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Tilting-Pad Journal Bearings (TPJB) are commonly used on high-performance turbomachinery due to their excellent stability properties at high speed when compared to other designs for oil film bearings. Hence, efforts have been made to improve the accuracy for the available models for these mechanical devices, achieving nowadays an elasto-thermo-hydrodynamic formulation. On the other hand, the basic design of the Tilting-Pad Journal Bearing has been modified in order to transform it into a smart machine element. One approach to do so is to inject pressurized oil directly into the bearing clearance through holes drilled across the bearing pads. By adjusting the injection pressure, it is possible to modify the dynamic characteristics of the bearing. A controllable lubrication regime is obtained, allowing to expand the operational boundaries of the original design. This work focuses on presenting an elasto-thermo-hydrodynamic model (ETHD) for the Tilting-Pad Journal Bearing, including the effect of the controllable lubrication system. The basic model is validated by comparing its results against theoretical and experimental results available in the literature. Then, the validated code is used to show the benefits of applying a controllable lubrication regime, by means of the modification of the thermal and dynamic behaviour of the bearing. [ABSTRACT FROM AUTHOR]

A theoretical investigation of the static and dynamic behaviour of a rigid plain journal bearing lubricated by oils containing polymer additives considering misalignment defect is presented. The lubricating oils which are non-Newtonian are modelled as couple-stress fluids. According to the V. K. Stokes' micro-continuum theory which takes into account the size of particles, these fluids are characterized by two physical constants, namely the dynamic viscosity (μ) and a second characteristic responsible for the couple stress in the fluid (η). The effects of the couple-stress on the static and dynamic behaviour of the plain journal bearing are studied by defining of a dimensionless couple-stress parameter. The obtained results showed that the presence of additives in the lubricant has non- negligible effects on the static and dynamic performance characteristics as well as the dynamic stability and response of the journal bearing especially at high values of couple-stresses parameter, i.e. for higher chain length of the additive molecule. However, their influence on the side leakage flow is negligible except for high values of eccentricity ratio. [ABSTRACT FROM AUTHOR]