Multi-parameters analysis on static bearing load and aerodynamic heat of hydrodynamic gas bearing with axial throughflow cooling
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摘要:
在运行状态稳定条件下,进行了带轴向通流冷却的动压气体轴承三维流-固耦合数值模拟,以分析静承载力和气动热的多参数影响关联。结果表明:在气膜层间隙中,旋转强剪切驱动的周向流动占主导机制,在强烈的旋转流驱动下,进口端的轴向通流被诱导而随之转动,随后在气膜厚度较大的区域向出口端运动,并与通道周向流动形成叠加而呈现螺旋状的流动迹线;无论是对于静承载力还是气动热,偏心率均是最重要的影响参数,对于静承载力而言,气膜平均间隙的影响显著高于轴向通流质量流量的影响,而对于气动热而言,轴向通流质量流量的影响则显著高于气膜平均间隙的影响;在静载荷水平相当时,小偏心率-小气膜平均间隙工况的气动热效应相对较弱,反之,大偏心率-大气膜平均间隙工况的气动热效应最为显著,其面临的散热问题也更为严重。
Abstract:Three-dimensional fluid-solid coupled numerical simulations were performed for the hydrodynamic gas bearing with an axial throughflow cooling under a stable operating condition, so as to illustrate the multi-parameter effects on the static bearing load and aerodynamic heat. The results showed that the circumferential flow driven by the strong shearing of rotor was dominant in the film-layer gap. The axial throughflow was forced to follow the circumferential flow at its inlet section. Then it moved axially toward the outlet mainly from the larger-thickness film-layer zone, making the three-dimensional flow take on an obvious spiral flow feature. Among the concerned parameters, the eccentricity was identified to be the most important parameter affecting the static bearing load and aerodynamic heat. The film-layer mean gap had a stronger influence than the axial throughflow mass-rate on the static bearing load, but the situation was opposite for the aerodynamic heat. When the static bearing load was kept nearly the same, it was found that the aerodynamic heat effect was weaker in the situation when the hydrodynamic gas bearing operated with a small eccentricity and also a small film-layer man gap. For the situation when the hydrodynamic gas bearing operated with a big eccentricity and also a big film-layer mean gap, the aerodynamic heat effect was stronger, bringing about a more crucial requirement of heat dissipation.
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表 1 轴承主要结构参数
Table 1. Main geometric parameters of journal bearing
mm 参数 数值 Ro 11.51 Ri 10.95 R 11.02 L 25 表 2 设计变量及变化范围
Table 2. Design variables and the design space
参数 取值下限 取值上限 Ci/mm 0.07 0.13 $ {\dot{m}}_{\mathrm{i}} $/(kg/h) 0 35 ε 0.5 0.9 表 3 正交参数表
Table 3. Orthogonal parameters
序号 Rez ε Ci/H 1 0 −0.5 0.125 2 940 0.6 0.161 3 2800 0.7 0.179 4 4700 0.8 0.196 5 6600 0.9 0.232 表 4 相同静承载力下的对比工况
Table 4. Testing samples under the same static bearing load
参数 工况1 工况2 工况3 Ci/mm 0.07 0.09 0.11 ε 0.7 0.8 0.9 Fcal/N 21.5 21.5 21.5 FCFD/N 21.5 21.6 22.9 Qcal/W 34.8 38.4 41.9 QCFD/W 33.4 37.9 45.3 -
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