Representation and Analysis of Geometric Uncertainties in Rotor Blades

2018 ◽  
Author(s):  
Luigi Carassale ◽  
Silvia Bruzzone ◽  
Andrea Cavicchi ◽  
Michela Marrè Brunenghi
Keyword(s):  
Natural Frequencies ◽  
Principal Component ◽  
Forced Response ◽  
Rotor Blades ◽  
Negative Effects ◽  
Sensitivity Matrix ◽  
Compressor Blades ◽  
Simplified Approach ◽  
Geometric Uncertainties

Geometric uncertainties involved in the rotor blade manufacturing process are a major concern for designers. The deviation of the produced components from their nominal geometry have an impact on the Natural Frequencies (NF) that, under certain circumstances, may have negative effects on the dynamic forced response in operative conditions. Geometric defects are usually limited by imposing dimensional tolerances based on empirical considerations, simplified approach that may lead to costly manufacturing requirements that still may not guarantee safe results. This paper proposes a probabilistic representation of the geometric uncertainties for rotor blades and defines a procedure to evaluate their effects on the blade NFs. The deviation from nominal geometry is represented through the Principal Component Analysis (PCA) where it is expressed as a sum of characteristic geometric shapes (GUMs) modulated by mutually uncorrelated random variables (Principal Components, PC). The effect of each GUM is then linearly propagated on the blade NFs and a sensitivity matrix is finally defined. The procedure is applied to a case-study that concerns a set of 50 nominally identical compressor blades and the ability of GUMs to represent the effects of geometric uncertainties is tested.

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.

Stator Blades Manufacturing Geometrical Variability in Axial Compressors and Impact on the Aeroelastic Excitation Forces

2021 ◽  
pp. 1-16
Author(s):  
Marco Gambitta ◽  
Arnold Kühhorn ◽  
Bernd Beirow ◽  
Sven Schrape
Keyword(s):  
Manufacturing Process ◽  
Axial Compressor ◽  
Reconstruction Algorithm ◽  
Forced Response ◽  
Rotor Blades ◽  
Compressor Blades ◽  
Input Uncertainty ◽  
Axial Compressors ◽  
Compressor Rotor ◽  
The Impact

Abstract The manufacturing geometrical variability is an unavoidable source of uncertainty in the realization of machinery components. Deviations of a part geometry from its nominal design are inevitably present due to the manufacturing process. In the aeroelastic forced response problem within axial compressors, these uncertainties may affect the vibration characteristics. Therefore, the impact of geometrical uncertainties due to the manufacturing process onto the modal forcing of axial compressor blades is investigated. The research focuses on the vibrational behavior of an axial compressor rotor blisk. In particular, the amplitude of the forces acting as source of excitation on the vibrating blades is studied. The geometrical variability of the upstream stator is investigated as input uncertainty. The variability is modeled starting from a series of optical surface scans. A stochastic model is created to represent the measured manufacturing geometrical deviations from the nominal model. A data reduction methodology is proposed to represent the uncertainty with a minimal set of variables. The manufacturing geometrical variability model allows to represent the input uncertainty and probabilistically evaluate its impact on the aeroelastic problem. An uncertainty quantification is performed in order to evaluate the resulting variability on the modal forcing acting on the vibrating rotor blades. Of particular interest is the possible rise of low engine orders due to the mistuned flow field along the annulus. A reconstruction algorithm allows the representation of the variability during one rotor revolution. The uncertainty on low harmonics of the modal rotor forcing can be therefore identified and quantified.

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.

Stator Blades Manufacturing Geometrical Variability in Axial Compressors and Impact on the Aeroelastic Excitation Forces

2021 ◽  
Author(s):  
Marco Gambitta ◽  
Arnold Kühhorn ◽  
Bernd Beirow ◽  
Sven Schrape
Keyword(s):  
Manufacturing Process ◽  
Axial Compressor ◽  
Reconstruction Algorithm ◽  
Forced Response ◽  
Rotor Blades ◽  
Compressor Blades ◽  
Input Uncertainty ◽  
Axial Compressors ◽  
Compressor Rotor ◽  
The Impact

Abstract The manufacturing geometrical variability is a source of uncertainty, which cannot be avoided in the realization of machinery components. Deviations of a part geometry from its nominal design are inevitably present due to the manufacturing process. In the case of the aeroelastic forced response problem within axial compressors, these uncertainties may affect the vibration characteristics. For this reason, the impact of geometrical uncertainties due to the manufacturing process onto the modal forcing of axial compressor blades is investigated in this study. The research focuses on the vibrational behavior of an axial compressor rotor blisk. In particular the amplitude of the forces acting as source of excitation on the vibrating blades is studied. The geometrical variability of the upstream stator is investigated as input uncertainty. The variability is modeled starting from a series of optical surface scans. A stochastic model is created to represent the measured manufacturing geometrical deviations from the nominal model. A data reduction methodology is proposed in order to represent the uncertainty with a minimal set of variables. The manufacturing geometrical variability model allows to represent the input uncertainty and probabilistically evaluate its impact on the aeroelastic problem. An uncertainty quantification is performed in order to evaluate the resulting variability on the modal forcing acting on the vibrating rotor blades. Of particular interest is the possible rise of low engine orders due to the mistuned flow field along the annulus. A reconstruction algorithm allows the representation of the variability during one rotor revolution. The uncertainty on low harmonics of the modal rotor forcing can be therefore identified and quantified.

Development and regional planning within the decentralized administrative frame: case study (the Jordanian Experiment)

2018 ◽  
Vol 1 (2) ◽  
pp. 60-72
Author(s):  
Mansour Safran
Keyword(s):  
Regional Planning ◽  
The Other ◽  
Negative Effects ◽  
Administrative Procedures ◽  
The Way

This aims to review and analyze the Jordanian experiment in the developmental regional planning field within the decentralized managerial methods, which is considered one of the primary basic provisions for applying and success of this kind of planning. The study shoed that Jordan has passed important steps in the way for implanting the decentralized administration, but these steps are still not enough to established the effective and active regional planning. The study reveled that there are many problems facing the decentralized regional planning in Jordan, despite of the clear goals that this planning is trying to achieve. These problems have resulted from the existing relationship between the decentralized administration process’ dimensions from one side, and between its levels which ranged from weak to medium decentralization from the other side, In spite of the official trends aiming at applying more of the decentralized administrative policies, still high portion of these procedures are theoretical, did not yet find a way to reality. Because any progress or success at the level of applying the decentralized administrative policies doubtless means greater effectiveness and influence on the development regional planning in life of the residents in the kingdom’s different regions. So, it is important to go a head in applying more steps and decentralized administrative procedures, gradually and continuously to guarantee the control over any negative effects that might result from Appling this kind of systems.   © 2018 JASET, International Scholars and Researchers Association

Modelling and Simulation of NO2 Dispersion Phenomenon in Atmosphere by Analytical-Experimental Methods

2008 ◽  
Vol 59 (10) ◽  
Author(s):  
Delia Perju ◽  
Harieta Pirlea ◽  
Gabriela-Alina Brusturean ◽  
Dana Silaghi-Perju ◽  
Sorin Marinescu
Keyword(s):  
Mathematical Model ◽  
Nitrogen Dioxide ◽  
Modeling And Simulation ◽  
Human Health ◽  
Experimental Methods ◽  
Negative Effects ◽  
Real Situation ◽  
Experimental Values ◽  
The Mathematical Model

The European laws and recently the Romanian ones impose more and more strict norms to the large nitrogen dioxide polluters. They are obligated to continuously improve the installations and products so that they limit and reduce the nitrogen dioxide pollution, because it has negative effects on the human health and environment. In this paper are presented these researches made within a case study for the Timi�oara municipality, regarding the modeling and simulation of the nitrogen dioxide dispersion phenomenon coming from various sources in atmosphere with the help of analytical-experimental methods. The mathematical model resulting from these researches is accurately enough to describe the real situation. This was confirmed by comparing the results obtained based on the model with real experimental values.

Patterns of Social Inclusion and Exclusion Among Youth Living in Stigmatized Neighborhoods

2020 ◽  
Author(s):  
Fabiana Espíndola Ferrer
Keyword(s):  
Social Integration ◽  
Residential Segregation ◽  
Neighborhood Effects ◽  
Social Inclusion ◽  
Urban Neighborhoods ◽  
High Poverty ◽  
Ethnographic Case Study ◽  
Negative Effects ◽  
The Social

This chapter is an ethnographic case study of the social integration trajectories of youth living in two stigmatized and poor neighborhoods in Montevideo. It explains the linkages between residential segregation and social inclusion and exclusion patterns in unequal urban neighborhoods. Most empirical neighborhood research on the effects of residential segregation in contexts of high poverty and extreme stigmatization have focused on its negative effects. However, the real mechanisms and mediations influencing the so-called neighborhood effects of residential segregation are still not well understood. Scholars have yet to isolate specific neighborhood effects and their contribution to processes of social inclusion and exclusion. Focusing on the biographical experiences of youth in marginalized neighborhoods, this ethnography demonstrates the relevance of social mediations that modulate both positive and negative residential segregation effects.

scholarly journals The Influence of Increased Salvage Felling on Forwarding Distance and the Removal—A Case Study from Croatia

Forests ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 7
Author(s):  
Andreja Đuka ◽  
Zoran Bumber ◽  
Tomislav Poršinsky ◽  
Ivica Papa ◽  
Tibor Pentek
Keyword(s):  
Spatial Distribution ◽  
Management Plan ◽  
Management Unit ◽  
Negative Effects ◽  
Forest Operations ◽  
Spatial Reference ◽  
Infrastructure Network ◽  
Gis Environment ◽  
Research Period

During the seven-year research period, the average annual removal was by 3274 m3 higher than the average annual removal prescribed by the existing management plan (MP). The main reason lies in the high amount of salvage felling volume at 55,238 m3 (38.3%) in both the main and the intermediate felling due to oak dieback. The analysis of forest accessibility took into account the spatial distribution of cutblocks (with ongoing felling operations) and the volume of felled timber for two proposed factors: (1) the position of the cutblock and (2) the position of the removal. Cutblock position factor took into account the spatial position of the felling areas/sites, while removal position factor besides the spatial reference took into account the amount of felled timber (i.e., volume) both concerning forest infrastructure network and forest operations. The analysed relative forest openness by using geo-processing workflows in GIS environment showed four types of opening areas in the studied management unit (MU): single-opened, multiple-opened, unopened and opened areas outside of the management unit. Negative effects of the piece-volume law and low harvesting densities on forest operations are highlighted in this research due to high amount of salvage felling particularly in the intermediate felling by replacing timber volume that should have come from thinnings.

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