Swan neck duct

A swan neck duct is a jet engine component, usually situated within the compression or turbine expansion system.{{cite book|last1=Soares|first1=Claire|title=Gas Turbines: A Handbook of Air, Land and Sea Applications|date=23 October 2014|publisher=Elsevier|isbn=9780124104853|page=179|url=https://books.google.com/books?id=ubJZAwAAQBAJ&q=swan+neck+duct+-wikipedia|accessdate=27 August 2016|language=en}}

Many jet engines have a short annular passageway, linking two components, where there is a large change in mean radius, from front to rear. The shape of the resulting passageway is often similar to that of a swan or goose neck. Consequently, such a passageway is called a swan (or goose) neck duct. The duct provides a continuous matching of the flows between the high pressure and low pressure turbines and a diffusion of the flow upstream of the low pressure turbine. For the latter purpose a swan neck duct is an example of an inter-turbine diffuser.{{cite conference|last1=Dominy|first1=Robert G.|last2=Kirkham|first2=David A.|title=The Influence of Blade Wakes on the Performance of Inter-Turbine Diffusers|conference=ASME 1994 International Gas Turbine and Aeroengine Congress and Exposition|date=13 June 1994|volume=1|pages=V001T01A072|doi=10.1115/94-GT-207|isbn=978-0-7918-7883-5|url=http://proceedings.asmedigitalcollection.asme.org/proceeding.aspx?articleid=2143575|accessdate=28 August 2016|doi-access=}}