壁面冷却空气对贫油吹熄特性影响的激光诊断研究  

Laser Diagnostics on the Effect of Wall Cooling Air on the Lean Blow-Off Characteristics

作　　者：王金石 苏守国 苏利民 蔡骁 王金华[1] 黄佐华[1] WANG Jinshi;SU Shouguo;SU Limin;CAI Xiao;WANG Jinhua;HUANG Zuohua(State Key Laboratory of Multiphase Flow in Power Engineering,Xi’an Jiaotong University,Xi’an 710049,China)

机构地区：[1]西安交通大学动力工程多相流国家重点实验室,西安710049

出　　处：《西安交通大学学报》2024年第4期64-74,共11页Journal of Xi'an Jiaotong University

基　　金：国家自然科学基金资助项目(52106183);中国博士后科学基金资助项目(2023T160513);中央高校基本科研业务费资助项目(xzy012022069)。

摘　　要：针对燃烧室中冷却壁面的冷却气膜会影响燃烧室内的流场、改变回流区结构,从而影响贫油吹熄特性这一问题,在一带有气膜冷却的旋流燃烧室上开展了不同壁面空气占比下的贫油吹熄极限测量。结果表明:壁面冷却空气占比达到0.2时,不同燃油流量下,以全局空气流量计算,燃烧室吹熄当量比降低的范围在0.09~0.1之间;以主流空气计算,吹熄当量比降低范围在0.01~0.028之间。为了更加深入研究这一规律的原因,开展了平面激光诱导荧光(PLIF)激光诊断测量,可知引入壁面冷却空气后,OH基更集中分布在靠近燃烧室底部的火焰根部。在稳定火焰工况中,与近吹熄火焰相比,在燃烧室底部附近的火焰中央有大量OH基分布,这将有助于火焰的稳定,并拓宽贫油吹熄极限。米氏散射实验结果表明,引入壁面冷却空气后可使燃油液滴更集中分布在燃烧室底部附近,这将导致根部火焰局部当量比提高,易于形成稳定的火焰。结合所得实验结果,在所使用的旋流模型燃烧室内,加入占比为0.2的壁面冷却空气,可以拓宽燃烧室的贫油吹熄极限,有助于火焰的稳定。研究结果有望对带有冷却气膜的燃烧室的燃烧稳定性调控问题提供一定的理论指导。The utilization of an air film for cooling the wall in the combustion chamber has an impact on the flow field and changes the structure of the recirculation zone,thus affecting the lean blow-off characteristics.To address this problem,measurements of the lean blow-off limit were conducted under different wall cooling air ratios in a swirl combustion chamber with cooling air.The results indicate that when the proportion of wall cooling air reaches 0.2,the reduction of the blow-off equivalent ratio of the combustion chamber calculated by the global air flow rate shall range from 0.09 to 0.1 under different fuel flow rates.The reduction of the blow-off equivalent ratio calculated by mainstream air shall range from 0.01 to 0.028.To further investigate the reasons for this phenomenon,plane laser induced fluorescence laser diagnostic measurements were conducted.The results show that after the addition of wall cooling air,the distribution of OH shall be more concentrated at the flame root near the bottom of the combustion chamber.Under stable flame conditions,a substantial amount of OH distribution is observed in the center of the flame near the bottom of the combustion chamber,compared with near blow-off flame conditions.It facilitates flame stabilization and expands the lean blow-off limit.Results from the Mie scattering experiment show that the addition of wall cooling air can result in an enhanced concentration of fuel droplets near the bottom of the combustion chamber,thus leading to an increase in the local equivalence ratio of the root flame and facilitating the formation of a stable flame.In combination with the experimental findings,it is evident that the addition of wall cooling air at a proportion of 0.2 can expand the blow-off limit in a swirl combustion chamber and contribute to the flame stability.The research results are expected to provide some theoretical guidance for the control of combustion stability in combustion chambers equipped with cooling air films.

关 键 词：壁面冷却空气 贫油吹熄 旋流喷雾燃烧 平面激光诱导荧光 

分 类 号：TK16[动力工程及工程热物理—热能工程]