颗粒捕集器喷油助燃再生旋流式燃烧器流场特性分析

Flow Characteristic Analysis of Swirling Burner for Injection Combustion-supporting Regeneration of DPF

颗粒捕集器喷油助燃再生燃烧器内的流场分布对气流组织及油气混合有重要影响,而供风形式是燃烧器内流场特性的主要影响因素之一。为了在燃烧室内形成稳定持续的回流,促进油气混合进程,分别采用双矩形口切向供风和直片式轴向旋流器供风两种供气形式,设计等入口截面面积的两种供风系统结构,并在相同发动机排气和补气条件下对燃烧器冷流场进行仿真分析。分析结果表明,两种供风形式均能形成可回流到油气混合室端面的中心回流区,轴向旋流器供风时的中心回流区的长度、最大回流速度、突扩位置的重附着区长度分别比双矩形口切向供风时大8.11%,5.63%和9.59%,且轴向旋流器供风时的湍动能大于双矩形口切向供风。对比结果显示,利用轴向旋流器供风更有利于促进混合过程的进行,对气流的组织更合理。

The distribution of flow field in the swirling burner for fuel-injected regeneration diesel particulate filter has impor-tant influence on the organization and mixing of airflow and the style of supplying air is one of the main influencing factors. In order to form the steady and continuous backflow in the burner to promote the mixing of fuel and air, the air supply forms of dual rectangle inlet pipe and straight-vane axial swirler were put forward, the corresponding system structures based on the same inlet section were designed, and the simulation of burner cold flow field was carried out under the conditions of the same engine exhaust and air supply. The results show that both air supply forms can form a central backflow zone which can return to the end of the fuel and air mixing chamber. Compared with the dual rectangle inlet pipe,the length of central backflow zone, the maximum backflow velocity and the length of reattachment region in sudden expansion position increases by 8. 11% , 5. 63% and 9. 59% respectively. In addition, the turbulent energy of axial swirler is larger than that of dual rectangle inlet pipe. Ac-cordingly, the axial swirler is more helpful to the proceeding of mixing process and organization of air flow.