前缘弯掠子午加速叶轮尾缘脱落涡的研究

本文采用DPIV实验研究方法,在不同转速工况下,对开式前缘弯掠子午加速风扇转子叶尖涡在叶轮尾缘的脱落流动现象进行了测量.结果表明:在不同转速下,转子尾缘处均存在明显的叶尖涡流动现象.该叶尖脱落涡流动现象具有相似性,随着转速的增大,叶尖涡区和吸力面之间的径向速度差增大,叶尖涡强度随转速增加而增强.随着转速的增大,叶尖涡和主流相互作用加剧,涡量负值增大,叶尖涡影响区域也逐渐扩大.径向速度梯度同样随转速增大而增大的结果,增强了叶尖涡对尾迹区作用的影响.最后,本文通过CFD对该开式风扇叶尖涡流动现象进行模拟,其结果给出了相似的叶尖涡在转子尾缘脱落流动现象,为前缘弯掠开式子午加速风扇在户室中央空调室外机上的应用和风机系统的优化设计及其降噪研究提供了重要的内流数据.

AN EXPERIMENTAL INVESTIGATION ON SHEDDING VORTEX FLOW OF LEADING EDGE SKEWED-SWEPT ROTOR

The tail-edge shedding vortex of an open skewed-swept flow rotor with meridian acceleration is measured at different rotary speed by DPIV measurement technology. The result shows that the tail-edge shedding vortex is visualized near the tail-edge of the blade tip. And the characteristic of shedding vortex flow structure is of similarity at various rotary speed of rotor blade. When rotary speed increases, vorticity intensity rises and differential magnitude of velocity vectors between vortex area and blade suction surface ascends. Furthermore, the interaction effect between tip vortex and main flow aggravates, the areas of negative vorticity intensity increases, and the effect range of shedding vortex extends. As the radial velocity gradient is intensified with the rotary speed, the effect of the shedding vortex on trailing wake is boosted up. Finally, a comparison is made between the PIV data and the CFD simulated results on internal flow, numerical analysis is based on the three-dimensional Navier-Stokes equations coupled with Turbulence model, it is shown that the similar flow phenomenon emerges on tail-edge of blade tip. The experimental and numerical results provide important data of internal flow for the optimization, the noise reduction and application of the leading edge skewed-swept rotors on the outdoor unit of the central air conditioners.