过贫当量比下贫预混旋流燃烧室点火燃烧特性

为确保贫预混旋流燃烧室能在过贫当量比条件下具有良好的点火性能,基于不同的点火燃料比,对贫预混旋流燃烧室在过贫当量比为0.013~0.502条件下的点火燃烧特性进行了实验研究.结果表明:在点火燃料比为10%、15%和20%条件下,贫预混旋流燃烧室能够分别在当量比区间为0.063~0.251、0.042~0.377和0.050~0.502内成功点火,并通过实验结果拟合计算出最小点火当量比分别为0.063、0.039和0.011;而燃烧室在点火燃料比为5%条件下均点火失败;随着当量比的减小,由于空气流量的增加而导致燃烧室出口温升逐渐减小,燃烧室烟气排放中CH4和CO浓度增加,燃烧效率也随之降低;虽然燃烧室在高点火燃料比时能够在更贫的当量比条件下点火成功,但由于过多的空气流量而导致燃烧室燃烧效率降低和污染物排放增多.保持一定的点火燃料流量对贫预混旋流燃烧室在过贫当量比条件下高效快速启动十分有利.

Combustion characteristics of ignition processes for lean premixed swirling combustor at ultralow equivalence ratios

To have good ignition performance of lean premixed swirling combustor (LPSC) at ultralow equivalence ratios, this paper researched experimentally the combustion characteristics of ignition processes for LPSC at the ultralow equivalence ratio conditions of 0.013~0.502 based on different conditions of ignition fuel ratio (F_n). The results indicate that, when F₂=10 %, F₃=15 % and F₄=20 %, LPSC can ignite successfully at the equivalence ratio intervals of 0.063-0.1,0.042-0.377 and 0.05-0.502 respectively, and the minimum values of equivalence ratio for ignition process are respectively 0.3,0.039 and 0.011 by the fitting calculations of experimental results, but LPSC fails to ignite at F₁=5 %. With decreasing equivalence ratio, the outlet temperature rise has a drop due to the increase of air massflow, which can lead to the rising of CH₄ and CO concentrations and the deceasing of combustion efficiency simultaneously. LPSC can ignite successfully at relatively low equivalence ratio for high F_n, but in which combustion efficiency deceases and pollutant emissions rise because of too much air massflow. Thus, keeping a certain massflow of ignition fuel is beneficial for high-efficiency and rapid startup of LPSC at ultralow equivalence ratio.