旋流喷射器流动与燃烧特性研究

Study of Flow and Combustion Characteristics of Swirl Injector

为了给低旋流喷射器（LSI）推广应用提供理论依据,自行设计具有两种旋流叶片角LSI。应用数值模拟方法确定不同LSI旋流数,旋流数范围为0.417-0.881。利用粒子成像测速（PIV）测试系统,对流通气流LSI在方形通道内展向平面和铅垂截面二维速度分布进行测试。对开放空间内低旋流喷嘴,流通甲烷气体和空气预混合燃烧特性进行实验研究。研究结果表明：当叶片角θ=37°,旋流数S≤0.576时,旋流诱导中心区域和周围空气旋转,形成具有中心区域和周围空气低速区域、中心低速区域分布特点的扩散流动。当叶片角θ=37°,甲烷和空气当量比φ=0.7,S≤0.576时,流通LSI气流产生与展向截面流场分布相似的中部凸起呈＂W＂型脱体蓝色火焰。随着旋流数S增加,在0.576≤S≤0.588范围内,火焰与喷口间的距离缩短,火焰转变为＂扫帚＂型火焰。当S=0.623时,形成高旋流贴体火焰。增大旋流叶片角,流场的扩张角增加,环形旋流区和中心直流区轴向速度沿中心轴衰减更快。

In order to provide theoretical basis for the application of low swirl injector（LSI）,a low swirl injector which had two kinds of swirl vane angle（θ） was designed. Numerical simulation method was used to determine the swirl number of different LSI,and the range of swirl number S was 0.417-0.881. Using PIV（Particle image velocimetry） system,the distribution of the two-dimension velocity vector on a span wise section and a vertical section in a rectangle channel,which formed by the flow through the LSI,were tested. An experimental study was carried out,about the combustion characteristics of the premixed methane and air flow through the low swirl injector in an open space. The results show that swirl flow induced the central flow and surrounding air to rotate,and formed a divergent flow and the distribution characteristics of a central low velocity region,a surrounding low velocity region,and an annular high velocity region,as θ=37° and S≤0.576. The flow through the LSI generated a‘W＇shaped blue flame which there is a peak in central region,and was similar to the velocity vector distribution,as θ=37°,methane and air equivalent ratio φ=0.7 and S≤0.576. As 0.576≤S≤0.588,with the swirl number increasing,the bottom edge of the flame gradually approached the nozzle of the LSI,the Wshaped flame gradually turns into the‘broom＇shaped,and eventually transforms into high swirl flow,as S=0.623. With the vane angle increasing,the divergent angle of the divergent flow increased,the axial velocity of flow in the annular swirl flow region and the central straight flow axial velocity decayed faster along the axis line.