Dynamic force coefficients and the mechanism of instability in hydrostatic journal bearings

Inherent restriction on stability of rotor‐aerostatic bearing system

“…Lund (1964Lund ( , 1967Lund ( , 1968 analyzed the four shoe-tilting pad and three-lobe air-journal bearings and acquired data related to the load capacities as well as the stiffness and damping coefficients that can be used to verify the whirl instability of aerostatic bearings, wherein, these analyses were performed based on first-order small-amplitude perturbation and found out relevant instability threshold by scanning the range of whirl frequency. Leonard and Rowe (1973) utilized mathematical relations to compute the dynamic coefficient and whirl mechanism of aerostatic bearing, thereto, the prediction of the occurrence of instability conformed to the experiment results, but such results could be applied in the context of small eccentricity. Wadhwa et al (1983) adopted the finite element method and modified perturbation formula to calculate the dynamic coefficient and whirl instability resulted from the orifice restriction gas bearing, thereto, the relevant results indicated that while having a higher restriction parameter, the change of pressure supply would have an obvious influence on the bearing performance, in addition, they also proved that aerostatic bearing would have a larger load capacity and higher stability than the plane journal bearing with same geometric and operating parameters.…”

Advances in Hydrostatic and Hybrid Bearing Technology

“…An interesting starting point for consideration of dynamic performance is the phenomenom of oil whip instability in fluid film bearings described by Newkirk and Taylor in 1925 (36). Lightly loaded journal bearings experience instability when the rotor speed approaches Leonard and Rowe (37) showed that the onset conditions could be accurately predicted for concentric and lightly loaded hybrid bearings. Figures 27 and 28 illustrate a simple rotor and coordinate system.…”

Nonlinear transient response of rough symmetric two lobe hole entry hybrid journal bearing system

“…The results of their study found that the bearing transient response is significantly altered because of a change in roughness orientation pattern. A small number of transient response studies of hydrostatic bearings have also been reported in the literature (Leonard and Rowe, 1973; Pang et al., 1993; San Andres, 1997; Yoshimoto and Kikuchi, 1999; Kushare and Sharma, 2014). The theoretical and experimental work of Leonard and Rowe (1973) highlights the mechanism of whirl instability in hydrodynamic bearings by showing how the hydrostatic stiffness raises the frequency of whirl onset.…”

“…A small number of transient response studies of hydrostatic bearings have also been reported in the literature (Leonard and Rowe, 1973; Pang et al., 1993; San Andres, 1997; Yoshimoto and Kikuchi, 1999; Kushare and Sharma, 2014). The theoretical and experimental work of Leonard and Rowe (1973) highlights the mechanism of whirl instability in hydrodynamic bearings by showing how the hydrostatic stiffness raises the frequency of whirl onset. San Andres (1997) compared a linear and non-linear transient response of recessed hydrostatic journal bearing for varieties of external loads.…”

“…(Sinhasan and Goyal, 1995; Newkirk and Taylor, 1925; Leonard and Rowe, 1973; Choy et al., 1992; Ramesh et al., 1995; Turaga et al., 1999, 2000; Lin, 2007; Jagadeesha et al., 2012; Malik et al., 1989; Khonsari, 1990; Wang et al., 2012; Pang et al., 1993; San Andres, 1997; Yoshimoto and Kikuchi,1999; Kushare and Sharma, 2014). The existence of stable behavior in the unstable region was determined by utilizing the linearinzed and non linearized analysis of hydrodynamic journal bearing systems are reported by many authors in their theoretical and experimental work (Newkirk and Lewis, 1925; Leonard and Rowe, 1973; Lund, 1987; Malik et al., 1989; Choy et al., 1992; Ramesh et al., 1995; Sinhasan and Goyal, 1995; Turaga et al.,1999, 2000; Lin, 2007; Jagadeesha et al., 2012). In 1925, the first experimental study to investigate the rotor dynamic instability in hydrodynamic journal bearings was carried out by Newkirk and Taylor (1925).…”