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Fan Blade Vibrations in Synchronous Machines
KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
2016 (English)Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

The design of a fan structure should be made in relation to both an aerodynamic aspect as well as a structural point of view to avoid both self-excited vibrations and forced response. If the blades start to vibrate it can cause high cycle fatigue until they break and cause severe damage. Research in the aerodynamic area is moving forward with an increase in computer power. It is however difficult and very time demanding to calculate the behavior of complex structures.Using an analytical approach on the other hand may lead to a very conservative design. This work has its focus on the structural point of view with a design of the blades towards best aerodynamic stability and to make the design procedure at ABB better towards an optimization. The theory describes the aerodynamic phenomena, structural dynamics as well as analyzing techniques to avoid high cycle fatigue.The analyzing techniques described in the theory have been applied to two different fan geometries used by ABB today. A new design procedure has been made to get a higher degree of freedom for more machine sizes as well as to save material and to get a safer structure.

Abstract [sv]

Designen på ett fläktblad måste vara utformat både i relation till en aerodynamisk aspekt lika mycket som till en strukturell aspekt för att undvika själv-exciterade vibrationer så väl som påtvingade vibrationer. Om bladen börjar vibrera och energi tillförs på bladen från luftflödet eller andra faktorer så att vibrationerna ökar för varje cykel kan detta leda till att bladen bryts av och orsakar stora skador. Forskning inom det aerodynamiska området går framåt i förhållande till ökad datorkraft. Ändå är det svårt och väldigt tidskrävande att räkna ut beteendet på komplicerade strukturer. Med hjälp av en analytisk tillämpning kan man dock hitta en konservativ design. Detta arbete har fokus på den strukturella aspekten med bästa möjliga aerodynamiska stabilitet och att kolla på ABB´s design för bästa optimering. Teorin beskriver det aerodynamiska och strukturella fenomenet men också olika tekniker för hur man undviker utmattning av bladen. Analysteknikerna som är beskrivna i teorin är applicerade på två olika fläktgeometrier som används av ABB idag. En ny design har tagits fram som kan ge större möjligheter.

Place, publisher, year, edition, pages
2016. , p. 42
National Category
Mechanical Engineering
Identifiers
URN: urn:nbn:se:kth:diva-200345OAI: oai:DiVA.org:kth-200345DiVA, id: diva2:1068437
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Examiners
Available from: 2017-01-25 Created: 2017-01-25Bibliographically approved

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CiteExportLink to record
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