{"id":{"repo_id":"salford","oai_identifier":"oai:salford-repository.worktribe.com:1336985"},"canonical_url":"https://search.dev.ndltd.org/etd/salford/oai:salford-repository.worktribe.com:1336985","repository":{"repo_id":"salford","name":"U. of Salford","base_url":"https://salford-repository.worktribe.com/oaiprovider"},"display":{"title":"Hydraulic characteristics of siphonic roof drainage outlets","abstract":"Siphonic roof drainage uses an innovative hydraulic design to increase the efficiency ofrainwater disposal. The roof outlet is a critical component of the system and not onlypromotes and sustains priming of the system but also controls the depth of approachflow. This thesis investigates the hydraulic characteristics of an idealised roof outlet toimprove outlet design.A literature survey was carried out and found that only a limited number of studies havebeen undertaken on single outlets on flat roofs. Therefore, the search was widened toinclude related subjects and the information was used to develop a programme ofexperimental testing.An idealised outlet was tested within a physical hydraulic model across a range ofgeometries to observe and measure the water flow rate, depth, pressure and the air flow.The relationships between the key parameters are presented and compared with thetheoretical values. The study confirmed that a baffle plate is essential for stable primingof the outlet and that the idealised geometry is sufficient to provide a stable and efficientoperation of the system. The maximum typical air flow rate during the priming sequencewas approximately a third of the water flow rate and occurred at less than half of themaximum water flow rate. The outlet should be designed to ensure rapid and stablepriming by creating a turbulent, well-mixed flow at the roof outlet. The depth ofapproach flow can be reduced by increasing the diameter of the baffle plate withinpractical limits and by reducing the height of the baffle.An empirical relationship was developed between the water radial velocity and thepulsing frequency of entrained air and is presented in the form of a modified Strouhalnumber. This relationship could be used to develop a non-intrusive flow measurementsystem in the air-regulated regime of operation.Tests were conducted on a small range of commercial outlets and the results comparedwell with those from the idealised outlet. The conclusions drawn from the idealisedoutlet would thus be useful in the development of commercial outlets.","abstract_html":"Siphonic roof drainage uses an innovative hydraulic design to increase the efficiency ofrainwater disposal. The roof outlet is a critical component of the system and not onlypromotes and sustains priming of the system but also controls the depth of approachflow. This thesis investigates the hydraulic characteristics of an idealised roof outlet toimprove outlet design.A literature survey was carried out and found that only a limited number of studies havebeen undertaken on single outlets on flat roofs. Therefore, the search was widened toinclude related subjects and the information was used to develop a programme ofexperimental testing.An idealised outlet was tested within a physical hydraulic model across a range ofgeometries to observe and measure the water flow rate, depth, pressure and the air flow.The relationships between the key parameters are presented and compared with thetheoretical values. The study confirmed that a baffle plate is essential for stable primingof the outlet and that the idealised geometry is sufficient to provide a stable and efficientoperation of the system. The maximum typical air flow rate during the priming sequencewas approximately a third of the water flow rate and occurred at less than half of themaximum water flow rate. The outlet should be designed to ensure rapid and stablepriming by creating a turbulent, well-mixed flow at the roof outlet. The depth ofapproach flow can be reduced by increasing the diameter of the baffle plate withinpractical limits and by reducing the height of the baffle.An empirical relationship was developed between the water radial velocity and thepulsing frequency of entrained air and is presented in the form of a modified Strouhalnumber. This relationship could be used to develop a non-intrusive flow measurementsystem in the air-regulated regime of operation.Tests were conducted on a small range of commercial outlets and the results comparedwell with those from the idealised outlet. The conclusions drawn from the idealisedoutlet would thus be useful in the development of commercial outlets.","abstract_has_math":false,"creators":["Rains, JP"],"institution":null,"degree_name":null,"degree_level":"Doctoral (Level 8)","degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2008,"date_issued":"2008","date_published":"2008","updated_at":"2026-07-24T04:26:09Z","subjects":[],"languages":["en"],"rights":[],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["oai:salford-repository.worktribe.com:1336985"],"render_values":[{"text":"oai:salford-repository.worktribe.com:1336985","href":null,"code":true}]}]},"links":{"outbound_url":null,"outbound_label":null,"outbound_source":null},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.sponsor","label":"Sponsor","values":["#1 FUNDER NOT LISTED"]},{"key":"dc:creator","label":"Author","values":["Rains, JP"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2008-01-01"]},{"key":"dc:date.issued","label":"Date","values":["2008"]},{"key":"dc:relation.isreferencedby","label":"Dc Relation Isreferencedby","values":["https://salford-repository.worktribe.com/output/1336985"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"dc:type.qualificationlevel","label":"Dc Type Qualificationlevel","values":["Doctoral (Level 8)"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["oai:salford-repository.worktribe.com:1336985"]},{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://salford-repository.worktribe.com/file/1336985/1/1111441X.pdf"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Siphonic roof drainage uses an innovative hydraulic design to increase the efficiency ofrainwater disposal. The roof outlet is a critical component of the system and not onlypromotes and sustains priming of the system but also controls the depth of approachflow. This thesis investigates the hydraulic characteristics of an idealised roof outlet toimprove outlet design.A literature survey was carried out and found that only a limited number of studies havebeen undertaken on single outlets on flat roofs. Therefore, the search was widened toinclude related subjects and the information was used to develop a programme ofexperimental testing.An idealised outlet was tested within a physical hydraulic model across a range ofgeometries to observe and measure the water flow rate, depth, pressure and the air flow.The relationships between the key parameters are presented and compared with thetheoretical values. The study confirmed that a baffle plate is essential for stable primingof the outlet and that the idealised geometry is sufficient to provide a stable and efficientoperation of the system. The maximum typical air flow rate during the priming sequencewas approximately a third of the water flow rate and occurred at less than half of themaximum water flow rate. The outlet should be designed to ensure rapid and stablepriming by creating a turbulent, well-mixed flow at the roof outlet. The depth ofapproach flow can be reduced by increasing the diameter of the baffle plate withinpractical limits and by reducing the height of the baffle.An empirical relationship was developed between the water radial velocity and thepulsing frequency of entrained air and is presented in the form of a modified Strouhalnumber. This relationship could be used to develop a non-intrusive flow measurementsystem in the air-regulated regime of operation.Tests were conducted on a small range of commercial outlets and the results comparedwell with those from the idealised outlet. The conclusions drawn from the idealisedoutlet would thus be useful in the development of commercial outlets."]},{"key":"dc:title","label":"Title","values":["Hydraulic characteristics of siphonic roof drainage outlets"]}]}],"canonical_facts":{"dc:contributor.sponsor":["#1 FUNDER NOT LISTED"],"dc:creator":["Rains, JP"],"dc:date":["2008-01-01"],"dc:date.issued":["2008"],"dc:description.abstract":["Siphonic roof drainage uses an innovative hydraulic design to increase the efficiency ofrainwater disposal. The roof outlet is a critical component of the system and not onlypromotes and sustains priming of the system but also controls the depth of approachflow. This thesis investigates the hydraulic characteristics of an idealised roof outlet toimprove outlet design.A literature survey was carried out and found that only a limited number of studies havebeen undertaken on single outlets on flat roofs. Therefore, the search was widened toinclude related subjects and the information was used to develop a programme ofexperimental testing.An idealised outlet was tested within a physical hydraulic model across a range ofgeometries to observe and measure the water flow rate, depth, pressure and the air flow.The relationships between the key parameters are presented and compared with thetheoretical values. The study confirmed that a baffle plate is essential for stable primingof the outlet and that the idealised geometry is sufficient to provide a stable and efficientoperation of the system. The maximum typical air flow rate during the priming sequencewas approximately a third of the water flow rate and occurred at less than half of themaximum water flow rate. The outlet should be designed to ensure rapid and stablepriming by creating a turbulent, well-mixed flow at the roof outlet. The depth ofapproach flow can be reduced by increasing the diameter of the baffle plate withinpractical limits and by reducing the height of the baffle.An empirical relationship was developed between the water radial velocity and thepulsing frequency of entrained air and is presented in the form of a modified Strouhalnumber. This relationship could be used to develop a non-intrusive flow measurementsystem in the air-regulated regime of operation.Tests were conducted on a small range of commercial outlets and the results comparedwell with those from the idealised outlet. The conclusions drawn from the idealisedoutlet would thus be useful in the development of commercial outlets."],"dc:identifier":["oai:salford-repository.worktribe.com:1336985"],"dc:identifier.uri":["https://salford-repository.worktribe.com/file/1336985/1/1111441X.pdf"],"dc:language":["en"],"dc:relation.isreferencedby":["https://salford-repository.worktribe.com/output/1336985"],"dc:title":["Hydraulic characteristics of siphonic roof drainage outlets"],"dc:type":["Thesis"],"dc:type.qualificationlevel":["Doctoral (Level 8)"]},"updated_at":"2026-07-24T04:26:09Z"}