Experimental study on the effect of cavitation of squeeze film damper under low oil supply pressure
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摘要:
挤压油膜阻尼器(squeeze film damper, SFD)正常工作时避免不了会出现油膜空穴,为了研究SFD长时间运行时转子基频振动变化以及SFD油膜空穴效应对SFD内外环金属表面空化侵蚀情况,基于全尺寸航空发动机高压转子试验台开展了低供油压力(0.02~0.05 MPa)下SFD空穴效应试验研究,考察SFD在临界转速处长时间运行时转子基频振动变化,以及长时间运行后油膜空穴对SFD内外表面形貌的影响,试验结果表明:长时间运行后SFD油膜空穴会对SFD内环表面产生侵蚀作用,形成水滴形、椭圆形以及形状不规则的凹坑群,证明了在临界转速附近考核SFD空穴效应是SFD低供油压力下安全运行必要的试验内容。
Abstract:Oil film cavitation can’t be avoided during normal operation of squeeze film damper (SFD). In order to study the change of rotor fundamental frequency vibration during long-term operation of SFD and the erosion of SFD oil film cavitation effect on the metal surface of inner and outer rings of SFD, experimental study of SFD cavitation effect under low oil supply pressure (0.02—0.05 MPa) was carried out based on a full-scale aeroengine high-pressure rotor test rig to investigate the change of rotor fundamental frequency vibration during long-term operation of SFD at critical speed, and the effect of oil film cavitation on the internal and external surface morphology of SFD after long-time operation. The experiment results showed that the SFD oil film cavitation could erode the surface of the inner ring of SFD after long-time operation, forming water drop, oval and irregular pit groups, proving that assessing the SFD cavitation effect near the critical speed is a necessary experiment content for the operation safety of SFD under low oil supply pressure.
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Key words:
- squeeze film damper /
- low oil supply pressure /
- critical speed /
- cavitation erosion /
- surface morphology
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表 1 工业相机详细参数
Table 1. Detailed parameters of industrial camera
参数 数值及说明 品牌 BASLER 型号 acA2440-75 μm 像素位深/位 12 感光芯片供应商 Sony 感光芯片 IMX250 分辨率/106像素 5 水平/垂直像素尺寸 3.45 μm×3.45 μm 感光芯片尺寸 8.4 mm×7.1 mm 表 2 表面损伤情况汇总
Table 2. Summary of surface damage
区域编号 对比组 运行
16 h后运行
32 h后最终凹坑
深度/mm9~10 × √ √ 0.8 12~13 × √ √ 0.2 18 × √ √ 1 27~28 × √ √ 0.1 29~30 × × √ <0.1 34 × × √ 0.2 注:表中×代表无凹坑,√ 代表有凹坑。SFD外环经过对比发现油膜区域损伤不严重,第1轮试验后仅发现一处较为明显的凹坑,第2轮试验后没有新增凹坑,最终凹坑深度远远小于0.1 mm。 表 3 评估空气是否进入SFD所需必要参数
Table 3. Necessary parameters to evaluate whether air enters SFD
参数 数值 转子工作时的滑油流量$ {Q_{{\mathrm{oil}}}} $ 36 L/h(0.01 L/s) SFD直径D/mm 235 油膜区长度L/mm 25 转子涡动半径$ e $/mm 0.015~0.02 转子工作转速$ \varOmega $/(r/min) 1891 -
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