Proposed Changes to the ASME Boiler and Pressure Vessel Code Section III Appendix N for Flow-Induced Vibrations

2015 ◽  
Author(s):  
Gregory A. Banyay ◽  
Gregory A. Meyer ◽  
Adam P. Walker
Keyword(s):  
Data Processing ◽  
Pressure Vessel ◽  
Structural Damping ◽  
Structural Dynamic ◽  
Acoustic Damping ◽  
Flow Induced Vibrations ◽  
Processing Algorithms ◽  
Complex Phenomena ◽  
Proper Orthogonal

This article outlines changes proposed for implementation in the ASME Boiler and Pressure Vessel Code Section III Appendix N pertaining to Flow-Induced Vibrations (FIV). Several portions of Appendix N were originally written multiple decades ago and are not necessarily readily prescriptive for present-day analyses. An ASME Task Group on Flow-Induced Vibrations has been formed to identify areas of improvement to Appendix N so that the Appendix may be more useable in present-day FIV analyses, and a means of establishing consensus for characterization of this complex phenomena. This paper identifies opportunities for improvement to portions of Appendix N pertaining to Turbulence, Acoustic, and associated Structural Dynamic Modeling, and Data Processing. Specific suggestions are made for the following: Characterization of acoustic damping and acoustic harmonic responses, updated considerations for aeroacoustic phenomena, structural damping quantification of nuclear components, systematic approaches to modeling (random) turbulence-induced vibrations (including RMS-to-Peak ratio), considerations for leakage flow-induced instabilities, and opportunities to employ computational methods are discussed. Opportunities for the applicability of data processing algorithms such as the proper orthogonal decomposition and circumferential wavenumber decomposition are also discussed and an updated methodology for combination of random and deterministic loads for FIV analyses is presented.

scholarly journals Spectral Decomposition of the Flow and Characterization of the Sound Signals through Stenoses with Different Levels of Severity

2021 ◽  
Vol 8 (3) ◽  
pp. 41
Author(s):  
Fardin Khalili ◽  
Peshala T. Gamage ◽  
Amirtahà Taebi ◽  
Mark E. Johnson ◽  
Randal B. Roberts ◽  
...  
Keyword(s):  
Pressure Fluctuations ◽  
High Energy ◽  
Sound Sources ◽  
Severity Level ◽  
Non Invasive ◽  
Flow Through ◽  
Severity Of The Disease ◽  
Proper Orthogonal ◽  
Different Levels

Treatments of atherosclerosis depend on the severity of the disease at the diagnosis time. Non-invasive diagnosis techniques, capable of detecting stenosis at early stages, are essential to reduce associated costs and mortality rates. We used computational fluid dynamics and acoustics analysis to extensively investigate the sound sources arising from high-turbulent fluctuating flow through stenosis. The frequency spectral analysis and proper orthogonal decomposition unveiled the frequency contents of the fluctuations for different severities and decomposed the flow into several frequency bandwidths. Results showed that high-intensity turbulent pressure fluctuations appeared inside the stenosis for severities above 70%, concentrated at plaque surface, and immediately in the post-stenotic region. Analysis of these fluctuations with the progression of the stenosis indicated that (a) there was a distinct break frequency for each severity level, ranging from 40 to 230 Hz, (b) acoustic spatial-frequency maps demonstrated the variation of the frequency content with respect to the distance from the stenosis, and (c) high-energy, high-frequency fluctuations existed inside the stenosis only for severe cases. This information can be essential for predicting the severity level of progressive stenosis, comprehending the nature of the sound sources, and determining the location of the stenosis with respect to the point of measurements.

Damage Detection in Flexible Propeller Beam Structures by Exploiting Impact-Induced Coupled Acceleration Signals

2011 ◽  
Author(s):  
Ioannis T. Georgiou
Keyword(s):  
Data Driven ◽  
Distributed Information ◽  
Modal Expansion ◽  
Shape Difference ◽  
Spatio Temporal ◽  
Temporal Sample ◽  
High Level ◽  
Proper Orthogonal ◽  
Acceleration Signals

A local damage at the tip of a composite propeller is diagnosed by properly comparing its impact-induced free coupled dynamics to that of a pristine wooden propeller of the same size and shape. This is accomplished by creating indirectly via collocated measurements distributed information for the coupled acceleration field of the propellers. The powerful data-driven modal expansion analysis delivered by the Proper Orthogonal Decomposition (POD) Transform reveals that ensembles of impact-induced collocated coupled experimental acceleration signals are underlined by a high level of spatio-temporal coherence. Thus they furnish a valuable spatio-temporal sample of coupled response induced by a point impulse. In view of this fact, a tri-axial sensor was placed on the propeller hub to collect collocated coupled acceleration signals induced via modal hammer nondestructive impacts and thus obtained a reduced order characterization of the coupled free dynamics. This experimental data-driven analysis reveals that the in-plane unit components of the POD modes for both propellers have similar shapes-nearly identical. For the damaged propeller this POD shape-difference is quite pronounced. The shapes of the POD modes are used to compute indices of difference reflecting directly damage. At the first POD energy level, the shape-difference indices of the damaged composite propeller are quite larger than those of the pristine wooden propeller.

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