钝体形状对旋流燃烧器出口流场影响的数值研究

借助CFD软件,对配置中心钝体的双通道旋流燃烧器出口流场进行了冷态数值模拟,分别获得了锥型、楔型和抛物线型三种钝体后的流场分布、速度分布、中心回流区尺寸和中心回流量大小等结果.经对比分析发现：在其他条件相同的情况下,非流线形的锥型钝体和楔型钝体与接近流线形的抛物线型钝体相比,中心回流区的长度分别增加了24%和17%;中心最大回流量分别增加了18.3%和6.5%.在将抛物线型钝体燃烧器的旋流二次风量加大50%时,其中心回流区长度虽有所增加,但仍不能达到锥型钝体和楔型钝体的相当程度.研究结果表明：非流线型钝体比流线型钝体具有更大的中心回流区尺寸和回流量;钝体形状是影响出口流场特性的关键因素;与楔型钝体和抛物线型钝体相比,锥型钝体具有更好的稳燃效果.图7表1参7

Numerical Study of the Effect of Bluff Body Configuration on the Flowfield Behind Swirl Burners

A cold state numerical simulation of the flow field behind a dual duct swirl burner,fitted with a central bluff body,is performed by making use of CFD software,wherewith the flow field,the velocity distribution,the central recirculation zone's dimension and flow volume are obtained in cases of an inserted cone shaped,a wedge-shaped and a parabolic shaped bluff body.Comparison and analysis show that,with conditions remaining the same,the central recirculation zone is extended by 24% and 17% respectively more for the cases of the non-streamlined cone shaped and the wedge shaped bluff body as compared with the case of the quasi-streamlined parabolic bluff body;the maximal recirculation volume also increasing respectively by 18.3% and 6.5%.Though the central recirculation zone,in case of the parabolic bluff body can be made to get longer by increasing the burners secondary swirling air by 50%,but it fails to come up to the length observed in cases of cone and wedge shaped bluff bodies.Study results indicate that a non-streamlined bluff body's recirculation zone has larger dimension and encloses a larger flow volume;its configuration is the outlet flow field's critical influencing factor and it has a more favorable effect on combustion stability than wedge or parabolic shaped bluff bodies.Figs 7,table 1 and refs 7.