Forced Response of Mistuned Bladed Disks in Gas Flow: A Comparative Study of Predictions and Full-Scale Experimental Results

2010 ◽  
Vol 132 (5) ◽  
Author(s):  
Evgeny Petrov ◽  
Luca Di Mare ◽  
Holger Hennings ◽  
Robert Elliott
Keyword(s):  
Data Exchange ◽  
Gas Flow ◽  
Numerical Study ◽  
Forced Response ◽  
Full Scale ◽  
Response Analysis ◽  
Test Rig ◽  
Bladed Disk ◽  
Resonance Frequencies ◽  
Underplatform Damper

An integrated experimental-numerical study of forced response for a mistuned bladed disk has been performed. A full chain for the predictive forced response analysis has been developed including data exchange between the computational fluid dynamics code and a code for the prediction of the nonlinear forced response for a bladed disk. The experimental measurements are performed at a full-scale single stage test rig with excitation by aerodynamic forces from gas flow. The numerical modeling approaches and the test rig setup are discussed. Comparison of experimentally measured and predicted values of blade resonance frequencies and response levels for a mistuned bladed disk without dampers is performed. A good correspondence between frequencies at which individual blades have maximum response levels is achieved. The effects of structural damping and underplatform damper parameters on amplitudes and resonance frequencies of the bladed disk are explored. It is shown that the underplatform damper significantly reduces scatters in values of the individual blade frequencies and maximum forced response levels.

Forced Response of Mistuned Bladed Discs in Gas Flow: A Comparative Study of Predictions and Full-Scale Experimental Results

2009 ◽  
Author(s):  
Evgeny Petrov ◽  
Luca Di Mare ◽  
Holger Hennings ◽  
Robert Elliott
Keyword(s):  
Data Exchange ◽  
Gas Flow ◽  
Numerical Study ◽  
Forced Response ◽  
Full Scale ◽  
Response Analysis ◽  
Test Rig ◽  
Good Correspondence ◽  
Resonance Frequencies ◽  
Underplatform Damper

An integrated experimental-numerical study of forced response for a mistuned bladed disc has been performed. A full chain for the predictive forced response analysis has been developed including data exchange between the CFD code and a code for the prediction of the nonlinear forced response for a bladed disc. The experimental measurements are performed at a full-scale single stage test rig with excitation by aerodynamic forces from gas flow. Numerical modelling approaches and the test rig setup are discussed. Comparison of experimentally measured and predicted values of blade resonance frequencies and response levels for a mistuned bladed disc without dampers is performed. A good correspondence between frequencies at which individual blades have maximum response levels is achieved. The effects of structural damping and underplatform damper parameters on amplitudes and resonance frequencies of the bladed disc are explored. It is shown that the underplatform damper significantly reduces scatters in values of the individual blade frequencies and maximum forced response levels.

A Study of Nonlinear Vibrations in a Frictionally Damped Turbine Bladed Disk With Comprehensive Modeling of Aerodynamic Effects

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
E. P. Petrov ◽  
Z.-I. Zachariadis ◽  
A. Beretta ◽  
R. Elliott
Keyword(s):  
Gas Flow ◽  
Aerodynamic Characteristics ◽  
Forced Response ◽  
New Method ◽  
Mode Shapes ◽  
Response Analysis ◽  
Influence Matrix ◽  
Bladed Disk ◽  
Resonance Frequencies ◽  
Comprehensive Modeling

A new effective method for comprehensive modeling of gas flow effects on vibration of nonlinear vibration of bladed disks has been developed for a case when the effect of the gas flow on the mode shapes is significant. The method separates completely the structural dynamics calculations from the significantly more computationally expensive computational fluid dynamics (CFD) calculations while providing the high accuracy of modeling for aerodynamic effects. A comprehensive analysis of the forced response using the new method has been performed for a realistic turbine bladed disk with root-disk joints, tip, and under-platform dampers. The full chain of aerodynamic and structural calculations are performed: (i) determination of boundary conditions for CFD, (ii) CFD analysis, (iii) calculation of the aerodynamic characteristics required by the new method, and (iv) nonlinear forced response analysis using the modal aerodynamic influence matrix (MAIM). The efficiency of the friction damping devices has been studied and compared for several resonance frequencies and engine orders. Advantages of the method for aerodynamic effect modeling have been demonstrated.

A Method for Forced Response Analysis of Mistuned Bladed Disks With Aerodynamic Effects Included

2010 ◽  
Vol 132 (6) ◽  
Author(s):  
E. P. Petrov
Keyword(s):  
Gas Flow ◽  
Forced Response ◽  
Response Analysis ◽  
Bladed Disks ◽  
Blade Vibration ◽  
Disk Model ◽  
Mechanical Coupling ◽  
Bladed Disk ◽  
Flexible Disk ◽  
Function Matrix

A method has been developed for high-accuracy analysis of forced response levels for mistuned bladed disks vibrating in gas flow. Aerodynamic damping, the interaction of vibrating blades through gas flow, and the effects of structural and aerodynamic mistuning are included in the bladed disk model. The method is applicable to cases of high mechanical coupling of blade vibration through a flexible disk and, possibly shrouds, to cases with stiff disks and low mechanical coupling. The interaction of different families of bladed disk modes is included in the analysis providing the capability of analyzing bladed disks with pronounced frequency veering effects. The method allows the use of industrial-size sector models of bladed disks for analysis of forced response of a mistuned structure. The frequency response function matrix of a structurally mistuned bladed disk is derived with aerodynamic forces included. A new phenomenon of reducing bladed disk forced response by mistuning to levels that are several times lower than those of their tuned counterparts is revealed and explained.

A Study of Nonlinear Vibrations in a Frictionally-Damped Turbine Bladed Disc With Comprehensive Modelling of Aerodynamic Effects

2012 ◽  
Author(s):  
E. P. Petrov ◽  
Z.-I. Zachariadis ◽  
A. Beretta ◽  
R. Elliott
Keyword(s):  
Gas Flow ◽  
Aerodynamic Characteristics ◽  
Forced Response ◽  
New Method ◽  
Mode Shapes ◽  
Response Analysis ◽  
Resonance Frequencies ◽  
Computational Fluid Dynamics Cfd ◽  
Flow Effects

A new effective method for comprehensive modelling of gas flow effects on vibration of nonlinear vibration of bladed discs has been developed for a case when effect of the gas flow on the mode shapes is significant. The method separates completely the structural dynamics calculations from the significantly more computationally expensive computational fluid dynamics (CFD) calculations while provides the high accuracy of modelling for aerodynamic effects. A comprehensive analysis of the forced response using the new method has been performed for a realistic turbine bladed disc with root-disc joints, tip and underplatform dampers. The full chain of aerodynamic and structural calculations are performed: (i) determination of boundary conditions for CFD; (ii) CFD analysis; (iii) calculation of the aerodynamic characteristics required by the new method; (iv) nonlinear forced response analysis using the MAIM. The efficiency of the friction damping devices has been studied and compared for several resonance frequencies and engine orders. Advantages of the method for aerodynamic effect modelling have been demonstrated.

Influence of Detailing on Aerodynamic Forcing of a Transonic Axial Turbine Stage and Forced-Response Prediction for Low-Engine-Order (LEO) Excitation

2017 ◽  
Author(s):  
Tobias R. Müller ◽  
Damian M. Vogt ◽  
Klemens Vogel ◽  
Bent A. Phillipsen ◽  
Peter Hönisch
Keyword(s):  
Numerical Study ◽  
Response Prediction ◽  
Forced Response ◽  
Resonance Excitation ◽  
Response Analysis ◽  
Turbine Stage ◽  
Flow Induced Vibration ◽  
Axial Turbine ◽  
Timing Data ◽  
Generalized Force

The effects of detailing on the prediction of forced-response in a transonic axial turbine stage, featuring a parted stator design, asymmetric inlet and outlet casings as well as rotor cavities, is investigated. Ensuring the mechanical integrity of components is of paramount importance for the safe and reliable operation of turbomachines. Among others, flow induced resonance excitation can lead to high-cycle fatigue (HCF) and potentially to damage of components unless properly damped. This numerical study is assessing the necessary degree of detailing in terms of spatial and temporal discretization, boundary conditions of the pre-stressed rotor geometry as well as geometrical detailing for the reliable prediction of the aerodynamic excitation of the structure. In this context, the sensitivity of the aerodynamic forcing is analyzed by means of the generalized force criterion, showing a significant influence for some of the investigated variations of the numerical model. Moreover, the origin and further progression of several low-engine-orders (LEO) within the flow field, as well as their interaction with different geometric details has been analyzed based on the numerical results obtained from a full 360° CFD-calculation of the investigated turbine stage. The predicted flow induced vibration of the structure has been validated by means of a full forced-response analysis, where a good agreement with tip-timing data has been found.

A Forced Response Analysis and Application of Impact Dampers to Rotordynamic Vibration Suppression in a Cryogenic Environment

1993 ◽  
Author(s):  
J. J. Moore ◽  
A. Palazzolo ◽  
R. Gadangi ◽  
T. A. Nale ◽  
S. A. Klusman ◽  
...  
Keyword(s):  
High Speed ◽  
Vibration Suppression ◽  
Forced Response ◽  
Optimum Operating ◽  
Response Analysis ◽  
Amplitude Dependence ◽  
Test Rig ◽  
Equivalent Viscous Damping ◽  
Impact Damper ◽  
The Impact

Abstract A high speed damper test rig has been assembled at Texas A&M University to develop rotordynamic dampers for rocket engine turbopumps that operate at cryogenic temperatures, such as those used in the Space Shuttle Main Engines (SSMEs). Damping is difficult to obtain in this class of turbomachinery due to the low temperature and viscosity of the operating fluid. An impact damper has been designed and tested as a means to obtain effective damping in a rotorbearing system. The performance and behavior of the impact damper is verified experimentally in a cryogenic test rig at Texas A&M. Analytical investigations indicate a strong amplitude dependence on the performance of the impact damper. An optimum operating amplitude exists and is determined both analytically and experimentally. In addition, the damper performance is characterized by an equivalent viscous damping coefficient. The test results prove the impact damper to be a viable means to suppress vibration in a cryogenic rotorbearing system.

Investigation of Damping Potential of Strip Damper on a Real Turbine Blade

2016 ◽  
Author(s):  
M. Afzal ◽  
I. Lopez Arteaga ◽  
L. Kari ◽  
V. Kharyton
Keyword(s):  
Boundary Conditions ◽  
Dynamic Properties ◽  
Equations Of Motion ◽  
Iterative Solution ◽  
Element Model ◽  
Forced Response ◽  
Contact Forces ◽  
Response Analysis ◽  
Bladed Disk ◽  
Different Types

This paper investigates the damping potential of strip dampers on a real turbine bladed disk. A 3D numerical friction contact model is used to compute the contact forces by means of the Alternate Frequency Time domain method. The Jacobian matrix required during the iterative solution is computed in parallel with the contact forces, by a quasi-analytical method. A finite element model of the strip dampers, that allows for an accurate description of their dynamic properties, is included in the steady-state forced response analysis of the bladed disk. Cyclic symmetry boundary conditions and the multiharmonic balance method are applied in the formulation of the equations of motion in the frequency domain. The nonlinear forced response analysis is performed with two different types of boundary conditions on the strip: (a) free-free and (b) elastic, and their influence is analyzed. The effect of the strip mass, thickness and the excitation levels on the forced response curve is investigated in detail.

Transient Forced Response Analysis of Mistuned Steam Turbine Blades During Startup and Coastdown

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Christian Siewert ◽  
Heinrich Stüer
Keyword(s):  
Mechanical Model ◽  
Turbine Blades ◽  
Forced Vibrations ◽  
Forced Response ◽  
The Self ◽  
Response Analysis ◽  
Computationally Efficient ◽  
Bladed Disk ◽  
Steam Turbine Blades ◽  
Number Of Publications

It is well known that the vibrational behavior of a mistuned bladed disk differs strongly from that of a tuned bladed disk. A large number of publications dealing with the dynamics of mistuned bladed disks are available in the literature. The vibrational phenomena analyzed in these publications are either forced vibrations or self-excited flutter vibrations. Nearly, all published literature on the forced vibrations of mistuned blades disks considers harmonic, i.e., steady-state, vibrations, whereas the self-excited flutter vibrations are analyzed by the evaluation of the margin against instabilities by means of a modal, or rather than eigenvalue, analysis. The transient forced response of mistuned bladed disk is not analyzed in detail so far. In this paper, a computationally efficient mechanical model of a mistuned bladed disk to compute the transient forced response is presented. This model is based on the well-known fundamental model of mistuning (FMM). With this model, the statistics of the transient forced response of a mistuned bladed disk is analyzed and compared to the results of harmonic forced response analysis.

Experimental and Numerical Investigation of Rotating Bladed Disk Forced Response Using Underplatform Friction Dampers

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Ibrahim A. Sever ◽  
Evgeny P. Petrov ◽  
David J. Ewins
Keyword(s):  
Measurement Techniques ◽  
Measured Data ◽  
Forced Response ◽  
Imperial College ◽  
Test Rig ◽  
Response Curves ◽  
Friction Dampers ◽  
Bladed Disk ◽  
Prediction Tools ◽  
Numerical Predictions

In this paper, we present a methodology and results from an experimental investigation of forced vibration response for a bladed disk with fitted underplatform “cottage-roof” friction dampers, together with the corresponding numerical predictions. A carefully designed and constructed rotating test rig is used to make precise measurements, which involve only the phenomena of interest. For this purpose, the measurement rig is operated under vacuum to eliminate aerodynamic effects on the rotating blisk and noncontact excitation and measurement techniques are employed so as not to modify the bladed disk dynamics. The experimental data measured are used for validation of multiharmonic balance-based prediction tools developed at the Imperial College. Predictions are carried out both with and without taking inherent mechanical mistuning into account, which is identified from measured data. Measured and predicted response curves are compared with each other and the degree of correlation is discussed.

Transient Forced Response Analysis of Mistuned Steam Turbine Blades During Start-Up and Coast-Down

2014 ◽  
Author(s):  
Christian Siewert ◽  
Heinrich Stüer
Keyword(s):  
Mechanical Model ◽  
Turbine Blades ◽  
Forced Vibrations ◽  
Forced Response ◽  
Response Analysis ◽  
Computationally Efficient ◽  
Bladed Disk ◽  
Start Up ◽  
Steam Turbine Blades ◽  
Number Of Publications

It is well-known that the vibrational behavior of a mistuned bladed disk differs strongly from that of a tuned bladed disk. A large number of publications dealing with the dynamics of mistuned bladed disks is available in the literature. The vibrational phenomena analyzed in these publications are either forced vibrations or self-excited flutter vibrations. Nearly all published literature on the forced vibrations of mistuned blades disks considers harmonic, i. e. steady-state, vibrations, whereas the self-excited flutter vibrations are analyzed by the evaluation of the margin against instabilities by means of a modal, or rather than eigenvalue, analysis. The transient forced response of mistuned bladed disk is not analyzed in detail so far. In this paper, a computationally efficient mechanical model of a mistuned bladed disk to compute the transient forced response is presented. This model is based on the well-known Fundamental Model of Mistuning. With this model, the statistics of the transient forced response of a mistuned bladed disk is analyzed and compared to the results of harmonic forced response analysis.

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