【摘要】 紊流扩散火焰存在于各类燃烧室之中。火焰中的浓度场(燃烧场)对于炉内的温度分布及热交换过程有重要影响。本文运用紊流射流理论,考虑到曾被前人忽略了的化学反应对流场密度分布的影响,从而得到更切合实际的浓度分布方程。此外,考虑到未混合度对燃烧反应产生的滞后作用,对浓度计算公式引入了修正系数。采用微型火焰浓度取样分析装置,测定了氢火焰中的浓度分布,其理论计算的浓度分布与实验结果是一致的。本研究将为进一步研究工业火焰的燃烧场提供基础。更多还原

【Abstract】 Turbulent diffusion flames can be found in various kinds of combustion chambers and flames. Research for the distribution of gas concentration in diffusion flames is of great importance to heat exchange and temperature distribution in combustion chambers or heating furnaces. Introducing the theory of turbulent motion, this paper takes the effect of chemical reactions on the density of gas mixture into account which was neglected in some previous works. Thus, the equations describing gas concentration distribution in turbulent diffusion flame are given as expressed by eq. 27, 28 and 29, which are probably geared further to the actual circumstance. A factor β, determined by tests, is introduced to modify the mixture fraction equivalent f such, that the delay of chemical reactions in combustion by unmixedness due to concentration fluctuation is then taken into consideration. The concentration of species in the free-jet hydrogen diffusion flames are measured by a microprobe sampler system (see Fig.2 and 3) for determining their axial and radial distribution. The results are shown as in Fig.4~11, in which the predicted calculation by using the above for-mulas is quite consistent with the experimental data. The present work is expected to lay the foundations for further research works on the concentration field in industrial flames.更多还原