Dynamic stability of herringbone-grooved journal gas bearing

Abstract

As the herringbone-grooved journal gas bearing can rotate silently at high speed with low friction, and moreover it can be small-sized, it is used a lot in the fields such as information appliances. In this paper, the equation of motion of the herringbone-grooved journal gas bearing is derived using the gas force which can be obtained by applying the Navier-Stokes equation for the grooved and the ridged parts of a journal. The stability analysis can be performed when a journal rotates with a high speed by using the stability analysis method of Routh-Hurwitz, the root locus of complex eigenvalue analysis, and the time history analysis due to transient response vibration. Comparing with the already published analytical results, the physical meanings which have not been clarified in the conventional study are reported as for the stability of herringbone-grooved journal gas bearing. The stability chart is shown to be determined by considering the forward whirl and the backward whirl. In addition, it is reported that the present analysis results show a good agreement with the already reported experimental results. Furthermore, the parameters study as for the specification of gas bearing is performed, and it is shown that the stability chart changes due to the influence of specifications complicatedly.