Effects of Fan Speed on Rotating Stall Inception and Recovery
Effects of Fan Speed on Rotating Stall Inception and Recovery
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DOI：
10.1115/1.4003243
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发表时间：
2010-10
影响因子：
1.7
通讯作者：
Minsuk Choi;M. Vahdati;M. Imregun
中科院分区：
文献类型：
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作者：
Minsuk Choi;M. Vahdati;M. Imregun
一个隐式的、时间精确的3D可压缩RANS求解器用于模拟现代风扇几何结构中的旋转失速开始和恢复，即所谓的旋转失速滞后。首先，采用全环空风机模型，在下游安装可变面积喷嘴，模拟了70%、80%和90%风机转速下的旋转失速。随着风扇转速的增加，失速单元的尺寸也增加，但失速单元的数量减少。一个大型失速单元预计将以80%和90%的速度沿环空旋转，而三个较小的单元以70%的速度旋转。在所有情况下，由于风扇叶片的高展弦比，回流被限制在近尖端区域，旋转失速不会发展成全跨失速。为了模拟失速恢复，在70%和90%的转速下，喷嘴面积逐渐增加，流量从旋转失速恢复到未失速运行状态。发现恢复过程受风扇转速影响。在70%的速度下，较大的扰动首先衰减，形成几乎对称的失速单元。此后，随着质量流量的进一步减小，失速细胞收缩成更小的失速细胞。在90%的风扇转速下，单个失速单元沿环空旋转，其消失导致恢复。试图解释失速开始和恢复模式对风扇速度的依赖。劳斯莱斯公司版权所有©2010
An implicit, time-accurate 3D compressible RANS solver is used to simulate rotating stall inception and recovery, the so-called rotating stall hysteresis, in a modern fan geometry. In the first instance, rotating stall was simulated for 70%, 80% and 90% fan speeds using a whole-annulus fan model with a variable-area nozzle downstream. As the fan speed is increased, the stall cell also increases in size but the number of stall cells decreases. One large stall cell is predicted to rotate along the annulus at 80% and 90% speeds, while there are three smaller cells at 70% speed. In all cases, the reverse flow is confined to the near-tip region and the rotating stall does not develop into a full-span stall because of the fan blade’s high-aspect ratio. To simulate stall recovery, the nozzle area was increased gradually at 70% and 90% speeds and the flow was seen to recover from rotating stall to reach an unstalled operating condition. The recovery process was found to be affected by the fan speed. At 70% speed, the large disturbances decay first to form almost symmetric stall cells. Thereafter, the stall cells shrink into smaller ones as the mass flow rate decreases further. At 90% fan speed, a single stall cell rotates along the annulus, the disappearance of which results in recovery. An attempt has been made to explain the dependence of the stall inception and recovery patterns on the fan speed.Copyright © 2010 by Rolls-Royce plc