离心风机涡旋结构及失稳流动特性分析

为了了解离心风机转子区域的失稳流动特性,基于SST k-ω湍流模型,探究了风机进流面非均匀流动特性与转子区域失稳流动的匹配关系,并基于涡动力学探究了转子失稳流道的涡旋尺度与结构.研究结果表明,在设计风量下,离心风机转子区域呈现明显的非均匀流动特性,可由气流速度、流动品质划分为稳流区和失稳区.同时,风机进流面流动特性与转子区域内流特性保持较好一致性,压力、速度、进流冲角皆呈现非均匀分布.进流面高速气流仅仅冲刷转子稳流区流道,而进流面低速流体在流经转子轴端后经由离心力的作用流至各个流道.通过使用进流冲角、环量、切向速度等方法,确定了额定工况下转子区域涡旋尺度、堵塞程度最为剧烈的流道,并通过湍动能及涡核分布成功捕捉堵塞流道的涡旋结构.

Analysis of vortex structure and unstable flow characteristics of centrifugal fan

In order to understand the unsteady flow characteristics in the rotor region of a centrifugal fan. The matching relationship between the non-uniform inlet flow characteristics and the unstable flow in the rotor region was investigated based on the SST k-ω turbulence model. The scale and structure of the vortex in unsteady flow path of the rotor based on vortex dynamics was studied. The results show that under the design flow condition, the rotor area of the centrifugal fan presents obvious non-uniform flow characteristics, which can be divided into stable flow area and blocking area according to the air velocity and flow quality. At the same time, the flow characteristics of the inlet surface of the fan are consistent with the flow characteristics in the rotor region, and the pressure, velocity and inlet attack angle are presented non-uniform distribution. The high-speed air on the inlet surface only scours the flow path in the stable flow area of the rotor, while the low-speed flow on the inlet surface flows to each flow passage through the centrifugal force after passing through the rotor shaft. By using the methods of inlet attack angle, circular rector and tangential velocity, the channel with the most severe vortex size and blockage degree in the rotor area under rated condition is determined, and the vortex structure in the unstable channel is successfully captured by TKE and the vortex core distribution.