This paper is a review of the literature about CFD modeling and analysis of journal, thrust, and aerostatic bearings; the advantages and disadvantages of each are specified, and the bearing problems that have been analyzed are discussed to improve their designs and performance. A CFD transient analysis of journal bearings was conducted using the dynamic mesh method together with movement algorithms while keeping a structured mesh of a good quality in the ANSYS Fluent software to determine the equilibrium position of the journal and calculate the dynamic coefficients. Finally, areas of opportunity for analyzing and designing fluid film bearings to improve their performance are proposed.

In this work, a novel methodology for the identification of stiffness and damping rotordynamic coefficients in a rotor-bearing system is proposed. The mathematical model for the identification process is based on the algebraic identification technique applied to a finite element (FE) model of a rotor-bearing system with multiple degree-of-freedom (DOF). This model considers the effects of rotational inertia, gyroscopic moments, shear deformations, external damping and linear forces attributable to stiffness and damping parameters of the supports. The proposed identifier only requires the system’s vibration response as input data. The performance of the proposed identifier is evaluated and analyzed for both schemes, constant and variable rotational speed of the rotor-bearing system, and numerical results are obtained. In the presented results, it can be observed that the proposed identifier accurately determines the stiffness and damping parameters of the bearings in less than 0.06 s. Moreover, the identification procedure rapidly converges to the estimated values in both tested conditions, constant and variable rotational speed.

In this paper, a mathematical model is presented to identify the direct dynamic coefficients (k_xx, k_zz, c_xx, c_zz) of a pressurized bearing in a rotor-bearing system. The presented mathematical model for online identification is the result of the application of the algebraic identification approach to a two-degree-of-freedom rotor-bearing model. The proposed identification model requires only the vibration response as the input data. The performance of the model was assessed by theoretically and experimentally testing the proposed identifier at different shaft frequencies and, for the experimental test, a pressurized bearing that has hydrodynamic and hydrostatic characteristics at a support pressure of 10 psi was considered. The working fluid is Chevron GST 32 oil. The results show negligible differences between the vibration response of the experimental rotor and those obtained numerically using the identified direct dynamic coefficients of the pressurized bearing. In addition, it is observed that the algebraic identifier determines the identified parameters in a time less than 0.2 s. The proposed identifier can be used in other types of bearings, which is a great advantage over other identifiers.

En este trabajo se propone el desarrollo de identificadores de los parámetros de masa, rigidez y amortiguamiento de un sistema rotor-cojinete simplificado de dos grados de libertad. La técnica utilizada para el desarrollo de los identificadores se conoce en la literatura como: técnica de identificación algebraica. Para el desarrollo de los identificadores paramétricos, se utilizó el modelo matemático de un sistema rotor-cojinete que considera los efectos de inercia traslacional y rotacional, así como, los efectos giroscópicos. Los identificadores algebraicos desarrollados determinan los valores de los parámetros físicos del sistema, para dos condiciones diferentes de velocidad de operación del rotor: velocidad constante y velocidad variable. La evaluación numérica de los identificadores muestra que, es posible determinar los valores de los parámetros de masa, amortiguamiento y rigidez del sistema rotor-cojinete en un pequeño intervalo de tiempo que va de los 0.1 a 0.28 segundos.