{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/106297"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/106297","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Experimental study of rapid pressure transients in a two-fluid, two-phase system and comparison to RELAP5","abstract":"The six-equation two-fluid two-phase model is a prevalent tool used to estimate the behavior of nuclear thermal hydraulic systems. This model requires use of closure relations, which have been developed over decades to provide greater accuracy and reliability to the simulations that utilize this model. Experimental work has been vital to the development of accurate closure relations. Fast transients can be particularly difficult to model, so experimental datasets are important for developing closure relations that apply to these scenarios. Previously, experiments like the Edwards pipe experiment (ISL, 2010) and the pipe experiment by Takeda and Toda (Takeda and Toda, 1971) have been instrumental to improving the modelling of transients. In this work, state-of-the-art measurement techniques and particle image velocimetry (PIV) are utilized to demonstrate the ability to record high fidelity measurements around an air-water interface during a fast pressure transient. Previously, it has not been possible to take high fidelity measurements for such an experiment due to the rapid measurement rate and accuracy required as well as the inability to take measurements directly on either side of a phase interface. By setting the phase interface in a glass viewport with piezoresistive pressure transducers on either side, pressure can be measured accurately at the rapid rate required, the water level can be tracked, and phase velocities on either side of the interface can be measured. The two experiments described in this thesis, a blowdown and a pressure surge, are designed to create a fast pressure transient wherein the interfacial behavior between the two fluids can be measured reliably. These measurements are compared against a RELAP5 simulation to support the validity of the methods described in this work. Both experiments produce high fidelity measurements that match the expected behavior. The pressure measurements from either side of the interface change concurrently with the movement of the phase interface and accurately capture dynamic pressure behavior during flow reversals. The PIV measurements show the phase velocities on either side of the interface match closely, as expected, and demonstrates the ability to perform PIV measurements on two distinct fluids from a single high-speed video. The blowdown experiment shows that pressure data align well with expected behavior predicted via RELAP5 simulation. With the pressure surge experiment, a slower variation showed good agreement with the simulation while faster cases resulted in significant instabilities in the simulation, showing that this fast pressure transient behavior can be difficult to simulate.","abstract_html":"The six-equation two-fluid two-phase model is a prevalent tool used to estimate the behavior of nuclear thermal hydraulic systems. This model requires use of closure relations, which have been developed over decades to provide greater accuracy and reliability to the simulations that utilize this model. Experimental work has been vital to the development of accurate closure relations. Fast transients can be particularly difficult to model, so experimental datasets are important for developing closure relations that apply to these scenarios. Previously, experiments like the Edwards pipe experiment (ISL, 2010) and the pipe experiment by Takeda and Toda (Takeda and Toda, 1971) have been instrumental to improving the modelling of transients. In this work, state-of-the-art measurement techniques and particle image velocimetry (PIV) are utilized to demonstrate the ability to record high fidelity measurements around an air-water interface during a fast pressure transient. Previously, it has not been possible to take high fidelity measurements for such an experiment due to the rapid measurement rate and accuracy required as well as the inability to take measurements directly on either side of a phase interface. By setting the phase interface in a glass viewport with piezoresistive pressure transducers on either side, pressure can be measured accurately at the rapid rate required, the water level can be tracked, and phase velocities on either side of the interface can be measured. The two experiments described in this thesis, a blowdown and a pressure surge, are designed to create a fast pressure transient wherein the interfacial behavior between the two fluids can be measured reliably. These measurements are compared against a RELAP5 simulation to support the validity of the methods described in this work. Both experiments produce high fidelity measurements that match the expected behavior. The pressure measurements from either side of the interface change concurrently with the movement of the phase interface and accurately capture dynamic pressure behavior during flow reversals. The PIV measurements show the phase velocities on either side of the interface match closely, as expected, and demonstrates the ability to perform PIV measurements on two distinct fluids from a single high-speed video. The blowdown experiment shows that pressure data align well with expected behavior predicted via RELAP5 simulation. With the pressure surge experiment, a slower variation showed good agreement with the simulation while faster cases resulted in significant instabilities in the simulation, showing that this fast pressure transient behavior can be difficult to simulate.","abstract_has_math":false,"creators":["Heald, Alex"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"M.S.","degree_level":"Thesis","degree_discipline":"Nuclear, Plasma, Radiolgc Engr","degree_department":null,"school":null,"contributors":["Brooks, Caleb S","Kozlowski, Tomasz"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2020,"date_issued":"2020-03-02T22:03:31Z","date_published":"2020-03-02T22:03:31Z","updated_at":"2026-07-22T22:24:45Z","subjects":["Particle Image Velocimetry","Pressure Transient"],"languages":["en"],"rights":["Copyright 2019 Alex Heald"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2142/106297","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Brooks, Caleb S","Kozlowski, Tomasz"]},{"key":"dc:creator","label":"Author","values":["Heald, Alex"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2020-03-02T22:03:31Z","2019-12-13","2019-12"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Nuclear, Plasma, Radiolgc Engr"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Thesis"]},{"key":"thesis:degree_name","label":"Degree Name","values":["M.S."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Particle Image Velocimetry","Pressure Transient"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2019 Alex Heald"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/106297"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["The six-equation two-fluid two-phase model is a prevalent tool used to estimate the behavior of nuclear thermal hydraulic systems. This model requires use of closure relations, which have been developed over decades to provide greater accuracy and reliability to the simulations that utilize this model. Experimental work has been vital to the development of accurate closure relations. Fast transients can be particularly difficult to model, so experimental datasets are important for developing closure relations that apply to these scenarios. Previously, experiments like the Edwards pipe experiment (ISL, 2010) and the pipe experiment by Takeda and Toda (Takeda and Toda, 1971) have been instrumental to improving the modelling of transients. In this work, state-of-the-art measurement techniques and particle image velocimetry (PIV) are utilized to demonstrate the ability to record high fidelity measurements around an air-water interface during a fast pressure transient. Previously, it has not been possible to take high fidelity measurements for such an experiment due to the rapid measurement rate and accuracy required as well as the inability to take measurements directly on either side of a phase interface. By setting the phase interface in a glass viewport with piezoresistive pressure transducers on either side, pressure can be measured accurately at the rapid rate required, the water level can be tracked, and phase velocities on either side of the interface can be measured. The two experiments described in this thesis, a blowdown and a pressure surge, are designed to create a fast pressure transient wherein the interfacial behavior between the two fluids can be measured reliably. These measurements are compared against a RELAP5 simulation to support the validity of the methods described in this work. Both experiments produce high fidelity measurements that match the expected behavior. The pressure measurements from either side of the interface change concurrently with the movement of the phase interface and accurately capture dynamic pressure behavior during flow reversals. The PIV measurements show the phase velocities on either side of the interface match closely, as expected, and demonstrates the ability to perform PIV measurements on two distinct fluids from a single high-speed video. The blowdown experiment shows that pressure data align well with expected behavior predicted via RELAP5 simulation. With the pressure surge experiment, a slower variation showed good agreement with the simulation while faster cases resulted in significant instabilities in the simulation, showing that this fast pressure transient behavior can be difficult to simulate.","Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2020-02-28 without embargo terms","The student, Alex Heald, accepted the attached license on 2019-12-13 at 10:56.","The student, Alex Heald, submitted this Thesis for approval on 2019-12-13 at 11:02.","This Thesis was approved for publication on 2019-12-13 at 12:53.","DSpace SAF Submission Ingestion Package generated from Vireo submission #14826 on 2020-02-28 at 17:17:10","Made available in DSpace on 2020-03-02T22:03:31Z (GMT). No. of bitstreams: 2 HEALD-THESIS-2019.pdf: 2604134 bytes, checksum: 154759c34ef17d76add08d7f810ad879 (MD5) LICENSE.txt: 4207 bytes, checksum: 8de9cda519bed3d5885402946dc8f358 (MD5) Previous issue date: 2019-12-13"]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Experimental study of rapid pressure transients in a two-fluid, two-phase system and comparison to RELAP5"]}]}],"canonical_facts":{"dc:contributor":["Brooks, Caleb S","Kozlowski, Tomasz"],"dc:creator":["Heald, Alex"],"dc:date":["2020-03-02T22:03:31Z","2019-12-13","2019-12"],"dc:description":["The six-equation two-fluid two-phase model is a prevalent tool used to estimate the behavior of nuclear thermal hydraulic systems. This model requires use of closure relations, which have been developed over decades to provide greater accuracy and reliability to the simulations that utilize this model. Experimental work has been vital to the development of accurate closure relations. Fast transients can be particularly difficult to model, so experimental datasets are important for developing closure relations that apply to these scenarios. Previously, experiments like the Edwards pipe experiment (ISL, 2010) and the pipe experiment by Takeda and Toda (Takeda and Toda, 1971) have been instrumental to improving the modelling of transients. In this work, state-of-the-art measurement techniques and particle image velocimetry (PIV) are utilized to demonstrate the ability to record high fidelity measurements around an air-water interface during a fast pressure transient. Previously, it has not been possible to take high fidelity measurements for such an experiment due to the rapid measurement rate and accuracy required as well as the inability to take measurements directly on either side of a phase interface. By setting the phase interface in a glass viewport with piezoresistive pressure transducers on either side, pressure can be measured accurately at the rapid rate required, the water level can be tracked, and phase velocities on either side of the interface can be measured. The two experiments described in this thesis, a blowdown and a pressure surge, are designed to create a fast pressure transient wherein the interfacial behavior between the two fluids can be measured reliably. These measurements are compared against a RELAP5 simulation to support the validity of the methods described in this work. Both experiments produce high fidelity measurements that match the expected behavior. The pressure measurements from either side of the interface change concurrently with the movement of the phase interface and accurately capture dynamic pressure behavior during flow reversals. The PIV measurements show the phase velocities on either side of the interface match closely, as expected, and demonstrates the ability to perform PIV measurements on two distinct fluids from a single high-speed video. The blowdown experiment shows that pressure data align well with expected behavior predicted via RELAP5 simulation. With the pressure surge experiment, a slower variation showed good agreement with the simulation while faster cases resulted in significant instabilities in the simulation, showing that this fast pressure transient behavior can be difficult to simulate.","Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2020-02-28 without embargo terms","The student, Alex Heald, accepted the attached license on 2019-12-13 at 10:56.","The student, Alex Heald, submitted this Thesis for approval on 2019-12-13 at 11:02.","This Thesis was approved for publication on 2019-12-13 at 12:53.","DSpace SAF Submission Ingestion Package generated from Vireo submission #14826 on 2020-02-28 at 17:17:10","Made available in DSpace on 2020-03-02T22:03:31Z (GMT). No. of bitstreams: 2 HEALD-THESIS-2019.pdf: 2604134 bytes, checksum: 154759c34ef17d76add08d7f810ad879 (MD5) LICENSE.txt: 4207 bytes, checksum: 8de9cda519bed3d5885402946dc8f358 (MD5) Previous issue date: 2019-12-13"],"dc:format":["application/pdf"],"dc:identifier":["http://hdl.handle.net/2142/106297"],"dc:language":["en"],"dc:rights":["Copyright 2019 Alex Heald"],"dc:subject":["Particle Image Velocimetry","Pressure Transient"],"dc:title":["Experimental study of rapid pressure transients in a two-fluid, two-phase system and comparison to RELAP5"],"dc:type":["text"],"thesis:degree_discipline":["Nuclear, Plasma, Radiolgc Engr"],"thesis:degree_level":["Thesis"],"thesis:degree_name":["M.S."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:24:45Z"}