Discussion of the Available Methods for Blade Vibration Measurement

2002 ◽  
Author(s):  
B. O. Al-Bedoor
Keyword(s):  
Torsional Vibration ◽  
Performance Monitoring ◽  
Measurement Techniques ◽  
Pressure Fluctuations ◽  
Experimental Studies ◽  
Vibration Measurement ◽  
Experimental Investigations ◽  
Main Rotor ◽  
Blade Vibration ◽  
Indirect Approach

Blade vibration has been recognized as one major and costly cause of failure in turbo-machinery. Its vibration measurement has attracted many investigators where until now there is no single reliable approach can be identified. Blade vibration measurement techniques can be classified into two broad categories, namely; (1) the direct approach that includes using strain gages, optical/laser methods, etc., to monitor directly the blade motion at one or more points on the blade span, (2) the indirect approach by extracting some vibration information form the lateral main rotor vibration and the casing/bearing cap vibration, pressure fluctuations, performance monitoring and thermal changes. Recently, a new indirect method has received attention of investigators which is monitoring the torsional vibration of the main rotor. This technique has been investigated by theoretical and experimental studies. The direct and indirect techniques are described in this survey paper and advantages and draw backs are discussed. From the results of this survey it seems that the indirect approach using the torsional vibration measurement is the most promising among all indirect techniques and further theoretical and experimental investigations are recommended.

scholarly journals Vibration Measurement of Rotating Blades Using a Root Embedded PZT Sensor

2008 ◽  
Vol 15 (5) ◽  
pp. 517-541 ◽  
Author(s):  
M. Sunar ◽  
B.O. Al-Bedoor
Keyword(s):  
Finite Element ◽  
Experimental Studies ◽  
Vibration Measurement ◽  
Mode Shapes ◽  
Rotating System ◽  
Blade Vibration ◽  
Wide Range ◽  
Finite Element Package ◽  
Steady State Responses ◽  
State Responses

Finite element and experimental studies are carried out to test the suitability of a piezoelectric (PZT) sensor in measuring vibrations of blades modeled as beams. The rotating system contains twelve blades mounted to the shaft through a rotor. The PZT sensor is secured in the root between the rotor and blade. First, finite element results are obtained using the finite element package ANSYS. A modal analysis is performed on the system to identify modes and mode shapes. Transient, harmonic and steady-state responses are then computed to test the ability of the PZT sensor in generating signals for blade vibrations. For the experimental part, the blade vibration signals are produced using the PZT sensor and a strain-gage, and the outputs are compared with each other. From both the finite element and experimental results, it is concluded that the root-embedded PZT sensor can be effectively used for blade vibration measurements in a wide range of cases.

scholarly journals Identification of the liquid mass fraction content in the wet steam

2019 ◽  
Vol 137 ◽  
pp. 01003
Author(s):  
Mirosław Majkut ◽  
Slawomłr Dykas ◽  
Krystian Smołka ◽  
Michał Strozik
Keyword(s):  
Experimental Research ◽  
Measurement Techniques ◽  
Experimental Studies ◽  
Experimental Investigations ◽  
Wet Steam ◽  
Numerical Work ◽  
Measurement Systems ◽  
University Of Technology ◽  
Measuring Techniques ◽  
Made In

The experimental research, initiated at the Institute of Power Engineering and Turbomachinery of the Silesian University of Technology at the end of the last century, created an opportunity to supplement knowledge about the phenomenon of steam flow with condensation, tested by numerical fluid mechanics by IMiUE employees. In parallel with the numerical work, significant progress has been made in experimental studies on thflow of wet steam. Recently, measuring techniques based on recording the phenomenon of extinction of light have been elaborated or improved. The basic value determined in the final stage in the experimental way was the contentof the liquid phase defined as the wetness fraction. The methodology of tests and experimental investigations was presented, as well as the applied and developed measurement systems. Next, some developed designs of X probe and their modifications are described. Article present also some examples of applications of the developed measurement techniques in application to experimental research conducted on wet steam in the IMiUE. Examples of comparison between experimental and numerical tests are also provided.

scholarly journals Pulsation and Vibration Measurement on Stator Side for Turbocharger Turbine Blade Vibration Monitoring

2020 ◽  
Vol 5 (2) ◽  
pp. 11
Author(s):  
Takashi Ando
Keyword(s):  
Acoustic Radiation ◽  
Measurement Techniques ◽  
Turbine Blades ◽  
Fuel Oil ◽  
Vibration Monitoring ◽  
Vibration Measurement ◽  
Heavy Fuel Oil ◽  
Blade Vibration ◽  
Vibration Sensors ◽  
Unburned Fuel

Mechanically robust turbine design with respect to blade vibration is challenging when dealing with nozzle-ring fouling and wear. Especially for engines operating with heavy fuel oil (HFO), the nozzle rings of the turbocharger turbines are prone to severe degradation in terms of contamination with unburned fuel deposits. This contamination will lead to an increased excitation of blade resonances in comparison to the nominal design. Due to the statistical character of contamination, long-term monitoring of blade vibration amplitudes would be beneficial. In the harsh environment of HFO operation, however, conventional blade vibration measurement techniques, such as those using strain gauges or blade tip timing, cannot work reliably for a long period. Thus, the objective of this research is to develop a method that enables the monitoring of turbine blades using pulsation or vibration sensors installed on the stator side. Almost a dozen turbines, both radial and axial, have been examined in order to determine a proper measurement chain/position and analytical method. Even though the challenges specific to the turbocharger turbine application—that high-frequency (up to 50 kHz) acoustic radiation from turbine blades has to be detected by a sensor on the stator side—were demanding, in the course of the investigations several clear examples of turbine blades engine-order resonance detection were gathered. Finally, the proposed method has been tested successfully in a power plant for over one year.

scholarly journals A Torsional Vibration Measurement Method for Rotating Blades Based on Blade Tip Timing

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Haonan Guo ◽  
Yongmin Yang ◽  
Fengjiao Guan ◽  
Haifeng Hu ◽  
Guoji Shen ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Torsional Vibration ◽  
Measurement Method ◽  
Optimization Method ◽  
Vibration Monitoring ◽  
Vibration Measurement ◽  
Stable Operation ◽  
Blade Vibration ◽  
Blade Tip ◽  
Types Of Faults

During the working process of the turbine, some types of faults can cause changes in the vibration characteristics of the blades. The real-time vibration monitoring of the blades is of great significance to the stable operation and state-based maintenance. Torsional vibration is a kind of blade vibration modes and results in failures such as cracks easily. Thus, it is important to measure it due to the harmfulness of torsional vibration. Firstly, the principle of blade tip timing (BTT) is introduced, and the models of the blade are built to analyze the characteristics of torsional vibration. Then, the compressed sensing theory is introduced, and its related parameters are determined according to the measurement requirements. Next, based on the condition that the blade rigidity axis is not bent and bent, respectively, the layout method of sensors is proposed and the numerical simulation of the measurement process is performed. The results of the above two types of numerical simulation verify the proposed measurement method. Finally, by analyzing the influencing factors of measurement uncertainty, the optimization method of sensors’ layout is further proposed. This study can provide important theoretical guidance for the measurement of blade torsional vibration.

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 Evaluation of Airlift Performance for Vertical Pumping of Water in Underground Mines

2021 ◽  
Author(s):  
Parviz Enany ◽  
Oleksandr Shevchenko ◽  
Carsten Drebenstedt
Keyword(s):  
Water Flow ◽  
High Efficiency ◽  
Experimental Studies ◽  
Theoretical Models ◽  
Injection System ◽  
Experimental Investigations ◽  
Flow Mode ◽  
New Device ◽  
Riser Pipe ◽  
Airlift Pump

AbstractThis paper presents experimental studies on the optimization of air–water flow in an airlift pump. Airlift pumps use compressed gas to verticall transport liquids and slurries. Due to the lack of theoretical equations for designing and predicting flow regimes, experimental investigations must be carried out to find the best condition to operate an airlift pump at high efficiency. We used a new air injection system and different submergence ratios to evaluate the output of a simple pump for vertical displacement of water in an underground mine. The tests were carried out in a new device with 5.64 m height and 10.2 cm circular riser pipe. Three air-jacket pipes, at different gas flows in the range of 0.002–0.09 m3/s were investigated with eight submergence ratios. It was found that with the same air flow rate, the most efficient flow of water was achieved when an air jacket with 3 mm diameter holes was used with a submergence ratio between 0.6 and 0.75. In addition, a comparison of practical results with two theoretical models proposed by other investigators showed that neither was able to accurately predict airlift performance in air–water flow mode.

scholarly journals Investigations on the Blade Vibration of a Radial Inflow Micro Gas Turbine Wheel

2007 ◽  
Vol 2007 ◽  
pp. 1-10 ◽  
Author(s):  
Shijie Guo
Keyword(s):  
Gas Turbine ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Turbine Blades ◽  
Pressure Fluctuations ◽  
Leading Edge ◽  
Coupled Modes ◽  
Blade Vibration ◽  
Turbine Wheel ◽  
Micro Gas Turbine

This paper demonstrates the investigations on the blade vibration of a radial inflow micro gas turbine wheel. Firstly, the dependence of Young's modulus on temperature was measured since it is a major concern in structure analysis. It is demonstrated that Young's modulus depends on temperature greatly and the dependence should be considered in vibration analysis, but the temperature gradient from the leading edge to the trailing edge of a blade can be ignored by applying the mean temperature. Secondly, turbine blades suffer many excitations during operation, such as pressure fluctuations (unsteady aerodynamic forces), torque fluctuations, and so forth. Meanwhile, they have many kinds of vibration modes, typical ones being blade-hub (disk) coupled modes and blade-shaft (torsional, longitudinal) coupled modes. Model experiments and FEM analysis were conducted to study the coupled vibrations and to identify the modes which are more likely to be excited. The results show that torque fluctuations and uniform pressure fluctuations are more likely to excite resonance of blade-shaft (torsional, longitudinal) coupled modes. Impact excitations and propagating pressure fluctuations are more likely to excite blade-hub (disk) coupled modes.

Leakage Flow Investigations on a Through-Wall Crack Related to Thermal Fatigue of Nuclear Power Plant Piping

2017 ◽  
Author(s):  
Stefan Schmid ◽  
Rudi Kulenovic ◽  
Eckart Laurien
Keyword(s):  
Experimental Data ◽  
Nuclear Power ◽  
Numerical Models ◽  
Measurement Techniques ◽  
Experimental Investigations ◽  
Leakage Flow ◽  
Test Rig ◽  
Reduced Pressure ◽  
Flow Rates ◽  
Set Up

For the validation of empirical models to calculate leakage flow rates in through-wall cracks of piping, reliable experimental data are essential. In this context, the Leakage Flow (LF) test rig was built up at the IKE for measurements of leakage flow rates with reduced pressure (maximum 1 MPA) and temperature (maximum 170 °C) compared to real plant conditions. The design of the test rig enables experimental investigations of through-wall cracks with different geometries and orientations by means of circular blank sheets with integrated cracks which are installed in the tubular test section of the test rig. In the paper, the experimental LF set-up and used measurement techniques are explained in detail. Furthermore, first leakage flow measurement results for one through-wall crack geometry and different imposed fluid pressures at ambient temperature conditions are presented and discussed. As an additional aspect the experimental data are used for the determination of the flow resistance of the investigated leak channel. Finally, the experimental results are compared with numerical results of WinLeck calculations to prove specifically in WinLeck implemented numerical models.

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.

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