Nonlinear study on a rigid rotor supported by herringbone grooved gas bearings: Theory and validation

The nonlinear behavior of a rigid rotor supported by herringbone grooved journal gas bearings (HGJBs) was investigated in this study. two-dimensional narrow groove theory (2D-NGT) adopted to model the HGJBs. A set integrated rotor-bearing state equations were built coupling motion and bearing Reynolds equation. An implicit integrator with adaptive time step method used solve those continuously. Two low-stability HGJBs implemented experimentally demonstrate analyze appearance self-excitation motions. theoretical successfully validated experimental data on predicting onset speed sub-synchronous vibration HGJB-rotor system whirl frequency ratio. predicted limit cycle amplitude increases as until contacts surface, which leads failure. Forward conical mode dominates self-excited during whole range motion. prediction shows that can still operate stable, even though is installed vertically, i.e., without static load bearings. This distinct advantage comparison plain As applies increases, well. For system, an increase from 36 krpm 75 0 4 times weight. indicates increased HGJB stability load. orbits show complex shapes when imbalance excitation considered simulation. Both synchronous are shown spectral analysis. Moreover, reduces [38,48] [40,42] 40 mgmm.