Theory of the Ducted Propeller — A Review 



Table 1 

 Comparison of Predictions of Two Models 



3(r^ r,)3r 



37 /dt 



Fig. 21 - (See (157)) Vortex system 

 of the ducted propeller at angle of 

 attack 



assumed to convect downstream with speed v. Each bound ring vortex, there- 

 fore, contributes a semi-infinite cylinder of straight trailing vortices. The cor- 

 responding shed vortices By/Bt constitute a similar cylinder composed of ring 

 vortices. The trailing vortices from the l-th propeller blade -3(r+ ri)/3r 

 are also assumed to convect downstream with speed V, forming regular helices 

 with advance ratio U/Qr. The shed vortices -Bfi/3t emitted from each blade 

 fall on these helices and are perpendicular locally to the trailing vortices. The 



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