Analysis of an Axial Compressor Blade Vibration Based on Wave Reflection Theory

1984 ◽  
Vol 106 (1) ◽  
pp. 57-64 ◽  
Author(s):  
J. A. Owczarek
Keyword(s):  
Rotor Blade ◽  
Wave Reflection ◽  
Axial Compressor ◽  
Compressor Blade ◽  
Rotor Blades ◽  
Wave Reflections ◽  
Blade Vibration ◽  
Blade Vibrations ◽  
Reflection Theory ◽  
Prediction Techniques

The paper describes application of the theory of wave reflection in turbomachines to rotor blade vibrations measured in an axial compressor stage. The blade vibrations analyzed could not be explained using various flutter prediction techniques. The wave reflection theory, first advanced in 1966, is expanded, and more general equations for the rotor blade excitation frequencies are derived. The results of the analysis indicate that all examined rotor blade vibrations can be explained by forced excitations caused by reflecting waves (pressure pulses). Wave reflections between the rotor blades and both the upstream and downstream stator vanes had to be considered.

Cold Blade Profile Generation Methodology for Compressor Rotor Blades Using FSI Approach

2017 ◽  
Author(s):  
Kirubakaran Purushothaman ◽  
Sankar Kumar Jeyaraman ◽  
Ajay Pratap ◽  
Kishore Prasad Deshkulkarni
Keyword(s):  
Aspect Ratio ◽  
Rotor Blade ◽  
Axial Compressor ◽  
Operating Conditions ◽  
Rotor Blades ◽  
Blade Profile ◽  
Interaction Technique ◽  
Compressor Rotor ◽  
Blade Shape ◽  
Blade Geometry

This paper describes a methodology for obtaining correct blade geometry of high aspect ratio axial compressor blades during running condition taking into account of blade untwist and bending. It discusses the detailed approach for generating cold blade geometry for axial compressor rotor blades from the design blade geometry using fluid structure interaction technique. Cold blade geometry represents the rotor blade shape at rest, which under running condition deflects and takes a new operating blade shape under centrifugal and aerodynamic loads. Aerodynamic performance of compressor primarily depends on this operating rotor blade shape. At design point it is expected to have the operating blade shape same as the intended design blade geometry and a slight mismatch will result in severe performance deterioration. Starting from design blade profile, an appropriate cold blade profile is generated by applying proper lean and pre-twist calculated using this methodology. Further improvements were carried out to arrive at the cold blade profile to match the stagger of design profile at design operating conditions with lower deflection and stress for first stage rotor blade. In rear stages, thermal effects will contribute more towards blade deflection values. But due to short blade span, deflection and untwist values will be of lower values. Hence difference between cold blade and design blade profile would be small. This methodology can especially be used for front stage compressor rotor blades for which aspect ratio is higher and deflections are large.

A Resonance Tracking Algorithm for the Prediction of Turbine Forced Response With Friction Dampers

2000 ◽  
Author(s):  
C. Bréard ◽  
J. S. Green ◽  
M. Vahdati ◽  
M. Imregun
Keyword(s):  
Rotor Blade ◽  
Turbine Blades ◽  
Turbine Rotor ◽  
Forced Response ◽  
Rotor Blades ◽  
Test Case ◽  
Friction Damper ◽  
Blade Vibration ◽  
Frequency Shifts ◽  
Friction Dampers

This paper presents an iterative method for determining the resonant speed shift when non-linear friction dampers are included in turbine blade roots. Such a need arises when conducting response calculations for turbine blades where the unsteady aerodynamic excitation must be computed at the exact resonant speed of interest. The inclusion of friction dampers is known to raise the resonant frequencies by up to 20% from the standard assembly frequencies. The iterative procedure uses a viscous, time-accurate flow representation for determining the aerodynamic forcing, a look-up table for evaluating the aerodynamic boundary conditions at any speed, and a time-domain friction damping module for resonance tracking. The methodology was applied to an HP turbine rotor test case where the resonances of interest were due to the 1T and 2F blade modes under 40 engine-order excitation. The forced response computations were conducted using a multi-stage approach in order to avoid errors associated with “linking” single stage computations since the spacing between the two bladerows was relatively small. Three friction damper elements were used for each rotor blade. To improve the computational efficiency, the number of rotor blades was decreased by 2 to 90 in order to obtain a stator/rotor blade ratio of 4/9. However, the blade geometry was skewed in order to match the capacity (mass flow rate) of the components and the condition being analysed. Frequency shifts of 3.2% and 20.0% were predicted for the 1T/40EO and 2F/40EO resonances in about 3 iterations. The predicted frequency shifts and the dynamic behaviour of the friction dampers were found to be within the expected range. Furthermore, the measured and predicted blade vibration amplitudes showed a good agreement, indicating that the methodology can be applied to industrial problems.

Study of Rotor Blades Vibration Behavior of Counter Rotating Fan Models

2014 ◽  
Author(s):  
A. Stepanov ◽  
V. Fateev ◽  
V. Mileshin
Keyword(s):  
Rotor Blade ◽  
Rotor Blades ◽  
Test Facility ◽  
Strain Gauges ◽  
Contactless Method ◽  
Blade Vibration ◽  
Vibration Behavior ◽  
Vibration Parameters ◽  
The Impact ◽  
Composite Blades

Three test campaigns were carried out at CIAM C-3A test facility (Turaevo, Russia) with the aim of investigating aerodynamic and acoustic performances of three counter rotating fan models under the European VITAL project [1–3]. The second fan configuration CRTF2a [2] differs from the reference fan configuration CRTF1 by thickened blades profiling designed for simulation the composite blades. The third version of counter rotating fan model CRTF2b [4] was manufactured according to “blisk” technology to simulate composite blades. Along with studies of aerodynamic and acoustic performances of fan models, the C-3A test facility provides an opportunity to investigate and estimate the rotor blades vibration behavior. The rotor blade as the most loaded fan component, experiences the impact of various types of flow disturbances leading to its resonance vibrations and sometimes creating conditions for initiation of flutter at rotor blade natural frequencies. This is the reason for extending the information content of the measurements, improvement the measurement tools and methodology. The contactless method of blade vibration measurements (tip-timing) was used on the basis of MIC-DPM equipment («Mera» Research and Production Enterprise, Russia) [5,6] in combination with a traditional technique of strain gauges installation for determination of counter rotating fan rotor blades vibration behavior. This work presents the description of applied methodologies for measurements of rotor blades vibration parameters. Additionally, the paper presents the measurement results of rotor blades vibration behavior for three counter rotating fan models studied by means of a strain gauges technique and a contactless blade tip-timing method as well as the comparison analysis of numerical and experimental results in relation to vibration behavior of tested fan models.

Resonance Reliability Analysis of Aeroengine Compressor Rotor Blade

2014 ◽  
Vol 472 ◽  
pp. 79-84
Author(s):  
Hai Feng Gao ◽  
Guang Chen Bai
Keyword(s):  
Vibration Frequency ◽  
Rotor Blade ◽  
Random Variables ◽  
Second Order ◽  
Rotor Blades ◽  
Rotor Speed ◽  
Blade Vibration ◽  
Compressor Rotor ◽  
Set Up ◽  
The Impact

To describe the frequency distribution of the rotor blades and improve the optimization, resonance reliability of the rotor blades was analyzed in this paper. Considering the variety of rand-om variables, we jointly used finite element method and response surface method. The Campbell diagram was set up to describe blade resonance by analyzing the compressor rotor blade vibration characteristics. For the second-order vibration failure of the rotor blade, we considered the impact of random variables with the rotor blade material, the blade dimension and the rotor speed. The pro-bability distribution and allowable reliability of the second-order vibration frequency was calculated, and the sensitivity of the random variables influencing vibration frequency was completed. The res-ults show that the resonance reliability with the confidence level 0.95 of the rotor blade are = 0.99753 with the excited order =4 and =0.99767 with the excited order =5,and basically ag-ree with the design requirements when the rotor speed =9916.2, and the factors mainly affe-cting the distribution of the second-order vibration frequency of the blades include elastic modulus, density and the rotor speed, with the sensitivity probabilities 35.09%,34.56% and 24.15% respecti-vely.

Forced Response Excitation Due to the Stator Vanes of Two and Three Compressor Stages Away

2021 ◽  
Author(s):  
Toshimasa Miura ◽  
Naoto Sakai ◽  
Naoki Kanazawa ◽  
Kentaro Nakayama
Keyword(s):  
Gas Turbines ◽  
Rotor Blade ◽  
High Efficiency ◽  
Potential Effect ◽  
Forced Response ◽  
Rotor Blades ◽  
Test Facility ◽  
Blade Vibration ◽  
Stator Vane ◽  
Aero Engines

Abstract State-of-the-art axial compressors of gas turbines employed in power generation plants and aero engines should have both high efficiency and small footprint. Thus, compressors are designed to have thin rotor blades and stator vanes with short axial distances. Recently, problems of high cycle fatigue (HCF) associated with forced response excitation have gradually increased as a result of these trends. Rotor blade fatigue can be caused not only by the wake and potential effect of the adjacent stator vane, but also by the stator vanes of two, three or four compressor stages away. Thus, accurate prediction and suppression methods are necessary in the design process. In this study, the problem of rotor blade vibration caused by the stator vanes of two and three compressor stages away is studied. In the first part of the study, one-way FSI simulation is carried out. To validate the accuracy of the simulation, experiments are also conducted using a gas turbine test facility. It is found that one-way FSI simulation can accurately predict the order of the vibration level. In the second part of the study, a method of controlling the blade vibration is investigated by optimizing the clocking of the stator vanes. It is confirmed that the vibration amplitude can be effectively suppressed without reducing the performance. Through this study, ways to evaluate and control the rotor blade vibration are validated.

Non-Synchronous Aeroacoustic Interaction in an Axial Multi-Stage Compressor

2019 ◽  
Vol 141 (10) ◽  
Author(s):  
Anne-Lise Fiquet ◽  
Christoph Brandstetter ◽  
Stéphane Aubert ◽  
Mickael Philit
Keyword(s):  
Rotor Blade ◽  
High Speed ◽  
Acoustic Mode ◽  
Blade Vibration ◽  
Unsteady Pressure ◽  
Multi Stage ◽  
Engine Order ◽  
Major Interest ◽  
Blade Vibrations ◽  
Magnet Coil

Abstract Non-engine order rotor blade vibration is an aeroelastic phenomenon of major interest for compressor designers resulting from excitation of rotor blade modes through aerodynamic instabilities. Indicators for a comparable type of instability, caused by propagating acoustic modes, have been observed in an experimental multistage high-speed compressor by Safran Helicopter Engines. It is intended to understand the cause of these instabilities by combining experimental data and numerical simulations. Unsteady pressure measurements were carried out by case-mounted and stator-mounted transducers. Rotor tip-timing and magnet-coil sensor systems were installed to measure the blade vibrations. Experimental results show non-engine order signatures in the unsteady pressure signal coherent to the shifted frequency of blade vibrations. In the present paper, the waveform of these oscillations is analyzed in detail, showing a dominant propagating acoustic mode interacting with vibrations of rotor 2. The root cause for the non-synchronous oscillations is identified as an acoustic mode that is cutoff downstream of rotor 3. During the test, the mode changes its frequency and circumferential order, affecting the amplitude of associated blade vibrations.

Self-Excited Blade Vibration Experimentally Investigated in Transonic Compressors: Acoustic Resonance

2015 ◽  
Author(s):  
F. Holzinger ◽  
F. Wartzek ◽  
M. Nestle ◽  
H.-P. Schiffer ◽  
S. Leichtfuß
Keyword(s):  
Rotor Blade ◽  
Guide Vane ◽  
Separated Flow ◽  
Acoustic Resonance ◽  
Rotating Stall ◽  
Rotor Blades ◽  
Inlet Guide Vane ◽  
Blade Vibration ◽  
Excited Vibration ◽  
Experimental Findings

This paper investigates the acoustically induced rotor blade vibration that occurred in a state-of-the-art 1.5-stage transonic research compressor. The compressor was designed with the unconventional goal to encounter self-excited blade vibration within its regular operating domain. Despite the design target to have the rotor blades reach negative aerodamping in the near stall region for high speeds and open inlet guide vane, no vibration occurred in that area prior to the onset of rotating stall. Self-excited vibrations were finally initiated when the compressor was operated at part speed with fully open inlet guide vane along nominal and low operating line. The mechanism of the fluid-structure-interaction behind the self-excited vibration is identified by means of unsteady compressor instrumentation data. Experimental findings point towards an acoustic resonance originating from separated flow in the variable inlet guide vanes. A detailed investigation based on highly resolved wall pressure data confirms this conclusion. The paper documents the spread in aerodynamic damping calculated by various partners with their respective aeroelastic tools for a single geometry and speed line. This significant spread proves the need for calibration of aeroelastic tools to reliably predict blade vibration. The paper contains a concise categorization of flow induced blade vibration and defines criteria to quickly distinguish the different types of blade vibration. It further gives a detailed description of a novel test compressor and thoroughly investigates the encountered rotor blade vibration.

Self-Excited Blade Vibration Experimentally Investigated in Transonic Compressors: Acoustic Resonance

2015 ◽  
Vol 138 (4) ◽  
Author(s):  
F. Holzinger ◽  
F. Wartzek ◽  
H.-P. Schiffer ◽  
S. Leichtfuss ◽  
M. Nestle
Keyword(s):  
Rotor Blade ◽  
Guide Vane ◽  
Separated Flow ◽  
Acoustic Resonance ◽  
Rotating Stall ◽  
Rotor Blades ◽  
Inlet Guide Vane ◽  
Blade Vibration ◽  
Excited Vibration ◽  
Experimental Findings

This paper investigates the acoustically induced rotor blade vibration that occurred in a state-of-the-art 1.5-stage transonic research compressor. The compressor was designed with the unconventional goal to encounter self-excited blade vibration within its regular operating domain. Despite the design target to have the rotor blades reach negative aerodamping in the near stall region for high speeds and open inlet guide vane, no vibration occurred in that area prior to the onset of rotating stall. Self-excited vibrations were finally initiated when the compressor was operated at part speed with fully open inlet guide vane along nominal and low operating line. The mechanism of the fluid–structure interaction behind the self-excited vibration is identified by means of unsteady compressor instrumentation data. Experimental findings point toward an acoustic resonance originating from separated flow in the variable inlet guide vanes (VIGV). A detailed investigation based on highly resolved wall-pressure data confirms this conclusion. This paper documents the spread in aerodynamic damping calculated by various partners with their respective aeroelastic tools for a single geometry and speed line. This significant spread proves the need for calibration of aeroelastic tools to reliably predict blade vibration. This paper contains a concise categorization of flow-induced blade vibration and defines criteria to quickly distinguish the different types of blade vibration. It further gives a detailed description of a novel test compressor and thoroughly investigates the encountered rotor blade vibration.

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