Feasibility of influencing the dynamic fluid film coefficients of a multirecess journal bearing by means of active hybrid lubrication

Abstract

The main objective of this research project is the investigation of multirecess hydrostatic journal bearings with active hybrid (hydrostatic and hydrodynamic) lubrication. This paper gives a theoretical contribution to the modeling of this kind of bearing, combining computational fluid dynamics and control techniques. The feasibility of influencing the dynamic fluid film coefficients (stiffness and damping) by means of a controllable fluid injection into opposed bearing recesses is investigated. By controlling the pressure and flow injection using servo control systems, it is possible to obtain significant modifications of active hybrid forces, which can be useful while reducing vibration and stabilizing rotating machines

Lateral dynamics and stability analysis of a gas compressor supported by hybrid and active lubricated multirecess journal bearing

“…The static dimensionless pressures ) (n 0 r P in the recesses 1,2,3 and 4 are: 0. 3389, 0.4680, 0.7194 and 0.4715, respectively. The feasibility of influencing the AHJB dynamic fluid film coefficients by the feedback control system gains, aiming at improving the stability of a very simple rotor-bearing system was investigated in Santos and Watanabe (2003). The compensation of the cross-coupling stiffness coefficients and the increase of the direct damping coefficients were proposed in Santos and Watanabe (2004), what leads to rotor-bearing systems with larger threshold of stability.…”

“…The mathematical model of the HJB is obtained basically by using the Reynolds' equation in the land surfaces and the flow continuity equation in the bearing recesses, as presented by Santos and Watanabe (2003). The modeling technique used is the small perturbation method applied to the journal steady state equilibrium position (Lund and Thomsen, 1978, and by Ghosh et al, 1989).…”

“…Furthermore, the higher the perturbation frequencies ω are, the smaller the derivative gain coefficient 2 g can be, if a controller with derivative part is adopted, once the journal velocities amplitudes are given by * ω X e and * ω Y e . Coupling the HJB and servo control system models, results in the complete mathematical model of AHJB (Santos and Watanabe, 2003), and the total fluid flow injected into the bearing recesses are determined as follows …”

The Stability’s Influencing Factors and Active Control of Hydrostatic Journal Bearing

“…Such equipment can change the pressure of supply oil by piston and valve, with the advantages of automatically compensating the influence due to oil viscosity's changes, as well as the advantages of consistent oil film thickness under different loads. Santos, et al [14] have studied journal bearing with multiple-recesses bearing. They have controlled oil flow injected into recess through servo valve control system, which possibly changes active hybrid pressure and then, is beneficial to reduce the vibration of rotor system.…”

Oil film shape prediction of hydrostatic thrust bearing under the condition of high speed and heavy load

“…Doshi and Bambhania (2013) optimized the oil film thickness of hydrostatic thrust bearing of circular cavity to adapt to high load, high stiffness, low flow and pressure uniform conditions. Santos and Watanabe (2003) carried out an in-depth study on the radial bearing of autonomous control of mixed lubrication, and obtained the oil film stiffness and damping factors. Controlling the pressure and flow can help in obtaining the best bearing capacity, while reducing vibration and improving operational stability, but the object of study is radial bearing.…”