Characteristics of Rotating stall in High Specific Speed diagonal Flow Fan and Suppression of Rotating Stall

高比速斜流风机旋转失速特性及旋转失速的抑制

• 批准号: 09650198
• 负责人: KANEKO Kenji
• 金额: $ 1.22万
• 依托单位: Saga University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1997
• 资助国家: 日本
• 起止时间: 1997 至 1998
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09650198/
• 关键词: Turbomachine; Diagonal Flow Turbomachine; Rotating Stall; Internal Flow; Suppresion of Rotating Stall; Improvement of Unstable Characteristics; 斜流ターボ羽根車; Turbomachine; Diagonal Flow Turbomachine; Rotating Stall; Internal Flow; Suppresion of Rotating Stall; Improvement of Unstable Characteristics; 斜流ターボ羽根車

In order to clarify the characteristics of rotating stall in a high specific speed diagonal flow fan with specific speed of 1620, and to propose an improved design for suppressing the rotating stall, experimental investigation has been conducted from the viewpoint of unsteady internal flow. The main results obtained are as follows.The rotating stall of the fan is observed in the range of low flow coefficient where total pressure curve indicates unstable character with positive gradient. Hysteresis appears in the pressure characteristics for small tip clearance only. The rotating stall disappears with increased tip clearance.The number of rotating stall cell is one, its speed is about 77% of the rotor speed. The cell occupies about 3/4 circumference and about 1/3 span at tip region.Velocity fluctuation in the cell is very strong at tip region and it becomes weak with decreasing radius.The inlet flow field with rotating stall is as follows. The flow outside of cell is similar to that of high flow region with regular variation by blade passing frequency. In the cell region flow field is very irregular, flow direction changes positive and negative.Total pressure field at rotor exit is measured with dual-phase-lock method. Total pressure is high in the cell region and its distribution is such that higher pressure is indicated at pressure side of the blade. Decay of the stall cell is very slow compared with decay of high pressure region with tip vortex.Two types of casing treatments with separator ring are developed and tested. With one of them the rotating stall is completely suppressed and fan characteristics curve is stabilized with negative gradient at low flow region. This is realized with little decrease in fan efficiency of 2% at design condition.The effectiveness of the casing treatment is discussed with the results of internal flow measurement from the viewpoint of unsteady flow.

为了阐明以1620的特定速度在高比对角线流风扇中旋转失速的特征，并提出了改进的设计以抑制旋转摊位，从不稳定的内部流动的角度进行了实验研究。所获得的主要结果如下。在低流量系数的范围内观察到风扇的旋转失速，而总压力曲线表明特征不稳定，呈正梯度。滞后仅出现在小尖端间隙的压力特征中。旋转摊位随着尖端间隙的增加而消失。旋转失速单元的数量是一个，其速度约为转子速度的77％。该单元在尖端区域占据约3/4圆周，大约1/3跨度。细胞在尖端区域的效率波动非常强，并且随着半径的减小而变得较弱。旋转失速的入口流场如下。细胞外部的流量与高流量区域的流动相似，并通过叶片传递频率定期变化。在细胞区域的流场非常不规则，流动方向变化正和负。转子出口处的局部压力场是用双相锁定方法测量的。总压力在细胞区域很高，其分布非常高，以至于在刀片的压力侧表示较高的压力。与尖端涡流的高压区域的衰减相比，失速细胞的衰减非常慢。开发并测试了两种类型的带有分离器环的套管处理。使用其中一个，旋转摊位被完全抑制，风扇特性曲线在低流动区域的负梯度稳定。这是在设计条件下的风扇效率降低2％的几乎没有降低的。从不稳定流量的角度来讨论套管处理的有效性。