Analysis of thermo-aerodynamic heat and flow characteristics in clearance of dynamic pressure gas thrust bearing
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摘要:
以波箔型动压气体止推轴承为研究对象,建立变截面气膜间隙润滑模型,研究了有无黏性耗散时动压气体止推轴承间隙压力场及温度场分布,获得几何参数以及转速对轴承间隙气膜压力和温度的影响规律。结果表明:考虑黏性耗散时,在收敛段末端和平直段外缘形成高温区;无黏性耗散时,轴承气膜高温区位于收敛间隙末端;轴承气膜温升随转速线性增加;考虑黏性耗散时,气膜温升随楔形因子的增加而减小,无黏性耗散热时则与之相反;气膜厚度越大,温升越小,厚度对轴承气膜温度分布无影响。本文参数范围内,黏性耗散产生的温升占比达90%。该研究证实了黏性耗散对动压气体止推轴承热流动物理机制有重要的影响,可为动压气体轴承设计和高效运行提供理论基础。
Abstract:In order to reveal the thermo-aerodynamic characteristics of foil-type dynamic pressure gas thrust bearings in the presence or absence of viscosity dissipation, the lubrication models in the cross-section air film gap were built, and the term of viscosity dissipation and pressure variation term in the energy equations were decoupled and discussed respectively. The effects of wedge factor, air film thickness and rotation speed on flow field of the air film were obtained. The temperature distributions in air film between the presence and absence of viscosity dissipation were presented and compared. Results showed that the peak temperature in the air film was located near the circumferential air outlet and the side of outer diameter in the presence of viscosity dissipation, while the peak value took place near the end of the convergence channel in the absence of viscosity dissipation. Contrary to the case without viscosity dissipation, the magnitude of temperature rise in the air film increased with the increase of wedge factor in the presence of viscosity dissipation. The magnitude of temperature rise increased with the increase of the rotational speed, and had no effect on the variation of air film thickness. This study confirmed that viscosity dissipation played a significant role in the temperature rise and flow field of the foil-type dynamic pressure gas thrust bearings. In high-speed working conditions, the temperature rise in the presence of viscosity dissipation accounted for more than 90%. The results are of significant importance by providing basic design guidelines for temperature rise of the air film.
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Key words:
- gas thrust bearing /
- viscous dissipation /
- temperature field /
- rotational speed /
- wedge factor
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表 1 计算工况
Table 1. Parameters of the calculation operating condition
参数 数值 初始最小气膜厚度h2/μm 8~36 楔形因子hf=h3/h2 2~8 转速n/104 (r/min) 2~10 轴承外半径R2/mm 21.5 轴承内半径R1/mm 12 扇形瓦张角β/(°) 60 节距比b 0.5 箔片数N 6 -
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