Steady-State Analysis of the Long Plain Journal Bearing in the Nanotechnology Environment

摘要

Effects of gas film rarefaction with fully diffused molecular accommodation at both containing walls are treated for the analysis of the steady-state operation of a long plain self-acting gas lubricated journal bearing. Derived Mass Content Rule (MCR) with allowance of gas film rarefaction reveals its dependence, not only on the ambient Knudsen number, but also on the variation of the rarefaction state in the end-leakage region. Approximate solutions, neglecting the latter effect, are computed for a long bearing operating at ε = 0.6 for 0.05 ≤ Λ ≤ 1500 with 0.1411 ≤ Kn_a ≤ 0.5644, corresponding to 500 nm ≥ C ≥ 125 nm for an air film at 50 ℃. The influence of rarefaction is considerable, even at Kn_a ≤ 0.1411. In general, rarefaction tends to suppress compressibility effect. At a small A, the load capacity at Kn_a= 0.5644 is only one-fifth of that of a continuum gas film. Potential risk of higher vulnerability to whirl instability is an additional concern.