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Analysis of the Unsteady Flow Field at Stall Conditions for a Low-Speed Low-Pressure Ratio Axial Fan With Full-Annulus Simulation
参考中译:低速低压比轴流通风机失速非定常流场全环空模拟分析


          

刊名:Journal of turbomachinery
作者:Bousquet, Yannick(Univ Toulouse)
Binder, Nicolas(Univ Toulouse)
Rojda, Ludovic(Univ Toulouse)
Thacker, Adrien(Univ Toulouse)
刊号:784B0012
ISSN:0889-504X
出版年:2022
年卷期:2022, vol.144, no.11
页码:111008
总页数:10
分类号:TK
关键词:compressor stallsurgeoperabilityfancompressorsimulationINCEPTION
参考中译:压缩机失速;喘振;可操作性;风扇;压缩机;模拟;启动
语种:eng
文摘:The present work analyzes the three-dimensional unsteady flow structure of a low-speed low-pressure ratio axial fan stage operating at stall conditions. Unsteady numerical simulations were conducted with the elsA software, which solves the unsteady Reynolds-averaged Navier-Stokes (URANS) equations on a full-annulus calculation domain for the rotor and the stator. The analyses will focus on a near stall operating point, the stall inception mechanisms, and the final rotating stall pattern. Numerical simulations are confronted with experimental measurements from high-frequency Kulite transducers mounted on the casing near the rotor blades and the stator blades. The results show that boundary layer separation occurs on the stator blade close to the hub region at near stall conditions. The reverse flow interacts with the main flow to form a vortex shedding phenomenon. The frequency is not clocked with the blade passage frequency, requiring unsteady full-annulus methodology even for a stable operating point. It is also shown that the final state of the rotating stall region is composed of a single part-span cell that occupies three-quarters of the circumference and rotates at 60% of the shaft speed. This pattern agrees with the experimental measurements in terms of both the number of cells and the rotational speed. Finally, the paper demonstrates that without inlet distortion, the mechanism of the onset of the rotating stall is incorrectly predicted by the simulation. However, when a total pressure inlet distortion is applied, the computational fluid dynamics produces the same inception mechanism that is observed experimentally.
参考中译:本文分析了低速低压比轴流风机级在失速工况下的三维非定常流动结构。采用ELSA软件进行了非定常数值模拟,在全环空计算区域内求解了转子和定子的非定常雷诺平均N-S方程。分析的重点将集中在近失速工作点、失速起始机制和最终的旋转失速模式。数值模拟与安装在转子叶片和定子叶片附近的机壳上的高频Kulite换能器的实验测量结果相吻合。结果表明,在近失速条件下,定子叶片靠近轮毂区域存在边界层分离现象。逆流与主流相互作用,形成旋涡脱落现象。该频率不与叶片通过频率同步,即使在稳定的工作点也需要不稳定的全环距方法。结果还表明,旋转失速区的最终状态是由一个占据四分之三圆周、以60%的轴速旋转的部分跨度单元组成。在细胞数目和转速方面,这一模式与实验测量结果一致。最后,通过仿真验证了在没有进气道变形的情况下,旋转失速发生的机理没有得到正确的预测。然而,当施加总压进口扭曲时,计算流体力学产生了与实验观察到的相同的初始机制。