Novel Dynamic Rotor and Blade Deformation and Vibration Monitoring Technique

2011 ◽  
Vol 134 (1) ◽  
Author(s):  
Thorsten Pfister ◽  
Philipp Günther ◽  
Florian Dreier ◽  
Jürgen Czarske
Keyword(s):  
Moving Objects ◽  
Measurement Techniques ◽  
Operating Conditions ◽  
Tip Clearance ◽  
Fiber Optic Sensor ◽  
Vibration Monitoring ◽  
Rotor Speed ◽  
Out Of Plane ◽  
High Measurement ◽  
Blade Tip

Monitoring rotor deformations and vibrations dynamically is an important task for improving both the safety and the lifetime as well as the energy efficiency of motors and turbo machines. However, due to the high rotor speed encountered in particular at turbo machines, this requires concurrently high measurement rate and high accuracy, which is hardly possible to achieve with currently available measurement techniques. To solve this problem, in this paper, we present a novel nonincremental interferometric optical sensor that measures simultaneously the in-plane velocity and the out-of-plane position of laterally moving objects with micrometer precision and concurrently with microsecond temporal resolution. It will be shown that this sensor exhibits the outstanding feature that its measurement uncertainty is generally independent of the object velocity, which enables precise deformation and vibration measurements also at high rotor speed. Moreover, this sensor does not require an in situ calibration and it allows a direct measurement of blade velocity variations in contrast to blade tip timing systems. For application under harsh environmental conditions such as high temperatures, a robust and miniaturized fiber-optic sensor setup was developed. To demonstrate the capability of this sensor, measurements of tip clearance changes and rotor blade vibrations at varying operating conditions of a transonic centrifugal compressor test rig at blade tip velocities up to 600 m/s are presented among others.

Novel Dynamic Rotor and Blade Deformation and Vibration Monitoring Technique

2011 ◽  
Author(s):  
Thorsten Pfister ◽  
Philipp Gu¨nther ◽  
Florian Dreier ◽  
Ju¨rgen Czarske
Keyword(s):  
Moving Objects ◽  
Measurement Techniques ◽  
Operating Conditions ◽  
Tip Clearance ◽  
Fiber Optic Sensor ◽  
Vibration Monitoring ◽  
Rotor Speed ◽  
Out Of Plane ◽  
High Measurement ◽  
Blade Tip

Monitoring rotor deformations and vibrations dynamically is an important task for improving both the safety and the lifetime as well as the energy efficiency of motors and turbo machines. However, due to the high rotor speed encountered in particular at turbo machines, this requires concurrently high measurement rate and high accuracy, which is hardly possible to achieve with currently available measurement techniques. To solve this problem, in this paper, we present a novel non-incremental interferometric optical sensor that measures simultaneously the in-plane velocity and the out-of-plane position of laterally moving objects with micrometer precision and concurrently with microsecond temporal resolution. It will be shown that this sensor exhibits the outstanding feature that its measurement uncertainty is generally independent of the object velocity, which enables precise deformation and vibration measurements also at high rotor speed. Moreover, this sensor does not require an in situ calibration and it allows a direct measurement of blade velocity variations in contrast to BTT systems. For application under harsh environmental conditions such as high temperatures, a robust and miniaturized fiber-optic sensor setup was developed. To demonstrate the capability of this sensor, measurements of tip clearance changes and rotor blade vibrations at varying operating conditions of a transonic centrifugal compressor test rig at blade tip velocities up to 600 m/s are presented amongst others.

Monitoring of Blade Vibrations and Tip Clearance at Non-Metallic Rotors in Turbo Machines

2012 ◽  
Author(s):  
Florian Dreier ◽  
Thorsten Pfister ◽  
Jürgen Czarske
Keyword(s):  
Vibration Amplitude ◽  
Moving Objects ◽  
Numerical Models ◽  
Measurement Techniques ◽  
Tip Clearance ◽  
Laser Doppler ◽  
Doppler Probe ◽  
Engine Order ◽  
Blade Vibrations ◽  
Blade Tip

In order to improve the safety, the lifetime and the energy efficiency of turbo machines, the dynamic behaviour of the rotor has to be analysed and optimized. Thus, rotor unbalances, dynamic deformations and blade vibrations as well as blade tip clearance changes have to be monitored during operation to optimize the rotor design and to validate numerical models. However, these are great challenges for metrology, since small, robust and non-contact measurement techniques are required offering both micrometer accuracy and microsecond temporal resolution which is not fulfilled with currently available measurement techniques. To solve this problem, we present in this contribution a miniaturized fiberoptic laser Doppler probe that measures simultaneously the in-plane velocity and the out-of-plane position of laterally moving objects. Experiments have been carried out demonstrating the capability of this sensor to measure engine order blade vibrations instantaneously. Assuming a single engine order and a known vibration frequency, only one laser Doppler probe is necessary to measure the vibration amplitude. Thus, in contrast to blade tip timing, only one optical access to the blade tip is sufficient to measure the vibration amplitude. Furthermore, the novel sensor performs even at composite materials such as strongly absorbing carbon-fiber-reinforced plastic (CFRP) which became more popular in rotors of turbo machines.

On Possibilities of Using Relative Shaft Vibration Signals for Rotating Blades Monitoring

2018 ◽  
Author(s):  
Jindrich Liska ◽  
Vojtech Vasicek ◽  
Jan Jakl
Keyword(s):  
Steam Turbine ◽  
Operating Conditions ◽  
Vibration Monitoring ◽  
Monitoring Systems ◽  
Blade Vibration ◽  
Vibration Signals ◽  
Rotating Blades ◽  
Timing Measurement ◽  
Blade Tip ◽  
Shaft Vibration

Ensuring the reliability of the steam turbine is the key for its long life. For this purpose monitoring systems are standardly used. Early detection of any failure can avoid possible economical and material losses. A monitoring of rotating blades vibration belongs to the very important tasks of the turbomachinery state assessment. Especially in terms of the last stages of low-pressure part, where the longest blades are vibrating at most. Commonly used methods for blade vibration monitoring are based on contact measurement using strain gauges or non-contact approach based on blade tip timing measurement. Rising demand for low-cost monitoring systems has initiated development of a new approach in blade vibration monitoring task. The presented approach is based on usage of relative rotor vibration signals. Its advantage is in using of standardly installed sensors making this approach economically interesting for the turbine operators compared to the traditionally used methods, mentioned above. This paper summarizes the symptoms of blade vibration phenomenon in relative shaft vibration signals, the impact of operating conditions on the blade vibration amplitude and its comparison to blade tip-timing measurement results. In addition of several examples, the article also describes an evaluation of proposed method in operation of steam turbine with power of 170MW.

Experimental Investigation of the Flow in the Pipe Diffuser of a Centrifugal Compressor Stage Under Selected Parameter Variations

2009 ◽  
Author(s):  
Uwe Zachau ◽  
Reinhard Niehuis ◽  
Herwart Hoenen ◽  
David C. Wisler
Keyword(s):  
Centrifugal Compressor ◽  
Measurement Techniques ◽  
Operating Conditions ◽  
Tip Clearance ◽  
Test Facility ◽  
Experimental Investigations ◽  
Pressure Side ◽  
Compressor Stage ◽  
Diffuser Flow ◽  
Parameter Variations

On a centrifugal compressor test facility various experimental investigations have been carried out contributing a valuable gain in knowledge on the fundamental flow physics within passage type diffusers. An extensive measurement series using various steady, unsteady and laser optical measurement techniques has been performed to detect the unsteady, highly three dimensional diffuser flow under various realistic operating conditions. Zachau et al. [1] presented the test facility and the results gathered under nominal conditions. As a follow-up the results of investigated parameter variations are now presented, covering bleed variations, impeller tip clearance and impeller-diffuser misalignment studies. The data is compared to the benchmark created from the nominal baseline data sets and evaluated with respect to the compressor stage performance. Zachau et al. [1] found that under nominal conditions the flow in the pipe diffuser separates on the pressure side in the first half of the pipe. In the last 30% of the pipe hardly any deceleration of the flow takes place. From this, special attention is given to the investigated parameter variations regarding a first proposal for a diffuser design change, which consists in shortening the diffuser. The results for each parameter variation are evaluated in detail in direct comparison to the nominal baseline configuration underlining the conclusion made earlier that the diffuser flow always separates on the pressure side with negligible deceleration in the last third of the diffusing pipe.

Sealing Technology: Rub Test Rig for Abrasive/Abradable Systems

2007 ◽  
Author(s):  
Ulrich Rathmann ◽  
Sven Olmes ◽  
Alex Simeon
Keyword(s):  
High Speed ◽  
Operating Conditions ◽  
Tip Clearance ◽  
Test Rig ◽  
Visual Appearance ◽  
Major Interest ◽  
Rubbing Behavior ◽  
Blade Tip ◽  
Detailed Assessment ◽  
The University

Performance and efficiency optimization is one of the major tasks in the turbo machinery industry. Therefore efforts for scientific and technical improvements focus on optimization and reduction of losses. Secondary losses are of major interest because of their parasitic character related to stage efficiency and power output. One of these losses is over tip leakage of blades. Common practice is a minimization of this clearance with abrasive/abradable combinations. With this technique the blade tip (abrasive material) can rub into its counterpart (heat-shield, abradable material on casings or liners) and therefore minimize the operating tip-clearance. This technology is well established in compressor and turbine engineering since many years [1]. Field experience shows that abrasive/abradable systems do not always work as intended. In some cases rubbing conditions are reversed so that the intended abradable cuts into the abrasive. Any benefit on operating tip-clearance will then be minor at best or even negative. Rubbing behavior is difficult to predict, especially for new materials or geometries where no experience is available. In close cooperation with the University of Applied Sciences Rapperswil (Switzerland), ALSTOM has developed a test rig that allows simulating engine-operating conditions and therefore evaluate abrasive/abradable combinations before actual implementation into an engine. The rig is designed to reproduce circumferential velocities and incursion rates that are typical for gas turbine engines in the compressor as well as in the turbine. Forces and temperatures are measured as quantitative data, visual appearance and metallographic condition of test specimens are recorded as qualitative data that allow a more detailed assessment of material combinations and operating conditions. This paper describes the design of a high-speed wear rig facility to test single blade and fully shrouded rub configurations. In addition the validation of the test rig against real engine experience and knowledge is shown.

scholarly journals Blade by Blade Tip Clearance Measurement

2011 ◽  
Vol 2011 ◽  
pp. 1-13 ◽  
Author(s):  
A. G. Sheard
Keyword(s):  
High Temperature ◽  
Gas Turbine ◽  
Measurement System ◽  
Measurement Techniques ◽  
Tip Clearance ◽  
Initial Development ◽  
Real World Applications ◽  
Blade Tip ◽  
Capacitance Probe ◽  
Blade Tip Clearance

This paper describes a capacitance-based tip clearance measurement system which engineers have used in the most demanding turbine test applications. The capacitance probe has survived extended use in a major European gas turbine manufacturer's high-temperature demonstrator unit, where it functioned reliably at a turbine entry temperature in excess of 1800 degrees Kelvin. This paper explores blade by blade tip clearance measurement techniques and examines probe performance under laboratory conditions in support of high-temperature installations. The paper outlines the blade by blade tip clearance measurement technique and describes the experimental facility used to study tip clearance measurement. The paper also fully describes the method used to calibrate the measurement system in order to ascertain measurement accuracy. The paper clarifies how the practical problems were overcome associated with making blade by blade tip clearance measurements in both compressor and turbine environments. Since its initial development, gas turbine development programmes have routinely used the clearance measurement system. The inherent robustness of the system has resulted in reliable in-service measurement of clearance in real world applications.

Numerical Study of Influence of Rotor Tip Gap Increase due to Age Deterioration in 3-Stage Gas Turbine

2020 ◽  
Author(s):  
Koichi Yonezawa ◽  
Junichi Sakamoto ◽  
Kazuyasu Sugiyama ◽  
Shuichi Ohmori ◽  
Shuichi Umezawa
Keyword(s):  
Gas Turbine ◽  
Rotor Blade ◽  
Cfd Simulation ◽  
Numerical Study ◽  
Operating Conditions ◽  
Tip Clearance ◽  
Tip Leakage Flow ◽  
Age Related ◽  
Balance Analysis ◽  
Blade Tip

Abstract Influences of age-related deterioration on the increase in rotor tip gap width are discussed numerically. In the gas turbine examined in the present study, there are two kinds of geometries around the rotor blade tip. In the first stage, there is clearance between the blade tip and the casing without any seal structures. On the other hand, there is a shroud and seal fin on the rotor blade tip. The blade geometries were measured using a 3-D scanner in a working power plant, and the tip clearances were varied by changing the casing contour. Steady-state CFD simulations were carried out. Tip gap widths were varied by shifting the casing wall. For simplicity, the blade geometries were not changed. The influence of tip clearance was examined by changing the geometries in each stage separately. Boundary conditions were determined using the previously developed hybrid method of heat balance analysis and CFD simulation, which can simulate the operating conditions of a working gas turbine. The results showed that the turbine performance degradation could spread to the following stage. Observation of entropy fields revealed that the increase in the tip leakage flow affected the flow in the following nozzle, and the loss increased.

scholarly journals Massively Parallel Large Eddy Simulation of Rotating Turbomachinery for Variable Speed Gas Turbine Engine Operation

Energies ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 703
Author(s):  
Nishan Jain ◽  
Luis Bravo ◽  
Dokyun Kim ◽  
Muthuvel Murugan ◽  
Anindya Ghoshal ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Large Scale ◽  
Operating Conditions ◽  
Tip Clearance ◽  
Massively Parallel ◽  
Rotor Speed ◽  
Tip Leakage Flow ◽  
Engine Operation ◽  
Large Eddy ◽  
The Impact

Gas turbine engines are required to operate at both design and off-design conditions that can lead to strongly unsteady flow-fields and aerodynamic losses severely impacting performance. Addressing this problem requires effective use of computational fluid dynamics tools and emerging models that resolve the large scale fields in detail while accurately modeling the under-resolved scale dynamics. The objective of the current study is to conduct massively parallel large eddy simulations (LES) of rotating turbomachinery that handle the near-wall dynamics using accurate wall models at relevant operating conditions. The finite volume compressible CharLES solver was employed to conduct the simulations over moving grids generated through Voronoi-based unstructured cells. A grid sensitivity analysis was carried out first to establish reliable parameters and assess the quality of the results. LES simulations were then conducted to understand the impact of blade tip clearance and operating conditions on the stage performance. Variations in tip clearance of 3% and 16% chord were considered in the analysis. Other design points included operation at 100% rotor speed and off-design conditions at 75% and 50% of the rotor speed. The simulation results showed that the adiabatic efficiency improves dramatically with reduction in tip gap due to the decrease in tip leakage flow and the resulting flow structures. The analysis also showed that the internal flow becomes highly unsteady, undergoing massive separation, as the rotor speed deviates from the design point. This study demonstrates the capability of the framework to simulate highly turbulent unsteady flows in a rotating turbomachinery environment. The results provide much needed insight and massive data to investigate novel design concepts for the US Army Future Vertical Lift program.

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