摘要
针对离心叶轮出口区域的流动分离问题,对影响离心叶轮出口流动分离的3种因素进行了数值研究。研究离心叶轮扩压度影响时发现:对于闭式叶轮,叶轮扩压度对出口的流动影响较大,当叶轮的进口与出口相对速度比大于2时,设计工况下叶轮出口出现了较大的流动分离区,这与传统的设计理论一致;对于半开式叶轮,设计工况下叶轮出口均出现了流动分离,且分离区的大小随着叶轮扩压度的增加而增大。研究叶顶间隙对离心叶轮出口流动分离影响时发现:叶顶间隙对叶轮出口流动分离区的大小影响显著,就所研究的叶轮而言,并非间隙越小分离区越小,当叶顶间隙为7.5%叶轮出口宽度时,叶轮出口流动分离区最小。研究叶片扩压器进口收敛角对半开式叶轮出口流动分离区的影响时发现,增大扩压器进口收敛角可以有效抑制叶轮出口的流动分离,但是收敛角过大,叶轮叶顶间隙区域附近的叶尖回流区增大,整级的气动性能降低。
The flow behavior near the centrifugal impeller outlet determines the impeller aerodynamic performance significantly and also influences the performance of the downstream components. The three factors affecting the impeller outlet flow separation were numerically investigated. For the shrouded centrifugal impeller, the impeller diffusion ratio has great influence on its outlet flow behavior; there is a large separation zone near the impeller outlet at the design flow rate when the centrifugal impeller inlet/outlet relative velocity ratio is above 2.0, which agrees with the conventional impeller design theories. For the unshrouded centrifugal impeller, there always exists a separation zone near the impeller outlet at the design flow rate when the inlet/outlet relative velocity ratio is high or low. The tip clearance has a significant influence on the scale of the impeller outlet flow separation zone. For the impeller studied here, the smaller tip clearance does not correspond to the smaller separation zone, and the separation zone is smallest when the tip clearance equals 7.5% of impeller outlet width. In addition, increasing the diffuser pinch angle is effective in controlling the impeller outlet flow separation, but an excessive pinch angle can enlarge the recirculation flow zone near the impeller tip clearance, which will lower the aerodynamic performance of the entire compressor stage.
出处
《西安交通大学学报》
EI
CAS
CSCD
北大核心
2013年第9期16-22,共7页
Journal of Xi'an Jiaotong University
基金
国家自然科学基金资助项目(50976085)
关键词
离心叶轮出口
流动分离
扩压度
收敛角
centrifugal impeller exit
flow separation
diffusion ratio
pinch angle
