Leakage-Induced Compressor Blade Excitation due to Inter-Segment Gaps

2012 ◽  
Author(s):  
Ronnie Bladh ◽  
Qingyuan Zhuang ◽  
Jiasen Hu ◽  
Johan Hammar
Keyword(s):  
Gas Turbine ◽  
Flow Speed ◽  
Rotor Blades ◽  
Unsteady Forces ◽  
Leakage Flows ◽  
Engine Order ◽  
Time Marching ◽  
Gas Turbine Compressor ◽  
Industrial Gas Turbine ◽  
Different Sources

A comprehensive investigation is presented related to leakage-induced blade excitation from shrouded vane segments found in industrial gas turbine compressors. The focus of the investigation is to explore the excitation mechanism acting on downstream rotor blades that stem from the particularly complex leakage flows around the hub inter-segment gaps. The aerodynamic forces are here determined using 3D nonlinear time-marching CFD simulations. The employed computational model encompasses the two rear-most stages in an existing industrial gas turbine compressor. The inter-segment gap is implemented in the next-to-last stator, varying from no gap to twice the nominal gap size. Obtained results indicate that the excitation induced by the inter-segment gap leakage flows is distinctly multi-harmonic and unexpectedly strong. As much as five times the excitation strength of upstream wakes was observed already for the nominal gap. The induced unsteady forces were found to derive from two different sources: (i) a large separation producing local forcing in the hub region; and (ii) circumferentially varying flow speed resulting in distributed forcing over the entire blade. The findings imply that the excitation induced by inter-segment gap leakage flows can be a significant contributor to blade vibratory responses in the intermediate engine order range, and thereby add to the knowledge base related to blade dynamic integrity.

Numerical Simulation of Blade Fault Signatures From Unsteady Wall Pressure Signals

1997 ◽  
Vol 119 (2) ◽  
pp. 362-369 ◽  
Author(s):  
V. Dedoussis ◽  
K. Mathioudakis ◽  
K. D. Papailiou
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Gas Turbine ◽  
Wall Pressure ◽  
Operating Point ◽  
Calculation Time ◽  
Rotating Blades ◽  
Time Signals ◽  
Gas Turbine Compressor ◽  
Industrial Gas Turbine

A method for establishing signatures of faults in the rotating blades of a gas turbine compressor is presented. The method employs a panel technique for the calculation of the flow field around blade cascades, with disrupted periodicity, a situation encountered when a blade fault has occurred. From this calculation, time signals of the pressure at a location on the casing wall, facing the rotating blades, are constituted. Processing these signals, in combination with “healthy” pressure signals, allows the constitution of fault signatures. The proposed method employs geometric data, as well as data about the operating point of the engine. It gives the possibility of establishing the fault signatures without the need of performing experiments with implanted faults. The successful application of the method is demonstrated by comparison of signatures obtained by simulation to signatures derived from experiments with implanted blade faults, in an industrial gas turbine.

scholarly journals Optimizing Automated Gas Turbine Fault Detection Using Statistical Pattern Recognition

1992 ◽  
Author(s):  
E. Loukis ◽  
K. Mathioudakis ◽  
K. Papailiou
Keyword(s):  
Decision Making ◽  
Pattern Recognition ◽  
Gas Turbine ◽  
Statistical Pattern Recognition ◽  
Dynamic Measurements ◽  
Statistical Pattern ◽  
Gas Turbine Compressor ◽  
Industrial Gas Turbine ◽  
Spectral Patterns ◽  
Automated Decision Making

A method enabling the automated diagnosis of Gas Turbine Compressor blade faults, based on the principles of statistical pattern recognition is initially presented. The decision making is based on the derivation of spectral patterns from dynamic measurements data and then the calculation of discriminants with respect to reference spectral patterns of the faults while it takes into account their statistical properties. A method of optimizing the selection of discriminants using dynamic measurements data is also presented. A few scalar discriminants are derived, in such a way that the maximum available discrimination potential is exploited. In this way the success rate of automated decision making is further improved, while the need for intuitive discriminant selection is eliminated. The effectiveness of the proposed methods is demonstrated by application to data coming from an Industrial Gas Turbine while extension to other aspects of Fault Diagnosis is discussed.

Casing Vibration and Gas Turbine Operating Conditions

1989 ◽  
Author(s):  
K. Mathioudakis ◽  
E. Loukis ◽  
K. D. Papailiou
Keyword(s):  
Gas Turbine ◽  
Transfer Functions ◽  
Parametric Identification ◽  
Fast Response ◽  
Operating Conditions ◽  
Rotor Blades ◽  
Unsteady Pressure ◽  
Signal Features ◽  
Surface Vibrations ◽  
Industrial Gas Turbine

The results from an experimental investigation of the compressor casing vibration of an industrial Gas Turbine are presented. It is demonstrated that statistical properties of acceleration signals can be linked with engine operating conditions. The power content of such signals is dominated by contributions originating from the stages of the compressor, while the contribution of the shaft excitation is secondary. Using non-parametric identification methods, accelerometer outputs are correlated to unsteady pressure measurements taken by fast response transducers at the inner surface of the compressor casing. The transfer functions allow reconstruction of unsteady pressure signal features from the accelerometer readings. A possibility is thus provided, for “seeing” the unsteady pressure field of the rotor blades without actually penetrating through the casing, but by simply observing its external surface vibrations.

Gas Turbine Compressor Dependability and Risk Mitigation Measures

2013 ◽  
Author(s):  
John R. Scheibel ◽  
Robert P. Dewey ◽  
Leonard Angello ◽  
Josh Barron
Keyword(s):  
Gas Turbine ◽  
Risk Mitigation ◽  
Acoustic Emissions ◽  
Mitigation Measures ◽  
Pressure Pulsations ◽  
Case Histories ◽  
Specific Component ◽  
Analysis And Evaluation ◽  
Gas Turbine Compressor ◽  
Industrial Gas Turbine

This paper addresses recent industrial gas turbine compressor dependability issues and risk mitigation measures viewed from the end user’s perspective. Industrial reliability-availability-maintainability statistics related to power generation applications are reviewed. Several case histories with specific component issues involving blades and vanes are covered. Case histories are used to summarize field experience, engineering analysis and evaluation of related design and operating modifications as appropriate. Recent progress with setting up a field monitoring demonstration using pressure pulsations, vibration and acoustic emissions is summarized.

scholarly journals Loss in Axial Compressor Bleed Systems

2019 ◽  
Author(s):  
S. D. Grimshaw ◽  
J. Brind ◽  
G. Pullan ◽  
R. Seki
Keyword(s):  
Gas Turbine ◽  
Control Volume ◽  
Axial Compressor ◽  
Thermodynamic Cycle ◽  
Loss Coefficient ◽  
Dynamic Head ◽  
Definition Of ◽  
Gas Turbine Compressor ◽  
Industrial Gas Turbine ◽  
Loss Mechanisms

Abstract Loss in axial compressor bleed systems is quantified, and the loss mechanisms identified, in order to determine how efficiency can be improved. For a given bleed air pressure requirement, reducing bleed system loss allows air to be bled from further upstream in the compressor, with benefits for the thermodynamic cycle. A definition of isentropic efficiency which includes bleed flow is used to account for this. Two cases with similar bleed systems are studied: a low-speed, single-stage research compressor and a large industrial gas turbine high-pressure compressor. A new method for characterising bleed system loss is introduced, using research compressor test results as a demonstration case. A loss coefficient is defined for a control volume including only flow passing through the bleed system. The coefficient takes a measured value of 95% bleed system inlet dynamic head, and is shown to be a weak function of compressor operating point and bleed rate, varying by ±2.2% over all tested conditions. This loss coefficient is the correct non-dimensional metric for quantifying and comparing bleed system performance. Computations of the research compressor and industrial gas turbine compressor identify the loss mechanisms in the bleed system flow. In both cases, approximately two-thirds of total loss is due to shearing of a high-velocity jet at the rear face of the bleed slot, one quarter is due to mixing in the plenum chamber and the remainder occurs in the off-take duct. Therefore, the main objective of a designer should be to diffuse the flow within the bleed slot. A redesigned bleed slot geometry is presented that achieves this objective and reduces the loss coefficient by 31%.

Influence of Tip Shroud Cavity Detailing on Turbine Blade Forcing Calculations

2014 ◽  
Author(s):  
Tobias Gezork ◽  
María A. Mayorca ◽  
Pieter Groth ◽  
Damian M. Vogt ◽  
Torsten Fransson
Keyword(s):  
Forced Response ◽  
Rotor Blades ◽  
Main Stream ◽  
Leakage Flows ◽  
Engine Order ◽  
Calculation Results ◽  
Flow Through ◽  
Downstream Flow ◽  
Shrouded Rotor ◽  
Tip Shroud

Forced response in turbomachinery refers to the vibration of a component due to an excitation originating from another component. Obstacles, such as struts and blade rows in the upstream and downstream flow path of a turbomachine engine lead to engine order (EO) excitations. To be able to predict the severity of these excitations, both aerodynamic and structural calculations are performed. There is a risk of critical high cycle fatigue (HCF) failure when the force acts at a resonance frequency. Customarily, forcing calculations exclude detailing features, such as leakage flows. The current investigation uses a two stage subsonic model steam turbine configuration with shrouded rotor blades to demonstrate the influence of neglecting flow through seal cavities for blade forcing predictions. Upstream and down-stream vanes are the excitation sources on the rotor blade. Calculation results are compared for a configuration including and excluding the tip shroud cavity. Computed data is compared to available pressure data from tests in the model turbine. The investigation shows for the first blade passing excitation at design point that the axial and circumferential rotor forcing change by +22%, respectively +4% when including the tip shroud cavity for the investigated configuration. The change in forcing arises from the interaction of the leakage flow with the main stream flow. For highly loaded designs this can be of importance if there is a critical excitation.

Package Design for a 5500 BHP Aeroderivative Industrial Gas Turbine

1997 ◽  
Author(s):  
Douglas L. Wenzel ◽  
Jeffrey M. Elmore
Keyword(s):  
Gas Turbine ◽  
New Product Development ◽  
Gas Generator ◽  
Package Design ◽  
Power Turbine ◽  
Total Product ◽  
Design Cycle ◽  
Management Techniques ◽  
Gas Turbine Compressor ◽  
Industrial Gas Turbine

The Cooper-Bessemer Rotating Products group of Cooper Energy Services has designed an all-new industrial gas turbine / compressor package based upon the Allison Engine Company 501-KC5 gas generator with a two-stage industrial power turbine. The latest project management techniques were employed to reduce design cycle time while optimizing total product quality, manufacturability, and reliability. The resulting gas turbine / compressor package is a low-risk, technologically conservative approach, designed to avoid the problems often associated with new product development.

scholarly journals Condition Assessment of Industrial Gas Turbine Compressor Using a Drift Soft Sensor Based in Autoencoder

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2708
Author(s):  
Martí de Castro-Cros ◽  
Stefano Rosso ◽  
Edgar Bahilo ◽  
Manel Velasco ◽  
Cecilio Angulo
Keyword(s):  
Gas Turbine ◽  
Good Condition ◽  
Condition Assessment ◽  
Soft Sensor ◽  
Soft Sensors ◽  
Gas Turbine Compressor ◽  
Industrial Gas Turbine ◽  
Long Term Performance ◽  
Changes Over Time ◽  
Term Performance

Maintenance is the process of preserving the good condition of a system to ensure its reliability and availability to perform specific operations. The way maintenance is nowadays performed in industry is changing thanks to the increasing availability of data and condition assessment methods. Soft sensors have been widely used over last years to monitor industrial processes and to predict process variables that are difficult to measured. The main objective of this study is to monitor and evaluate the condition of the compressor in a particular industrial gas turbine by developing a soft sensor following an autoencoder architecture. The data used to monitor and analyze its condition were captured by several sensors located along the compressor for around five years. The condition assessment of an industrial gas turbine compressor reveals significant changes over time, as well as a drift in its performance. These results lead to a qualitative indicator of the compressor behavior in long-term performance.

scholarly journals An Investigation on Failure Analysis of Titanium Gas Turbine Compressor Blades

2007 ◽  
Vol 561-565 ◽  
pp. 2241-2244
Author(s):  
H. Sepehri Amin ◽  
Ahmad Kermanpur ◽  
Saeed Ziaei-Rad ◽  
Hassan Farhangi ◽  
M. Mosaddeghfar
Keyword(s):  
Gas Turbine ◽  
Failure Process ◽  
Compressor Blades ◽  
Blade Root ◽  
Debris Particles ◽  
Blade Alloy ◽  
Beach Marks ◽  
Gas Turbine Compressor ◽  
Industrial Gas Turbine ◽  
Experimental Characterisation

Several premature failures were occurred in the high-pressure section of an industrial gas turbine compressor due to the fracture of Titanium blade roots. In this work, the failure process of the compressor blades was investigated based on the experimental characterisation. Macro/microfractographic studies were carried out on the fracture surfaces. Optical and scanning electron microscopy of the blade airfoil and root were performed. Mechanical properties of the blade alloy were also evaluated and compared with the standard specifications. The experimental results showed no metallurgical and mechanical defects for the blade materials. Microstructures of the blade root and airfoil as well as the hardness and tensile properties were all comparable with those reported in the standard specification AMS 4928Q. Fractography experiments showed clearly multiple crack initiation sites and fatigue beach marks. Debris particles were observed on the fracture surface of samples and in the mouth of initiated cracks. The blade surface in contact to the disc in the dovetail region showed a higher surface roughness than the other surfaces. Based on the results obtained, the fretting fatigue mechanism was proposed for the premature failures. It was concluded that the stress concentration has been caused by either unsuitable curvature ratio of the disk dovetail, incorrect design of the blade or insufficient distance between the blade root and the disk in dovetail region.

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