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.

Influence of a Cylindrical Exhaust Hood Installation on the Last Stage Rotor Blades of a Low Pressure Model Steam Turbine

2017 ◽  
Author(s):  
Fabian F. Müller ◽  
Markus Schatz ◽  
Damian M. Vogt ◽  
Jens Aschenbruck
Keyword(s):  
Flow Field ◽  
Steam Turbine ◽  
Operating Conditions ◽  
Rotor Blades ◽  
Pressure Measurements ◽  
Exhaust Hood ◽  
Blade Vibration ◽  
Time Resolved ◽  
Vibration Behavior ◽  
Last Stage

The influence of a cylindrical strut shortly downstream of the bladerow on the vibration behavior of the last stage rotor blades of a single stage LP model steam turbine was investigated in the present study. Steam turbine retrofits often result in an increase of turbine size, aiming for more power and higher efficiency. As the existing LP steam turbine exhaust hoods are generally not modified, the last stage rotor blades frequently move closer to installations within the exhaust hood. To capture the influence of such an installation on the flow field characteristics, extensive flow field measurements using pneumatic probes were conducted at the turbine outlet plane. In addition, time-resolved pressure measurements along the casing contour of the diffuser and on the surface of the cylinder were made, aiming for the identification of pressure fluctuations induced by the flow around the installation. Blade vibration behavior was measured at three different operating conditions by means of a tip timing system. Despite the considerable changes in the flow field and its frequency content, no significant impact on blade vibration amplitudes were observed for the investigated case and considered operating conditions. Nevertheless, time-resolved pressure measurements suggest that notable pressure oscillations induced by the vortex shedding can reach the upstream bladerow.

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.

scholarly journals Modeling and Analysis of the Rotor Blade Refurbishment Process at the Corpus Christi Army Depot

2015 ◽  
Vol 3 (2) ◽  
pp. 124-130
Author(s):  
Nathanial Green ◽  
David Jaye ◽  
Stephen Kerns ◽  
Gene Lesinski
Keyword(s):  
Rotor Blade ◽  
Performance Metrics ◽  
Discrete Event ◽  
Rotor Blades ◽  
Modeling And Analysis ◽  
Corpus Christi ◽  
Event Simulation ◽  
The Impact ◽  
Budget Reductions ◽  
Rotary Wing

Much of the Army’s equipment is coming to the end of its planned life cycle.  At the same time, the Department of Defense and the Army are facing severe budget reductions for the foreseeable future.  As a result, the planned modernization and acquisition of new equipment will be delayed.  The Army is now forced to keep and maintain current equipment as opposed to retiring old systems and buying new ones.  With the increased investment in the current systems, the organizations and depots that maintain and refurbish the Army’s equipment are becoming increasingly valuable assets.  Corpus Christi Army Depot (CCAD) is the Army’s only facility for repair and overhaul of rotary wing aircraft.  CCAD receives approximately 10 rotor blades per day for the Black Hawk helicopter.  Each blade is routed through a detailed inspection and rework process consisting of approximately 67 sequential operations which take approximately 45 days per blade.  Recently CCAD has expanded and reorganized the rotor blade refurbishment facility which provides an opportunity to re-examine processes, adjust positioning of work stations, and improve efficiency.  In this research we develop a discrete-event simulation model of the CCAD rotor blade refurbishment process in order to identify inefficiencies and examine “what if” scenarios to improve key performance metrics.  The key performance metrics used to analyze model input include throughput, work in progress, mean queue time, mean queue size, and workstation utilization.  The baseline model revealed that there were two crucial bottlenecks that severely limited the throughput and overall performance of the refurbishment process.  Adjusting the capacities of these workstations was very effective in reducing the number of blades in WIP and reducing the impact of the queues in front of these stations, but failed to increase the throughput to the desired amount.  Additionally, we found that the loss of one whirl tower’s production would not be a significant factor for CCAD’s performance in terms of throughput since operating with only one whirl tower did not significantly impact metrics of interest for the process.

scholarly journals The Effect of Non-Conservative Compressive Force on the Vibration of Rotating Composite Blades

Vibration ◽  
2020 ◽  
Vol 3 (4) ◽  
pp. 478-490
Author(s):  
Mohammadreza Amoozgar ◽  
Mahdi Bodaghi ◽  
Rafic M. Ajaj
Keyword(s):  
Dynamic Behavior ◽  
Nonlinear Differential Equations ◽  
Compressive Force ◽  
Rotor Blades ◽  
Axial Compressive Force ◽  
Composite Blade ◽  
Vibration Behavior ◽  
Time Space ◽  
Blade Tip ◽  
Composite Blades

This paper investigates the effectiveness of a resonance avoidance concept for composite rotor blades featuring extension–twist elastic coupling. The concept uses a tendon, attached to the tip of the blade, to apply a proper amount of compressive force to tune the vibration behavior of the blade actively. The tendon is simulated by applying a non-conservative axial compressive force applied to the blade tip. The main load carrying part of the structure is the composite spar box, which has an antisymmetric layup configuration. The nonlinear dynamic behavior of the composite blade is modelled by using the geometrically exact fully intrinsic beam equations. The resulting nonlinear differential equations are discretized using a time–space scheme, and the stationary and rotating frequencies of the blade are obtained. It is observed that the proposed resonance avoidance mechanism is effective for tuning the vibration behavior of composite blades. The applied compressive force can shift the frequencies and the location at which the frequency veering take place. Furthermore, the compressive force can also cause the composite blade to get unstable depending on the layup ply angle. Finally, the results, highlighting the importance of compressive force and ply angle on the dynamic behavior of composite blades, are presented and discussed.

scholarly journals Full scale deformation measurements of a wind turbine rotor in comparison with aeroelastic simulations

2020 ◽  
Author(s):  
Stephanie Lehnhoff ◽  
Alejandro Gómez González ◽  
Jörg R. Seume
Keyword(s):  
Wind Turbine ◽  
Rotor Blade ◽  
Plane Deformation ◽  
Field Measurements ◽  
Turbine Rotor ◽  
Rotor Blades ◽  
Strain Gauges ◽  
Aeroelastic Simulations ◽  
Good Agreement ◽  
Wind Turbine Rotor

Abstract. The measurement of deformation and vibration of wind turbine rotor blades becomes highly important as the length of rotor blades increases with the growth in demand for wind power. The requirement for field validation of the aeroelastic behaviour of wind turbines increases with the scale of the deformation, in particular for modern blades with very high flexibility and coupling between different vibration modes. However, performing full-scale field measurements for rotor blade deformation is not trivial and requires high temporal and spatial resolution. A promising deformation measurement technique is based on an optical method called Digital Image Correlation (DIC). A system for the application of DIC for full field measurements of wind turbine rotors has been developed and validated in the past years by ForWind, Institute of Turbomachinery and Fluid Dynamics, Leibniz Universität Hannover. The whole rotor of the wind turbine is monitored with a stereo camera system from the ground during measurement. Recently, DIC measurements on a Siemens Gamesa SWT-4.0-130 test turbine were performed on the tip of all blades with synchronized measurement of the inflow conditions by a ground-based LiDAR. As the turbine was additionally equipped with strain gauges in the blade root of all blades, the DIC results can be directly compared to the actual prevailing loads. In the end, the measured deformations are compared to aeroelastic simulations. The deformation measured with DIC on the rotor blade tips shows the same qualitative behaviour when compared to loads measured with strain gauges in the blade root. This confirms that the DIC measurements correlate with the prevailing loads in reality. The comparison with aeroelastic simulations shows that the amplitude and trend of the in-plane deformation is in very good agreement with the DIC measurements. The out-of-plane deformation shows slight differences, which could be caused by the difference between real wind conditions and the wind statistics on which the simulations are based. The combined rotor blade pitch and torsion angle measured with DIC is in good agreement with the actual pitch value of the turbine. A detailed comparison with aeroelastic simulations shows that the amplitude of torsion measured with DIC is higher which might be caused by an inaccuracy of the experimental setup. This will be focus of future work. All in all, DIC shows very good agreement with comparative measurements and simulations which shows that it is a suitable method for measurements of deformation and torsion of multi-megawatt wind turbine rotor blades.

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.

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 ◽  
Computational Cost ◽  
Forced Response ◽  
Test Facility ◽  
Vibration Level ◽  
Blade Vibration ◽  
High Rotational Speed ◽  
Axial Compressors

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, in many cases, axial compressors are designed to have thin rotor blades and stator vanes with short axial distances, and are driven at high rotational speed. 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 method of them under the resonance condition are necessary in the design process. Concerning the forced response excitation associated with the adjacent stator vanes, there are many previous studies on simulating the vibration by fluid structure interaction (FSI) simulation. In these studies, the aerodynamic force acting on the blade is simulated by an efficient unsteady computational fluid dynamics (CFD) method such as the nonlinear harmonic (NLH) method. These methods can be available in commercial CFD solvers and can significantly reduce computational cost. However, there are few examples of the problems associated with the stator vanes from two and three compressor stages away and no efficient simulation method is available. In this study, the problem of rotor blade vibration caused by the stator vanes of two and three compressor stages away is studied. Ways to accurately predict and effectively control the vibration are also investigated. In the first part of the study, one-way FSI simulation is carried out using a full annulus CFD model. To validate the accuracy of the simulation, experiments are also conducted using a gas turbine test facility. The vibration level of the blade is measured using a blade tip timing (BTT) measurement system and the obtained results are compared with the simulated data. 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 forced response excitation is investigated by optimizing the clocking of the stator vanes. It is confirmed that by controlling the clocking of the stator vanes, the vibration amplitude can be effectively suppressed without reducing the compressor performance. Through this study, ways to evaluate and control the unsteady pressure force and vibration response of the rotor blade are validated. By optimizing the clocking of stator vanes, the blade vibration level can be effectively reduced.

Tip-Shroud Labyrinth Seal Effect on the Flutter Stability of Turbine Rotor Blades

2019 ◽  
Vol 141 (10) ◽  
Author(s):  
Roque Corral ◽  
Michele Greco ◽  
Almudena Vega
Keyword(s):  
Rotor Blade ◽  
Labyrinth Seal ◽  
Turbine Rotor ◽  
Rotor Blades ◽  
Labyrinth Seals ◽  
Turbine Rotor Blade ◽  
The Stability ◽  
Shrouded Rotor ◽  
Tip Shroud ◽  
The Impact

Abstract The effect of the tip-shroud seal on the flutter onset of a shrouded turbine rotor blade, representative of a modern gas turbine, is numerically tested, and the contributions to the work per cycle of the aerofoil and the tip shroud are clearly identified. The numerical simulations are conducted using a linearized frequency-domain solver. The flutter stability of the shrouded rotor blade is evaluated for an edgewise mode and compared with the standard industrial approach of not including the tip-shroud cavity. It turns out that including the tip shroud significantly changes the stability prediction of the rotor blade. This is due to two facts. First, the amplitude of the unsteady pressure created in the inter-fin cavity due to the motion of the airfoil is much greater than that of the airfoil. The impact of this contribution increases with the frequency. Second, the effect of the outer shroud of the rotor blade, which usually is not included either in the simulations, has an opposite trend with the nodal diameter than the airfoil reducing the maximum and minimum damping. It is concluded that the combined effect of the seal and its platform tends to stabilize the edgewise mode of the rotor blade for all the examined nodal diameters and reduced frequencies. Finally, the numerical results are shown to be consistent with those obtained using an analytical simplified model to account for the effect of the labyrinth seals.

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