文氏管对旋流流场影响的数值研究

Numerical Simulation for Effects of Venturi Tube

关键词:  流场  文氏管  回流区  扩张角

Key words:  Flow field  Venturi  Recirculation zone  Divergence angle

摘要:

为了研究文氏管对旋流流场的影响，将文氏管+套筒组合的旋流器，通过与无文氏管的旋流器、带内文氏管的旋流器和带外套筒的旋流器这三种结构的性能对比发现，文氏管不仅对旋转射流起到过渡作用，使速度场周向分布均匀，而且对射流速度大小起到一定的调节作用；文氏管的存在可以使流场局部湍动能增大，但因文氏管结构的差异会造成旋流强度不同程度的变化，引起回流区尺寸变化；文氏管+套筒组合的旋流器不仅能提供较强的旋流流场，使火焰筒内回流区面积较大，而且对燃烧室进气压力的调节范围也较广，一定范围内能保证流场结构的稳定；此外，套筒扩张角的增大能促进回流区的径向扩张，使回流区宽度增大；存在一个临界的内文氏管扩张角57°，使文氏管+套筒组合的旋流器流场回流区结构出现分离，形成两个独立的回流区。

Abstract:

In order to investigate the effects of venturi on the swirling flow field，four kinds of swirlers which are respectively with no venturi，an inner venturi，an outer sleeve and both venturi and sleeve were studied. The results show that venturi not only can play the role of transition for the rotating jet that makes the velocity circumferential distribution uniform，but also can adjust the velocity magnitude. The existence of venturi can increase the turbulent kinetic energy of the local flow field，but it also may cause the variation of swirl intensity so that the recirculation zone size is changed. The swirler with both venturi and sleeve can provide the stronger swirl flow，so the recirculation zone area is larger. Also it has the wide adjustable range of the combustor chamber inlet pressure，so the structure of flow field is stable，besides，the increment of the sleeve divergence angle can promote the radial expansion of recirculation zone，so the width of recirculation zone increases. When the divergence angle of inner venturi reaches the critical angle of 57°，the recirculation zone in the case of the swirler with both venture and sleeve splits into two independent parts.