Numerical solution of the boltzmann-based lubrication equation for multi-leaf gas microbearing with different load configurations

The lubrication characteristics of multi-leaf aerodynamic microbearings influence the reliable operation and service life of microfluidic devices directly. Based on the linearized Boltzmann rarefaction model with three adjustable coefficients, the dynamic gas film pressure, film thickness and Poiseuille flow ratio can be expressed as two superimposing static and complex perturbed terms. The modified Reynolds equation including complete variable disturbance of multi-leaf microbearings for different load configurations are derived, which solved by the finite difference algorithm, partial derivative method and over-relaxation iteration simultaneously. The effects of preload factor, pad location and perturbation frequency on load capacity and dynamic coefficients of multi-leaf/cylindrical microbearings are investigated in detail. Results indicate that the gas film peak pressure of multi-leaf microbearings is higher at greater pad preload, and the direct stiffness coefficients of multi-leaf microbearing for load between pad are larger because of pumping effect within axial grooves that decrease the degree of rarefied gas flow.