Abstract
In this study we make clear whirling instability of a rotor supported with grooved hydrostatic gas journal bearings. The pressure of gas film is increased as a whole by circumferential grooves. As a result the diagonal terms of stiffness matrix K_<xx> can be increased. Then the rotor becomes stable. And we can stabilize a rotor supported with grooved hydrostatic gas journal bearings by choosing the optimum feeding parameter Γ, depth and width of grooves in order to increase K_<xx> within the range in which damping doesn't become negative.
