关键词: 预旋系统；叶型喷嘴；无量纲叶高；流量系数；预旋效率

Abstract: Preswirl nozzle is regarded as an important part of the preswirl system，whose performance is directly related to the temperature drop of preswirl system . The cascade vane preswirl nozzle with the same outlet area，with the preswirl angle of 12° and with the non-dimensional blade height of 0.12，0.25，0.5，1，2 ，were numerically simulated respectively under pressure ratio range from 1.1 to 1.9. The computational models are standalone models which contain only the inlet chamber，preswirl nozzle and exit chamber. The investigated parameters are velocity contour，outlet velocity，outlet flow angle，discharge coefficient and preswirl effectiveness. The flow characteristics of simple drilled hole nozzle，aerodynamic hole nozzle and cascade vane preswirl nozzle are compared as well. Results show that the discharge coefficient and preswirl effectiveness of the cascade vane preswirl nozzle increased by more than 20%，compared with that of the simple drilled hole，and the preswirl effectiveness of the cascade vane preswirl nozzle increased by about 5%，compared with that of aerodynamic hole. Both the discharge coefficient and preswirl effectiveness increase with the increase of pressure ratio. Discharge coefficient and preswirl effectiveness increase firstly and then decrease slightly with the increase of non-dimensional blade height. When non-dimensional blade height is less than 0.5，the discharge coefficient and preswirl effectiveness of the cascade vane preswirl nozzle will decrease remarkably.

Key words: Preswirl system；Cascade vane preswirl nozzle；Non-dimensional blade height；Discharge coefficient；Preswirl effectiveness