Quantification of multiple fault parameters in flexible turbo-generator systems with incomplete rundown vibration data

Lal, Mohit; Tiwari, Rajiv

doi:10.1016/j.ymssp.2013.06.025

Cited by 24 publications

(6 citation statements)

References 30 publications

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“…From vector X D m in Eq. 15, it may observe that dynamic reduction scheme has limitations, the associated DOFs corresponding to the parameters that need to be estimated cannot eliminate [28]. In the present research work, coupling and AMB characteristic parameters need to be evaluated.…”

Section: Methodology Development Using Dynamic Reduction [31]mentioning

confidence: 92%

“…The characteristic specification of dual rotor system and AMB is listed in table 1 [1], [17] and [28]. A forced response with phase plot is presented in figure 3.…”

Section: Development Of Numerical Signalmentioning

confidence: 99%

“…The expression for misalignment forces and moments are presented in ref. [28]. The frequency range considered here is same as used for estimating characteristic parameters, i.e., Case A and B (10-50 Hz).…”

Section: Case B: Operating Speeds In Between the Fourth And Fifth Crimentioning

confidence: 99%

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Dual flexible rotor system with active magnetic bearings for unbalance and coupling misalignment faults analysis

Kuppa

Lal

2019

Sādhanā

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Rotating machines are the backbone of the present industrial world. Early fault detection and conditioning of these machines are primary concern of the researchers associated in this field. There are various faults (assembly error, coupling misalignment, looseness, imbalance, rotor crack, etc.) that cause malfunction of rotating machinery. Imbalance is one of the oldest problem and still challenging to perfectly balance the rotor. Imbalance leads to another inherent fault, i.e., coupling misalignment, especially in dual rotor or rotor train system. Imbalance and misalignment cause excessive vibration in the system that tends to shatter failure of the critical components of rotating machinery. In this article, active magnetic bearings (AMBs) are utilized to suppress the excessive vibration generated due to imbalance and misalignment. To regulate the controlling current of AMB a proportional integral derivative (PID) feedback controller is employed. A quantification technique is suggested to evaluate the tuned AMB characteristics along with imbalance and coupling misalignment dynamic parameters. A finite element method (FEM) modelling with high-frequency reduction scheme is utilized to acquire reduced system equations of motion. There are two advantages of employing condensation scheme, first, it reduces the number of sensors required and second, only linear (practically measurable) degrees of freedom are present in equations of motion derived. A SIMULINK TM code is prepared to solve a reduced linear differential equation. The time series feedback signals (current and displacement) obtained are transformed into a frequency series utilizing Fast Fourier Transformation (FFT) and utilized in developed algorithm. To establish the accuracy and effectiveness of the methodology, the estimated parameters are evaluated under two different frequency bands against measurement and modelling error (5% variation in mass of the disc and bearing characteristic parameters).

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Section: Methodology Development Using Dynamic Reduction [31]mentioning

confidence: 92%

“…The characteristic specification of dual rotor system and AMB is listed in table 1 [1], [17] and [28]. A forced response with phase plot is presented in figure 3.…”

Section: Development Of Numerical Signalmentioning

confidence: 99%

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Dual flexible rotor system with active magnetic bearings for unbalance and coupling misalignment faults analysis

Kuppa

Lal

2019

Sādhanā

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“…(2) for known rotor dynamic parameters and unbalance information. A high-frequency condensation scheme [41] has been used to eliminate immeasurable DOFs that exclude linear DOFs at bearing location and includes all other linear and angular DOFs. The advantage of this condensation is that it can be applied to eliminate those DOFs also at which parameters are to be estimated, for example, coupling DOFs.…”

Section: Identification Algorithmmentioning

confidence: 99%

Experimental identification of shaft misalignment in a turbo-generator system

Lal

Tiwari

2018

Sādhanā

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Precise and authentic estimation of the dynamic features of rotating machines and prevention of failure requires accurate experimental characterisation of their critical components, for example, bearings and couplings. These are difficult to model theoretically, and they often suffer from uncertain parameters in their model. Especially, when there is a misalignment in the rotor system, dynamic characterisation of bearings and couplings changes drastically. In the present study, multiple fault parameters (MFPs) of critical components of turbo-generator, that is, bearing and coupling together with residual unbalances (RUs), are evaluated experimentally using model-based methodology. A test rig was developed and used for experimentation in which different levels of misalignment was introduced. After estimating the MFPs, then the accuracy was checked through an impact test on the rotor test rig. The effect of different levels of misalignments on estimated parameters was studied.

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“…Bert and Wu 6 analyzed the dynamic characteristics of a nonlinear torsional flexible coupling with elastic links, and obtained the quasi-static performance of torque and angular displacement at constant rotational velocity by the equations of motions. Lal and Tiwari 7,8 focused on the misalignments of the flexible coupling, and developed an identification algorithm to estimate the dynamic parameters of the coupling by means of the least-squares fit technique in frequency domain, which belongs to the field of the inverse problem. Al-Hussain 9 studied the effect of the misalignment of two rigid rotors connected by a flexible coupling on the stability of rotating machinery.…”

Section: Introductionmentioning

confidence: 99%

Online measurement of torsional stiffness and fault analysis for flexible coupling under working condition

Guo

et al. 2016

Proceedings of the Institution of Mechanical Engineers, Part C:

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In this paper, a method of measuring the relative torsional angles of the flexible coupling under working condition was developed. A double-encoder measurement system was proposed to get the torsional angles. The torsional angles were divided into ''constant torsional angle'' and ''alternating torsional angle''. The measured results were analyzed further, which were applied to a series of flexible couplings. Firstly, the torsional stiffness of D-type flexible coupling was obtained according to the relationship between torques and torsional angles. The proposed method overcomes the difficulty that the angular displacements of flexible coupling cannot be measured online under operating condition. The feasibility and accuracy of the method developed in this study was verified by comparing stiffness curve with unloading curve obtained from static torsional experiment and values from factory inspection report. Furthermore, in view of the tear fault of Atype flexible coupling in a diesel generator set, the maximum alternating torsional angles of A-type, B-type, and C-type flexible couplings were measured under working condition, then safety margins were obtained for the diesel generator set. According to the safety margins of the three kinds of couplings, C-type flexible coupling is chosen to replace A-type, which provided the basis for type selection of flexible coupling. Finally, the method developed in this study would also be applied to the operation monitoring and fault diagnosis of flexible coupling online.

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Quantification of multiple fault parameters in flexible turbo-generator systems with incomplete rundown vibration data

Cited by 24 publications

References 30 publications

Dual flexible rotor system with active magnetic bearings for unbalance and coupling misalignment faults analysis

Dual flexible rotor system with active magnetic bearings for unbalance and coupling misalignment faults analysis

Experimental identification of shaft misalignment in a turbo-generator system

Online measurement of torsional stiffness and fault analysis for flexible coupling under working condition

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