Multi-Stage Coupled Forced Response of Aircraft Engine Compressor and Turbine Bladed Discs

2016 ◽  
Author(s):  
Romuald Rzadkowski ◽  
Artur Maurin
Keyword(s):  
Maximum Stress ◽  
Aircraft Engine ◽  
Forced Response ◽  
Rotor Blades ◽  
Mode Shapes ◽  
Finite Element Models ◽  
Free And Forced Vibrations ◽  
Multi Stage ◽  
Engine Compressor ◽  
Engine Rotor

Considered here is the effect of multistage coupling on the dynamics of an aircraft engine rotor with eight mistuned bladed discs on a drum-disc shaft during foreign object ingestion (FOI). In the dynamic model, each disc had a different number of rotor blades. Free and forced vibrations were examined using finite element models of single rotating blades, bladed discs and an entire rotor with bladed discs. Calculations of the mode shapes of flexible mistuned bladed disc-shaft assemblies took into account simultaneous excitations of the first and second stages of the compressor and the turbine bladed disc with 0EO, 1EO and 2EO. The thus obtained maximal stress values of all of the rotor blades were carefully examined and compared with a tuned system to discover resonance conditions and coupling effects. Our investigation has shown that mistuning changes the stress distribution in individual rotor blades and the level of maximum stress increases in relation to single or multiple bladed disc excitation.

Multistage Coupling of Mistuned Aircraft Engine Bladed Discs in a Forced Vibration Analysis

2014 ◽  
Author(s):  
Romuald Rzadkowski ◽  
Artur Maurin
Keyword(s):  
Maximum Stress ◽  
Aircraft Engine ◽  
Forced Vibrations ◽  
Rotor Blades ◽  
Mode Shapes ◽  
Finite Element Models ◽  
Free And Forced Vibrations ◽  
Maximal Stress ◽  
Forced Vibration Analysis ◽  
Engine Rotor

Considered here is the effect of multistage coupling on the dynamics of an aircraft engine rotor with eight mistuned bladed discs on a drum-disc shaft. Each disc had a different number of rotor blades. Free and forced vibrations were examined using finite element models of single rotating blades, bladed discs, and an entire rotor. Calculations of the global rotating mode shapes of flexible mistuned bladed discs-shaft assemblies took into account the excitation of the turbine bladed disc with 0EO, 1EO and 2EO forces. The thus obtained maximal stress values of all of the rotor blades were carefully examined and compared with a tuned system to discover resonance conditions and coupling effects. Mistuning changes the stress distribution in individual rotor blades and the level of maximum stress increases or decreases as compared to bladed discs which are analyzed without the shaft.

Geometrical Variability Modelling of Axial Compressor Blisk Aerofoils and Evaluation of Impact on the Forced Response Problem

2020 ◽  
Author(s):  
Marco Gambitta ◽  
Arnold Kühhorn ◽  
Sven Schrape
Keyword(s):  
Computational Models ◽  
Axial Compressor ◽  
Principal Component ◽  
Forced Response ◽  
Rotor Blades ◽  
Civil Aviation ◽  
Mode Shapes ◽  
Stochastic Representation ◽  
Compressor Blades ◽  
Multiple Variable

Abstract The present work focuses on the effect of the manufacturing geometrical variability on the high-pressure compressor of a turbofan engine for civil aviation. The deviations of the geometry over the axial compressor blades are studied and modeled for the representation in the computational models. Such variability is of particular interest for the forced response problem, where small deviations of the geometry from the ideal nominal model can cause significant differences in the vibrational responses. The information regarding the geometrical mistuning is extracted from a set of manufactured components surface scans of a blade integrated disk (blisk) rotor. The optically measured geometries are parameterized, defining a set of opportune variables to describe the deviations. The dimension of the variables domain is reduced using the principal component analysis approach and a reconstruction of the modeled geometries is performed for the implementation in CFD and FEM solvers. The generated model allows a stochastic representation of the variability, providing an optimal set of variables to represent it. The aeroelastic analyses considering geometry based mistuning is carried out on a test-rig case, focusing on how such variability can affect the modal forcing generated on the blades. The force generated by the unsteady pressure field over the selected vibrational mode shapes of the rotor blades is computed through a validated CFD model. The uncertainty quantification of the geometrical variability effect on the modal forcing is performed employing Monte Carlo methods on a reduced model for the CFD solution, based on a single passage multi-blade row setup. The amplitude shift of the unsteady modal forcing is studied for different engine orders. In particular the scatter of the main engine orders forcing amplitudes for the manufactured blades can be compared with the nominal responses to predict the possible amplification due to the geometrical variability. Finally the results are compared to a full assembly computational model to assess the influence of multiple variable blades.

scholarly journals Forced Response Analysis of an Aerodynamically Detuned Supersonic Turbomachine Rotor

1986 ◽  
Vol 108 (2) ◽  
pp. 117-124 ◽  
Author(s):  
D. Hoyniak ◽  
S. Fleeter
Keyword(s):  
High Performance ◽  
Maximum Amplitude ◽  
Aircraft Engine ◽  
Forced Response ◽  
Rotor Blades ◽  
Response Analysis ◽  
Axial Component ◽  
Compressor Blades ◽  
Response Characteristics ◽  
Influence Coefficients

High-performance aircraft engine fan and compressor blades are vulnerable to aerodynamically forced vibrations generated by inlet flow distortions due to wakes from upstream blade and vane rows, atmospheric gusts, and maldistributions in inlet ducts. In this paper, an analysis is developed to predict the flow-induced forced response behavior of an aerodynamically detuned rotor operating in a supersonic flow with a subsonic axial component. The aerodynamic detuning is achieved by alternating the circumferential spacing of adjacent rotor blades. The total unsteady aerodynamic loading acting on the blading, due to the convection of the transverse gust past the airfoil cascade and the resulting motion of the cascade, is developed in terms of influence coefficients. This analysis is then utilized to investigate the effect of aerodynamic detuning on the forced response characteristics of a 12-bladed rotor, with Verdon’s Cascade B flow geometry as a uniformly spaced baseline configuration. The results of this study indicate that for forward traveling wave gust excitations, aerodynamic detuning is generally very beneficial, resulting in significantly decreased maximum amplitude blade responses for many interblade phase angles.

Multi-Stage Modeling of Turbine Engine Rotor Vibration

2005 ◽  
Author(s):  
Sang Heon Song ◽  
Matthew P. Castanier ◽  
Christophe Pierre
Keyword(s):  
Finite Element ◽  
Element Model ◽  
Forced Response ◽  
Interface Motion ◽  
Turbine Engine ◽  
Reduced Order ◽  
Common Basis ◽  
Multi Stage ◽  
Small Set ◽  
Engine Rotor

In this study, an efficient approach for modeling the vibration of multi-stage rotors is proposed in order to allow more realistic predictions of the free and forced response of bladed disks. The reduced-order modeling approach is based on component mode synthesis, with each stage (bladed disk) treated as a separate component. Thus, each component retains cyclic symmetry, and single-sector models may be used for calculating the component modes. Because adjacent stages typically have different numbers of blades, the single-stage models are synthesized by projecting the stage-to-stage interface motion onto a common basis of circumferentially harmonic shapes. In this manner, any mismatch between sector sizes and finite element meshes at the interface can be handled systematically and automatically, without requiring additional multi-point constraints. For further size reduction, secondary modal analysis is performed on the entire synthesized model. Therefore, only a small set of multi-stage modes are retained in the final reduced-order model, yielding an extremely compact model that retains high accuracy relative to the parent finite element model.

Closed-Form Exact Solutions for Viscously Damped Free and Forced Vibrations of Longitudinal and Torsional Bars

2017 ◽  
Vol 17 (08) ◽  
pp. 1750093 ◽  
Author(s):  
Jae-Hoon Kang
Keyword(s):  
Free Vibration ◽  
Closed Form ◽  
Closed Form Solution ◽  
Forced Vibrations ◽  
Form Solution ◽  
Forced Response ◽  
Mode Shapes ◽  
Viscous Damping ◽  
Vibration Displacement ◽  
Free And Forced Vibrations

This paper studies the viscously damped free and forced vibrations of longitudinal and torsional bars. The method is exact and yields closed form solution for the vibration displacement in contrast with the well-known eigenfunction superposition (ES) method, which requires expression of the distributed forcing functions and displacement response functions as infinite series sums of free vibration eigenfunctions. The viscously damped natural frequency equation and the critical viscous damping equation are exactly derived for the bars. Then the viscously damped free vibration frequencies and corresponding damped mode shapes are calculated and plotted, aside from the undamped free vibration and corresponding mode shapes typically computed and used in vibration problems. The longitudinal or torsional amplitude versus forcing frequency curves showing the forced response to distributed loadings are plotted for various viscous damping parameters. It is found that the viscous damping affects the natural frequencies and the corresponding mode shapes of longitudinal and torsional bars, especially for the fundamental frequency.

Analysis and Optimization of the Static and Dynamic Characteristics of Head Frame

2011 ◽  
Vol 418-420 ◽  
pp. 2055-2059 ◽  
Author(s):  
Yu Lin Wang ◽  
Na Jin ◽  
Kai Liao ◽  
Rui Jin Guo ◽  
Hu Tian Feng
Keyword(s):  
Machine Tool ◽  
Dynamic Characteristics ◽  
Maximum Stress ◽  
Dynamic Performance ◽  
Mode Shapes ◽  
Cnc Machine ◽  
Static And Dynamic Characteristics ◽  
Maximum Deformation ◽  
Improvement Measures ◽  
Optimal Measure

The head frame is a key component which plays a supportive and accommodative role in the spindle system of CNC machine tool. Improving the static and dynamic characteristics has profound significance to the development of machine tool and product performance. The simplified finite element modal is established with ANSYS to carry out the static and modal analysis. The results showed that the maximum deformation of the head frame was 0.0066mm, the maximum stress was 3.94Mpa, the deformation of most region was no more than 0.0007mm, which all verified that the head frame had a good stiffness and deforming resistance; several improvement measures for dynamic performance were also proposed by analyzing the mode shapes, and the 1st order natural frequency increased 7.33% while the head frame mass only increased 1.58% applying the optimal measure, which improved the dynamic characteristics of the head frame effectively.

A Method for Use of Cyclic Symmetry Properties in Analysis of Nonlinear Multiharmonic Vibrations of Bladed Disks

2004 ◽  
Vol 126 (1) ◽  
pp. 175-183 ◽  
Author(s):  
E. P. Petrov
Keyword(s):  
High Efficiency ◽  
Equations Of Motion ◽  
Linear Part ◽  
Forced Response ◽  
Mode Shapes ◽  
Solution Technique ◽  
Disk Model ◽  
Sector Model ◽  
Bladed Disk ◽  
Symmetry Properties

An effective method for analysis of periodic forced response of nonlinear cyclically symmetric structures has been developed. The method allows multiharmonic forced response to be calculated for a whole bladed disk using a periodic sector model without any loss of accuracy in calculations and modeling. A rigorous proof of the validity of the reduction of the whole nonlinear structure to a sector is provided. Types of bladed disk forcing for which the method may be applied are formulated. A multiharmonic formulation and a solution technique for equations of motion have been derived for two cases of description for a linear part of the bladed disk model: (i) using sector finite element matrices and (ii) using sector mode shapes and frequencies. Calculations validating the developed method and a numerical investigation of a realistic high-pressure turbine bladed disk with shrouds have demonstrated the high efficiency of the method.

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