Estimation of Forcing Function for a Geometrically Mistuned Bladed Rotor Via Modified Modal Domain Analysis

2015 ◽  
Vol 138 (4) ◽  
Author(s):  
Vinod Vishwakarma ◽  
Alok Sinha
Keyword(s):  
Estimation Algorithm ◽  
Element Model ◽  
Domain Analysis ◽  
Dynamic Responses ◽  
Function Estimation ◽  
Mass Model ◽  
Reduced Order ◽  
Bladed Disk ◽  
Forcing Function ◽  
Bladed Rotor

Modified modal domain analysis (MMDA) is a method to generate an accurate reduced-order model (ROM) of a bladed disk with geometric mistuning. An algorithm based on the MMDA ROM and a state observer is developed to estimate forcing functions for synchronous (including integer multiples) conditions from the dynamic responses obtained at few nodal locations of blades. The method is tested on a simple spring-mass model, finite element model (FEM) of a geometrically mistuned academic rotor, and FEM of a bladed rotor of an industrial-scale transonic research compressor. The accuracy of the forcing function estimation algorithm is examined by varying the order of ROM and the number of vibration output signals.

Estimation of Forcing Function for a Geometrically Mistuned Bladed Rotor via Modified Modal Domain Analysis

2015 ◽  
Author(s):  
Vinod Vishwakarma ◽  
Alok Sinha
Keyword(s):  
Estimation Algorithm ◽  
Element Model ◽  
Domain Analysis ◽  
Reduced Order Model ◽  
Dynamic Responses ◽  
Order Model ◽  
Mass Model ◽  
Reduced Order ◽  
Forcing Function ◽  
Bladed Rotor

Modified Modal Domain Analysis (MMDA) is a method to generate an accurate reduced order model (ROM) of a bladed disk with geometric mistuning. An algorithm based on MMDA ROM and a state observer is developed to estimate forcing functions for synchronous (including integer multiples) conditions from the dynamic responses obtained at few nodal locations of blades. The method is tested on a simple spring-mass model, finite element model (FEM) of a geometrically mistuned academic rotor and FEM of a bladed rotor of an industrial scale transonic research compressor. The accuracy of the forcing function estimation algorithm is examined by varying the order of reduced-order model and the number of vibration output signals.

Reduced-Order Model of a Bladed Rotor With Geometric Mistuning

2007 ◽  
Author(s):  
Alok Sinha
Keyword(s):  
Proper Orthogonal Decomposition ◽  
Orthogonal Decomposition ◽  
Reduced Order Model ◽  
Order Model ◽  
Reduced Order ◽  
Coordinate Measurement ◽  
Coordinate Measurement Machine ◽  
Bladed Disk ◽  
Bladed Rotor ◽  
Proper Orthogonal

This paper deals with the development of an accurate reduced-order model of a bladed disk with geometric mistuning. The method is based on vibratory modes of various tuned systems and proper orthogonal decomposition of coordinate measurement machine (CMM) data on blade geometries. Results for an academic rotor are presented to establish the validity of the technique.

Accuracies of Reduced Order Models of a Bladed Rotor With Geometric Mistuning

2013 ◽  
Vol 136 (7) ◽  
Author(s):  
Yasharth Bhartiya ◽  
Alok Sinha
Keyword(s):  
Natural Frequencies ◽  
Domain Analysis ◽  
Forced Response ◽  
Reduced Order Model ◽  
Mode Shapes ◽  
Reduced Order Models ◽  
Order Model ◽  
Reduced Order ◽  
Model Based ◽  
Bladed Rotor

The results from a reduced order model based on frequency mistuning are compared with those from recently developed modified modal domain analysis (MMDA). For the academic bladed rotor considered in this paper, the frequency mistuning analysis is unable to capture the effects of geometric mistuning, whereas MMDA provides accurate estimates of natural frequencies, mode shapes, and forced response.

Modified Modal Domain Analysis of a Bladed Rotor Using Coordinate Measurement Machine Data on Geometric Mistuning

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
Vinod Vishwakarma ◽  
Alok Sinha ◽  
Yasharth Bhartiya ◽  
Jeffery M. Brown
Keyword(s):  
Natural Frequencies ◽  
Domain Analysis ◽  
Reduced Order Modeling ◽  
Forced Response ◽  
Mode Shapes ◽  
Reduced Order ◽  
Coordinate Measurement ◽  
Coordinate Measurement Machine ◽  
Bladed Rotor ◽  
Proper Orthogonal

Modified modal domain analysis (MMDA), a reduced order modeling technique, is applied to a geometrically mistuned integrally bladed rotor to obtain its natural frequencies, mode shapes, and forced response. The geometric mistuning of blades is described in terms of proper orthogonal decomposition (POD) of the coordinate measurement machine (CMM) data. Results from MMDA are compared to those from the full (360 deg) rotor Ansys model. It is found that the MMDA can accurately predict natural frequencies, mode shapes, and forced response. The effects of the number of POD features and the number of tuned modes used as bases for model reduction are examined. Results from frequency mistuning approaches, fundamental mistuning model (FMM) and subset of nominal modes (SNM), are also generated and compared to those from full (360 deg) rotor Ansys model. It is clearly seen that FMM and SNM are unable to yield accurate results whereas MMDA yields highly accurate results.

Modeling the Microslip in the Flange Joint and Its Effect on the Dynamics of a Multistage Bladed Disk Assembly

2017 ◽  
Vol 13 (1) ◽  
Author(s):  
Christian M. Firrone ◽  
Giuseppe Battiato ◽  
Bogdan I. Epureanu
Keyword(s):  
Element Model ◽  
Forced Response ◽  
Flange Joint ◽  
Reduced Order ◽  
Bladed Disk ◽  
Simple Geometry ◽  
Bladed Disk Assembly ◽  
Joint Contact ◽  
Turbine Disks ◽  
Complex Architecture

The complex architecture of aircraft engines requires demanding computational efforts when the dynamic coupling of their components has to be predicted. For this reason, numerically efficient reduced-order models (ROM) have been developed with the aim of performing modal analyses and forced response computations on complex multistage assemblies being computationally fast. In this paper, the flange joint connecting two turbine disks of a multistage assembly is studied as a source of nonlinearities due to friction damping occurring at the joint contact interface. An analytic contact model is proposed to calculate the local microslip based on the different deformations that the two flanges in contact take during vibration. The model is first introduced using a simple geometry representing two flanges in contact, and then, it is applied to a reduced finite element model in order to calculate the nonlinear forced response.

scholarly journals Mistuning Analysis of a Detuned Bladed-Disk With Geometrical Nonlinearities

2019 ◽  
Author(s):  
Anthony Picou ◽  
Evangéline Capiez-Lernout ◽  
Christian Soize ◽  
Moustapha Mbaye
Keyword(s):  
Probabilistic Approach ◽  
Element Model ◽  
Deterministic Approach ◽  
Complex Dynamic ◽  
Order Model ◽  
Numerical Application ◽  
Reduced Order ◽  
Bladed Disk ◽  
Geometrical Nonlinearities ◽  
Disk Structure

Abstract This work concerns the nonlinear numerical analysis of mistuned blades for a rotating detuned bladed-disk structure with geometrical nonlinearities. The detuning phenomenon is taken into account through a deterministic approach by modifying material properties of some blades. A nonlinear reduced-order model is obtained by setting up a basis using a double projection method. The mistuning uncertainties are implemented through a nonparametric probabilistic approach for which the level of uncertainties is controlled by a hyperparameter. A numerical application is carried out on a bladed-disk structure made up of 24 blades whose finite element model has about 800,000 dofs exhibiting complex dynamic behaviors.

Dynamic Responses of Arch Dams Considering Different Reservoir Models

2011 ◽  
Vol 250-253 ◽  
pp. 3923-3926
Author(s):  
Shao Qing Hu ◽  
Bai Tao Sun
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Water Level ◽  
Element Model ◽  
Arch Dam ◽  
Dynamic Responses ◽  
Additional Mass ◽  
Mass Model ◽  
Arch Dams ◽  
Reservoir Models

In this paper, the dynamic responses of an arch dam in the case of normal water level and operating low water level were simulated by using additional mass model and incompressible finite element model for reservoir respectively. The results showed that the reservoir models have a great impact on dynamic response of arch dams. The maximum principle tensile stress using incompressible finite element model of fluid is less than that using additional mass model. With the depth of the reservoir water increasing, the hydrodynamic pressure acting ton the dam surface caused by earthquake force increased and the dynamic responses of dam also increased.

Application of a Reduced Order Modeling Technique for Mistuned Bladed Disk-Shaft Assemblies

2007 ◽  
Author(s):  
Bartolome´ Segui´ ◽  
Euro Casanova
Keyword(s):  
Finite Element ◽  
Synthesis Method ◽  
Element Model ◽  
Reduced Order Modeling ◽  
Forced Response ◽  
Modeling Technique ◽  
Disk Model ◽  
Reduced Order ◽  
Bladed Disk ◽  
Global Dynamic

This paper presents a reduced-order modeling technique, based on a component mode synthesis method specifically tailored for bladed disks, that allows the resulting low-order model to be attached to a shaft. Mistuning is included in the bladed disk model and the shaft is modeled using uniaxial finite elements according to the rotordynamic approach. The proposed formulation is applied to an example finite element model of a bladed disk, for both tuned and mistuned blades. Comparisons are made between the reduced model and the full finite element solution for free and forced responses in order to assess the methodology. The forced response amplitudes of the blades are found to vary significantly with the inclusion of a flexible shaft. This work suggest that stage independent analyses might not be adequate for predicting the global dynamic response of rotating assemblies of turbomachines.

Integrally Bladed Rotor Mistuning Identification and Model Updating Using Geometric Mistuning Models

2020 ◽  
Author(s):  
Joseph A. Beck ◽  
Jeffrey M. Brown ◽  
Daniel L. Gillaugh ◽  
Emily B. Carper ◽  
Alex A. Kaszynski
Keyword(s):  
Elastic Modulus ◽  
Model Updating ◽  
Element Model ◽  
Analytical Models ◽  
Optical Scanners ◽  
Reduced Order ◽  
Optical Scanning ◽  
Numerical Predictions ◽  
Simulated Test ◽  
Bladed Rotor

Abstract Non-uniform manufacturing variations and uneven usage wear and damage, referred to as mistuning, can drastically alter the dynamic response of Integrally Blade Rotors (IBR)s. Optical scanners, combined with Finite Element Model (FEM) mesh metamorphosis algorithms, have provided capabilities to create analytical models that reduce the effect of geometrical uncertainties in numerical predictions. However, deviations in material properties cannot be obtained via optical scanning, so additional approaches are needed. A geometric mistuning Reduced-Order Model (ROM) is developed and modified to solve for unknown IBR sector eigenvalues that are linearly proportional to Elastic modulus. The developed approach accounts for both proportional and non-proportional mistuning and allows updating of the Elastic modulus for each sector in the ROM. Different tuned and mistuned modal reduction procedures are employed to understand the implications of each for identifying mistuning. Simulated test data with known inputs indicate the efficiency and accuracy of the method and improvements over using a traditional, tuned mode approach. The developed methods are then extended to bench-level traveling wave excitation data to discern how sector frequencies vary due to geometry and modulus mistuning.

Structural Response Due to Blade Vane Interaction

1984 ◽  
Vol 106 (1) ◽  
pp. 50-56 ◽  
Author(s):  
R. L. Jay ◽  
J. C. MacBain ◽  
D. W. Burns
Keyword(s):  
Dynamic Response ◽  
Structural Response ◽  
Analytical Description ◽  
Rotor Blades ◽  
Dynamic Responses ◽  
Strain Gages ◽  
Bladed Disk ◽  
Forcing Function ◽  
The Difference ◽  
Strong Dynamic

The structural response of a bladed turbine disk due to excitation from an upstream stator row was measured using strain gages. Rig testing performed in a realistic aerodynamic environment was preceded by a static vibratory search in which individual blade frequencies and system modes were identified by strain response and holography. In the rig testing special emphasis was placed on identifying the dynamic response resulting from the interaction between the vanes and blades. An analytical description of the forcing function which results from the difference between the number of blades and the number of vanes is presented and correlated with detailed blade responses both in terms of amplitude and interblade phasing. In particular, the combination of 26 inlet vanes and the 30 rotor blades yielded strong dynamic responses in two modes of the four diametral family. The experimental results augmented by the analytical formulation of excitation created by the difference in vane and blade numbers have conclusively identified a mechanism for large blade dynamic response which should be considered in the design phase of bladed disk systems.

Sign in / Sign up

Export Citation Format

Share Document