分级旋流火焰贫熄火特性试验与数值研究

Experimental and Numerical Study on Lean Blowout Characteristics of a Stratified Swirl Flame

依托分级旋流燃烧器,对3种旋流强度、3种空气分级比及4个预燃级当量比的熄火特性进行实验研究和数值研究。固定预燃级当量比,逐渐降低主燃级燃料流量直至熄火获得熄火边界。研究结果表明:预燃级当量比较高的分级旋流火焰,由于其火焰根部能够在很宽的范围内保持较为稳定的状态,因此该情况下的分级火焰熄火边界较宽。熄火主要经历火焰拉长、角涡回火、火焰沿轴向窜动等几个主要过程。采用数值方法能够捕捉到熄火过程的主要特征现象。对3种熄火极限预测方法进行讨论,选取特征温度法,制定新的熄火极限判定标准。得到适用于本研究分级旋流火焰的熄火极限预测方法。

Based on stratified swirl flame,the lean blowout characteristics of three swirl intensities,three air split ratios and four pilot stage equivalence ratios were studied by experimental and numerical methods.The blowout boundary can be obtained by gradually reducing the main stage fuel flow until blowout occurs with fixed pilot stage equivalence ratio.The results show that,the flame root can keep a stable state in a wide range when the pilot stage equivalence ratio is high.Therefore,the blowout boundary of the stratified flame in this case is wide.Blowout mainly includes several main processes such as flame lengthening,corner vortex flashback,and flame axial movement.The numerical method can capture the main characteristic phenomena of the blowout.The three prediction methods of blowout boundary are discussed.The feature temperature method is selected to determine the new blowout boundary judgment standard,and the prediction method of blowout boundary applicable to this study is obtained.