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对于非预混火焰来说,燃烧反应区被扩散掺混作用控制,火焰体现出比较强的分布式特征,在扰动较大的情形下,火焰面会出现被撕裂的特征。这种情况下,热斑的产生和演化问题就成了非预混火焰稳定性研究中的一个重要问题。以一个理想二维平板非预混火焰为研究对象,在伯克-舒曼经典假设的前提下,通过格林函数法理论计算非预混火焰热斑的产生与演化的整个过程。研究发现较小的St数、较大的Pe数以及较快的对流速度有利于热斑向燃烧区下游的传播。这些结果将有助于理解非预混燃烧不稳定性的相关机理以及发展相应的控制方法。
For the non-premixed flame, the combustion reaction zone is controlled by the diffusion mixing. The flame shows a strong distributed characteristic. In the case of large disturbance, the flame surface will be torn. In this case, the problem of hot spot generation and evolution becomes an important issue in the study of non-premixed flame stability. Taking an ideal two-dimensional slab non-premixed flame as the research object, the whole process of the generation and evolution of non-premixed flame hot spots was calculated by Green’s function theory under the premise of the classic Burke-Schumann assumption. It is found that the smaller St number, the larger Pe number and the faster convective velocity facilitate the propagation of hot spots to the downstream of the combustion zone. These results will help to understand the related mechanisms of non-premixed combustion instability and develop corresponding control methods.