burning velocity, ST, estimated from the results of turbulence measurements and previous studies on turbulent premixed Bunsen flames by Kobayashi et al., indicating the similarity between the turbulent premixed combustion with and without packed pebbles at high pressure. Flame extinction during propagation at high pressure was also seen as well as at ordinary pressure, the extinction mechanism being explained based on the competition between the heat release in turbulent flames and turbulent heat transfer to the pebbles.