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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

基本信息

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

项目摘要

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

为了阐明高比转速开式闭环离心叶轮不稳定流动的机理，并分析环槽布置对导流轮失速的影响和扩压器宽度对导流轮失速的影响，进行了3D湍流模拟和实验工作。结果发现，稳定流模拟对于理解非定常失速现象非常有帮助，并得出以下结论：（1）初期不稳定流是由叶尖泄漏流与累积逆流区相互作用产生的邻近叶片压力侧附近的卷绕涡流引起的，其中似乎包含了由于叶尖泄漏而产生的强流向涡量分量。 (2)入口再循环的形成对于抑制导轮失速引起的不稳定流动非常有效，一个因素是叶尖泄漏涡流与反向流动一起产生的吸力，另一个因素是入口再循环流量的增加导致流动发生率的减小，而入口再循环流量随通流量的减小而增加。(3)吸环槽的最佳位置为 (4)当逆流区延伸至扩压器出口时，会发生扩压器失速引起的不稳定流动。(5)通过从扩压器宽度开始减小扩压器宽度，可抑制在 φ=0.278 至 0.213 之间发生的不稳定流动。将叶轮出口高度降低至扩压器入口与R=1.2之间的三分之二，从而不影响扩压器内的压力恢复。(6)通过引入导流轮入口环槽布置以及扩压器扩压器宽度变窄，试验鼓风机的不稳定流量范围由φ=0.316降至0.174，总计显着减小约45% 退出。少