SUPPRESSION OF UNSTABLE FLOW IN CENTRIFUGAL BLOWERS BY THREE-DIMENSIONAL SEPARATION CONTROL

三维分离控制抑制离心风机不稳定流动

• 批准号: 10650183
• 负责人: ISHIDA Masahiro
• 金额: $ 2.3万
• 依托单位: NAGASAKI UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10650183/
• 关键词: CENTRIFUGAL BLOWER; UNSTABLE FLOW; 3-D SEPARATION; DIFFUSER STALL; INDUCER STALL; STALL MARGIN; WALL ROUGHNESS CONTROL; INLET RECIRCULATION; 人工循環流形成

In most low specific speed type centrifugal impellers having backward leaning blade, the unstable flow such as rotating stall occurs in the vaneless diffuser and it is caused by the 3-D boundary layer separation mainly on the hub side wall not on the shroud side wall. On the other hand, in most high specific speed type open shrouded centrifugal impellers with radial blade, the unstable flow is caused by the flow separation in the inducer due to the excessive deceleration of relative velocity. The objective of this study is to suppress the unstable flow in each type of centrifugal blower without deteriorating blower characteristics.By positioning the completely rough wall locally on the hub side diffuser wall alone in the vaneless diffuser, the flow rate of rotating stall inception was decreased by 42% at a small pressure drop less than 1%. This is based on the fact that the local reverse flow occurs firstly in the hub side in most centrifugal blowers with the backswept blade impeller. … More The 3-D boundary layer calculation shows that the increase in wall shear component normal to the main-flow direction decreases markedly the skewed angle of the 3-D boundary layer, and results in suppression of the 3-D separation. It is also clarified theoretically that the diffuser pressure recovery is hardly deteriorated by the rough wall positioned downstream of R=1.2 because the increase in the radial momentum change, resulting from reduction in the skewed angle of the 3-D boundary layer, supports the adverse pressure gradient.A ring groove arrangement was proposed to suppress unstable flow in a centrifugal blower with the radial blade impeller. The ring groove arrangement connects the impeller inlet upstream and the inducer throat tip, and forms an inlet recirculation through a bypass for the two regions. The inlet recirculation at small flow rates results in a decrease in the flow rate of unstab1e flow inception. An up to 8% improvement in surge margin was obtained by the ring groove arrangement at a small expense of the delivery pressure drop. A 3-D turbulent flow calculation was conducted to investigate effect s of the inlet recirculation on the main through-flow and unstable flow suppression in the impeller. The calculated results were compared with the experimental ones. It is found that the critical flow incidence is about 7.4 degrees for separation bubble formation at the blade leading edge, and the surge suppression is mainly due to decrease in flow incidence at the impeller leading based on the inlet recirculation flow. Less

在大多数具有后倾叶片的低比转速型离心叶轮中，在无叶扩压器中发生旋转失速等不稳定流动，并且其主要是由轮毂侧壁而不是围带侧壁上的三维边界层分离引起的。另一方面，在大多数高比转速型径向叶片开式闭式离心叶轮中，由于相对速度的过度减速，诱导轮中的流动分离导致不稳定的流动。本研究的目的是抑制不稳定的流动在每一种类型的离心鼓风机不恶化鼓风机的特性。通过定位在轮毂侧扩压器壁的局部完全粗糙的壁单独在无叶扩压器，旋转失速开始的流量减少了42%，在一个小的压力降小于1%。这是基于这样一个事实，即在大多数具有后掠叶片叶轮的离心式鼓风机中，局部回流首先发生在轮毂侧。 ...更多信息 三维边界层计算表明，垂直于主流方向的壁面剪切分量的增加显著减小了三维边界层的偏斜角，从而抑制了三维分离。理论分析还表明，在R=1.2的下游设置粗糙壁面，由于三维边界层斜角的减小，径向动量变化的增加，支持了逆压梯度的存在，使得扩压器的压力恢复几乎没有恶化。环形槽布置连接叶轮进口上游和诱导轮喉部尖端，并通过两个区域的旁路形成进口再循环。小流量下的进口回流导致不稳定流起始流量的减小。环槽布置以较小的出口压降为代价，使喘振裕度提高了8%。通过三维湍流计算，研究了进口回流对叶轮内部主流流动的影响及对叶轮内部不稳定流动的抑制。计算结果与实验结果进行了比较。结果表明，叶片前缘形成分离泡的临界冲角约为7.4 °，叶轮前缘的回流使冲角减小是抑制喘振的主要原因。少

项目成果

H. Ueki: "Laser 2-Focus Velocimeter for Flow Measurements in Turbomachinery"Turbomachinery. 28, No.5(in Japanese). (2000)

H. Ueki：“用于涡轮机械流量测量的激光 2 焦点测速仪”涡轮机械。

Ishida, masahiro: "Suppression of Rotating Stall in Vaneless Difusser by Wall Roughness Control"Proc. of 3rd Intrnational Conference on Pumps and Fans. 1. 232-241 (1998)

石田正宏：“通过壁粗糙度控制抑制无叶扩压器中的旋转失速”Proc。

Sun, Zixiang: "A Computional Study on Optimum Inducer Geometry for Stall Suppression in a Centrifugal Blower"Proceedings of ASME 2000 FED Summer Meeting in Boston, USA. FEDSM2000-11059 (印刷中). (2000)

孙子翔：“离心式鼓风机失速抑制的最佳导流轮几何形状的计算研究”美国波士顿 ASME 2000 FED 夏季会议论文集 FEDSM2000-11059（出版中）。

D. Sakaguchi: "Unstable Flow Supression by Ring Groove in a centrifugal Blower"Proc. Of 5th Joint Symposium of Nagasaki University and Cheju National University on Science and Technology. 1. 57-60 (1998)

D. Sakaguchi：“离心鼓风机中环槽的不稳定流动抑制”Proc。

Z. Sun: "Flow Analysis and Surge Supression in a Centrifugal Blower"Proc. Of 3rd Intl. Conf. on Pumps and Fans. 1. 204-214 (1998)

Z. Sun：“离心鼓风机中的流动分析和喘振抑制”Proc。