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Heat-transfer simulations applied to electrical machines
KTH, School of Engineering Sciences (SCI), Engineering Mechanics.ORCID iD: 0000-0001-5143-2143
2020 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Electrification and energy efficiency are two important aspects in present scenarios describing a sustainable future. Electric motors constitute a large fractionof industry’s electricity demand today, and it is expected to remain high inthe future. Electrification of the transport sector is expected in a sustainabledevelopment scenario, leading to a large increase in electric vehicles. Theirpropulsion systems will contain one or several motors.Development of new energy efficient motors and generators requires highresolution methods for studying and describing heat transfer phenomena. Thissince temperature level affects a motors efficiency and effective and efficientcooling allows for using less active material in the motor.In this work simulations of temperature distribution in a motor for tractionapplications are performed with different specifications of the loss distributionand distribution of coolant flow. Simulation results are compared to measuredvalues. The comparison shows how the simulation results differ in comparisonto the measurements. It can be concluded that attention needs to be paid tohow the simulation is defined when comparing to measured data.In establishing high resolution simulation approaches, the heat transfersystem constituting of an impinging jet on a flat plate is considered as aprototype problem. A Large-Eddy Simulation (LES) approach is employed tostudy the heat transfer and gather heat transfer data. Statistical analysis ofsampled heat transfer data shows behavior which is previously unpublished.The application of Proper Orthogonal Decomposition (POD), on the heattransfer field, and Extended Proper Orthogonal Decomposition (EPOD), linkingheat transfer modes with fluid flow modes, regarding the impinging jet systemis performed for the first time. The results show a clear correlation betweenstructures in the heat transfer field and structures in the fluid flow field.The investigated simulation methods and approaches can be employed instudies of heat transfer in electric machines.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2020. , p. 47
Series
TRITA-SCI-FOU ; 41
Keywords [en]
energy efficiency, heat transfer, electric machines, high fidelity simulation, modal analysis
National Category
Fluid Mechanics Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Engineering Mechanics; Electrical Engineering
Identifiers
URN: urn:nbn:se:kth:diva-286686ISBN: 978-91-7873-723-9 (print)OAI: oai:DiVA.org:kth-286686DiVA, id: diva2:1504375
Presentation
2020-12-18, Live-streaming via Zoom: https://kth-se.zoom.us/j/69094308730, Stockholm, 14:00 (English)
Opponent
Supervisors
Funder
Swedish Foundation for Strategic Research Available from: 2020-11-27 Created: 2020-11-27 Last updated: 2025-02-09Bibliographically approved
List of papers
1. Thermal Modelling of Totally Enclosed Fan Cooled motors
Open this publication in new window or tab >>Thermal Modelling of Totally Enclosed Fan Cooled motors
2018 (English)Conference paper, Published paper (Refereed)
Abstract [en]

This paper undertakes an investigation into thermal modelling of Totally Enclosed Fan-Cooled (TEFC) motors used in traction applications. In the process, a 3D Computational Fluid Dynamics (CFD)-based Conjugate Heat Transfer (CHT) model is utilized, including the realistic stator geometry with cooling channels and considering the rotor rotation through the multiple reference frame approach. Extended air flow measurement data are used to determine the modelled air speed through the cooling channels and account for the impact of partial duct blockage. Loss distributions obtained via a transient electromagnetic Finite Element (FE) model are used in the process of heat source definition. Additionally, a simplified net radiation model is integrated in the boundary definitions along with natural convection. The main purpose of this paper is to highlight how different modelling approaches affect the obtained temperature distribution. The particular focus of this work is on the stator side and can be extended to various rotor structures. The methodology developed is applied for the thermal characterization of a prototype Interior Permanent Magnet (IPM) motor.

National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering Fluid Mechanics
Research subject
Engineering Mechanics; Electrical Engineering
Identifiers
urn:nbn:se:kth:diva-286679 (URN)978-1-5386-2477-7 (ISBN)
Conference
XIII International Conference on Electrical Machines (ICEM)
Note

QC 20201216

Available from: 2020-11-27 Created: 2020-11-27 Last updated: 2025-02-09Bibliographically approved
2. Large Eddy Simulation of Circular Impinging Jet for Heat Transfer Applications
Open this publication in new window or tab >>Large Eddy Simulation of Circular Impinging Jet for Heat Transfer Applications
2019 (English)In: Proceedings XII ERCOFTAC Workshop Direct and Large Eddy Simulation / [ed] Manuel García-VillalbaHans KuertenMaria Vittoria Salvetti, Springer Nature , 2019, Vol. 27, p. 69-75Conference paper, Published paper (Refereed)
Abstract [en]

Impinging jets are being used in a wide range of applications, e.g., food processing, turbine blade cooling, and automobile windscreen defrosting. While early studies are about half a century old, impinging jets are still being explored and new features are revealed constantly through experimental and numerical investigations.

Place, publisher, year, edition, pages
Springer Nature, 2019
National Category
Fluid Mechanics
Identifiers
urn:nbn:se:kth:diva-286682 (URN)10.1007/978-3-030-42822-8_9 (DOI)2-s2.0-85085202396 (Scopus ID)
Conference
ERCOFTAC Workshop Direct and Large Eddy Simulation XII
Funder
Swedish Foundation for Strategic Research
Note

QC 20210114

Available from: 2020-11-27 Created: 2020-11-27 Last updated: 2025-02-09Bibliographically approved
3. Heat transfer and associated coherent structures of a single impinging jet from around nozzle
Open this publication in new window or tab >>Heat transfer and associated coherent structures of a single impinging jet from around nozzle
(English)Manuscript (preprint) (Other academic)
National Category
Fluid Mechanics
Identifiers
urn:nbn:se:kth:diva-286684 (URN)
Funder
Swedish Foundation for Strategic Research
Note

QC 20201216

Available from: 2020-11-27 Created: 2020-11-27 Last updated: 2025-02-09Bibliographically approved

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