Recovery Process from Rotating Stall in a Fan
Recovery Process from Rotating Stall in a Fan
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DOI：
10.2514/1.46847
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发表时间：
2011-11
影响因子：
1.9
通讯作者：
Minsuk Choi;M. Vahdati
中科院分区：
文献类型：
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作者：
Minsuk Choi;M. Vahdati
基于网格-顶点有限体积法和混合单元非结构网格，采用隐式、时间精度、三维、可压缩的雷诺平均N-S方程，研究了跨音速风扇旋转失速的恢复过程。众所周知，将操作点从旋转失速移动到非失速状态所需的节气门开度比在失速开始时关闭节气门所需的大。这种称为滞后的现象对压缩机的运行有很大的影响，因为在某些情况下，即使节气门或喷嘴大开度，风扇也可能无法从失速中恢复。本文的目的是论证利用计算流体力学来捕捉风扇磁滞回线的可行性，并探索这一过程中的流动特性。本研究以现代民用设计中典型的宽弦风扇叶片为基准几何形状。用减小喷嘴面积的全环空模型模拟了70%设计转速下的旋转失速，当流量减小到超过近失速时，在机匣附近出现了部分跨度失速。然后逐渐打开喷嘴，内部气流从旋转失速恢复到非失速运行状态。正如预期的那样，数值预测的最终工况比近失速工况具有更高的质量流量和更低的总压比。将回收过程中的数值结果与在相似几何形状和流动条件下在试验台上获得的测量数据进行了比较。比较表明，两者在质量上是一致的。
An implicit, time-accurate, three-dimensional, compressible Reynolds-averaged Navier–Stokes solver, based on a cell-vertex finite volume methodology and mixed-element unstructured grids, was applied to the study of the recovery process from rotating stall on a transonic fan. It is well known that a larger throttle opening is required to move an operating point from rotating stall to an unstalled condition than for the throttle closing at stall inception. This phenomenon, referred to as hysteresis, has a significant influence on the compressor operation, since the fanmay not recover fromstall in some cases, in spite of a large opening of the throttle or nozzle. The objectives of this paper are to demonstrate the feasibility of using computational fluid dynamics for capturing the hysteresis loop of a fan and to explore the flow features during this process. Awide-chord fan blade, typical ofmodern civil designs, was used as the benchmark geometry for this study. Rotating stall at 70% of the design speed was simulated using a whole-annulus model bydecreasing the nozzle area.As themassflowratewas decreasedbeyond the near-stall condition, a part-span stall was seen to develop near the casing. The nozzle was then opened gradually and the internal flow recovered from rotating stall to an unstalled operating condition. As expected, the numerically predicted final operating condition had higher mass flow rate and lower total pressure ratio than those at near-stall condition. The numerical results during recovery were compared against the measured data, which were obtained on a test rig with an analogous geometry and flow conditions. The comparison showed qualitatively good agreement.