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18 pages, 2180 KiB

Open AccessArticle

The Inertial Disturbances of Fluid Movement in the Chamber of a Liquid Autobalancer

by Vasyl Lozynskyi, Thaer Shihab, Ilona Drach and Liubomyr Ropyak

Machines 2024, 12(1), 39; https://doi.org/10.3390/machines12010039 - 05 Jan 2024

Viewed by 1082

This article analyses the problem of automatic balancing rotors with a liquid balancer, which is a cylindrical chamber partially filled liquid of a certain density. This problem is related to the problem of the dynamics of bodies with cavities partially filled with liquid. [...] Read more.

This article analyses the problem of automatic balancing rotors with a liquid balancer, which is a cylindrical chamber partially filled liquid of a certain density. This problem is related to the problem of the dynamics of bodies with cavities partially filled with liquid. As part of this task, we analyzed disturbances in the relative motion of the fluid in the ABD chamber caused by the Coriolis force inertia. The distortions of the free surface of the liquid were found, resonant phenomena in the flow of the working fluid were investigated, and the physical explanation of the received results given should be taken into account when designing the corresponding ones self-balancing devices. It was established that the axial component of the Coriolis inertial force causes peculiar wave phenomena in the correcting fluid movement. For the given nature of undisturbed motion, the conditions of this phenomenon’s occurrence are determined only by the geometric dimensions of the cylindrical chamber and the thickness of the liquid layer in undisturbed motion, and do not depend on the intensity of rotation of the liquid, nor on its density. It is shown that a decrease in the “ABD chamber height–radius” ratio leads to stabilization of the movement of the system. Experimental verification has been performed; theoretical results on the developed stand for work research rotor system with a vertical axis of rotation. Full article

(This article belongs to the Special Issue Rotor Dynamics and Rotating Machinery)

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18 pages, 2955 KiB

Open AccessEditor’s ChoiceArticle

The Friction of Radially Loaded Hybrid Spindle Bearings under High Speeds

by Marcus Gärtner, Christian Brecher, Stephan Neus, Hans-Martin Eckel, Andreas Bartelt, Maik Hoppert and Mohammad Reza Ilkhani

Machines 2023, 11(6), 649; https://doi.org/10.3390/machines11060649 - 15 Jun 2023

Viewed by 1105

Abstract

Friction losses are an important parameter for evaluating the operational behaviour of high-speed rolling bearings. Specifically, in machine tool applications, the bearings are subjected to high radial loads and high speeds, which lead to increased forces in the rolling contact and, as a [...] Read more.

Friction losses are an important parameter for evaluating the operational behaviour of high-speed rolling bearings. Specifically, in machine tool applications, the bearings are subjected to high radial loads and high speeds, which lead to increased forces in the rolling contact and, as a result, increased bearing friction. In this high-speed application, hybrid spindle bearings, typically made of ceramic balls and steel raceways, show better frictional behaviour compared to full steel-made bearings. Therefore, precise knowledge of the friction characteristics of high-speed hybrid bearings can improve friction models and generalise them to spindle bearings with different types, geometries, and operating conditions. In this article, a new straightforward and cost-efficient method for measuring the frictional torque in spindle bearings is presented. A rigidly arranged 7008 hybrid spindle bearing pair was tested up to rotational speeds of 24,000 rpm and high radial loads of 3 kN. The effects of oil–air and grease lubrication are discussed in characteristic diagrams of the tested bearings. Then, based on the test results, a friction calculation model is presented and validated for the outer race control and minimised power dissipation regarding the influence of radial forces. Full article

(This article belongs to the Special Issue Rotor Dynamics and Rotating Machinery)

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17 pages, 6555 KiB

Open AccessArticle

Comparative Evaluation of High-Speed Bearingless Cross-Flow Fan Designs for Lithography Excimer Lasers

by Ivana Bagaric, Rennan Hu, Daniel Steinert, Thomas Nussbaumer and Johann Walter Kolar

Machines 2023, 11(6), 611; https://doi.org/10.3390/machines11060611 - 02 Jun 2023

Cited by 1 | Viewed by 1098

Abstract

This study conducted a comparative evaluation of two bearingless cross-flow fan designs for applications in deep ultraviolet lithography excimer lasers, where maximizing the speed and power of the fan has a direct influence on the throughput and scanning speed of these devices. Using [...] Read more.

This study conducted a comparative evaluation of two bearingless cross-flow fan designs for applications in deep ultraviolet lithography excimer lasers, where maximizing the speed and power of the fan has a direct influence on the throughput and scanning speed of these devices. Using bearingless motor technology enables a combined generation of bearing force and drive torque and leads to a compact, hermetically sealed, and conveniently maintainable drive system. With identical bearingless motors on both rotor sides, it is possible to drive the cross-flow fan symmetrically to high rotational speeds at low torsional loads. The rotor prototypes were optimised, analysed, and pushed to high-speed operation and evaluated with respect to their rotor dynamic and fluid dynamic performance using finite element methods and experimental measurements. For both prototypes, successful numerical studies were performed, where a modal analysis enabled theoretical predictions of expected resonance frequencies, and a CFD analysis visualised local flow effects and provided cross-flow fan design comparisons. A stable operation of up to 12,000 rpm and 5500 rpm was accomplished for the two elaborated designs. Full article

(This article belongs to the Special Issue Rotor Dynamics and Rotating Machinery)

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16 pages, 7118 KiB

Open AccessEditor’s ChoiceArticle

Typical Fault Modeling and Vibration Characteristics of the Turbocharger Rotor System

by Jiahao Wang, Huabing Wen, Haiyu Qian, Junhua Guo, Junchao Zhu, Jiwei Dong and Hua Shen

Machines 2023, 11(2), 311; https://doi.org/10.3390/machines11020311 - 20 Feb 2023

Cited by 2 | Viewed by 1196

Abstract

To study the typical failure mechanism (rotor unbalance, rotor friction, and rotor crack) and vibration characteristics of the turbocharger rotor system, a rotor system dynamics simulation model was established by an improved four-node aggregate parameter method. The geometric and physical characteristics of the [...] Read more.

To study the typical failure mechanism (rotor unbalance, rotor friction, and rotor crack) and vibration characteristics of the turbocharger rotor system, a rotor system dynamics simulation model was established by an improved four-node aggregate parameter method. The geometric and physical characteristics of the rotor system under three failure states and its dynamics under operation were analyzed. Thus, a typical failure dynamics simulation model of the rotor system was established. On this basis, the output failure simulation signal was extracted using the Hu invariant moment feature extraction method to analyze the system vibration characteristics under each typical failure state of the rotor system. The results show that the model in this paper can effectively reduce the computational volume and computational time, and the errors of numerical simulation were less than 3%. When an unbalance fault occurred in the rotor system, the shaft trajectory was “0” shaped and the response spectrum was dominated by 1X. When the rotor system was frictional, the shaft trajectory was a slightly concave “8” shape, and the response spectrum was dominated by 0.5X. When the rotor system was cracked, the axial trajectory was a “vortex”, and the response spectrum was dominated by 0.5X. Thus, the study of typical failure mechanism and vibration characteristics of a turbocharger rotor system by simulation calculation is effective and has good research prospects, providing an important technical reference for dynamic analysis and fault diagnosis of the rotor system. Full article

(This article belongs to the Special Issue Rotor Dynamics and Rotating Machinery)

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23 pages, 9947 KiB

Open AccessArticle

Estimation of Unmeasurable Vibration of a Rotating Machine Using Kalman Filter

by Neda Neisi, Vesa Nieminen, Emil Kurvinen, Ville Lämsä and Jussi Sopanen

Machines 2022, 10(12), 1116; https://doi.org/10.3390/machines10121116 - 24 Nov 2022

Cited by 1 | Viewed by 1561

Abstract

Rotating machines are typically equipped with vibration sensors at the bearing location and the information from these sensors is used for condition monitoring. Installing additional sensors may not be possible due to limitations of the installation and cost. Thus, the internal condition of [...] Read more.

Rotating machines are typically equipped with vibration sensors at the bearing location and the information from these sensors is used for condition monitoring. Installing additional sensors may not be possible due to limitations of the installation and cost. Thus, the internal condition of machines might be difficult to evaluate. This study presents a numerical and experimental study on the case of a rotor supported by four rolling element bearings (REBs). As such, the study resembles a complex real-life industrial multi-fault scenario: a lack of information, uncertainties, and nonlinearities increase the overall complexity of the system. The study provides a methodology for modeling and analyzing complicated systems without prior information. First, the unknown model parameters of the system are approximated using measurement data and the linearized model. Thereafter, the Unscented Kalman Filter (UKF) is applied to the estimation of the vibration characteristics in unmeasured locations. As a result, the estimation of unmeasured vibration characteristics has a reasonable agreement with the rotor whirling, and the estimated results are within a 95% confidence interval. The proposed methodology can be considered as a transfer learning method that can be further used in other identification problems in the field of rotating machinery. Full article

(This article belongs to the Special Issue Rotor Dynamics and Rotating Machinery)

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15 pages, 3782 KiB

Open AccessArticle

An Approach on V-Shaped Milling for Rotor Balancing of Armatures

by Mengxuan Li, Yuhang Sun, Ruiwen Dong, Weiyu Chen and Dong Jiang

Machines 2022, 10(12), 1106; https://doi.org/10.3390/machines10121106 - 22 Nov 2022

Viewed by 1596

Abstract

In order to improve the dynamic balancing accuracy of the micromotor armature, a method of V-shaped milling based on a discrete vector model for unbalance correction is proposed. The discrete vector model is fitted according to the parameters of the milling cutter and [...] Read more.

In order to improve the dynamic balancing accuracy of the micromotor armature, a method of V-shaped milling based on a discrete vector model for unbalance correction is proposed. The discrete vector model is fitted according to the parameters of the milling cutter and rotor, and then all the unit unbalance vectors in the discrete vector model are added to the milling center. The numerical relationship between the milling depth and the removal of the mass unbalance vector is obtained, and the accuracy of the model is verified via comparison with the data of the simulation experiments. The complexity of the integral formula of the numerical milling model makes it difficult to apply in practice. The discrete vector model does not require integration of the numerical formula and only considers the milling area as being composed of countless discrete blocks, which greatly simplifies the process of solving the unbalance vector. In view of the different thicknesses of the tooth surface of the armature, in order to avoid damage to the armature during milling, the unbalanced vector is decomposed at the center of the tooth surface by force decomposition. The experimental results show that this proposed method can effectively improve the dynamic balancing accuracy of the micromotor armature. Full article

(This article belongs to the Special Issue Rotor Dynamics and Rotating Machinery)

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26 pages, 15829 KiB

Open AccessArticle

Rotor Fault Diagnosis Using Domain-Adversarial Neural Network with Time-Frequency Analysis

by Yongjie Xu, Jingze Liu, Zhou Wan, Dahai Zhang and Dong Jiang

Machines 2022, 10(8), 610; https://doi.org/10.3390/machines10080610 - 26 Jul 2022

Cited by 13 | Viewed by 1586

Abstract

Intelligent fault diagnosis of rotors always requires a large amount of labeled samples, but insufficient vibration signals can be obtained in operational rotor systems for detecting the fault modes. To solve this problem, a domain-adaptive transfer learning model based on a small number [...] Read more.

Intelligent fault diagnosis of rotors always requires a large amount of labeled samples, but insufficient vibration signals can be obtained in operational rotor systems for detecting the fault modes. To solve this problem, a domain-adaptive transfer learning model based on a small number of samples is proposed. Time-domain vibration signals are collected by overlapping sampling and converted into time-frequency diagrams by using short-time Fourier transform (STFT) and characteristics in the time domain and frequency domain of vibration signals are reserved. The features of source domain and target domain are projected into the same feature space through a domain-adversarial neural network (DANN). This method is verified by a simulated gas generator rotor and experimental rig of rotor. Both the transfer in the identical machine (TIM) and transfer across different machines (TDM) are realized. The results show that this method has high diagnosis accuracy and good robustness for different types of faults. By training a large number of simulation samples and a small number of experimental samples in TDM, high fault diagnosis accuracy is achieved, avoiding collecting a large amount of experimental data as the source domain to train the fault diagnosis model. Then, the problem of insufficient rotor fault samples can be solved. Full article

(This article belongs to the Special Issue Rotor Dynamics and Rotating Machinery)

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32 pages, 14278 KiB

Open AccessArticle

Speed-Dependent Bearing Models for Dynamic Simulations of Vertical Rotors

by Gudeta Berhanu Benti, Rolf Gustavsson and Jan-Olov Aidanpää

Machines 2022, 10(7), 556; https://doi.org/10.3390/machines10070556 - 10 Jul 2022

Cited by 1 | Viewed by 1658

Abstract

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 [...] Read more.

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 (

R_{a d j}^{2}

) 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. Full article

(This article belongs to the Special Issue Rotor Dynamics and Rotating Machinery)

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Review

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35 pages, 7321 KiB

Open AccessReview

Fluid Film Bearings and CFD Modeling: A Review

by Demetrio Pérez-Vigueras, Jorge Colín-Ocampo, Andrés Blanco-Ortega, Rafael Campos-Amezcua, Cuauhtémoc Mazón-Valadez, Víctor I. Rodríguez-Reyes and Saulo Jesús Landa-Damas

Machines 2023, 11(11), 1030; https://doi.org/10.3390/machines11111030 - 17 Nov 2023

Viewed by 1752

Abstract

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. [...] Read more.

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. Full article

(This article belongs to the Special Issue Rotor Dynamics and Rotating Machinery)

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