Compensation for encoder geometry and shaft speed variation in time interval torsional vibration measurement

2005 ◽  
Vol 286 (4-5) ◽  
pp. 897-920 ◽  
Author(s):  
Brian R. Resor ◽  
Martin W. Trethewey ◽  
Kenneth P. Maynard
Keyword(s):  
Torsional Vibration ◽  
Vibration Measurement ◽  
Time Interval ◽  
Shaft Speed ◽  
Speed Variation

Measurement of Torsional Vibration in Rotating Machinery

1986 ◽  
Vol 108 (4) ◽  
pp. 565-577 ◽  
Author(s):  
J. M. Vance ◽  
R. S. French
Keyword(s):  
Torsional Vibration ◽  
Measurement Techniques ◽  
Time History ◽  
Rotating Machinery ◽  
Drive Train ◽  
Vibration Measurement ◽  
Time Interval ◽  
Advantages And Disadvantages ◽  
System A ◽  
History Of

Five techniques for measurement of torsional vibration in a drive train are described, along with the advantages and disadvantages of each. Two laboratory test rigs, designed and constructed for experimental evaluation of various torsional vibration measurement techniques, are described. The measurement techniques investigated fall into three categories: a) those using signals from strain gages, b) those using signals from a magnetically transduced gear, and c) using signals optically transduced from a special tape applied to the shaft. One of the techniques described requires no specialized instrumentation other than a spectrum analyzer, which is now typically available in plants with rotating machinery. Another technique is capable of producing a detailed time history of torsional oscillations during acceleration of the drive train (i.e., startup), using a time interval measurement system. A comparison of results from the various techniques is given, and recommendations are made for several types of applications.

scholarly journals Experimental Study of the Shaft Penetration Factor on the Torsional Dynamic Response of a Drive Train

Machines ◽  
2018 ◽  
Vol 6 (3) ◽  
pp. 31 ◽  
Author(s):  
Hans Meeus ◽  
Björn Verrelst ◽  
David Moens ◽  
Patrick Guillaume ◽  
Dirk Lefeber
Keyword(s):  
Experimental Study ◽  
Torsional Vibration ◽  
Torsional Stiffness ◽  
Vibration Measurement ◽  
Dynamic Amplification Factor ◽  
Torsional Mode ◽  
Penetration Factor ◽  
Torsional Response ◽  
Major Interest ◽  
Drive Trains

Typical rotating machinery drive trains are prone to torsional vibrations. Especially those drive trains that comprise one or more couplings which connect the multiple shafts. Since these vibrations rarely produce noise or vibration of the stationary frame, their presence is hardly noticeable. Moreover, unless an expensive torsional-related problem has become obvious, such drive trains are not instrumented with torsional vibration measurement equipment. Excessive levels can easily cause damage or even complete failure of the machine. So, when designing or retrofitting a machine, a comprehensive and detailed numerical torsional vibration analysis is crucial to avoid such problems. However, to accurately calculate the torsional modes, one has to account for the penetration effect of the shaft in the coupling hub, indicated by the shaft penetration factor, on the torsional stiffness calculation. Many guidelines and assumptions have been published for the stiffness calculation, however, its effect on the damping and the dynamic amplification factor are less known. In this paper, the effect of the shaft penetration factor, and hence coupling hub-to-shaft connection, on the dynamic torsional response of the system is determined by an experimental study. More specifically, the damping is of major interest. Accordingly, a novel academic test setup is developed in which several configurations, with each a different shaft penetration factor, are considered. Besides, different amplitude levels, along with both a sweep up and down excitation, are used to identify their effect on the torsional response. The measurement results show a significant influence of the shaft penetration factor on the system’s first torsional mode. By increasing the shaft penetration factor, and thus decreasing the hub-to-shaft interference, a clear eigenfrequency drop along with an equally noticeable damping increase, is witnessed. On the contrary, the influence of the sweep up versus down excitation is less pronounced.

scholarly journals A Fiber Bragg Grating Based Torsional Vibration Sensor for Rotating Machinery

Sensors ◽  
2018 ◽  
Vol 18 (8) ◽  
pp. 2669 ◽  
Author(s):  
Jingjing Wang ◽  
Li Wei ◽  
Ruiya Li ◽  
Qin Liu ◽  
Lingling Yu
Keyword(s):  
Optical Fiber ◽  
Fiber Bragg Grating ◽  
Torsional Vibration ◽  
Electromagnetic Interference ◽  
Vibration Sensor ◽  
Vibration Measurement ◽  
Bragg Grating ◽  
Structural Parameter ◽  
Measurement Sensitivity ◽  
Fiber System

This paper proposes a new type of torsional vibration sensor based on fiber Bragg grating (FBG). The sensor has two mass ball optical fiber systems. The optical fiber is directly treated as an elastomer and a mass ball is fixed in the middle of the fiber in each mass ball fiber system, which is advantageously small, lightweight, and has anti-electromagnetic interference properties. The torsional vibration signal can be calculated by the four FBGs’ wavelength shifts, which are caused by mass balls. The difference in the two sets of mass ball optical fiber systems achieves anti-horizontal vibration and anti-temperature interference. The principle and model of the sensor, as well as numerical analysis and structural parameter design, are introduced. The experimental conclusions show that the minimum torsional natural frequency of the sensor is 27.35 Hz and the torsional vibration measurement sensitivity is 0.3603 pm/(rad/s2).

Electronic Torsional Vibration Elimination for Synchronous Motor Driven Turbomachinery

2011 ◽  
Author(s):  
Christof Sihler ◽  
Simon Schramm ◽  
Valerio Rossi ◽  
Andrea Lenzi ◽  
Valerio Depau
Keyword(s):  
Mechanical System ◽  
Power Electronics ◽  
Torsional Vibration ◽  
Oil And Gas Industry ◽  
Torque Ripple ◽  
Air Gap ◽  
Vibration Measurement ◽  
Vibration Level ◽  
Variable Speed ◽  
Electrical Drive

The oil and gas industry has a growing demand for electrically driven trains operated at variable speeds. Variable frequency electrical drives enable increased operational flexibility and energy efficiency. One drawback of power electronics driven systems is the generation of non-fundamental air-gap torque ripple components due to electrical harmonics. The air-gap torque ripple can interact with the mechanical system at natural torsional frequencies of the drive train. Uncontrolled excited torsional vibration can silently lead to coupling failure due to fatigue. The coincidence of electrical drive harmonics and natural torsional frequencies of the mechanical system is sometimes unavoidable, due to the large variable speed range of the compressor as for process requirements. For those types of applications, a damping system utilizing available power electronics has been developed that can be applied to new units but also as a retrofit solution in existing variable speed trains. Electronic torsional vibration elimination (eTVe) is based on an angular vibration measurement in the mechanical system and an interface to the existing inverter control of the electrical drive. An important milestone of the eTVe development was achieved in 2010, in site testing this new solution to Liquid Natural Gas (LNG) production trains and demonstrating that it can completely eliminate torsional vibrations. With eTVe a residual torsional vibration level was achieved that was lower than the vibration level measured while the LNG train was only gas turbine driven. This torsional performance was achieved with a standard load commutated inverter drive (LCI). LCIs are one of the most widespread electrical drive technology for gas compression trains because of excellent reliability records, and it is the only one referenced solution for electric power larger than 45 MW.

Development of a Torsional Behavior Powertrain Model for Multiple Misfire Detection

2005 ◽  
Author(s):  
Fabrizio Ponti
Keyword(s):  
Torsional Vibration ◽  
Engine Speed ◽  
Experimental Tests ◽  
Detection Algorithm ◽  
Operating Conditions ◽  
False Alarms ◽  
Time Interval ◽  
Short Time Interval ◽  
Torsional Behavior ◽  
Misfire Detection

Many methodologies have been developed in the past for misfire detection purposes based on the analysis of the instantaneous engine speed. The missing combustion is usually detected thanks to the sudden engine speed decrease that takes place after a misfire event. Misfire detection and in particular cylinder isolation is anyhow still a challenging issue for engines with a high number of cylinders, for engine operating conditions at low load or high engine speed and for multiple misfire events. When a misfire event takes place in fact a torsional vibration is excited and shows up in the instantaneous engine speed waveform. If a multiple misfire occurs this torsional vibration is excited more than once in a very short time interval. The interaction among these successive vibrations can generate false alarms or misdetection, and an increased complexity when dealing with cylinder isolation. The paper presents the development of a powertrain torsional behavior model in order to identify the effects of a misfire event on the instantaneous engine speed signal. The identified waveform has then been used to filter out the torsional vibration effects in order to enlighten the missing combustions even in the case of multiple misfire events. The model response is also used to quicken the setup process for the detection algorithm employed, evaluating before running specific experimental tests on a test bench facility, the values for the threshold and the optimal setup of the procedure. The proposed algorithm is developed in this paper for an SI L4 engine; Its application to other engine configurations is possible, as it is also discussed in the paper.

Instantaneous Engine Speed Analysis for Cylinder Isolation in Multiple Misfire Events

2003 ◽  
Author(s):  
Fabrizio Ponti
Keyword(s):  
Torsional Vibration ◽  
Engine Speed ◽  
Operating Conditions ◽  
Spark Ignition Engine ◽  
Detection Methods ◽  
False Alarms ◽  
Time Interval ◽  
Short Time Interval ◽  
Operating Range ◽  
Misfire Detection

Misfire detection is a subject that has been deep studied during the last years and many methodologies have been developed for this purpose. Affordably detecting the misfire event and isolating the cylinder where the missing combustion took place can be considered a solved problem for engines with a limited number of cylinders. Misfire detection and in particular cylinder isolation is still challenging for engine operating conditions at very low load and high engine speed, for engines with a high number of cylinders, or when more than one misfire event is present within the same engine cycle (multiple misfire). In particular this last malfunctioning condition is very challenging, and its detection is enforced by the international regulations without requiring cylinder isolation, but only the number of misfiring cylinders. Many methodologies have been developed in the past based on the analysis of the instantaneous engine speed. The missing combustion effect on this signal is anyway very low when the number of cylinders is high and for engine operating conditions at low engine speed, giving rise to misdetection or false alarms as already mentioned. In addition when a misfire event takes place a torsional vibration is excited and shows up in the instantaneous engine speed waveform. If a multiple misfire occurs this torsional vibration is excited more than once in a very short time interval. The interaction among these successive vibrations can further generate false alarms or misdetection, and an increased complexity when dealing with cylinder isolation is necessary. The approach here presented permits enhancing existing misfire detection methods through optimized algorithm that allows correctly isolating the multiple misfiring cylinders over the entire engine operating range. This has been obtained by proper identifying the effect of the torsional vibration over the instantaneous engine speed. The identified waveform has been then used to filter out the torsional vibration effects in order to enlighten the effects of the missing combustions. In addition a proper instantaneous engine speed windowing has been introduced in order to increase the detection signal to noise ratio over the whole engine operating range. The integration of these two signal processing techniques has proven to be very effective on the engine investigated in this study, and it is easily extendible to other engine architectures. Particular care has been devoted to satisfy on-board implementation requirements in terms of memory allocation and computational power. The tests have been conducted on an L4 1.2 liter spark ignition engine mounted in a test cell. In-cylinder pressure signals have been acquired in order to validate the methodology here developed.

Probabilistic Torsional Vibration Analysis of a Marine Diesel Engine Shafting System: The Level Crossing Problem

1989 ◽  
Vol 56 (4) ◽  
pp. 953-959 ◽  
Author(s):  
Efstratios Nikolaidis ◽  
Anastassios N. Perakis ◽  
Michael G. Parsons
Keyword(s):  
Diesel Engine ◽  
Torsional Vibration ◽  
Probabilistic Approach ◽  
Series Representation ◽  
Harmonic Series ◽  
Complex Conjugate ◽  
Time Interval ◽  
Marine Diesel Engine ◽  
Level Crossing ◽  
Marine Diesel

A probabilistic approach to the torsional vibration problem of a marine diesel engine shafting system has been developed. In this analysis, the shafting shear stress is found to be a Gaussian, harmonizable cyclostationary process with a harmonic series representation consisting of two complex conjugate components. In this paper, the level crossing problem for this stress process is studied. Two methods for estimating the probability that the stress exceeds a specified threshold at least once over a given time interval are presented. In the first method, a local maximum of the process is approximated by the value of the corresponding envelope at the time of occurrence of this maximum. A Markov-type condition is assumed to hold for the local maxima. The second method assumes that the maximum of the process over a reasonable number of cycles is approximately equal to that of the envelope process. The envelope crossings are assumed to constitute a Poisson process. The two methods are applied to estimate the upcrossing probability in various cases. The results of both approaches are found to be in good agreement with those from Monte Carlo simulation.

Methodology Development for Torsional Vibration Measurement and Processing in Powertrains

2015 ◽  
Author(s):  
Rohit Ravindran ◽  
Debajit Das ◽  
Keval Kamani ◽  
P Sivaraman ◽  
Gyan Arora
Keyword(s):  
Torsional Vibration ◽  
Vibration Measurement ◽  
Methodology Development
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