受限空间下散热对微火焰稳定性的影响

以无水液体乙醇为燃料,用铁铬合金电热丝为燃烧室内反应物加热,采用实验与数值模拟相结合的方法研究乙醇-空气小尺度层流扩散火焰散热对受限空间微火焰稳定性的影响。结果表明,采用电热丝向受限空间内的燃烧反应物加热,可以减少散热损失的影响,对稳燃有一定的帮助。电加热功率为合适值时,稳定燃烧极限最宽。电加热可提高火焰温度,增大化学反应速率,使火焰中心向上游移动。一定范围内,电加热功率的增幅大于散热的增幅,外加热功率对散热损失有抑制作用,增强微火焰的稳定性。

Effect of Heat Loss on Micro Flame Stability in Confined Space

The characteristics of ethanol-air microscale laminar-flow diffusion combustion were investigated. Combined with experimental study and numerical simulation, the effects of surface heat loss on the flame stability in the confined space were systematically analyzed. The surface heat loss was controlled by electrical heating inside. According to the results, the electrical heating reduced the effects of heat loss and enhanced the stability effectively. Using the appropriate electrical heating power, it reached the widest stability limits of combustion. The flame feature size and temperature distribution were both changed by the electrical heating. The electrical heating raised the flame temperature. The chemical reaction rate became bigger, and the micro-flame shifed upstream. Within a certain range, the electrical heating increase was greater than the increase of the heat loss. The electrical heating inhibited the heat loss and enhanced the stability.