径向入流冷却箔片型气体动压止推轴承气动和热特性数值研究

Numerical Investigation on Aerodynamic and Thermal Characteristics of Hydrodynamic Foil Thrust Bearing with a Radial Cooling Inflow

关键词:  动压止推轴承  气动性能  热性能  径向入流冷却  流固耦合

Key words:  Hydrodynamic thrust bearing  Aerodynamic performance  Thermal performance  Radial cooling inflow  Fluid-solid coupled

摘要:

针对高转速箔片型气体动压止推轴承的热管理需求，在轴承运行状态稳定、弹性变形恒定的主要假设前提下开展了带冷却空气径向入流的三维流-固耦合数值模拟，以获得旋转速度、径向入流质量流量和气膜层出口方式对气动和热特性的影响。研究结果表明，气膜间隙出口方式对转盘表面压力分布具有明显的影响，相对于气膜间隙出口完全封严情形，无封严出口下径向入流可以贯通气膜层通道，使得转盘和止推顶箔冷却效果得以改善、径向入流压降减小，但同时也带来止推力下降10.7%~32.5%的负面影响；径向入流质量流量的增加不仅可以起到有效的冷却作用，而且对轴承止推力也起到了较好的增强作用；气膜间隙出口封严方式对转盘和止推顶箔冷却效果的影响在高转速下更为显著，对径向入流压降和止推力的影响则在较大的径向入流质量流量下较为明显，止推力增幅随流量变化从0.8%提升至23.3%，压降则提高了0.5%~15%。

Abstract:

In accordance with the need of thermal management of hydrodynamic foil thrust bearing with high rotational speed， a steady three-dimensional fluid-solid coupled numerical simulation is performed to illustrate the effects of rotational speed， radial inflow mass-rate and outlet scheme on aerodynamic and thermal behaviors of foil thrust bearing with a radial cooling inflow， by assuming that the bearing works in a stability condition with fixed elastic deformation. The results show that the outlet scheme of film-layer gap has an obvious influence on the pressure distribution on the rotating disc surface. Compared with the film-layer sealed outlet situation， the radial inflow is able to penetrate the film-layer gap in the unsealed outlet situation， improving the cooling capacity of rotating disk and top thrust foil as well as decreasing the pressure drop of radial inflow. However， a negative influence of 10.7%~32.5% reduction on the thrust bearing capacity is also introduced by this unsealed outlet scheme. The increase of radial inflow mass-rate not only enhances the cooling capacity， but also strengthens the thrust bearing capacity. In general， the effect of film-layer outlet scheme on the cooling capacity of rotating disc and top thrust foil behaves more pronouncedly under higher rotational speeds. Its influence on the pressure drop of radial inflow and the thrust bearing capacity is more significant under bigger radial inflow situations， where the increasing in thrust bearing capacity rises from 0.8% to 23.3% with mass-rate and the pressure drop increases by 0.5% to 15%.