scholarly journals Dynamics of Multistage Bladed Disks Systems

2007 ◽  
Vol 129 (4) ◽  
pp. 1058-1064 ◽  
Author(s):  
Denis Laxalde ◽  
Jean-Pierre Lombard ◽  
Fabrice Thouverez
Keyword(s):  
Degrees Of Freedom ◽  
Original Method ◽  
Order Type ◽  
Forced Response ◽  
Dynamical Analysis ◽  
Nodal Diameter ◽  
Engine Order ◽  
Set Up ◽  
Synchronous Engine

This paper presents a new and original method for dynamical analysis of multistage cyclic structures such as turbomachinery compressors or turbines. Each stage is modeled cyclically by its elementary sector and the interstage coupling is achieved through a cyclic recombination of the interface degrees of freedom. This method is quite simple to set up; it allows us to handle the finite element models of each stage’s sector directly and, as in classical cyclic symmetry analysis, to study the nodal diameter problems separately. The method is first validated on a simple case study which shows good agreements with a complete 360 deg reference calculation. An industrial example involving two HP compressor stages is then presented. Then the forced response application is presented in which synchronous engine order type excitations are considered.

scholarly journals Dynamics of Multi-Stage Bladed Disks Systems

2007 ◽  
Author(s):  
Denis Laxalde ◽  
Jean-Pierre Lombard ◽  
Fabrice Thouverez
Keyword(s):  
Degrees Of Freedom ◽  
Original Method ◽  
Order Type ◽  
Forced Response ◽  
Dynamical Analysis ◽  
Nodal Diameter ◽  
Multi Stage ◽  
Engine Order ◽  
Set Up

This paper presents a new and original method for dynamical analysis of multi-stage cyclic structures such as turbomachinery compressors or turbines. Each stage is modeled cyclically by its elementary sector and the inter-stage coupling is achieved through a cyclic recombination of the interface degrees of freedom. This method is quite simple to set-up; it allows to handle the finite element models of each stage’s sector directly and, as in classical cyclic symmetry analysis, to study the nodal diameter problems separately. The method is first validated on a simple case study which shows good agreements with a complete 360° reference calculation. An industrial example involving two HP compressor stages is then presented. Then the forced response application is presented in which synchronous of engine order type excitations are considered.

Dynamics of Bladed Disks With Frictional Coupling and Alternate Mistuning Pattern

2014 ◽  
Author(s):  
Sebastian Tatzko ◽  
Lars Panning von-Scheidt ◽  
Joerg Wallaschek
Keyword(s):  
Traveling Waves ◽  
Low Cost ◽  
Forced Response ◽  
Main Task ◽  
Lumped Mass ◽  
Bladed Disks ◽  
Nodal Diameter ◽  
Engine Order ◽  
Pure Coulomb ◽  
Machinery Design

In the field of turbo machinery design frictional coupling has been found to be a low cost method to increase the mechanical damping of bladed disks. Underplatform dampers (UPD’s) are commonly used which are metal devices pressed against the blades by centrifugal forces. The main task is to find the optimum value of the contact normal force to maximize energy dissipation. This optimum strongly depends on the excitation of the structure. Traveling waves are excited by engine order excitation and flutter. Flutter caused by fluid structure interaction can be reduced by intentional mistuning of the bladed disk whereas forced response levels will be typically increased by mistuning. A compromise is alternate mistuning. The present paper deals with the influence of alternate mistuning on frictional coupling of blisks. Firstly, the dynamics of a tuned blisk are explained with a simplified lumped mass cyclic oscillator model. It is pointed out that eigenfrequencies of traveling waves around the blisk are influenced by structural coupling. Alternate mistuning leads to mode coupling with the possibility of energy transfer. The performance of friction coupling strongly depends on the nodal diameter mode shape of vibration which is stated analytically for pure Coulomb sliding contact. Following this, a simplified blisk model with underplatform dampers is developed to analyze alternate mistuning and frictional coupling. The simulation results show a significant influence of the mistuning on the damping performance.

On Force Control of an Engine Order–Type Excitation Applied to a Bladed Disk With Underplatform Dampers

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
Christian M. Firrone ◽  
Teresa M. Berruti ◽  
Muzio M. Gola
Keyword(s):  
Force Control ◽  
Order Type ◽  
Forced Response ◽  
Good Precision ◽  
Force Amplitude ◽  
Excitation System ◽  
Bladed Disks ◽  
Nonlinear Dynamic Response ◽  
Bladed Disk ◽  
Engine Order

The paper presents an original multiple excitation system based on electromagnets with force control. The system is specifically designed in order to investigate the dynamics of bladed disks, since it mimics the excitation existing in a real engine. Moreover, the system is suitable for forced response tests of bladed disks with nonlinear dynamic response, like in the case of presence of friction contacts, since the amplitude of the exciting force is known with good precision. For this purpose, a device called force-measuring electromagnet (FMEM) was designed and employed during the system calibration. The excitation system is applied to the test rig Octopus, which includes underplatform dampers (UPDs). Tests were carried out under different excitation force amplitude values. The tests put in evidence the presence of mistuning and the UPDs' capability of attenuating the mistuning phenomena.

Investigation of Alternate Mistuned Turbine Blades Non-Linear Coupled by Underplatform Dampers

2013 ◽  
Author(s):  
S. Tatzko ◽  
L. Panning-von Scheidt ◽  
J. Wallaschek ◽  
A. Kayser ◽  
G. Walz
Keyword(s):  
Turbine Blades ◽  
Forced Response ◽  
Mode Shapes ◽  
Nodal Diameter ◽  
Frictional Contacts ◽  
Bladed Disk ◽  
Engine Order ◽  
Bladed Disk Assembly ◽  
Last Stage ◽  
Software Code

Freestanding turbine blades have typically low structural damping and thus require additional friction damping devices, such as underplatform dampers. The friction coupling between neighboring blades reduces response amplitude and increases resonance frequency. Along with forced response excitation large blades, especially of last stage, could be excited by fluid structural interaction (flutter). To prevent such excitation alternate mistuned blade patterns are beneficial disturbing traveling waves in the stage. In this paper the influence of alternate mistuning is investigated with a simplified oscillator chain as well as a bladed disk assembly coupled by frictional contacts. It is pointed out that the performance of friction coupling can be improved by alternate mistuning as long as the engine order of the excitation is below quarter of the number of blades. Alternate mistuning causes a mode coupling between two nodal diameter vibration mode shapes allowing for energy transfer. The in-house developed software code DATAR is enhanced and alternate mistuning can be applied to the blades as well as to the damping elements. For validation the DATAR code was applied to an alternate mistuned last stage blade of a Siemens gas turbine and compared with available field engine measurement.

Effects of Harmonic Intentional Mistuning on the Free Response of Bladed Disks

1999 ◽  
Author(s):  
Michael E. Brewer ◽  
Matthew P. Castanier ◽  
Christophe Pierre
Keyword(s):  
Forced Response ◽  
Lumped Parameter Model ◽  
Free Response ◽  
Bladed Disks ◽  
Nodal Diameter ◽  
Bladed Disk ◽  
Lumped Parameter ◽  
Engine Order ◽  
Bladed Disk Assembly ◽  
Random Mistuning

Abstract In this paper, the free response of bladed disks with intentional mistuning is considered in detail. A simple lumped-parameter model of a bladed disk is employed. Intentional mistuning is included by applying a sinusoidal variation to the nominal blade stiffnesses. It is shown that if the intentional mistuning harmonic number and the number of blades have a common integer factor greater than one, then the eigenvalue problem reduces to a set of smaller problems. It is found that the ratio of intentional mistuning strength to the interblade coupling strength is a key parameter for the free response. As this ratio increases, the modes become localized. More importantly, the modes of the intentionally mistuned system have several non-zero nodal diameter components, in contrast to the tuned system which has pure nodal diameter modes. Furthermore, if only random mistuning is present, each mode of the bladed disk assembly still retains a strong nodal diameter component. However, the modes of the system with intentional mistuning and random mistuning tend to have more evenly distributed nodal diameter components. This shows why intentional mistuning can be effective in reducing the maximum blade forced response for engine order excitation.

Developing capital accounting practices in the integrated reporting system of agricultural organizations

2020 ◽  
Vol 23 (8) ◽  
pp. 906-921
Author(s):  
R.A. Alborov ◽  
S.M. Kontsevaya ◽  
S.V. Kozmenkova
Keyword(s):  
Original Method ◽  
Theory And Practice ◽  
Integrated Reporting ◽  
Governance System ◽  
Analysis And Synthesis ◽  
Agricultural Organizations ◽  
Set Up ◽  
Definition Of ◽  
Methodological Aspects ◽  
Agricultural Organization

Subject. This article deals with the theory-and practice-relevant issues of classification and content definition of different types of capital used as sources of operations financing, and recommendations for developing their accounting in agricultural organizations. Objectives. The article aims to substantiate the organizational and methodological aspects of capital accounting development to generate information on value reserve and creation of value as new in the organization's integrated reporting. The article also aims to define the classification and content of capital types as sources of financing for the organization's activities and develop recommendations for developing the accounting of the availability, increase, reduction or transformation of the relevant types of capital in the organization's business activities. Methods. For the study, we used the methods of analysis and synthesis, induction and deduction, analogy, and comparison. The scientific works of domestic specialists and regulations, including the International Standard on Integrated Reporting (IR) are the methodological basis of this work. Results. The article defines conceptual provisions and offers practical recommendations on the set-up and development of capital flow accounting in the corporate governance system of the agricultural organization. It clarifies the classification and economic content of capital as a source of funding for the organization's reproduction activities. The article also offers an original method of accounting for the value reserve (balances) and capital changes. Conclusions and Relevance. The practical application of the developed recommendations for value accounting and capital changes will help generate all the necessary information in the integrated reporting of the agricultural organization to assess its reserves of value, create value as new, economic, environmental, and social efficiency of the organization's activities. The results of the study can be used to develop the theory, methodology and techniques of accounting of capital types as sources of financing of value creation as a result of the agricultural organization's business activities.

scholarly journals Hybrid Seven-bar Press Mechanism

2018 ◽  
Vol 12 (3) ◽  
pp. 181-187
Author(s):  
M. Erkan Kütük ◽  
L. Canan Dülger
Keyword(s):  
Genetic Algorithm ◽  
Objective Function ◽  
Design Optimization ◽  
Hybrid System ◽  
Degrees Of Freedom ◽  
Dimensional Synthesis ◽  
Design Variables ◽  
Optimization Study ◽  
Metal Stamping

An optimization study with kinetostatic analysis is performed on hybrid seven-bar press mechanism. This study is based on previous studies performed on planar hybrid seven-bar linkage. Dimensional synthesis is performed, and optimum link lengths for the mechanism are found. Optimization study is performed by using genetic algorithm (GA). Genetic Algorithm Toolbox is used with Optimization Toolbox in MATLAB®. The design variables and the constraints are used during design optimization. The objective function is determined and eight precision points are used. A seven-bar linkage system with two degrees of freedom is chosen as an example. Metal stamping operation with a dwell is taken as the case study. Having completed optimization, the kinetostatic analysis is performed. All forces on the links and the crank torques are calculated on the hybrid system with the optimized link lengths

scholarly journals Towards Zero Emissions Noosa

2019 ◽  
Vol 11 (17) ◽  
pp. 4679
Author(s):  
Carina Anderson ◽  
Robert Passey ◽  
Jeremy De Valck ◽  
Rakibuzzaman Shah
Keyword(s):  
Community Engagement ◽  
Focal Point ◽  
Contextual Information ◽  
Renewable Electricity ◽  
Community Group ◽  
Course Of Action ◽  
Engagement Process ◽  
Set Up ◽  
External Consultant

This paper reports on a case study of the community group Zero Emissions Noosa, whose goal is for 100% renewable electricity in the Noosa Shire (Queensland, Australia) by 2026. Described within this paper are the processes used by Zero Emissions Noosa to set up their zero emissions plan, involving community engagement and the use of an external consultant. The external consultant was employed to produce a detailed report outlining how to successfully achieve zero emissions from electricity in the Noosa Shire by 2026. This paper explains how and why the community engagement process used to produce the report was just as important as the outcomes of the report itself. Modeling was undertaken, and both detailed and contextual information was provided. Inclusion of the community in developing the scenario parameters for the modeling had a number of benefits including establishing the context within which their actions would occur and focusing their efforts on options that were technically feasible, financially viable and within their capabilities to implement. This provided a focal point for the community in calling meetings and contacting stakeholders. Rather than prescribing a particular course of action, it also resulted in a toolbox of options, a range of possible solutions that is flexible enough to fit into whatever actions are preferred by the community. The approach and outcomes discussed in this paper should, therefore, be useful to other communities with similar carbon emission reduction goals.

scholarly journals Galloping Stability and Wind Tunnel Test of Iced Quad Bundled Conductors considering Wake Effect

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Xiaohui Liu ◽  
Ming Zou ◽  
Chuan Wu ◽  
Mengqi Cai ◽  
Guangyun Min ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
Transmission Lines ◽  
Degrees Of Freedom ◽  
Wind Tunnel Test ◽  
Aerodynamic Coefficients ◽  
Wake Effect ◽  
Aerodynamic Coefficient ◽  
Set Up ◽  
The Stability ◽  
Three Degrees Of Freedom

A new quad bundle conductor galloping model considering wake effect is proposed to solve the problem of different aerodynamic coefficients of each subconductor of iced quad bundle conductor. Based on the quasistatic theory, a new 3-DOF (three degrees of freedom) galloping model of iced quad bundle conductors is established, which can accurately reflect the energy transfer and galloping of quad bundle conductor in three directions. After a series of formula derivations, the conductor stability judgment formula is obtained. In the wind tunnel test, according to the actual engineering situation, different variables are set up to accurately simulate the galloping of iced quad bundle conductor under the wind, and the aerodynamic coefficient is obtained. Finally, according to the stability judgment formula of this paper, calculate the critical wind speed of conductor galloping through programming. The dates of wind tunnel test and calculation in this paper can be used in the antigalloping design of transmission lines.

scholarly journals Nonlinear Behavior of a Magnetic Bearing System

1995 ◽  
Vol 117 (3) ◽  
pp. 582-588 ◽  
Author(s):  
L. N. Virgin ◽  
T. F. Walsh ◽  
J. D. Knight
Keyword(s):  
Degrees Of Freedom ◽  
Initial Conditions ◽  
Nonlinear Behavior ◽  
Analytical Techniques ◽  
Magnetic Bearing ◽  
Forced Response ◽  
The Mathematical Model ◽  
Two Degree Of Freedom ◽  
Sensitivity To Initial Conditions ◽  
Bearing System

This paper describes the results of a study into the dynamic behavior of a magnetic bearing system. The research focuses attention on the influence of nonlinearities on the forced response of a two-degree-of-freedom rotating mass suspended by magnetic bearings and subject to rotating unbalance and feedback control. Geometric coupling between the degrees of freedom leads to a pair of nonlinear ordinary differential equations, which are then solved using both numerical simulation and approximate analytical techniques. The system exhibits a variety of interesting and somewhat unexpected phenomena including various amplitude driven bifurcational events, sensitivity to initial conditions, and the complete loss of stability associated with the escape from the potential well in which the system can be thought to be oscillating. An approximate criterion to avoid this last possibility is developed based on concepts of limiting the response of the system. The present paper may be considered as an extension to an earlier study by the same authors, which described the practical context of the work, free vibration, control aspects, and derivation of the mathematical model.

Sign in / Sign up

Export Citation Format

Share Document