Assessing Sensitivity of Vibratory
Mode Frequencies to Variation in
Geometric Parameters
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Vibration in turbine blades must be prevented
Modal analysis can with FEA can determine
frequencies
Variation in geometric parameters affects
frequency
Presenter: Dan Snyder
File: /home/u9/engr/snyded/pub_html/EP/alternative_project.odp
Date: 10/5/2010
Overhead sheet 1
Develop Parametric Blade Model
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Create “flexible” turbine blade defined by
numerical parameters.
Using Unigraphics (CAD software)
Blade can be altered from normal conditions by
changing geometric parameters
Presenter: Dan Snyder
File: /home/u9/engr/snyded/pub_html/EP/alternative_project.odp
Date: 10/5/2010
Overhead sheet 2
Sample Design Space
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Whole set of parameters forms a “design space”
Define normalized parameters with specified
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Sample design space using Latin Hypercube
Sampling
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Upper limit
Lower limit
Zero mean
For N variables, create N combinations of variables
Orthogonal Sample Space
Each set of parameters represents a potential
configuration of a real blade
Presenter: Dan Snyder
File: /home/u9/engr/snyded/pub_html/EP/alternative_project.odp
Date: 10/5/2010
Overhead sheet 3
Analyze Potential Blade
Configurations
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Analyze all configurations of real blades using
ANSYS
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Modal Analysis
Boundary conditions similar to engine operation
Find first 5 mode frequencies
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Automate using iSight
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Develop Predictive Regression Function
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Linear / Non-linear
Least Squares Minimization
Presenter: Dan Snyder
File: /home/u9/engr/snyded/pub_html/EP/alternative_project.odp
Date: 10/5/2010
Overhead sheet 4
Summary
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This project will simulate random variation in
turbine blades
The effect of geometry variation on frequency will
be quantified
A predictive model will be created to predict
frequency based on geometric parameters.
Presenter: Dan Snyder
File: /home/u9/engr/snyded/pub_html/EP/alternative_project.odp
Date: 10/5/2010
Overhead sheet 5
Discussion
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How many parameters will be required to create a
realistic and flexible model?
How many configurations should be analyzed to
create dense enough variable space?
What type of regression function should be used?
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Linear / non-linear?
Presenter: Dan Snyder
File: /home/u9/engr/snyded/pub_html/EP/alternative_project.odp
Date: 10/5/2010
Overhead sheet 6