关键词: 多叶波箔型动压气体轴承, 多箔叠加, 多楔形气膜间隙, 双向流固耦合, 承载力, 多物理场

Abstract: To reveal the fluid structure coupling mechanism of multi blade wavy foil type dynamic pressure gas bearings, a coupling analysis method was established for the shear flow and elastic foil combination de-formation in the rotating static multi wedge channel of this type of bearing. The parameter distribution of the unsteady flow field of the rotating static gap gas film and the unsteady deformation of the elastic foil combination were numerically studied. The re-search results confirm that there is a strong fluid elastic coupling effect in multi blade wave foil type dynamic pres-sure gas bearings. When multiple wedge-shaped channels are coupled with eccentricity, different elastic foils corre-spond to multiple discrete high/low pressure zones in the gas film. The high pressure zone is located in the conver-gence area of the channel, while the low pressure zone is located at the sudden expansion step connected to adja-cent foils. The fluid elastic coupling weakens the pulsation amplitude in the high-pressure region of the gas film and strengthens the pressure pulsation amplitude in the low-pressure region. The local expansion of flow channels in the high-pressure zone induces flow separation and increases shear flow instability. The 1st and 2nd elastic foils de-form in the direction of the bearing sleeve, while the 4th and 5th elastic foils deform in the direction of the rotating shaft, which corresponds to the distribution of the high-pressure and low-pressure areas of the rotating static air film. The low-pressure zone of the static gas film induced separation between the top foil and its adjacent overlapping foil. The influence of rotational speed, eccentricity, clearance scale, and elastic foil stiffness on the fluid elastic coupling performance of bearings was obtained. The gas film pressure in the fluid domain is positively correlated with the bearing capacity, speed, and eccentricity, while negatively correlated with the clearance scale. High rotational speed and large eccentricity induce an in-crease in the peak value of the low-pressure region in the rotor static gap. Under fluid-structure coupling, there is a certain lag in the vibration frequency of the top foil compared to pressure pulsation. The amplitude of foil vibration and gas film pressure pulsation in the high-pressure region of the fluid do-main is greater than that in the low-pressure region of the fluid domain. The reduction of clearance scale enhances the bearing capacity by reducing the peak pressure in the low-pressure area.

Key words: Multi leaf wave foil type dynamic pressure gas bearing, Multi foil stacking, Multi wedge air film gap, Bidirectional fluid structure coupling, Carrying capacity, Multiphysical fields