Effects of Contact Interface Parameters on Vibration of Turbine Bladed Disks With Underplatform Dampers

2012 ◽  
Vol 134 (3) ◽  
Author(s):  
C. W. Schwingshackl ◽  
E. P. Petrov ◽  
D. J. Ewins
Keyword(s):  
Structural Integrity ◽  
Nonlinear Modeling ◽  
Turbine Blades ◽  
Contact Interface ◽  
Bladed Disks ◽  
Normal Contact ◽  
Input Parameters ◽  
Software Codes ◽  
Interface Parameters ◽  
Underplatform Damper

The design of high cycle fatigue resistant bladed disks requires the ability to predict the expected damping of the structure in order to evaluate the dynamic behavior and ensure structural integrity. Highly sophisticated software codes are available today for this nonlinear analysis, but their correct use requires a good understanding of the correct model generation and the input parameters involved to ensure a reliable prediction of the blade behavior. The aim of the work described in this paper is to determine the suitability of current modeling approaches and to enhance the quality of the nonlinear modeling of turbine blades with underplatform dampers. This includes an investigation of a choice of the required input parameters, an evaluation of their best use in nonlinear friction analysis, and an assessment of the sensitivity of the response to variations in these parameters. Part of the problem is that the input parameters come with varying degrees of uncertainty because some are experimentally determined, others are derived from analysis, and a final set are often based on estimates from previous experience. In this investigation the model of a commercial turbine bladed disk with an underplatform damper is studied, and its first flap, first torsion, and first edgewise modes are considered for 6 EO and 36 EO excitation. The influence of different contact interface meshes on the results is investigated, together with several distributions of the static normal contact loads, to enhance the model setup and, hence, increase accuracy in the response predictions of the blade with an underplatform damper. A parametric analysis is carried out on the friction contact parameters and the correct setup of the nonlinear contact model to determine their influence on the dynamic response and to define the required accuracy of the input parameters.

Effects of Contact Interface Parameters on Vibration of Turbine Bladed Disks With Underplatform Dampers

2011 ◽  
Author(s):  
C. W. Schwingshackl ◽  
E. P. Petrov ◽  
D. J. Ewins
Keyword(s):  
Structural Integrity ◽  
Turbine Blades ◽  
Contact Interface ◽  
Bladed Disks ◽  
Normal Contact ◽  
Input Parameters ◽  
Software Codes ◽  
Model Setup ◽  
Interface Parameters ◽  
Underplatform Damper

The design of high cycle fatigue resistant bladed disks requires the ability to predict the expected damping of the structure in order to evaluate the dynamic behaviour and ensure structural integrity. Highly sophisticated software codes are available today for this nonlinear analysis but their correct use requires a good understanding of the correct model generation and the input parameters involved to ensure a reliable prediction of the blade behaviour. The aim of the work described in this paper is to determine the suitability of current modelling approaches and to enhance the quality of the nonlinear modelling of turbine blades with underplatform dampers. This includes an investigation of a choice of the required input parameters, an evaluation of their best use in nonlinear friction analysis, and an assessment of the sensitivity of the response to variations in these parameters. Part of the problem is that the input parameters come with varying degrees of uncertainty, since some are experimentally determined, others are derived from analysis and a final set are often based on estimates from previous experience. In this investigation the model of a commercial turbine bladed disc with an underplatform damper is studied and its first flap, first torsion and first edgewise modes are considered for 6EO and 36EO excitation. The influence of different contact interface meshes on the results is investigated, together with several distributions of the static normal contact loads to enhance the model setup and hence increase accuracy in the response predictions of the blade with an underplatform damper. A parametric analysis is carried out on the friction contact parameters and the correct setup of the nonlinear contact model to determine their influence on the dynamic response and to define the required accuracy of the input parameters.

scholarly journals Adaptive control of normal load at the friction interface of bladed disks using giant magnetostrictive material

2020 ◽  
Vol 31 (8) ◽  
pp. 1111-1125
Author(s):  
Mohammad Afzal ◽  
Leif Kari ◽  
Ines Lopez Arteaga
Keyword(s):  
Adaptive Control ◽  
Normal Load ◽  
Contact Load ◽  
Operating Parameters ◽  
Contact Interface ◽  
Bladed Disks ◽  
Normal Contact ◽  
Bladed Disk ◽  
Magnetostrictive Actuators ◽  
Interface Parameters

A novel application of magnetostrictive actuators in underplatform dampers of bladed disks is proposed for adaptive control of the normal load at the friction interface to achieve the desired friction damping in the structure. Friction damping in a bladed disk depends on operating parameters, such as rotational speed, engine excitation order, nodal diameter normal contact load, and contact interface parameters, such as contact stiffness and friction coefficient. The operating parameters have a fixed value, whereas the contact interface parameters vary in an unpredictable way at an operating point. However, the ability to vary some of these parameters such as the normal contact load in a controlled manner is desirable to attain an optimum damping in the bladed disk at different operating conditions. Under the influence of an external magnetic field, magnetostrictive materials develop an internal strain that can be exploited to vary the normal contact load at the friction interface, which makes them a potentially good candidate for this application. A commercially available magnetostrictive alloy, Terfenol-D is considered in this analysis that is capable of providing magnetostrain up to 2 × 10-3 under prestress and a blocked force over 1500 N. A linearized model of the magnetostrictive material, which is accurate enough for a direct current application, is employed to compute the output force of the actuator. A nonlinear finite element contact analysis is performed to compute the normal contact load between the blade platform and the underplatform damper as a result of magnetostrictive actuation. The nonlinear contact analysis is performed for different actuator mounting configurations and the obtained results are discussed. The proposed solution is potentially applicable to adaptively control vibratory stresses in bladed disks and consequently to reduce failure due to high-cycle fatigue. Finally, the practical challenges in employing magnetostrictive actuators in underplatform dampers are discussed.

Method for Direct Parametric Analysis of Nonlinear Forced Response of Bladed Disks With Friction Contact Interfaces

2004 ◽  
Vol 126 (4) ◽  
pp. 654-662 ◽  
Author(s):  
E. P. Petrov
Keyword(s):  
Parametric Analysis ◽  
Large Scale ◽  
Normal Load ◽  
Forced Response ◽  
Finite Element Models ◽  
Contact Interface ◽  
Friction Contact ◽  
Bladed Disks ◽  
Interface Parameters ◽  
Contact Parameters

An effective method for direct parametric analysis of periodic nonlinear forced response of bladed disks with friction contact interfaces has been developed. The method allows, forced response levels to be calculated directly as a function of contact interface parameters such as the friction coefficient, contact surface stiffness (normal and tangential coefficients), clearances, interferences, and the normal stresses at the contact interfaces. The method is based on exact expressions for sensitivities of the multiharmonic interaction forces with respect to variation of all parameters of the friction contact interfaces. These novel expressions are derived in the paper for a friction contact model, accounting for the normal load variation and the possibility of separation-contact transitions. Numerical analysis of effects of the contact parameters on forced response levels has been performed using large-scale finite element models of a practical bladed turbine disk with underplatform dampers and with shroud contacts.

Multiharmonic Analysis and Design of Shroud Friction Joints of Bladed Disks Subject to Microslip

2012 ◽  
Author(s):  
Malte Krack ◽  
Anna Herzog ◽  
Lars Panning-von Scheidt ◽  
Jörg Wallaschek ◽  
Christian Siewert ◽  
...  
Keyword(s):  
Contact Area ◽  
Turbine Blades ◽  
Synthesis Method ◽  
Forced Response ◽  
Internal Resonances ◽  
Bladed Disks ◽  
Normal Contact ◽  
Analysis And Design ◽  
Contact Points ◽  
Highly Nonlinear

Vibration reduction of turbine blades by means of friction damping in shroud joints is a well-established technology in the field of turbomachinery dynamics. Three-dimensional contact constraints in the shroud coupling can induce highly nonlinear dynamics in the bladed disk assembly. Moreover, large normal contact stresses, which are typical for this application, necessitate the consideration of microslip effects. This study focuses on the accurate prediction of the forced response of tuned bladed disks subject to friction joints. In order to account for extended friction interfaces, the contact area is discretized into several contact points. Microslip behavior is explicitly enforced by a non-uniform normal pressure distribution. Local elastic properties of the contact area are accurately captured in the reduced order model of the structure by employing a component mode synthesis method. The steady-state forced response is efficiently computed using a Multi-Harmonic Balance ansatz. Thus, it is possible to study and explain the occurrence of internal resonances. Planar Coulomb friction and unilateral normal contact conditions are considered in terms of the Dynamic Lagrangian formulation. The normal preload of the shroud interface is varied in order to study the effect on vibration amplitude and resonance frequency.

scholarly journals On the Efficiency of a Conical Underplatform Damper for Turbines

2021 ◽  
Vol 143 (2) ◽  
Author(s):  
E. Denimal ◽  
C. Wong ◽  
L. Salles ◽  
L. Pesaresi
Keyword(s):  
High Cycle Fatigue ◽  
Turbine Blades ◽  
Nonlinear Dynamic Analysis ◽  
Damping Capacity ◽  
Rolling Motion ◽  
Aircraft Engines ◽  
Contact Interface ◽  
Pure Rolling ◽  
Underplatform Damper ◽  
Phase Motion

Abstract Underplatform dampers (UPDs) are commonly used in aircraft engines to limit the risk of high-cycle fatigue of turbine blades. The latter is located in a groove between two consecutive blades. The dry friction contact interface between the damper and the blades dissipates energy and so reduces the vibration amplitudes. Two common geometries of dampers are used nowadays, namely wedge and cylindrical dampers, but their efficiency is limited when the blades have an in-phase motion (or a motion close to it), since the damper tends to have a pure rolling motion. The objective of this study is to analyze a new damper geometry, based on a conical shape, which prevents from this pure rolling motion of the damper and ensures a high kinematic slip. The objective of this study is to demonstrate the damping efficiency of this geometry. Hence, in a first part, the kinematic slip is approximated with analytical considerations. Then, a nonlinear dynamic analysis is performed, and the damping efficiency of this new geometry is compared to the wedge and the cylindrical geometries. The results demonstrate that the conical damper has a high damping capacity and is more efficient and more robust than the two others.

scholarly journals Review of Icing Effects on Wind Turbine in Cold Regions

2018 ◽  
Vol 72 ◽  
pp. 01007 ◽  
Author(s):  
Faizan Afzal ◽  
Muhammad S. Virk
Keyword(s):  
Wind Turbine ◽  
Structural Integrity ◽  
Turbine Blades ◽  
Leading Edge ◽  
Added Mass ◽  
Cold Climate ◽  
Ice Accretion ◽  
Wind Turbine Blades ◽  
Turbine Performance ◽  
Ice Shedding

This paper describes a brief overview of main issues related to atmospheric ice accretion on wind turbines installed in cold climate region. Icing has significant effects on wind turbine performance particularly from aerodynamic and structural integrity perspective, as ice accumulates mainly on the leading edge of the blades that change its aerodynamic profile shape and effects its structural dynamics due to added mass effects of ice. This research aims to provide an overview and develop further understanding of the effects of atmospheric ice accretion on wind turbine blades. One of the operational challenges of the wind turbine blade operation in icing condition is also to overcome the process of ice shedding, which may happen due to vibrations or bending of the blades. Ice shedding is dangerous phenomenon, hazardous for equipment and personnel in the immediate area.

scholarly journals A Review of Recent Advancements in Offshore Wind Turbine Technology

Energies ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 579
Author(s):  
Taimoor Asim ◽  
Sheikh Zahidul Islam ◽  
Arman Hemmati ◽  
Muhammad Saif Ullah Khalid
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Structural Integrity ◽  
Turbine Blades ◽  
Offshore Wind ◽  
System Level ◽  
Offshore Wind Turbine ◽  
Component Level ◽  
Foundation Design ◽  
Offshore Wind Turbines

Offshore wind turbines are becoming increasingly popular due to their higher wind energy harnessing capabilities and lower visual pollution. Researchers around the globe have been reporting significant scientific advancements in offshore wind turbines technology, addressing key issues, such as aerodynamic characteristics of turbine blades, dynamic response of the turbine, structural integrity of the turbine foundation, design of the mooring cables, ground scouring and cost modelling for commercial viability. These investigations range from component-level design and analysis to system-level response and optimization using a multitude of analytical, empirical and numerical techniques. With such wide-ranging studies available in the public domain, there is a need to carry out an extensive yet critical literature review on the recent advancements in offshore wind turbine technology. Offshore wind turbine blades’ aerodynamics and the structural integrity of offshore wind turbines are of particular importance, which can lead towards system’s optimal design and operation, leading to reduced maintenance costs. Thus, in this study, our focus is to highlight key knowledge gaps in the scientific investigations on offshore wind turbines’ aerodynamic and structural response. It is envisaged that this study will pave the way for future concentrated efforts in better understanding the complex behavior of these machines.

Acoustic Emission for Structural Integrity Assessment of Wind Turbine Blades

2014 ◽  
pp. 369-382 ◽  
Author(s):  
Nikolaos K. Tsopelas ◽  
Dimitrios G. Papasalouros ◽  
Athanasios A. Anastasopoulos ◽  
Dimitrios A. Kourousis ◽  
Jason W. Dong
Keyword(s):  
Acoustic Emission ◽  
Wind Turbine ◽  
Structural Integrity ◽  
Turbine Blades ◽  
Wind Turbine Blades ◽  
Integrity Assessment

scholarly journals A Computational Visualization of Three Dimensional Flow: Finding Optimum Heat Transfer and Pressure Drop Characteristics From Short Cross-Pin Arrays and Comparison With Two Dimensional Calculations

1999 ◽  
Author(s):  
E. E. Donahoo ◽  
C. Camci ◽  
A. K. Kulkarni ◽  
A. D. Belegundu
Keyword(s):  
Heat Transfer ◽  
Turbine Blade ◽  
Structural Integrity ◽  
Turbine Blades ◽  
Circular Cross Section ◽  
Internal Cooling ◽  
Flow And Heat Transfer ◽  
High Heat Transfer ◽  
Spacing Ratio ◽  
Cooling Passage

There are many heat transfer augmentation methods that are employed in turbine blade design, such as impingement cooling, film cooling, serpentine passages, trip strips, vortex chambers, and pin fins. The use of crosspins in the trailing edge section of turbine blades is commonly a viable option due to their ability to promote turbulence as well as supply structural integrity and stiffness to the blade itself. Numerous crosspin shapes and arrangements are possible, but only certain configurations offer high heat transfer capability while maintaining taw total pressure loss. This study preseots results from 3-D numerical simulations of airflow through a turbine blade internal cooling passage. The simulations model viscous flow and heat transfer over full crosspins of circular cross-section with fixed height-to-diameter ratio of 0.5, fixed transverse-to-diameter spacing ratio of 1.5, and varying streamwise spacing. Preliminary analysis indicates that endwall effects dominate the flow and heat transfer at lower Reynolds numbers. The flow dynamics involved with the relative dose proximity of the endwalls for such short crosspins have a definite influeoce on crosspin efficiency for downstream rows.

Optimisation Techniques Applied to the Design of Gas Turbine Blades Cooling Systems

2006 ◽  
Author(s):  
Gianlorenzo Bucchieri ◽  
Massimo Galbiati ◽  
Daniele Coutandin ◽  
Stefano Zecchi
Keyword(s):  
Best Practice ◽  
Optimization Algorithms ◽  
Turbine Blades ◽  
Geometrical Parameters ◽  
Cfd Model ◽  
Cfd Validation ◽  
Mean Values ◽  
Input Parameters ◽  
And Performance ◽  
Practice Methods

This paper addresses the methodology used to design the layout of the tip cooling nozzles of a high pressure rotor blade turbine. The methodology used is through a complete CAE approach, by means of a parametric CFD model which is run several times for the exploration of several designs by an optimizer. Hence the design is carried out automatically by parallel computations, with the optimization algorithms taking the decisions rather than the design engineer. The engineer instead takes decision regarding the physical settings of the CFD model to employ, the number and the extension of the geometrical parameters of the blade tip holes and the optimization algorithms to be employed. From CFD validation the final design of the tip cooling geometry found by the optimizer has proved to be better than the base design, which used mean values of all input parameters, and than the design proposed by an experienced heat transfer AVIO engineer, who used standard best practice methods. Furthermore the large number of experiences gained by the simulations run by the optimizer allowed the designer to find laws, functions and correlation between input parameters and performance output, with a further and deeper insight on this specific design problem.

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