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SUMMARY:Modelling the reduction of installed jet noise by using swept trai
 ling edges - Dr Benshuai Lyu (DAMTP\, University of Cambridge)
DTSTART:20180531T100000Z
DTEND:20180531T110000Z
UID:TALK106093@talks.cam.ac.uk
CONTACT:Matthew Priddin
DESCRIPTION:Jet noise still dominates aircraft noise during take-off. With
  the aim of reducing jet noise and increasing engine efficiency\, modern a
 ircraft engines grow increasingly large. However\, the increasingly large 
 engine diameter leads to an increase of jet noise\, which is commonly know
 n as installed jet noise. Previous experiments have shown that using an ai
 rcraft wing with a swept trailing edge reduces installed jet noise. Howeve
 r\, its mechanism remains to be known and its modelling heavily relies on 
 numerical procedures. In this talk\, I will present a robust and efficient
  semi-analytical model that is newly developed to model the sound due to t
 he scattering of instability waves by an aircraft wing with a swept traili
 ng edge. The model is based on the Schwartzchild method and the Amiet's ap
 proach is used to obtain the far-field sound. The model can correctly pred
 ict both the reduction in installed jet noise and the change to directivit
 y patterns observed in experiments due to the use of swept wings. It is fo
 und that the principle physical mechanism of sound reduction is the destru
 ctive interference effect. It is concluded that in order to obtain an effe
 ctive noise reduction\, both the span and the swept angle of the wing have
  to be large.
LOCATION:CMS\, MR11
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