Analysis of Whirling Vibration Due to Morton Effect by Using Frequency Transfer Function Model in Journal Bearings

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Shota Yabui ◽  
Jotaro Chiba ◽  
Takafumi Suzuki ◽  
Shigeyuki Tomimatsu ◽  
Tsuyoshi Inoue
Keyword(s):  
Experimental Data ◽  
High Efficiency ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Rotating Machinery ◽  
Rotating Shaft ◽  
Control Engineering ◽  
Proposed Model ◽  
Bending Mode ◽  
Morton Effect

Abstract In recent years, rotating machinery has been required to operate at high rotational speeds for high efficiency. However, with increase in the rotational speed, the rotating machinery may become unstable. One cause of unstable vibrations is the Morton effect that occurs in journal bearings. Thus, developing a mathematical model to predict the Morton effect is desirable to avoid the occurrence of such unstable vibrations. In this study, a model based on a frequency response that can quantitatively evaluate the Morton-effect-induced vibrations in rotating machinery supported by a journal bearing was developed. Experimental data were collected for modeling by using an experimental rig. Using the experimental data pertaining to the journal position in the journal bearing and temperature of the journal, a model for the Morton effect was established based on the frequency responses. From a control engineering viewpoint, the journal bearing was considered to be a proportional differential controller. In addition, the Morton-effect-induced vibrations were considered as a new bending mode of a rotating shaft, caused by thermal differences. Subsequently, the developed model was evaluated in the frequency domain. The characteristics of the vibrations, determined using the proposed model, exhibited good correlation with those corresponding to experimental data. The experimental data agreed well with the predicted results, and the results demonstrated the usefulness of the proposed method for predicting the Morton effect.

Transfer Function Modeling and Experimental Variation of Rotor System Considering Morton Effect Caused in Journal Bearing

2019 ◽  
Author(s):  
Shota Yabui ◽  
Jotaro Chiba ◽  
Takafumi Suzuki ◽  
Shigeyuki Tomimatsu ◽  
Tsuyoshi Inoue
Keyword(s):  
Experimental Data ◽  
Frequency Domain ◽  
Rotational Speed ◽  
Journal Bearing ◽  
Rotating Machinery ◽  
Rotating Shaft ◽  
High Rotational Speed ◽  
Proposed Model ◽  
Morton Effect ◽  
Unstable Vibration

Abstract In recent years, a rotating machinery are required to operate at high rotational speed for high efficiency. However, the rotating machinery may become unstable due to the increase of rotational speed. One cause of unstable vibration is the Morton Effect generated in a journal bearing. To avoid unstable vibration due to the Morton Effect, construction of a mathematical model for predicting it becomes an important subject. Many researches on the Morton Effect have been conducted previously. Conventional researches are mostly divided into two types. The first one is a study based on detailed numerical simulation using computational fluid dynamics (CFD), thermoshydrodynamics (THD) and so on. It tries to find solution of a differential equation which indicates the Morton Effect induced vibration for a specific machine or a test rig. Therefore, this approach has led not comprehensive model. The other one is a study expressed by a simple mathematical formula. However, modeling in the time domain has been mainly focused and modeling in the frequency domain has not been investigated in detail. In this research, a model based on the frequency response that can quantitatively evaluate the Morton Effect induced vibration in the rotating machinery supported by the journal bearing is developed. First, experimental data was collected for modeling by using an experimental rig. Using these experimental data of journal position in the journal bearing and temperature of journal, a model of the Morton Effect was constructed based on frequency responses. In the proposed method, the characteristic of the journal bearing was considered as a proportional differential controller from control engineering point of view. In addition, the proposed model considers the Morton Effect induced vibration as a new bending mode of a rotating shaft caused by thermal difference. Then, the developed model of the Morton Effect was evaluated in the frequency domain. The characteristics of vibration calculated by the proposed model indicated good correlation with that of the experimental data. Finally, the behavior of the rotating shaft at another rotational speed was predicted by using the proposed model. It was confirmed that the experimental data well agreed with the predicted results. These results show the usefulness of the proposed method of this research for predicting the Morton Effect.

Modeling a Hydrodynamic Bearing With Provision for Misalignments and Textures

2019 ◽  
Vol 142 (4) ◽  
Author(s):  
Chunxing Gu ◽  
Xianghui Meng ◽  
Shuwen Wang ◽  
Xiaohong Ding
Keyword(s):  
High Efficiency ◽  
Journal Bearing ◽  
Effective Means ◽  
Surface Texturing ◽  
Tribological Performance ◽  
Journal Bearings ◽  
Time Varying ◽  
Hydrodynamic Bearing ◽  
Proposed Model ◽  
Effect Of Surface

Abstract Surface texturing is one effective means to improve bearing performance. Available studies are mainly focused on the perfectly aligned journal bearing with textures. The studies involving the effect of surface texturing on the misaligned bearing are still limited. In the present study, a transient mixed lubrication model that allows predicting evolution of friction characteristics with high efficiency was proposed. The misalignment of journal bearing under the time-varying applied load was considered using two deflection angles. The performance of journal bearing with provision for misalignments and textures was studied using the proposed model. The results involving the orbits of the journal center and the energy loss of different misaligned journal bearings were obtained. The influences of misalignment degree and surface texturing on these parameters were analyzed. The results show that along with the increased deflection angles, the effect of texturing on the tribological performance of journal bearing would turn beneficial into harmful.

scholarly journals Experiments on an Ultrastable Gas Journal Bearing

1967 ◽  
Vol 89 (4) ◽  
pp. 433-438 ◽  
Author(s):  
S. B. Malanoski
Keyword(s):  
Experimental Data ◽  
Steady State ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Design Data ◽  
Attitude Angle ◽  
Angle Data ◽  
The Stability ◽  
Data Design ◽  
Gas Journal Bearing

Shallow grooving in a herringbone pattern has been proposed to enhance the stability of both gas and liquid-lubricated journal bearings. It has been shown theoretically that this possibility is particularly advantageous for unloaded journal bearings. This paper describes corroborating experiments. The experiments included the running of an unloaded bearing up to speeds of 60,000 rpm and the collection of steady-state load-displacement, attitude angle data at intermediate speeds up to and including 60,000 rpm. No sign of bearing whirl instability was detected. There was good correlation between theoretical and experimental data. Design data for the partially grooved journal bearing is included for future designs.

Applicaton of Modal Filtration for Damage Detection of Rotating Shaft

2009 ◽  
Vol 413-414 ◽  
pp. 373-380 ◽  
Author(s):  
Krzysztof Mendrok ◽  
Jarosław Bednarz ◽  
Tadeusz Uhl
Keyword(s):  
Experimental Data ◽  
Damage Detection ◽  
Experimental Verification ◽  
Diagnostic Procedure ◽  
Rotating Machinery ◽  
Laser Vibrometer ◽  
Rotating Shaft ◽  
Output Only

The paper describes a modification of the method which uses the modal filtration for damage detection [11] to make it suitable for rotating machinery. Authors have formulated a diagnostic procedure which is based on the output only data measured during object operation. The measurement can be performed both by accelerometers placed on the shaft bearing cages and directly on the shaft with use of the laser vibrometer. The procedure was verified on the experimental data. For the experimental verification authors have used the laboratory stand which allows simulation of different faults.

Surface Finish and Clearance Effects on Journal-Bearing Load Capacity and Friction

1959 ◽  
Vol 81 (2) ◽  
pp. 245-252 ◽  
Author(s):  
F. W. Ocvirk ◽  
G. B. DuBois
Keyword(s):  
Experimental Data ◽  
Film Thickness ◽  
Surface Finish ◽  
Journal Bearing ◽  
Load Capacity ◽  
Journal Bearings ◽  
Oil Film ◽  
Bearing Clearance ◽  
Bearing Load

A method of relating surface finish to minimum oil-film thickness and the corresponding load capacity of plain journal bearings is presented with supporting experimental data. The effect of clearance on load capacity and friction are shown on graphs indicating an optimum bearing clearance.

Theoretical Contributions to the Study of Gas-Lubricated Journal Bearings

1962 ◽  
Vol 84 (1) ◽  
pp. 123-131
Author(s):  
Y. Katto ◽  
N. Soda
Keyword(s):  
Experimental Data ◽  
Approximate Solution ◽  
Theoretical Study ◽  
Journal Bearing ◽  
Isothermal Condition ◽  
Approximate Solutions ◽  
Journal Bearings ◽  
Eccentricity Ratio ◽  
Intermediate Condition ◽  
Comparison With Experimental Data

As a theoretical study of the hydrodynamic, gas-lubricated journal bearings, the paper presents approximate solutions with fair accuracy for high values of eccentricity ratio. In addition, an approximate solution available for clarifying the characteristics of journal bearing operating at low revolution speeds is reported. Comparison with experimental data reveals the fact that actual bearings operate under an intermediate condition between isothermal and adiabatic when running at high revolution speeds, while under the isothermal condition at low speeds.

Approximate analytical model for fluid film force of finite length plain journal bearing

2011 ◽  
Vol 226 (5) ◽  
pp. 1345-1355 ◽  
Author(s):  
Y L Wang ◽  
Z S Liu ◽  
W J Kang ◽  
J J Yan
Keyword(s):  
Analytical Model ◽  
Finite Length ◽  
Journal Bearing ◽  
Separation Of Variables ◽  
Current Model ◽  
Dynamic Performance ◽  
Journal Bearings ◽  
Force Model ◽  
Oil Film ◽  
Proposed Model

Non-linear dynamic performance of rotor–bearing systems supported by plain journal bearings strongly depends on the mathematical oil film force model. In this article, the analytical solution of oil film pressure for finite length plain journal bearing is obtained by employing the separation of variables method to analytically solve the Reynolds equation based on dynamic Gümbel boundary conditions. The analytical expression of oil film force is then derived by applying the integral method. The expression of the pressure is analysed to investigate the pressure distribution. The oil film force of the analytical model is compared with the results from other methods, namely, long bearing approximation, short bearing approximation, as well as the finite difference method. The results clearly validate the current model. The proposed model also proved to be efficient for analysing the dynamic characteristics of a rigid rotor supported by plain journal bearings.

Experimental Study of Stabilisation of Small Size Journal Bearing With Oil Supply Groove by Using Starved Lubrication and Bearing Orientation Angle Change

2007 ◽  
Author(s):  
Masayuki Ochiai ◽  
Hiromu Hashimoto
Keyword(s):  
Experimental Study ◽  
High Speed ◽  
Journal Bearing ◽  
Orientation Angle ◽  
Journal Bearings ◽  
Rotating Machinery ◽  
Angle Change ◽  
Tilting Pad ◽  
Starved Lubrication ◽  
Rotating Machineries

Journal bearings are widely used for supporting high speed rotating machinery such as turbine, compressor and HDD spindle etc, because of their high load carrying capacity, stability and durability. Recently, the engineering trend is oriented to higher speed and smaller sizes of rotating machinery, and then it is important to enhance stabilities for the journal bearings. Tilting pad journal bearing is generally used for high-speed rotating machineries because of their advantages of stabilization. However, there are some problems using for compact size rotating machineries for their high manufacturing cost and complicated structure. Therefore, it is necessary to enhance the stability of more simple bearings compared with tilting pad bearing in order to use for small size rotating machinery. This paper describes the stabilization method of journal bearing based on the combination mechanism with starved lubrication and orientation angle change. From the results of stability experimental study of journal bearings, it is clarified that the stabilization of bearings is improved drastically by using above techniques.

Experimental Study on the Stabilization of Small-Bore Journal Bearings by Controlling Starved Lubrication and Bearing Orientation Angle

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
Hiromu Hashimoto ◽  
Masayuki Ochiai
Keyword(s):  
High Speed ◽  
Journal Bearing ◽  
Orientation Angle ◽  
Journal Bearings ◽  
Rotating Machinery ◽  
Manufacturing Cost ◽  
Compact Size ◽  
Tilting Pad ◽  
Starved Lubrication ◽  
Rotating Machineries

Journal bearings are widely used for supporting high-speed rotating machinery, such as turbine, compressor, and HDD spindle, because of their high load carrying capacity, stability, and durability. Recently, the engineering trend is oriented to higher speed and smaller sizes of rotating machinery, and then it is important to enhance stabilities for the small-bore journal bearings. Tilting pad journal bearing is generally used for high-speed rotating machineries because of their advantages of stabilization. However, there are some problems using compact size rotating machineries for their high manufacturing cost and complicated structure. Therefore, it is necessary to enhance the stability of more simple bearings compared with tilting pad bearing in order to use for small-size rotating machinery. This paper describes the stabilization method of the small-bore journal bearing based on the combination mechanism with starved lubrication and orientation angle change. It is found that the stabilization of small-bore journal bearings is improved drastically by hybrid lubrication combining these two kinds of mechanism.

scholarly journals Stability analysis of Morton effect for journal bearing based on control engineering

2020 ◽  
Vol 2020 (0) ◽  
pp. J10102
Author(s):  
Shota Yabui ◽  
Takafumi Suzuki ◽  
Shigeyuki Tomimatsu ◽  
Tsuyoshi Inoue
Keyword(s):  
Stability Analysis ◽  
Journal Bearing ◽  
Control Engineering ◽  
Morton Effect
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