Numerical and Experimental Study on the Dynamic Bearing Properties of a Four-Pad and Eight-Pad Tilting Pad Journal Bearings in a Vertical Rotor

Benti, Gudeta Berhanu; Rondon, David; Gustavsson, Rolf; Aidanpää, Jan-Olov

doi:10.1115/1.4052032

Cited by 6 publications

(4 citation statements)

References 36 publications

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“…The bearing was modeled as direct and cross-coupled stiffness and damping coefficients and included in the K and C matrices of Equation ( 1) for the rotordynamic simulations. The procedure that was used in this paper to determine the bearing coefficients closely resembles the method used in [24]. The bearing coefficients were precalculated by solving the fluid film lubrication model and represented using exponential functions as well as sine/cosine functions.…”

Section: Model Of the Tpjbmentioning

confidence: 99%

Cost-Effective Design Modification of a Sleeve Bearing with Large Bearing Clearance

Benti,

Aidanpää,

Gustavsson

2024

Applied Sciences

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In 2015, a 45 MW vertical hydropower machine exhibited excessive vibration after refurbishment. Measurements revealed a substantial bearing clearance at the lower generator guide bearing. Consequently, the bearing was unable to generate sufficient opposing force to drive the rotor toward the bearing center, resulting in more pronounced overall system vibration. Addressing this challenge required a cost-effective and feasible solution for mitigating the vibration problem. To this end, a design modification was implemented wherein the lower generator guide bearing (originally a sleeve bearing) was modified to a four-lobe bearing by offsetting the two halves of the bearing twice in two axes. Numerical simulations and experimentations were conducted, and the dynamics of the machine before and after the design modification were investigated. Both the simulation and experimental results showed that the machine with the four-lobe bearing improved the system stability and reduced the vibration amplitudes. The numerical simulation result demonstrated that, due to the design modification, the first and second critical speeds were effectively eliminated for a speed range of up to three times the nominal speed. Furthermore, for nominal operation with unbalanced magnetic pull, the four-lobe bearing provided a stability advantage in terms of the modal parameters relative to the original sleeve bearing.

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Section: Model Of the Tpjbmentioning

confidence: 99%

Cost-Effective Design Modification of a Sleeve Bearing with Large Bearing Clearance

Benti,

Aidanpää,

Gustavsson

2024

Applied Sciences

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“…Besides, amplitude peaks at the third (3 × Ω) and fifth (5 × Ω) frequency orders exist in both simulation and experiment. These frequencies are associated with the number of pads (n = 4) [34] and they exist as a single frequency at 4 × Ω in the rotating coordinates. Furthermore, other frequency orders also appeared in the experiment, although their amplitudes were not as pronounced as in the 1 × Ω and 3 × Ω (and 5 × Ω in some cases) frequency orders.…”

Section: Frequency Response Function (Fft)mentioning

confidence: 99%

“…Nässelqvist et al [30] approximated bearing coefficients using sinusoidal equations over the range of journal radial positions. Synnegård et al [33] and Benti et al [34] described how the TPJBs can excite the system and cause vibration at certain frequencies due to the number of pads.…”

Section: Introductionmentioning

confidence: 99%

Speed-Dependent Bearing Models for Dynamic Simulations of Vertical Rotors

Benti

Gustavsson²,

Aidanpää³

2022

Machines

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Many dynamic simulations of a rotor with a journal bearing employ non-linear fluid-film lubrication models and calculate the bearing coefficients at each time step. However, calculating such a simulation is tedious and computationally expensive. This paper presents a simplified dynamic simulation model of a vertical rotor with tilting pad journal bearings under constant and variable (transient) rotor spin speed. The dynamics of a four-shoes tilting pad journal bearing are predefined using polynomial equations prior to the unbalance response simulations of the rotor-bearing system. The Navier–Stokes lubrication model is solved numerically, with the bearing coefficients calculated for six different rotor speeds and nine different eccentricity amplitudes. Using a MATLAB inbuilt function (poly53), the stiffness and damping coefficients are fitted by a two-dimensional polynomial regression and the model is qualitatively evaluated for goodness-of-fit. The percentage relative error (RMSE%) is less than 10%, and the adjusted R-square () is greater than 0.99. Prior to the unbalance response simulations, the bearing parameters are defined as a function of rotor speed and journal location. The simulation models are validated with an experiment based on the displacements of the rotor and the forces acting on the bearings. Similar patterns have been observed for both simulated and measured orbits and forces. The resultant response amplitudes increase with the rotor speed and unbalanced magnitude. Both simulation and experimental results follow a similar trend, and the amplitudes agree with slight deviations. The frequency content of the responses from the simulations is similar to those from the experiments. Amplitude peaks, which are associated with the unbalance force (1 × Ω) and the number of pads (3 × Ω and 5 × Ω), appeared in the responses from both simulations and experiments. Furthermore, the suggested simulation model is found to be at least three times faster than a classical simulation procedure that used FEM to solve the Reynolds equation at each time step.

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“…Edoardo et al [4] established a thermohydrodynamic model to predict the static parameters such as stiffness and damping coefficient and minimum oil film thickness of tilting pad journal bearings by training neural networks. Benti et al [5] studied the influence of the number of tiles on the dynamic characteristics of the tilting pad journal bearing, and compared the experimental and numerical results. In this paper, a dynamic and static pressure tilting pad journal sliding bearing model is established.…”

Section: Introductionmentioning

confidence: 99%

Lubrication Performance Analysis of Tilting Pad Journal Bearing with Dynamic and Static Pressure

Zou,

Chen,

et al. 2024

Advances in Transdisciplinary Engineering

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The application of bearing technology in the field of intelligent equipment and special robots continues to promote technological innovation and industrial upgrading, such as the improvement of bearing materials and the development of intelligent bearings, which helps to improve the performance and operation efficiency of equipment. In this paper, the model of dynamic and static pressure tilting pad journal bearing is established, and the influence of eccentricity and preload on the static characteristics of dynamic and static pressure tilting pad journal bearing is studied. The results show that along the rotation direction of the journal, the oil film thickness decreases gradually, the static pressure of the pad increases gradually, and the lower pad is the main bearing pad; With the increase of eccentricity and preload coefficient, the bearing load coefficient and friction coefficient also increase.

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Numerical and Experimental Study on the Dynamic Bearing Properties of a Four-Pad and Eight-Pad Tilting Pad Journal Bearings in a Vertical Rotor

Cited by 6 publications

References 36 publications

Cost-Effective Design Modification of a Sleeve Bearing with Large Bearing Clearance

Cost-Effective Design Modification of a Sleeve Bearing with Large Bearing Clearance

Speed-Dependent Bearing Models for Dynamic Simulations of Vertical Rotors

Lubrication Performance Analysis of Tilting Pad Journal Bearing with Dynamic and Static Pressure

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