Near wall high resolution particle image velocimetry and data reconstruction for high speed flows
The aim of this work was to understand the physical requirements as well as to develop methodology required to employ Time Resolved Digital Particle Image Velocimetry (TRDPIV) for measuring high speed, high magnification, near wall flow fields. Previous attempts to perform measurements such as this...
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ndltd-VTETD-oai-vtechworks.lib.vt.edu-10919-326532020-09-26T05:35:10Z Near wall high resolution particle image velocimetry and data reconstruction for high speed flows Raben, Samuel Mechanical Engineering Ball, Kenneth S. Thole, Karen A. Vlachos, Pavlos P. Ng, Fai Particle Image Velocimetry Proper Orthogonal Decomposition Data Reconstruction Wall Jet High Magnification Near Wall The aim of this work was to understand the physical requirements as well as to develop methodology required to employ Time Resolved Digital Particle Image Velocimetry (TRDPIV) for measuring high speed, high magnification, near wall flow fields. Previous attempts to perform measurements such as this have been unsuccessful because of both limitations in equipment as well as proper methodology for processing of the data. This work addresses those issues and successfully demonstrates a test inside of a transonic turbine cascade as well as a high speed high magnification wall jet. From previous studies it was established that flow tracer delivery is not a trivial task in a high speed high back pressure environment. Any TRDPIV measurement requires uniform spatial seeding density, but time-resolved measurements require uniform temporal seeding density as well. To this end, a high pressure particle generator was developed. This advancement enhanced current capability beyond what was previously attainable. Unfortunately, this was not sufficient to resolve the issue of seeding all together, and an advanced data reconstruction methodology was developed to reconstruct areas of the flow field that where lost do to inhomogeneous seeding. This reconstruction methodology, based on Proper Orthogonal Decomposition (POD), has been shown to produce errors in corrected velocities below tradition spatial techniques alone. The combination of both particle generator and reconstruction methodology was instrumental for successfully acquiring TRDPIV measurements in a high speed high pressure environment such as a transonic wind tunnel facility. This work also investigates the development of a turbulent wall jet. This experiment helped in demonstrating the capability of taking high speed high magnification TRDPIV measurements. This experiment was very unique in that it is one of only a few experiments that studied the developing region of these jets. The Reynolds number ranged for this experiment from 150 â 10,000 which corresponded to velocities of 1 - 80 m/s. The results from this experiment showed good agreement with currently published time averaged data. Using scaling laws for fully developed jets a new scaling law was found for the developing region of the jet that could be applied to all Reynolds numbers in this study. A temporal investigation was also carried out using the temporal coefficients from POD. A vortex identification scheme was also applied to all of the Reynolds numbers showing clear trends as Reynolds number increased. Master of Science 2014-03-14T20:36:29Z 2014-03-14T20:36:29Z 2008-04-28 2008-05-12 2008-06-06 2008-06-06 Thesis etd-05122008-164705 http://hdl.handle.net/10919/32653 http://scholar.lib.vt.edu/theses/available/etd-05122008-164705/ Raben_Thesis2.pdf In Copyright http://rightsstatements.org/vocab/InC/1.0/ application/pdf Virginia Tech |
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Particle Image Velocimetry Proper Orthogonal Decomposition Data Reconstruction Wall Jet High Magnification Near Wall |
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Particle Image Velocimetry Proper Orthogonal Decomposition Data Reconstruction Wall Jet High Magnification Near Wall Raben, Samuel Near wall high resolution particle image velocimetry and data reconstruction for high speed flows |
description |
The aim of this work was to understand the physical requirements as well as to develop methodology required to employ Time Resolved Digital Particle Image Velocimetry (TRDPIV) for measuring high speed, high magnification, near wall flow fields. Previous attempts to perform measurements such as this have been unsuccessful because of both limitations in equipment as well as proper methodology for processing of the data. This work addresses those issues and successfully demonstrates a test inside of a transonic turbine cascade as well as a high speed high magnification wall jet.
From previous studies it was established that flow tracer delivery is not a trivial task in a high speed high back pressure environment. Any TRDPIV measurement requires uniform spatial seeding density, but time-resolved measurements require uniform temporal seeding density as well. To this end, a high pressure particle generator was developed. This advancement enhanced current capability beyond what was previously attainable. Unfortunately, this was not sufficient to resolve the issue of seeding all together, and an advanced data reconstruction methodology was developed to reconstruct areas of the flow field that where lost do to inhomogeneous seeding. This reconstruction methodology, based on Proper Orthogonal Decomposition (POD), has been shown to produce errors in corrected velocities below tradition spatial techniques alone. The combination of both particle generator and reconstruction methodology was instrumental for successfully acquiring TRDPIV measurements in a high speed high pressure environment such as a transonic wind tunnel facility.
This work also investigates the development of a turbulent wall jet. This experiment helped in demonstrating the capability of taking high speed high magnification TRDPIV measurements. This experiment was very unique in that it is one of only a few experiments that studied the developing region of these jets. The Reynolds number ranged for this experiment from 150 â 10,000 which corresponded to velocities of 1 - 80 m/s. The results from this experiment showed good agreement with currently published time averaged data. Using scaling laws for fully developed jets a new scaling law was found for the developing region of the jet that could be applied to all Reynolds numbers in this study. A temporal investigation was also carried out using the temporal coefficients from POD. A vortex identification scheme was also applied to all of the Reynolds numbers showing clear trends as Reynolds number increased. === Master of Science |
author2 |
Mechanical Engineering |
author_facet |
Mechanical Engineering Raben, Samuel |
author |
Raben, Samuel |
author_sort |
Raben, Samuel |
title |
Near wall high resolution particle image velocimetry and data reconstruction for high speed flows |
title_short |
Near wall high resolution particle image velocimetry and data reconstruction for high speed flows |
title_full |
Near wall high resolution particle image velocimetry and data reconstruction for high speed flows |
title_fullStr |
Near wall high resolution particle image velocimetry and data reconstruction for high speed flows |
title_full_unstemmed |
Near wall high resolution particle image velocimetry and data reconstruction for high speed flows |
title_sort |
near wall high resolution particle image velocimetry and data reconstruction for high speed flows |
publisher |
Virginia Tech |
publishDate |
2014 |
url |
http://hdl.handle.net/10919/32653 http://scholar.lib.vt.edu/theses/available/etd-05122008-164705/ |
work_keys_str_mv |
AT rabensamuel nearwallhighresolutionparticleimagevelocimetryanddatareconstructionforhighspeedflows |
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1719341877610676224 |