双级轴向旋流器性能评估方法（一）——综合旋流强度的影响

开展了双级轴向旋流燃烧室反应流场和燃烧性能的理论与数值研究。发展建立了一种多级旋流器性能评估方法，提出了综合旋流强度和能量利用率两个准则数来对旋流器性能进行评估，研究发现，旋流强度和流阻系数是影响旋流器能量利用率的主要因素。采用数值方法研究了双级旋流之间的相互作用机理，结果表明:双级旋流器之间，一级旋流强度对回流区宽度影响较大；综合旋流强度是影响燃烧室整体性能的直接因素；当综合旋流强度小于0.43时，为弱旋流；综合旋流强度介于0.43～0.6之间时，为中等旋流，有十分弱小的回流区；当综合旋流强度大于0.6时，呈强旋流，一定会有回流区出现；当综合旋流强度大于1.03时，为非常强的旋流；综合旋流强度一定时，双级旋流能够增加收益，能量利用较好。通过与实验及数值结果比较发现，该多级旋流器性能评估方法能够对旋流器性能进行准确评估，为未来多级旋流器的设计与性能评估提供了一种实用有效的方法。 

Performance evaluation methods of two-stage axial swirler: Ⅰ influence of total swirling intensity

Theoretical and numerical studies on the reaction flow field and combustion performance of two-stage axial swirler combustors were carried out.A performance evaluation method of multi-stage swirlers was developed.In addition,the total swirl intensity and energy utilization efficiency were put forward to evaluate the swirler performance.It was found that the total swirl intensity and flow resistance coefficient were the main influential factors to the swirler energy utilization efficiency.The interaction between the two stage swirlers was investigated numerically.And the results indicate that the inner swirl intensity has a greater impact on the width of central toroidal recirculation zone (CTRZ).The total swirl intensity plays a most important effect on combustor overall performance.When the total swirl intensity is less than 0.43,weak swirling flows will be produced;when the total swirl intensity is between 0.43 and 0.6,medium strength swirling flows will be produced and weak CTRZs are presented;when the total swirl intensity is more than 0.6,strong swirling flows will be produced and moderate CTRZs are presented at the same time;when the total swirl intensity is more than 1.03,very strong swirling flows will be generated.If the total swirl intensity is constant,a two stage axial swirler will get better energy utilization efficiency than a single stage axial swirler.The results by the evaluation method are compared with the experimental and numerical results.It's found that the evaluation method for multi stage axial swirler performance can accurately evaluate the performance of swirlers,providing a practical and effective method for the design of multi-stage swirlers in the future.