An Energy Method for Assessing the Damping of Turbine Blade Underplatform Damper and Forced Response Verification

2021 ◽  
Author(s):  
Shimin Gao ◽  
Yanrong Wang ◽  
Zhiwei Sun
Keyword(s):  
Turbine Blade ◽  
Energy Method ◽  
Forced Response ◽  
Underplatform Damper

Innovative Design, Structural Optimization and Additive Manufacturing of New-Generation Turbine Blades

2020 ◽  
Author(s):  
Andrea Amedei ◽  
Enrico Meli ◽  
Andrea Rindi ◽  
Benedetta Romani ◽  
Lorenzo Pinelli ◽  
...  
Keyword(s):  
Topology Optimization ◽  
Additive Manufacturing ◽  
Structural Optimization ◽  
Turbine Blade ◽  
Turbine Blades ◽  
Forced Response ◽  
Mode Shapes ◽  
Structural Topology Optimization ◽  
Structural Topology ◽  
New Generation

Abstract The need for high performances is pushing the complexity of mechanical design at very high levels, especially for turbomachinery components. In this field, structural topology optimization methods together with additive manufacturing techniques for high resistant alloys are considered very promising tools, but their potentialities have not been deeply investigated yet for critical rotating components like new-generation turbine blades. In this framework, this research work proposes a methodology for the design, the optimization and the additive manufacturing of extremely stressed turbomachinery components like turbine blade-rows. The presented procedure pays particular attention to important aspects of the problems as fluid-structure interactions (forced response and flutter phenomena) and fatigue of materials, going beyond the standard structural optimization approaches found in the literature. The new design strategy enables a substantial reduction of the component mass, limiting the maximum stress and improving the vibrational behaviour of the system in terms of eigenfrequencies, modal shapes and fatigue life. Furthermore, the numerical procedure shows robustness and efficiency, making the proposed methodology a good tool for rapid design and prototyping, and for reducing the design costs and the time-to-market typical of this kind of mechanical elements. The procedure has been applied to a low-pressure turbine rotor to improve the aeromechanical behavior while keeping the aerodynamic performance. From the original geometry, mode-shapes, forcing functions (due to rotor/stator interactions) and aerodynamic damping have been numerically evaluated and are used as input data for the following topological optimization. Finally, the optimized geometry has been verified in order to confirm the improved aeromechanical design. After the structural topology optimization, the final geometries provided by the procedure have been then properly rendered to make them suitable for additive manufacturing. Some prototypes of the new optimized turbine blade have been manufactured from aluminum to be tested mechanically and in terms of fatigue.

Modelling a Friction Damper: Analysis of the Experimental Data and Comparison With Numerical Results

2006 ◽  
Author(s):  
Christian M. Firrone ◽  
Daniele Botto ◽  
Muzio M. Gola
Keyword(s):  
Experimental Data ◽  
Dry Friction ◽  
Negative Impact ◽  
Real Life ◽  
Forced Response ◽  
Nonlinear Frequency ◽  
Friction Damper ◽  
Typical Application ◽  
Static Test ◽  
Underplatform Damper

High cycle fatigue is one of the main causes of failure of blades in turbomachinery. The negative impact of HCF on turbomachinery blades can be reduced by dry friction vibration damping. A typical application of dry friction damping in gas turbine is the so called “underplatform damper”. In this work a ‘real life’ asymmetric underplatform damper is experimentally tested with two real blades. A static test rig is used to obtain the nonlinear frequency response function of a mock-up made with two real blades with an underplatform damper between them. This paper addresses an underplatform damper model taking into account damper rotation. The proper mathematical formulations have been developed and forced response calculation of the system have been performed. Comparison with experimental data are carried out for different values of excitation forces and for pre-load similar to real centrifugal force values.

Fatigue Damage Prevention on Turbine Blades: Study of Underplatform Damper Shape

2007 ◽  
Vol 347 ◽  
pp. 159-164 ◽  
Author(s):  
Teresa Berruti ◽  
Christian M. Firrone ◽  
M. Pizzolante ◽  
Muzio M. Gola
Keyword(s):  
Turbine Blades ◽  
Forced Vibrations ◽  
Forced Response ◽  
Numerical Code ◽  
Vibration Energy ◽  
Test Rig ◽  
Blade Vibration ◽  
Static Test ◽  
Underplatform Damper ◽  
Contact Parameters

Forced vibrations can lead to an irreparable damage of a blade array. Devices called “underplatform damper” that dissipate the vibration energy are employed in order to reduce blade vibration amplitude. The present paper deals with the design of the underplatform damper. A numerical code to calculate the forced response of a blade array with dampers has been previously purposely developed. A method is here proposed for the estimation of the unknown contact parameters demanded by the code. The computation results are here validated by means of comparison with experimental results on a static test rig. Three dampers with different shape are tested.

scholarly journals The Effect of Blade Discretization on Resonant Turbine Blade Response

1983 ◽  
Author(s):  
Chia-Fu Sheng ◽  
John G. Mosimann
Keyword(s):  
Turbine Blade ◽  
Timoshenko Beam ◽  
Energy Method ◽  
Lumped Mass ◽  
Ideal Case ◽  
Higher Modes ◽  
The Ideal

The two methods currently used in industry to calculate blade resonant responses, the energy method and the transmissibility method, are discussed relative to accuracy and facility. Although identical in form for the ideal case, the methods differ in accuracy for practical cases depending on discretization, i.e., model lumped mass breakup fineness. For clarity, the equations for these two methods are derived for a Timoshenko beam and solved numerically for a beam with varying discretization. The results show resonant stress differences up to 30% for higher modes using limited but equal discretization, proving the practical superiority of the energy method over the transmissibility method by example as well as by theory.

Application of the Modal Approach for Prediction of Forced Response Amplitudes for Fan Blades

2018 ◽  
Author(s):  
Franziska Eichner ◽  
Joachim Belz
Keyword(s):  
Energy Method ◽  
Natural Frequencies ◽  
Resonant Mode ◽  
Forced Response ◽  
Vibrational Amplitude ◽  
Campbell Diagram ◽  
Modal Approach ◽  
Blade Row ◽  
The Impact ◽  
Blade Row Interaction

Forced response is the main reason for high cycle fatigue in turbomachinery. Not all resonance points in the operating range can be avoided especially for low order excitation. For highly flexible CFRP fans an accurate calculation of vibration amplitudes is required. Forced response analyses were performed for blade row interaction and boundary layer ingestion. The resonance points considered were identified in the Campbell diagram. Forced response amplitudes were calculated using a modal approach and results are compared to the widely used energy method. For the unsteady simulations a time-linearised URANS method was applied. If only the resonant mode was considered the forced response amplitude from the modal approach was confirmed with the energy method. Thereby forced response due to BLI showed higher vibration amplitudes than for blade row interaction. The impact of modes which are not in resonant to the total deformation were investigated by using the modal approach, which so far, only considers one excitation order. A doubling of vibrational amplitude was shown in the case of blade row interaction for higher rotational speeds. The first and third mode-shape as well as modes with similar natural frequencies were identified as critical cases. The behaviour in the vicinity of resonance shows high vibration amplitudes over a larger frequency range. This is also valid for high modes with many nodal diameters, which have a greater risk of critical strain.

Practical Use of Unsteady CFD and FEM Forced Response Calculation in the Design of Axial Turbocharger Turbines

2005 ◽  
Author(s):  
D. Filsinger ◽  
Ch. Frank ◽  
O. Scha¨fer
Keyword(s):  
Turbine Blade ◽  
Complete Information ◽  
Forced Response ◽  
Mode Shapes ◽  
Simple Type ◽  
Reference Case ◽  
Pulse Charging ◽  
Bending Mode ◽  
Blade Vibrations ◽  
Computational Fluid Dynamics Cfd

One of the challenges in the design of rotating machinery is the issue of vibrations. The structure, no matter if talking about compressors or turbines, is subject to various sources of excitation that lead to vibrations under resonance conditions. This paper deals with the question of turbine blade vibrations. It describes practical examples of the implementation of unsteady computational fluid dynamics (CFD) and forced response calculation by means of finite element methods (FEM) applied to the design and development procedure of axial turbocharger turbines. The four examples deal with various questions which rise at different stages in the development process of turbines. One example concerns to the expected excitation of the rotor due to the stator. It demonstrates the advantages of using CFD in the prediction of this kind of excitation. Another one deals with an engine application, for which the influence of the inlet housing on the blade excitation had to be assessed. Both examples rely on the comparison of calculated excitation to the corresponding experimental strain gauge measurement for a reference case. This reference case can be used for calibration. A further case study concerns to blade vibrations in pulse charging systems. It was the intention not only to determine a spatial resolution of the excitation, but also to calculate true stresses by means of forced response calculations with FEM. In this example first bending mode shapes of the turbine blade of a rather simple type were investigated. Higher, more complex mode shapes were also investigated to prove the method. In this example, dynamic stresses were also estimated, using calculated excitation as input for forced response calculations. The results show that the use of modern numerical methods reduces cost and required time in the design of axial turbocharger turbines. They help to substantially reduce the experimental effort, while even more complete information concerning excitation and response of the structure is made available for the designer.

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.

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