Thrust deduction and a proposed formula for its radial distribution

Abstract

A general introduction is given about wake and thrust-deduction. Several theories about the nature of thrust deduction are dealt with. It appears that the part of the thrust deduction, arising from circumferential inequality of the velocity field, consists mainly of frictional thrust deduction.

A new concept, the local thrust deduction coefficient, is introduced and a formula is given with which it is possible to calculate the radial distribution of the local thrust deduction over the screw disc.

It appears from calculations that the relation between local and total thrust deduction and wake coefficients can approximately be given by the formula: $${\displaystyle \frac{1-{\mathit{t}}^{\prime }}{1-\mathit{t}}}={\left({\displaystyle \frac{1-{\mathit{w}}^{\prime }}{1-\mathit{w}}}\right)}^{\frac{1}{4}}$$