Study on Mechanism of Unstable Flow Inception at Small Flow Rates in a Centrifugal Blower

离心鼓风机小流量不稳定流动萌生机理研究

• 批准号: 14550154
• 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: 2002
• 资助国家: 日本
• 起止时间: 2002 至 2003
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-14550154/
• 关键词: Centrifugal Blower; Unstable Flow at Small Flow Rate; CFD Analysis; Inducer Stall; Diffuser Stall; Improvement in Stall Margin; Formation of Inlet Recirculation; Reduction of Diffuser Width; ディフューザ失速; 低流領域不安定流動; Centrifugal Blower; Unstable Flow at Small Flow Rate; CFD Analysis; Inducer Stall; Diffuser Stall; Improvement in Stall Margin; Formation of Inlet Recirculation; Reduction of Diffuser Width; ディフューザ失速; 低流領域不安定流動

In order to clarify the mechanism of the unstable flow inception in a high specific speed type open shrouded centrifugal impeller, and to analyze the effect of the ring groove arrangement on inducer stall and/or that of the diffuser width on diffuser stall, the 3-D turbulent flow simulation and the experimental work were performed. It was found that the steady flow simulation was very helpful for understanding unsteady stall phenomena, and the following concluding remarks were obtained.(1)The incipient unstable flow is caused by the rolling-up vortex flow near the pressure side of the adjacent blade, resulting from the interaction between the tip leakage flow and the accumulated reverse flow zone, in which the strong streamwise vorticity component seems to be included due to the tip leakage vortex.(2)The formation of inlet recirculation is very effective for suppression of the unstable flow due to inducer stall, one factor is the suction of the tip leakage vortex together with the reve … More rse flow, and another one is a decrease in the flow incidence due to an increase in the inlet recirculation flow rate, which increases with a decrease in the through-flow rate.(3)The optimum location of the suction ring groove is in the region near the inducer tip throat, resulting i n suppression of inducer stall (without deterioration of the impeller characteristics even at the design flow rate.(4)The unstable flow due to diffuser stall occurs when the reverse flow zone extends to the diffuser exit.(5)The unstable flow occurring between φ=0.278 and 0.213 was suppressed by reducing the diffuser width from the impeller exit height to two-thirds between the diffuser inlet and R=1.2, by which the pressure recovery in the diffuser is not deteriorated.(6)The unstable flow range of the test blower was reduced significantly by about 45% in total from φ=0.316 to 0.174 by implementing the ring groove arrangement for the inducer inlet as well as the narrowed diffuser width for the diffuser exit. Less

为了澄清高特异性速度类型开放式离心叶轮中不稳定流动的机制，并分析了环槽布置对诱导剂摊位和/或扩散宽度对扩散剂宽度对扩散器停顿的影响，进行了3​​-D-D-D-D湍流模拟和实验性工作。 It was found that the steady flow simulation was very helpful for understanding unsteady stall phenomena, and the following conclusions were obtained.(1)The Incipient unstable flow is caused by the rolling-up vortex flow near the pressure side of the adjacent blade, resulting from the interaction between the tip leakage flow and the accumulated reverse flow zone, in which the strong streamwise vorticity component seems to be included due to the tip leakage （2）入口再循环的形成对于抑制由于诱导剂失速而引起的不稳定流动非常有效，一个因素是假设尖端泄漏涡流与REVE以及REVE的假设……更多的RSE流动，另一个因素是由于降低了降低的速度，该流量会增加，这会增加降低的位置，该率降低了降低率（3）。诱导剂尖端喉咙附近的区域导致诱导杆摊位（即使在设计流量时也不会降低叶轮特征的变质。（4）（4）由于扩散摊位延伸到扩散器出口时，由于扩散摊位的不稳定而发生的不稳定流动发生。在扩散器入口和r = 1.2之间的高度到三分之二，未确定扩散器中的压力恢复。（6）通过实现诱导的接收器的范围扩散的范围，将测试鼓风机的不稳定流量从φ= 0.316显着降低至0.174，从φ= 0.316降低到0.174，并通过实现诱导的Inlet的范围来进行范围。较少的