Numerical Analysis of the Effects of Different Rotor Tip Gaps in a Radial Turbine Operating at High Pressure Ratios Reaching Choked Flow

[EN] To operate, radial turbines used in turbochargers require a minimum tip gap between the rotor blades and the stationary wall casing (shroud). This gap generates leakage flow driven by the pressure difference between the pressure and suction side. The tip leakage flow is largely unturned, which...

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Detalles Bibliográficos
Autores: Galindo, José|||0000-0001-6068-182X, Tiseira, Andrés-Omar|||0000-0001-9472-2386, Navarro, Roberto|||0000-0003-2587-4954, Echavarria-Olaya, Juan David|||0000-0002-9611-0751, Inhestern, Lukas Benjamin
Tipo de recurso: artículo
Fecha de publicación:2022
País:España
Institución:Universitat Politècnica de València (UPV)
Repositorio:RiuNet. Repositorio Institucional de la Universitat Politécnica de Valéncia
Idioma:inglés
OAI Identifier:oai:riunet.upv.es:10251/193529
Acceso en línea:https://riunet.upv.es/handle/10251/193529
Access Level:acceso abierto
Palabra clave:Choked flow
Sonic conditions
CFD
Tip gap
Tip leakage
Scraping flow
Pressure profile
INGENIERIA AEROESPACIAL
MAQUINAS Y MOTORES TERMICOS
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spelling Numerical Analysis of the Effects of Different Rotor Tip Gaps in a Radial Turbine Operating at High Pressure Ratios Reaching Choked FlowGalindo, José|||0000-0001-6068-182XTiseira, Andrés-Omar|||0000-0001-9472-2386Navarro, Roberto|||0000-0003-2587-4954Echavarria-Olaya, Juan David|||0000-0002-9611-0751Inhestern, Lukas BenjaminChoked flowSonic conditionsCFDTip gapTip leakageScraping flowPressure profileINGENIERIA AEROESPACIALMAQUINAS Y MOTORES TERMICOS[EN] To operate, radial turbines used in turbochargers require a minimum tip gap between the rotor blades and the stationary wall casing (shroud). This gap generates leakage flow driven by the pressure difference between the pressure and suction side. The tip leakage flow is largely unturned, which translates into a reduction of the shaft work due to the decrease in the total pressure. This paper investigates the flow through the rotor blade tip gap and the effects on the main flow when the turbine operates at a lower and higher pressure ratio with the presence of supersonic regions at the rotor trailing edge for two rotational speeds using computational fluid dynamics (CFD). The rotor tip gap has been decreased and increased up to 50% of the original tip gap geometry given by the manufacturer. Depending on the operational point, the results reveal that a reduction of 50% of the tip gap can lead to an increase of almost 3% in the efficiency, whereas a rise in 50% in the gap penalty the efficiency up to 3%. Furthermore, a supersonic region appears in the tip gap just when the flow enters through the pressure side, then the flow accelerates, leaving the suction side with a higher relative Mach number, generating a vortex by mixing with the mainstream. The effects of the vortex with the variation of the tip gap on the choked area at the rotor trailing edge presents a more significant change at higher than lower speeds. At a higher speed, the choked region closer to the shroud is due to the high relative inlet flow angle and the effects of the high relative motion of the shroud wall. Furthermore, this relative motion forces the tip leakage vortex to stay closer to the tip suction side, generating a subsonic region, which increases with the tip gap height. The leakage flow at lower and higher rotational speed does not affect the main flow close to the hub. However, close to the shroud, the velocity profile changes, and the generated entropy increases when the flow goes through the tip gap.The work has been partially supported by the Subprograma de Formación de Profesorado Universitario (FPU). Ministerio de Universidades. FPU18/02628.MDPI AGDepartamento de Máquinas y Motores TérmicosEscuela Técnica Superior de Ingeniería Aeroespacial y Diseño IndustrialInstituto Universitario de Investigación CMT - Clean Mobility & ThermofluidsMinisterio de UniversidadesRepositorio Institucional de la Universitat Politècnica de València Riunet20222022-12-01journal articlehttp://purl.org/coar/resource_type/c_6501VoRhttp://purl.org/coar/version/c_970fb48d4fbd8a85info:eu-repo/semantics/articleapplication/pdfhttps://riunet.upv.es/handle/10251/193529reponame:RiuNet. Repositorio Institucional de la Universitat Politécnica de Valénciainstname:Universitat Politècnica de València (UPV)InglésengMinisterio de Universidades MIU FPU18%2F02628open accesshttp://purl.org/coar/access_right/c_abf2Reconocimiento (by)http://creativecommons.org/licenses/by/4.0/info:eu-repo/semantics/openAccessoai:riunet.upv.es:10251/1935292026-06-13T07:49:27Z
dc.title.none.fl_str_mv Numerical Analysis of the Effects of Different Rotor Tip Gaps in a Radial Turbine Operating at High Pressure Ratios Reaching Choked Flow
title Numerical Analysis of the Effects of Different Rotor Tip Gaps in a Radial Turbine Operating at High Pressure Ratios Reaching Choked Flow
spellingShingle Numerical Analysis of the Effects of Different Rotor Tip Gaps in a Radial Turbine Operating at High Pressure Ratios Reaching Choked Flow
Galindo, José|||0000-0001-6068-182X
Choked flow
Sonic conditions
CFD
Tip gap
Tip leakage
Scraping flow
Pressure profile
INGENIERIA AEROESPACIAL
MAQUINAS Y MOTORES TERMICOS
title_short Numerical Analysis of the Effects of Different Rotor Tip Gaps in a Radial Turbine Operating at High Pressure Ratios Reaching Choked Flow
title_full Numerical Analysis of the Effects of Different Rotor Tip Gaps in a Radial Turbine Operating at High Pressure Ratios Reaching Choked Flow
title_fullStr Numerical Analysis of the Effects of Different Rotor Tip Gaps in a Radial Turbine Operating at High Pressure Ratios Reaching Choked Flow
title_full_unstemmed Numerical Analysis of the Effects of Different Rotor Tip Gaps in a Radial Turbine Operating at High Pressure Ratios Reaching Choked Flow
title_sort Numerical Analysis of the Effects of Different Rotor Tip Gaps in a Radial Turbine Operating at High Pressure Ratios Reaching Choked Flow
dc.creator.none.fl_str_mv Galindo, José|||0000-0001-6068-182X
Tiseira, Andrés-Omar|||0000-0001-9472-2386
Navarro, Roberto|||0000-0003-2587-4954
Echavarria-Olaya, Juan David|||0000-0002-9611-0751
Inhestern, Lukas Benjamin
author Galindo, José|||0000-0001-6068-182X
author_facet Galindo, José|||0000-0001-6068-182X
Tiseira, Andrés-Omar|||0000-0001-9472-2386
Navarro, Roberto|||0000-0003-2587-4954
Echavarria-Olaya, Juan David|||0000-0002-9611-0751
Inhestern, Lukas Benjamin
author_role author
author2 Tiseira, Andrés-Omar|||0000-0001-9472-2386
Navarro, Roberto|||0000-0003-2587-4954
Echavarria-Olaya, Juan David|||0000-0002-9611-0751
Inhestern, Lukas Benjamin
author2_role author
author
author
author
dc.contributor.none.fl_str_mv Departamento de Máquinas y Motores Térmicos
Escuela Técnica Superior de Ingeniería Aeroespacial y Diseño Industrial
Instituto Universitario de Investigación CMT - Clean Mobility & Thermofluids
Ministerio de Universidades
Repositorio Institucional de la Universitat Politècnica de València Riunet
dc.subject.none.fl_str_mv Choked flow
Sonic conditions
CFD
Tip gap
Tip leakage
Scraping flow
Pressure profile
INGENIERIA AEROESPACIAL
MAQUINAS Y MOTORES TERMICOS
topic Choked flow
Sonic conditions
CFD
Tip gap
Tip leakage
Scraping flow
Pressure profile
INGENIERIA AEROESPACIAL
MAQUINAS Y MOTORES TERMICOS
description [EN] To operate, radial turbines used in turbochargers require a minimum tip gap between the rotor blades and the stationary wall casing (shroud). This gap generates leakage flow driven by the pressure difference between the pressure and suction side. The tip leakage flow is largely unturned, which translates into a reduction of the shaft work due to the decrease in the total pressure. This paper investigates the flow through the rotor blade tip gap and the effects on the main flow when the turbine operates at a lower and higher pressure ratio with the presence of supersonic regions at the rotor trailing edge for two rotational speeds using computational fluid dynamics (CFD). The rotor tip gap has been decreased and increased up to 50% of the original tip gap geometry given by the manufacturer. Depending on the operational point, the results reveal that a reduction of 50% of the tip gap can lead to an increase of almost 3% in the efficiency, whereas a rise in 50% in the gap penalty the efficiency up to 3%. Furthermore, a supersonic region appears in the tip gap just when the flow enters through the pressure side, then the flow accelerates, leaving the suction side with a higher relative Mach number, generating a vortex by mixing with the mainstream. The effects of the vortex with the variation of the tip gap on the choked area at the rotor trailing edge presents a more significant change at higher than lower speeds. At a higher speed, the choked region closer to the shroud is due to the high relative inlet flow angle and the effects of the high relative motion of the shroud wall. Furthermore, this relative motion forces the tip leakage vortex to stay closer to the tip suction side, generating a subsonic region, which increases with the tip gap height. The leakage flow at lower and higher rotational speed does not affect the main flow close to the hub. However, close to the shroud, the velocity profile changes, and the generated entropy increases when the flow goes through the tip gap.
publishDate 2022
dc.date.none.fl_str_mv 2022
2022-12-01
dc.type.none.fl_str_mv journal article
http://purl.org/coar/resource_type/c_6501
VoR
http://purl.org/coar/version/c_970fb48d4fbd8a85
dc.type.openaire.fl_str_mv info:eu-repo/semantics/article
format article
dc.identifier.none.fl_str_mv https://riunet.upv.es/handle/10251/193529
url https://riunet.upv.es/handle/10251/193529
dc.language.none.fl_str_mv Inglés
eng
language_invalid_str_mv Inglés
language eng
dc.relation.none.fl_str_mv Ministerio de Universidades MIU FPU18%2F02628
dc.rights.none.fl_str_mv open access
http://purl.org/coar/access_right/c_abf2
Reconocimiento (by)
http://creativecommons.org/licenses/by/4.0/
dc.rights.openaire.fl_str_mv info:eu-repo/semantics/openAccess
rights_invalid_str_mv open access
http://purl.org/coar/access_right/c_abf2
Reconocimiento (by)
http://creativecommons.org/licenses/by/4.0/
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv application/pdf
dc.publisher.none.fl_str_mv MDPI AG
publisher.none.fl_str_mv MDPI AG
dc.source.none.fl_str_mv reponame:RiuNet. Repositorio Institucional de la Universitat Politécnica de Valéncia
instname:Universitat Politècnica de València (UPV)
instname_str Universitat Politècnica de València (UPV)
reponame_str RiuNet. Repositorio Institucional de la Universitat Politécnica de Valéncia
collection RiuNet. Repositorio Institucional de la Universitat Politécnica de Valéncia
repository.name.fl_str_mv
repository.mail.fl_str_mv
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score 15,300719

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