FLAME SPREAD OVER LIQUID FUELS AT GRAVITY AND MICRO-GRAVITY CONDITIONS

重力和微重力条件下液体燃料上的火焰传播

• 批准号: 08044161
• 负责人: ITO Akihiko
• 金额: $ 2.82万
• 依托单位: OITA UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for international Scientific Research
• 财政年份: 1996
• 资助国家: 日本
• 起止时间: 1996 至 1997
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08044161/
• 关键词: Combustion; Liquid fuel; Flame spread; Micro gravity; Surface tension flow; Bouyancy; Flash point; Fuel vapor concentration; 微小重力

The phenomenon of flame spread over Liquid id of current interest because of its importance to fire safety and the curiosity of fundamental mechanism of the flame spread. To clarify the effects of gravity on flame spread the experimental research was excuted for measuring velocity, temperture and vapor concentration profies both in sub-flash and super-flash conditions using particle track laser sheet method, infrared thermography and dual-wave length holographic interferometry. These results were compaired with NASA's microgravity test conducted aboard a sounding rocket. Thefollowing conclusions are deduced ;1. Two circulation cells exist in the sub-surface liquid just ahead of the flame leading edge in sub-flash conditions, which are mainly controlled by the thermocopillary force, whiele the buoyancy force secondarily effects to circulation growth and chenges the temperature field in the sub-suface liquid. the circulation cells have 3-dimensional structure.2. The cold temperature zone … More exists in sub-surface liquid whose temperature is below flash point. The cold zone clearly obstruct crawing flame from shifting to jumping stage, because no substrantial fuel vapor is accumunilated ahead of flame leading edge. The jump phase occurs after the cold temperature valley disappears. The cold zone is derived by the interaction between the surface tension flow and buoyancy driven flow.3. the infrared image revealed that the cold zone in mug conditions is much larger than that of 1g conditions. The surface temperature in the cold zone in mug is not beyond the flash point, so that the flame steadily spreads with no pulsating in mug conditions.4. In gas-phase, two recirculation cells are created. One is formed in horizontal plane to the fuel surface, and the other is formed in vertical plane perpendicular to the fuel surface. Both circulation cells are formed when there is : (1) surface convection moving to the flame spread direction and (2) gas-phase convection in the free-stream air moving opposite to the flame spread direction. The recirculation cells contribute to make the flammable layr to be uniform.5. Even with forced air flow of the sama order of magnitude as that induced naturally by buoyancy in lg, the mug flame spreads steadily and very slowly, which spead is about half that of 1g. The absence of liquid-phase buoyancy in mug leads to a very differnt liquid-phase surface temperature filed. Less

火焰的现象分布在当前感兴趣的液体ID上，因为它对火灾安全的重要性以及火焰基本机制的好奇心。为了阐明重力对火焰扩散的影响，实验研究是使用颗粒轨道激光片方法，红外热摄影和双波长度全息摄影的速度，温度和蒸气浓度谱的精致。这些结果与NASA的微重力测试相比，在发声的火箭上进行。推导以下结论； 1。在亚闪存条件下，在火焰前缘之前的地下液体中存在两个圆形细胞，这些条件主要由热层次力控制，而浮力次要效应对循环生长的次要效应，并在亚面液体中的温度场降临。圆形细胞具有3维结构。2。冷温度区……更多的次面液体，其温度低于闪点。寒冷的区域显然会阻碍从转移到跳跃阶段的爬行火焰，因为没有不合格的燃料蒸气在火焰前缘之前积聚。跳跃相发生在冷温谷消失之后。冷区是由表面张力流与浮力驱动流量之间的相互作用得出的。3。红外图像显示，杯子条件下的冷区大得多，远大于1G条件。杯子中冷区的表面温度不超出闪点，因此火焰在杯子条件下静静地散布而没有脉动。4。在气相中，创建了两个再循环细胞。一种是在水平面到燃料表面的水平面形成，另一个是在垂直于燃料表面的垂直平面形成的。当存在时形成两个圆形细胞：（1）表面转换向火焰扩散方向，（2）在自由流空气中与火焰扩散方向相反的自由流空气中的气相结构。再循环细胞有助于使可燃烧的行动均匀。5。即使是SAMA数量级的强迫空气流动，因为LG在LG中自然引起的气流，杯子的火焰也会安静而缓慢地散布，这大约是1G的一半。杯子中没有液相浮力导致液态相表面温度非常不同。较少的

项目成果

小西忠司: "液体燃料の蒸発に伴う液面下の対流" 第46回応用力学連合講演会予稿集. 101-102 (1997)

Tadashi Konishi：“液体燃料蒸发导致的液体表面下的对流”第 46 届应用力学联盟会议记录 101-102 (1997)。

小西 忠司: "液体然料表面上を伝ぱする火炎先端近傍の濃度分布" 第35回燃焼シンポジウム講演論文集. (1997)

小西正：“液体天然材料表面传播的火焰尖端附近的浓度分布”第 35 届燃烧研讨会论文集（1997 年）。

T.Konishi: "Transient Two-Dimensional Fuel-Concentration Measuremen Technique" Applied Optics. 36,33. 8815-8819 (1997)

T.Konishi：“瞬态二维燃料浓度测量技术”应用光学。

T.Konishi: "Liquid Convection Underneath Fuel Surface due to Evaporati" Theoretical Applied Mechanichs. No.46. 231-236 (1997)

T.Konishi：“由于蒸发而导致燃料表面下的液体对流”理论应用力学。

A.Ito: "The Measurement of Transient Two-Dimensional profiles of Velocity and Fuel-Concentration over liquids" Proceedings of the ASME Heat Transfer Division. HDT-352. 141-148 (1997)

A.Ito：“液体上的速度和燃料浓度的瞬态二维分布的测量”ASME 传热部门的会议记录。