scholarly journals Non-Contact Measurement of Blade Vibration in an Axial Compressor

Sensors ◽  
2019 ◽  
Vol 20 (1) ◽  
pp. 68 ◽  
Author(s):  
Radoslaw Przysowa ◽  
Peter Russhard
Keyword(s):  
Axial Compressor ◽  
Rotating Stall ◽  
Compressor Blades ◽  
Blade Vibration ◽  
Work Related ◽  
Higher Order Modes ◽  
Pearson Coefficient ◽  
Engine Order ◽  
Simultaneous Resonances ◽  
Timing System

Complex blade responses such as a rotating stall or simultaneous resonances are common in modern engines and their observation can be a challenge even for state-of-the-art tip-timing systems and trained operators. This paper analyses forced vibrations of axial compressor blades, measured during the bench tests of the SO-3 turbojet. In relation to earlier studies conducted in Poland with a small number of sensors, a multichannel tip-timing system let us observe simultaneous responses or higher-order modes. To find possible symptoms of a failure, blade responses in a healthy and unhealthy engine configuration with an inlet blocker were studied. The used analysis methods covered all-blade spectrum and the circumferential fitting of blade deflections to the harmonic oscillator model. The Pearson coefficient of correlation between the measured and predicted tip deflection is calculated to evaluate fitting results. It helps to avoid common operator mistakes and misinterpreting the results. The proposed modal solver can track the vibration frequency and adjust the engine order on the fly. That way, synchronous and asynchronous vibrations are observed and analysed together with an extended variant of least squares. This approach saves a lot of work related to configuring the conventional tip-timing solver.

scholarly journals Non-Contact Measurement of Blade Vibration in an Axial Compressor

2019 ◽  
Author(s):  
Radoslaw Przysowa ◽  
Peter Russhard
Keyword(s):  
State Of The Art ◽  
Axial Compressor ◽  
Rotating Stall ◽  
Compressor Blades ◽  
Blade Vibration ◽  
Work Related ◽  
Higher Order Modes ◽  
Engine Order ◽  
Simultaneous Resonances ◽  
Timing System

Complex blade responses such as a rotating stall or simultaneous resonances are common in modern engines and their observation can be a challenge even for state-of-the-art tip-timing systems and trained operators. This paper analyses forced vibrations of axial compressor blades, measured during the bench tests of the SO-3 turbojet. In relation to earlier studies conducted in ITWL with a small number of sensors, a multichannel tip-timing system let us observe simultaneous responses or higher-order modes. To find possible symptoms of a failure, blade responses in a healthy and unhealthy engine configuration with an inlet blocker were studied. The used analysis methods covered all-blade spectrum and the circumferential fitting of blade deflections to the harmonic oscillator model. The proposed modal solver can track the vibration frequency and adjust the engine order on the fly. That way, synchronous and asynchronous vibrations are observed and analysed together with an extended variant of least squares. The proposed approach helps to avoid common mistakes and saves a lot of work related to configuring the conventional solver.

Near Stall Behavior of a Transonic Compressor Rotor With Casing Treatment

2016 ◽  
Author(s):  
Christoph Brandstetter ◽  
Felix Holzinger ◽  
Heinz-Peter Schiffer ◽  
Sina Stapelfeldt ◽  
Mehdi Vahdati
Keyword(s):  
Stability Limit ◽  
Rotating Stall ◽  
Rotor Blades ◽  
Transient Effects ◽  
Stability Range ◽  
Blade Vibration ◽  
Casing Treatment ◽  
Transonic Compressor ◽  
Compressor Rotor ◽  
Engine Order

The aerodynamic and aeroelastic performance of an advanced axial slot casing treatment (CT) was investigated on a modern one and a half stage transonic compressor test rig. It is generally accepted that a well designed CT can extend the aerodynamic stability range of a compressor to lower mass flows. The extension of stall margin of the compressor rotor blades by using CT has been the subject of numerous research articles but much less attention has been paid to the behavior of the compressor in direct vicinity of the stability limit. For the compressor investigated here, two different phenomena were repeatedly observed near stall: 1) self-excited blade vibration, and 2) low engine order fluctuations developing into rotating stall. The current investigation firstly aims to identify the triggers for each of these phenomena. It then focusses on the aerodynamic and aeromechanical mechanism which lead to the formation of low engine order fluctuations shortly before stall. In order to measure the unsteady and transient effects, the system was instrumented with unsteady wall pressure transducers, a capacitive tip-timing system and strain gauges on the rotor blades. The flow structure in the blade tip region was measured via Particle Image Velocimetry underneath the CT-Cavities. Measurements showed a strong correlation between CT activity and the development of the low frequency oscillations with associated blade vibrations. Using numerical simulations, presented and validated in this paper, this correlation was attributed to an aerodynamic coupling between rotor passages through the recirculation of fluid inside the cavities.

scholarly journals The Analysis Of Synchronous Blade Vibration Using Linear Sine Fitting

2014 ◽  
Vol 30 (1) ◽  
pp. 5-19 ◽  
Author(s):  
Radosław Przysowa
Keyword(s):  
Axial Compressor ◽  
Process Data ◽  
Blade Vibration ◽  
Record Times ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Engine Order ◽  
Blade Tip ◽  
Vibration Parameters ◽  
Real Test

Abstract In Blade Tip Timing several sensors installed circumferentially in the casing are used to record times of arrival (TOA) and observe deflections of blade tips. This paper aims to demonstrate methodology of model-based processing of aliased data. It focuses on the blade vibration excited by the forces synchronous with engine rotation, which are called integral responses. The driven harmonic oscillator with single degree of freedom (SDOF) is used to analyse blade vibration measured by tip-timing sensors during engine deceleration. When integral engine order EO is known, the linear sine fitting techniques can be used to process data from sensors to estimate amplitude, phase and frequency of blade vibration in each rotation. The oscillator model is implemented in MATLAB and used to generate resonance curves and simulate blade responses observed with tip sensors, installed in the axial compressor. Generated TOA data are fitted to the sine function to estimate vibration parameters. The validated procedure is then employed to analyze real test data.

scholarly journals Determination of Serviceability Limits of a Turboshaft Engine by the Criterion of Blade Natural Frequency and Stall Margin

2019 ◽  
Author(s):  
Yaroslav Dvirnyk ◽  
Dmytro Pavlenko ◽  
Radoslaw Przysowa
Keyword(s):  
Axial Compressor ◽  
Operational Experience ◽  
Compressor Blades ◽  
Blade Vibration ◽  
Stall Margin ◽  
Wear Process ◽  
Gradual Loss ◽  
And Performance ◽  
Turboshaft Engine ◽  
Particle Separator

This paper analyses the health and performance of 12-stage axial compressor of the TV3-117VM/VMA turboshaft operated in a desert environment. The results of the dimensional control of 4,800 worn blades are analysed to model the wear process. Operational experience and numerical simulations are used to assess the effectiveness of an Inlet Particle Separator. Numerical modal analysis is performed to generate the Campbell diagram of worn blades and identify resonant blade vibration which can lead to high cycle fatigue (HCF). It is shown that the gradual loss of the stall margin over time determines the serviceability limits of compressor blades. Recommendations setting out go / no-go criteria are made to maintenance and repair organisations.

Effects of Blade Damage on the Performance of a Transonic Axial Compressor Rotor

2012 ◽  
Author(s):  
Yanling Li ◽  
Abdulnaser Sayma
Keyword(s):  
Axial Compressor ◽  
Rotating Stall ◽  
Rotor Blades ◽  
Design Stage ◽  
Compressor Blades ◽  
Stall Margin ◽  
Compressor Rotor ◽  
Surge Margin ◽  
Compressor Performance ◽  
Transonic Axial Compressor

Gas turbine axial compressor blades may encounter damage during service for various reasons. Debris from casing or foreign objects may impact blades causing damage near the rotor’s tip. This may result in deterioration of performance and reduction in the surge margin. Ability to assess the effect of damaged blades on the compressor performance and stability is important at both the design stage and in service. The damage to compressor blades breaks the cyclic symmetry of the compressor assembly. Thus computations have to be performed using the whole annulus. Moreover, if rotating stall or surge occurs, the downstream boundary conditions are not known and simulations become difficult. This paper presents an unsteady CFD analysis of compressor performance with tip curl damage. Tip curl damage typically occurs when rotor blades hit a loose casing liner. The computations were performed up to the stall boundary, predicting rotating stall patterns. The aim is to assess the effect of blade damage on stall margin and provide better understanding of the flow behaviour during rotating stall. Computations for the undamaged rotor are also performed for comparison. A transonic axial compressor rotor is used for the time-accurate numerical unsteady flow simulations, with a variable choked nozzle downstream simulating an experimental throttle. One damaged blade was introduced in the rotor assembly and computations were performed at 60% of the design rotational speed. It was found that there is no significant effect on the compressor stall margin due to one damaged blade despite the differences in rotating stall patterns between the undamaged and damaged assemblies.

scholarly journals Determination of Serviceability Limits of a Turboshaft Engine by the Criterion of Blade Natural Frequency and Stall Margin

Aerospace ◽  
2019 ◽  
Vol 6 (12) ◽  
pp. 132 ◽  
Author(s):  
Yaroslav Dvirnyk ◽  
Dmytro Pavlenko ◽  
Radoslaw Przysowa
Keyword(s):  
Axial Compressor ◽  
Operational Experience ◽  
Two Phase ◽  
Compressor Blades ◽  
Stall Margin ◽  
Wear Process ◽  
Engine Order ◽  
Gradual Loss ◽  
And Performance ◽  
Turboshaft Engine

This paper analyzes the health and performance of the 12-stage axial compressor of the TV3-117VM/VMA turboshaft operated in a desert environment. The results of the dimensional control of 4800 worn blades are analyzed to model the wear process. Operational experience and two-phase flow simulations are used to assess the effectiveness of an inlet particle separator. Numerical modal analysis is performed to generate the Campbell diagram of the worn blades and identify resonant blade vibrations which can lead to high cycle fatigue (HCF): mode 7 engine order 30 in the first stage and mode 8 engine order 60 in the fourth. It is also shown that the gradual loss of the stall margin over time determines the serviceability limits of compressor blades. In particular, the chord wear of sixth-stage blades as high as 6.19 mm results in a reduction of the stall margin by 15–17% and a permanent stall at 770–790 flight hours. In addition, recommendations setting out go/no-go criteria are made to maintenance and repair organizations.

A Discussion on the Advancement of Blade Tip Timing Data Processing

2017 ◽  
Author(s):  
Vsevolod Kharyton ◽  
Grigorios Dimitriadis ◽  
Colin Defise
Keyword(s):  
Digital Signal ◽  
Minimum Variance ◽  
Rotating Stall ◽  
Blade Vibration ◽  
Variable Threshold ◽  
Engine Order ◽  
Timing Data ◽  
Large Scope ◽  
Blade Tip ◽  
Frequency Aliasing

The Blade Tip Timing method (BTT) is a well-known approach permitting individual blade vibration behavior characterization. The technique is becoming increasingly popular among turbomachinery vibration specialists. Its advantages include its non-intrusive nature and its capability of being used for long-term monitoring, both in on-line and offline analysis. However, the main drawback of BTT is frequency aliasing. Frequency aliasing effects in tip timing can be reduced by means of the application of different methods from digital signal analysis that can exploit the non-uniform nature of the data sampled by BTT. This non-uniformity is due to the fact that an optimization of the circumferential distribution of BTT probes is usually required in order to improve the data quality for targeted modes of blade vibration and/or orders of excitation. The BTT data analysis methods considered in this study are the non-uniform Fourier transform, the minimum variance spectrum estimator approach, a multi-channel technique using in-between samples interpolation, the Lombe-Scargle periodogram and an iterative variable threshold procedure. These methods will be applied to measured data representing quite a large scope of events occurring during gas-turbine compressor operation, e.g. synchronous engine order resonance crossing, rotating stall, suspected limit-cycle oscillations. Finally, the frequency estimates obtained from all these methods will be summarized.

scholarly journals Determination of serviceability limits of a turboshaft engine by the criterion of blade natural frequency and stall margin

2019 ◽  
Vol 304 ◽  
pp. 03004
Author(s):  
Yaroslav Dvirnyk ◽  
Dmytro Pavlenko ◽  
Radoslaw Przysowa
Keyword(s):  
Axial Compressor ◽  
Operational Experience ◽  
Compressor Blades ◽  
Blade Vibration ◽  
Stall Margin ◽  
Wear Process ◽  
Gradual Loss ◽  
And Performance ◽  
Turboshaft Engine ◽  
Particle Separator

This paper analyses the health and performance of 12–stage axial compressor of the TV3–117VM/VMA turboshaft operated in a desert environment. The results of the dimensional control of 4,800 worn blades are analysed to model the wear process. Operational experience is used to assess the effectiveness of an Inlet Particle Separator. Numerical modal analysis is performed to generate the Campbell diagram of worn blades and identify resonant blade vibration which can lead to high cycle fatigue (HCF). It is shown that the gradual loss of the stall margin over time determines the serviceability limits of compressor blades. Recommendations setting out go / no–go criteria are made to maintenance and repair organisations.

Modal Analysis of the Axial Compressor Blade: Advanced Time-Dependent Electronic Interferometry and Finite Element Method

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Mykhaylo Tkach ◽  
Serhii Morhun ◽  
Yuri Zolotoy ◽  
Irina Zhuk
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Finite Element ◽  
High Reliability ◽  
Axial Compressor ◽  
Time Dependent ◽  
Experimental Setup ◽  
Vibration Modes ◽  
Compressor Blades ◽  
Isoparametric Finite Element

AbstractNatural frequencies and vibration modes of axial compressor blades are investigated. A refined mathematical model based on the usage of an eight-nodal curvilinear isoparametric finite element was applied. The verification of the model is carried out by finding the frequencies and vibration modes of a smooth cylindrical shell and comparing them with experimental data. A high-precision experimental setup based on an advanced method of time-dependent electronic interferometry was developed for this aim. Thus, the objective of the study is to verify the adequacy of the refined mathematical model by means of the advanced time-dependent electronic interferometry experimental method. The divergence of the results of frequency measurements between numerical calculations and experimental data does not exceed 5 % that indicates the adequacy and high reliability of the developed mathematical model. The developed mathematical model and experimental setup can be used later in the study of blades with more complex geometric and strength characteristics or in cases when the real boundary conditions or mechanical characteristics of material are uncertain.

Sign in / Sign up

Export Citation Format

Share Document