Improvements in Screw Fans and Propellers.
Year: 1893

page_text: Date of Application, 23rd Dec., 1893
Complete Specification Left, 14th Sept., 1891-Accepted, 27th Oct., 1894
PROVISIONAL SPECIFICATION.
Improvements in Screw Fans and Propellers.
I, GEORGE THEODORE SEYDEL, of 177 Müllerstrasse, Berlin, N., Germany,
Engineer and Manufacturer, do hereby declare the nature of this invention to be as
follows:-
For imparting motion to air and water under conditions of small resistance
to motion or heights to be traversed, screw fans and propellers have heretofore
been employed the blades of which have had either flat surfaces arranged obliquely
to the axis of rotation, or screw-shaped surfaces. The fans or propellers provided
with blades having screw-shaped surfaces have had a superior useful effect to those
having blades with flat surfaces, but they are considerably more difficult to
construct than the latter.
Now this invention has reference to the construction of screw fans and propellers
the blades of which are quite as easy and simple to construct as the fans or
propellers provided with flat wings, and yet are of even higher efficiency than those
having screw-shaped blades as heretofore constructed.
According thereto that portion of each blade which constitutes the front or
forward portion of the blade during the rotation of the fan or propeller is made as
an unbroken, suitable flat surface arranged at an angle to the plane containing the
axis of rotation, whilst the succeeding or rearward portion of the blade is divided
into several distinct parts which are bent outwards at different angles of inclination
to a plane arranged at right angles to the axis of rotation, in such a way that the
part nearest the centre of motion has the greatest angle of inclination to the said
plane, whilst the said angle is less for each succeeding part, so that at the outermost
part it is the least inclined. In consequence of this arrangement the particles of air
acted upon by the blades are moved outward, or in a radial direction, to a less
degree by centrifugal force than would otherwise be the case.
The greatest action which the blade exerts upon the particles of air or water to
be moved takes place on its surface, and owing to the fact that this surface is
interrupted, the action which is exerted by centrifugal force in a radial direction is
also interrupted. Particles of air that pass beyond the outer edge of the innermost
part of the blade enter a body of air which is less dense and is less strongly urged
by centrifugal force. They can consequently increase only in a small degree the
motion of the particles under the influence of the next outermost part of the
blade. The same takes place with reference to the particles of air passing the outer
edge of the last mentioned part of the blade. It has been found by experiment
that the velocity of the fluid set in motion by fans or propellers of the construction
described, is more uniform at all parts of the cross section of the fluid in motion,
than in ordinary screw propellers. On the other hand however, it has been found
disadvantageous to also interrupt the forward-edge of the blade in a like manner to
the rearward-edge and consequently disadvantageous to construct each of the blades
as a number of surfaces separated from one another.
A screw fan or propeller constructed according to this invention may be employed
as a ship's propeller as well as for imparting motion to air and water."
Dated this 23rd day of December 1893.

page_text: improvements in Screw Fans and Propellers.
I, GEORGE THEODORE SEYDEL, of 177 Müllerstrasse, Berlin, N., Germany,
Engineer and Manufacturer, do hereby declare the nature of this invention and
in what manner the same is to be performed to be particularly described and
ascertained in and by the following statement :-
For imparting motion to air and water under conditions of small resistance to
motion or heights to he traversed, screw fans and propellers have heretofore been
employed, the blades of which have had either flat surfaces arranged obliquely to
the axis of rotation, or screw-shaped surfaces. The fans or propellers provided
with blades having screw-shaped surfaces have had a superior useful effect to those
having blades with flat surfaces but they are considerably more difficult to construct
than the latter.
Now this invention has reference to the construction of screw fans or propellers
the blades of which are quite as easy and simple to construct as the fans or propellers
provided with flat wings yet which are of even higher efficiency than those having
screw-shaped blades as heretofore constructed.
In the accompanying drawings,
Fig. 1 shows in front elevation, a screw fan or propeller constructed according to
my invention; and
Fig. 2 shows in plan to a larger scale, the construction of one of the blades.
As will be seen from these figures, that portion a of each blade which constitutes
the front or forward portion of the blade during the rotation of the fan or propeller,
is made as an unbroken, suitable flat surface arranged at an angle to the plane
containing the axis of rotation, whilst the succeeding or rearward portion of the
blade is divided into several distinct parts b, c, d, which are bent outwards at
different angles of inclination to a plane arranged at right angles to the axis
of rotation, in such a way that the part nearest the axis of rotation has the
greatest angle of inclination to the said plane, whilst the said angle is less for each
succeeding part, so that the outermost part is the least inclined. In consequence of
this arrangement when the fan or propeller is rotated in air, the particles of air
which are pushed forward by the blades will be moved in a radial direction, by
centrifugal force to a less degree than would otherwise be the case.
The greatest
action which the blade will exert upon the particles of air to be moved, will take
place on its surface; and owing to the fact that this surface is interrupted, the
action, which will be exerted by centrifugal force in a radial direction, will be also
interrupted. Particles of air that pass beyond the outer edge 6 of the innermost
part of the blade will enter a body of air that is less dense and is less strongly
urged by centrifugal force. They can consequently increase only in a small degree
the radial motion of the particles under the influences of the next part c of the
blade. The same action will take place with reference to the particles of air
passing the outer edge c' of the part c. It has been found by experiment, that the
velocity of the fluid set in motion by fans or propellers of the construction described,
is more uniform at all parts of the cross section of the fluid in motion, than in
ordinary screw propellers. On the other hand, however, it has been found
disadvantageous to interrupt the forward portion of the blade in a like manner to
the rearward portion and consequently disadvantageous to construct each of the
blades as a number of surfaces separated from one another.
A screw fan or propeller constructed according to this invention may be
employed as a ship's propeller as well as for imparting motion to air and water.

page_text: Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
A screw fan or propeller the blades of which each consists of a forward portion a
formed with an uninterrupted surface inclined to the axis of rotation of the fan or
propeller and of a rearward portion which is divided into several parts b, c, d, bent
at different angles to a plane at right angles to the said axis of rotation,
substantially as hereinbefore described with reference to the accompanying
drawings.
For the Applicant,
W. LLOYD WISE,
46, Lincoln's Inn Fields, London, W.C., Chartered Patent Agent.