Notes on Ducted Fan Design

Abstract

In general, conventional compressor stages are designed by the cascade method, while high stagger low solidity ducted fans are designed on modified isolated aerofoil theory. The purpose of these notes is to provide a basis for disussion on the relative merits of the two methods and on the desirabi1ity of extending one method to cover the whole range of blading likely to be required in compressors and fans. Attention has been mainly oonfined to low speed two-dimensional considerations. It is suggested that the cascade approach could provide a basis for the formulation of a unified design method. A project of this nature mould necessitate a programme of testing and performance analysis of typical fans; high stagger cascade tests might also provide supporting data, although there could be doubts as to their sigmficance.