A journal bearing with variable geometry for the suppression of vibrations in rotating shafts: Simulation, design, construction and experiment

Improving stability and operation of turbine rotors using adjustable journal bearings

“…For the 3-arc bearing, the resulting fluid film forces are given in Eqs. (10) and (11). The angle at each point of the defined grid can be easily defined at the th i pad as ,i +i δ…”

“…Then, for the greater circumferential angles at the pad, cavitation is assumed to occur and the developed negative pressure is assumed to be zero at Eqs. (8) to (11). The definition of the angle where zero pressure is noticed is not used as a boundary condition for the evaluation of the pressure distribution in Appendix A, but it is yielded from the evaluation with the boundary conditions to assume zero pressure at the beginning and the end of the pad.…”

“…Again, the negative pressures are not included in the numerical integration in Eqs. (8) to (11). Although the Gumbel/half Sommerfeld cavitation model is supposed to yield a fair approximation to the performance of only narrow bearings and at low eccentricities, its simplicity and compactness of its mathematics constitutes a useful tool in this preliminary analysis of such a lubrication problem that aims to the estimation of the variance of stiffness and damping coefficients under adjustable bearing geometry.…”

“…A quite complete overview of the experimental and theoretical achievements on mechatronics applied to controllable journal bearings can be found in [5]. Many concepts for bearing adjustability/control utilize active oil injection [6][7][8] while other proposed concepts incorporating movable bearing pads, among others the very recent [9][10][11][12], the application of external forces in the bearing shell or the journal, for example magnetic [13][14][15][16], or piezo-mechanical [17][18][19] without changing the bearing's clearance geometry.…”

An improved recursive least square–based adaptive input shaping for zero residual vibration control of flexible system

“…Passive methods include introducing damping materials and modifying the design of mechanics. 1 Proactive methods include feedback control and input shaping. 2 Because of less difficulty and low costs, input-shaping technology has attracted a lot of attention and has become the hotspot in the field.…”