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.

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.

scholarly journals Video-Tachometer Methodology for Wind Turbine Rotor Speed Measurement

Sensors ◽  
2020 ◽  
Vol 20 (24) ◽  
pp. 7314
Author(s):  
Francesco Natili ◽  
Francesco Castellani ◽  
Davide Astolfi ◽  
Matteo Becchetti
Keyword(s):  
Wind Turbine ◽  
Rotational Speed ◽  
Wind Farm ◽  
Turbine Rotor ◽  
Rotating Machinery ◽  
Speed Estimation ◽  
Rotor Speed ◽  
High Rotational Speed ◽  
Speed Measurement ◽  
Wind Turbine Rotor

The measurement of the rotational speed of rotating machinery is typically performed based on mechanical adherence; for example, in encoders. Nevertheless, it can be of interest in various types of applications to develop contactless vision-based methodologies to measure the speed of rotating machinery. In particular, contactless rotor speed measurement methods have several potential applications for wind turbine technology, in the context of non-intrusive condition monitoring approaches. The present study is devoted exactly to this problem: a ground level video-tachometer measurement technique and an image analysis algorithm for wind turbine rotor speed estimation are proposed. The methodology is based on the comparison between a reference frame and each frame of the video through the covariance matrix: a covariance time series is thus obtained, from which the rotational speed is estimated by passing to the frequency domain through the spectrogram. This procedure guarantees the robustness of the rotational speed estimation, despite the intrinsic non-stationarity of the system and the possible signal disturbances. The method is tested and discussed based on two experimental environments with different characteristics: the former is a small wind turbine model (with a 0.45 m rotor diameter) in the wind tunnel facility of the University of Perugia, whose critical aspect is the high rotational speed (up to the order of 1500 RPM). The latter test case is a wind turbine with a 44 m rotor diameter which is part of an industrial wind farm: in this case, the critical point regards the fact that measurements are acquired in uncontrolled conditions. It is shown that the method is robust enough to overcome the critical aspects of both test cases and to provide reliable rotational speed estimates.

A Rotation-Speed Measurement System Based on Magneto-Inductive Effect

2020 ◽  
Vol 18 (4) ◽  
pp. 299-303
Author(s):  
Tao Wang ◽  
Bicong Wang ◽  
Yuyi Chen ◽  
Yufeng Luo
Keyword(s):  
Direct Current ◽  
Measurement System ◽  
Rotational Speed ◽  
Inductive Effect ◽  
Rotation Speed ◽  
Rotating Shaft ◽  
High Rotational Speed ◽  
Sensing System ◽  
Dc Motors ◽  
Speed Measurement

There are few reports on high rotational speed measurement of brushless direct current (DC) motors based on giant magneto-inductive effect. In this study, a rotational speed measurement system based on giant magneto-inductive effect is established for measuring the rotational speeds of DC motors. Successive sawtooth waves are found when rotating shaft is close to the GMI sensor. Through using the magneto-inductive sensing system, different high rotational speeds (1500∼24000 r/min) of the motor are accurately measured. Therefore, this giant magneto-inductive sensor may be used for high rotational speed measurement of motors.

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.

Nonlinear Vibration of a Saturated Water Journal Bearing and Bifurcation Analysis

2017 ◽  
Author(s):  
Tadayoshi Shoyama
Keyword(s):  
Rotational Speed ◽  
Journal Bearing ◽  
Dynamic Properties ◽  
Ambient Pressure ◽  
Equation Of Motion ◽  
Nonlinear Phenomena ◽  
Rotating Shaft ◽  
Saturated Water ◽  
Commercial Code ◽  
Turbo Compressor

We developed a turbo compressor that has water-lubricated bearings driven at 30,000 rpm in a saturation condition, where the ambient pressure is at the saturation point of the discharged lubricant water. Such a saturated water journal bearing is located at both end of the rotor, each of which has a conical part to produce thrust force without another thrust bearing or a thrust collar. The bearings are supported with nonlinear elastomeric O-rings. At rotational speed over 15,000 rpm, the rotor showed many sub-harmonic vibrations that are nonlinear phenomena unpredictable from a linear equation of motion. Instead, a stability analysis with a bifurcation diagram is an effective method to tackle these problems. In this paper, we investigated these rotor vibrations by bifurcation diagrams of the vibrations measured in experiments of saturated water journal bearings. The angular velocity was used as a bifurcation parameter. The bifurcations among synchronous, sub-harmonic, and chaotic vibrations were shown. Next, the nonlinear dynamics of the rotating rigid shaft were analyzed numerically with the nonlinear stiffness obtained by a commercial code that utilizes the two-dimensional Reynolds equation. The dynamic properties of the supporting structure were modeled with a complex stiffness coefficient. The equation of motion of the rotating shaft was solved numerically in a time domain with these dynamic properties. MATLAB Simulink code was built to integrate the equations. As a result, a Hopf bifurcation was found and a sub-harmonic limit cycle appeared spontaneously. The rotational speed and such other properties as the unbalanced force and the damping of the supporting structures were parameterized to investigate the onset and the amplitude of these vibrations. These numerical results agreed well with the experimental results.

scholarly journals Geometric Tolerance Applications and Analysis Method in Rotational Mechanical Components

2020 ◽  
Vol 8 (6) ◽  
pp. 1366-1369
Keyword(s):  
Rotational Speed ◽  
Life Time ◽  
Rotating Machinery ◽  
Analysis Method ◽  
High Rotational Speed ◽  
Essential Requirement ◽  
Geometric Tolerance ◽  
Time Component ◽  
Mechanical Components ◽  
The Impact

This paper focus a review on geometrical tolerance application and effects in rotational mechanical components. In today’s rapid competition on pump and turbomachinery industry the geometrical tolerancing process plays a significant role in high rotational speed of shaft. The imbalance force and misalignment of the shaft during rotating is the cause of the system's vibration. Therefore, Geometrical Dimensioning and Tolerance (GD&T) has been considered as an essential requirement to be fulfilled by rotating machinery manufacturers and assembly worker. The impact and the level of damage to critical parts of the machine were reviewed as a benchmark for further study to reduce the problem and improve the life time component. As a result, there are extensive researches such as optimisation of tolerance for mechanical components in rotating machinery

Dual Release Model to Evaluate Dissolution Profiles from Swellable Drug Polyelectrolyte Matrices

2020 ◽  
Vol 17 (6) ◽  
pp. 511-522 ◽  
Author(s):  
Alicia Graciela Cid ◽  
María Verónica Ramírez-Rigo ◽  
María Celeste Palena ◽  
Elio Emilio Gonzo ◽  
Alvaro Federico Jimenez-Kairuz ◽  
...  
Keyword(s):  
Experimental Data ◽  
Drug Release ◽  
Inflection Point ◽  
Release Profile ◽  
Experimental Point ◽  
Extended Model ◽  
Release Process ◽  
Proposed Model ◽  
Dual Release ◽  
Release Model

Background: Mathematical modeling in modified drug release is an important tool that allows predicting the release rate of drugs in their surrounding environment and elucidates the transport mechanisms involved in the process. Objective: The aim of this work was to develop a mathematical model that allows evaluating the release profile of drugs from polymeric carriers in which the swelling phenomenon is present. Methods: Swellable matrices based on ionic complexes of alginic acid or carboxymethylcellulose with ciprofloxacin were prepared and the effect of adding the polymer sodium salt on the swelling process and the drug release was evaluated. Experimental data from the ciprofloxacin release profiles were mathematically adjusted, considering the mechanisms involved in each stage of the release process. Results: A proposed model, named “Dual Release” model, was able to properly fit the experimental data of matrices presenting the swelling phenomenon, characterized by an inflection point in their release profile. This entails applying the extended model of Korsmeyer-Peppas to estimate the percentage of drug released from the first experimental point up to the inflection point and then a model called Lumped until the final time, allowing to adequately represent the complete range of the drug release profile. Different parameters of pharmaceutical relevance were calculated using the proposed model to compare the profiles of the studied matrices. Conclusion: The “Dual Release” model proposed in this article can be used to predict the behavior of complex systems in which different mechanisms are involved in the release process.

A Multiple Harmonic Open-Loop Controller for Hydro/Aerodynamic Force Measurements in Rotating Machinery Using Magnetic Bearings

2002 ◽  
Vol 124 (4) ◽  
pp. 827-834 ◽  
Author(s):  
D. O. Baun ◽  
E. H. Maslen ◽  
C. R. Knospe ◽  
R. D. Flack
Keyword(s):  
Frequency Domain ◽  
Time Domain ◽  
Open Loop ◽  
Rotating Machinery ◽  
Operating Conditions ◽  
Rotor Vibration ◽  
Aerodynamic Forces ◽  
Analog Input ◽  
Input And Output ◽  
The Time Domain

Inherent in the construction of many experimental apparatus designed to measure the hydro/aerodynamic forces of rotating machinery are features that contribute undesirable parasitic forces to the measured or test forces. Typically, these parasitic forces are due to seals, drive couplings, and hydraulic and/or inertial unbalance. To obtain accurate and sensitive measurement of the hydro/aerodynamic forces in these situations, it is necessary to subtract the parasitic forces from the test forces. In general, both the test forces and the parasitic forces will be dependent on the system operating conditions including the specific motion of the rotor. Therefore, to properly remove the parasitic forces the vibration orbits and operating conditions must be the same in tests for determining the hydro/aerodynamic forces and tests for determining the parasitic forces. This, in turn, necessitates a means by which the test rotor’s motion can be accurately controlled to an arbitrarily defined trajectory. Here in, an interrupt-driven multiple harmonic open-loop controller was developed and implemented on a laboratory centrifugal pump rotor supported in magnetic bearings (active load cells) for this purpose. This allowed the simultaneous control of subharmonic, synchronous, and superharmonic rotor vibration frequencies with each frequency independently forced to some user defined orbital path. The open-loop controller was implemented on a standard PC using commercially available analog input and output cards. All analog input and output functions, transformation of the position signals from the time domain to the frequency domain, and transformation of the open-loop control signals from the frequency domain to the time domain were performed in an interrupt service routine. Rotor vibration was attenuated to the noise floor, vibration amplitude ≈0.2 μm, or forced to a user specified orbital trajectory. Between the whirl frequencies of 14 and 2 times running speed, the orbit semi-major and semi-minor axis magnitudes were controlled to within 0.5% of the requested axis magnitudes. The ellipse angles and amplitude phase angles of the imposed orbits were within 0.3 deg and 1.0 deg, respectively, of their requested counterparts.

Performances of HSK Tool Interfaces under High Rotational Speed

CIRP Annals ◽  
2001 ◽  
Vol 50 (1) ◽  
pp. 281-284 ◽  
Author(s):  
T. Aoyama ◽  
I. Inasaki
Keyword(s):  
Rotational Speed ◽  
High Rotational Speed
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