Improvements in Rotating Ventilators or Fans.
Year: 1897

page_text: Date of Application, 13th Feb., 1897-Accepted, 20th Mar., 1897
Improvements in Rotating Ventilators or Fans.
I, HENRY HAUSER, Civil Engineer of Madrid, Spain, 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 :-
This invention relates to the construction of rotary ventilators or fans or air
propellers running at speeds exceeding a hundred revolutions per minute, as for
example two hundred, these fans being of the kind to give the air or other gas.
with which. they are surrounded a motion parallel to the axis of rotation of
the fan.
Hitherto it has been usual to design such fans for high speeds with the same.
number of blades, as those intended for low speeds without regard to the fact that
in high speed fans a large number of blades causes useless churning of the air and
waste of power as each blade tends to interfere with and obstruct air already set.
in motion by preceding blades.
According to my invention I therefore use a small number of blades spacing
them in such a way that air set in motion by one blade is not obstructed by a.
following blade, the number and arrangement of the blades being designed to suit
the speed at which the fan is intended to work. Preferably 1 construct such fans
with only two or three blades.
The form of the blades is such as to give the air a direction of motion parallel
to the axis of rotation only giving them a curvature determined in the following.
way:
Each blade in the flat is of a trapezoidal form as shown in Figures 1 and 2.
The narrower end B being that next the axis and the wider end A at the
periphery. The outer corners may be rounded as in Figure 1 and the sides may
be curved as shown in Figure 2. The blade is so bent as to make an angle with
the plane of rotation decreasing from the axis to the periphery in order to give
uniform impulse to the air in all parts of the plane of rotation. If the section of
the blade is a straight line the angles of this line at the axis and periphery are not
greater than 45° and 25° respectively as shewn in Figures 3 and 4.
3
If the section of the blade is a curve, this curve is convex on the suction side.
marked with an arrow in Figures 4 and 6, and concave on the delivery side, and is.
unsymmetrical in reference to the axis of rotation BA as shewn in Figures 5
and 6 where it will be scen that a tangent to the curve at the leading or forward
edge makes an angle not exceeding 30° next the axis and 6° at the periphery of
the blade and that a tangent to the curve at the following edge makes an angle not
exceeding 50° next the axis and 30° at the periphery so that the air is gradually
set in motion in the desired direction without churning it or imparting wasteful
motion in other directions.
Having now particularly described and ascertained the nature of this inven--
tion and in what manner the same is to be performed, declare that what 1
claim is:
1. In high speed ventilators or fans the use of such a number of blades that the
air set in motion by one blade is not interfered with or obstructed by a following
blade.
2. Making each blade with an inclination to the plane of rotation gradually-

page_text: decreasing from the axis to the periphery so that approximately the same velocity
in a direction parallel to the axis is imparted to the air throughout the length of
the blade.
3. Making each blade with curvature such as to set the air in motion gradually
and in a direction parallel to the axis.
Dated this 13th day of February 1897
ABEL & IMRAY,
Agents for the Applicant.