Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~2(~Z54S
- 1
This invention relates to a method and apparatus for
generating hydroelectric power from a waterway, such as a
river.
It is common to use a turbine drivingly connected to
an electric generator to generate hydroelectric power, where
the turbine is positioned in the flow of the waterway, as at
the oot of a dam or other drop in the waterway. The turbine
is commonly positioned so that its axis of rotation is gen-
erally parallel to the flow of water, and its blades are
generally transverse to such flow, with a downstream inclin-
ation thereto. With such an arrangement, the angle of inci-
dence and resultant turbulence of the water impacting with
the blades of the turbine impedes the efficiency of its oper-
ation. This efficiency is further diminished because some
water will flow between the turbine blades without striking
them, with resultant loss of kinetic energy. Thus, the full
force of the falling water is not being utilized to drive the
turbine. Moreover, efficiency of these turbines is not great-
er than 70-80%, with the result that they must be quite large
to e~ficiently produce hydroelectric po~er~ The large size
not only results in difficulty in transport and installation,
but also in a high manufacturing cost.
Addikionally, such turbines are only effective when
used in conjunction with large drops in the waterway, or, as
~S it is phrased in the art, with "high heads", having a minimum
drop of 25 feet. The high head waterway requirement, coupled
with the extremely large capital investment required, severe-
ly limits the number of installations where such turbines can
be economically used.
For these and other reasons, many electric power
authorities have turned away from hydroelectric power genera-
tion to other forms of electrical power generation, particularly
nuclear power, which poses its own set of problems.
lZO;~
-- 2 ~
Conventional water wheels have been used in the past
to drive machinery, particularly with waterways having "low
heads", iOe., drops less than 25 feet. They have not, how-
ever, been used to any degree to generate hydroelectric
power, as they suffer from many of the same problems as do
turbines, having an even lower efficiency. More specifically,
as the water is dropped from above onto the bLades of the
water wheel, much splashing and turbulence is created, with
the result that a large percentage of the water is ~ot re-
tained on the blades of the wheel. Moreover, what water isretained on the blades is often dumped from the wheel in such
a manner so as to impede the further rotation oE the wheel.
That is, the leading edges of the blades continue to be in
contact with a portion of the water beyond the point where
such portion ceases to ex~rt a downward rotational torque on
the wheel, but xather, resists rotation thereof.
The present invention relates to the use of an improved
water wheel for use in the generation of hydroelectric power,
which water wheel overcomes the above limitations of the
prior art.
The novel water wheel of the invention includesa flow-
duct which encloses the blades of the water wheel on three
sides, which directs the flow of water onto the blades of the
water wheel, and which assists in maintaining the water on the
blades so as to take advantage of the full weight of the water
to drive the water wheel. Novel sealing ~lamps form a seal
between the sides of the flow-duct and the sides of the wheel,
further reducing turbulence and loss of water through leakage
and splashing, so as to gain maximum rotational torque from
the water flow.
The point of discharge of the water from the water
wheel can be controlled by the length of the flow-d~ct, so
that the water can be exhausted at a point where it ceases to
exert a downward rotational torque on the wheel.
5~5
_ 3 _
The blades of the water whee] are curved upwardly to
hold more water than a flat blade of similar dimensions.
Water wheels constructed according to ~he invention can
be effectively used with low head waterways having a mod~rate
flow and minimum drop of about 5 ~eet. Where the flow is mo-
derate ~nd the drop is 15 feet, up to approximately 90% effi-
ciency can be achieved, This invention therefore makes many
small waterways available for hydroelectric generation on an
efficient scale for the first -time, While the present inven-
tion may also be used in place of -the aforementioned turbines
for high head hydroelectric generation, where an efficiency
similar to that of the turbine systems can be expected, the
invention is, because of its simple design, installation and
operation, likely to find its most frequent application in
smaller more remote locations, such as Northern ~ntario, where
small waten~ays adaptable to the invention are abundant and
conventional supplies of electric power are not readily
available.
There is thus provided, according to the present inven-
tion, a method of generating hydroelectric power from a lowhead waterway comprising the steps of: channelling water from
the waterway into a spillway; directing -the water from the
spillway onto upwardly curved blades of a water wheel sur-
rounded by a flow-duct so as to cause downward rotational
motion of the wheel; discharging the water from the water
wheel substantially at a point where the water ceases to ex-
ert a downward rotational torque on the water wheel, and
driving electrical generating means from said rotational
movement of the water wheel.
There is also provided according to the present inven-
tion an apparatus for generating hydroelectric power from a
low head waterway comprising: a support structure; a water
S~S
-- 4 --
wheel having upwardly curved blades arranged around its cir-
cumfer~nkial periphery, said water wheel being mounted ~or
rota-tion on the support structure; a flow-duct having two side
walls and a floor together defining a water retention portion
of generally U-shaped cross-section surrounding said periphery
so as to enclose the blades of such peripheral portion on
three sides; sealing means adjustably fitted on the side walls
so as to lessen leakage of water from between said periphery
and said side walls; a spillway having a first higher upstream
end adapted for fluid communication with the waterway and a
second lower downstream end adapted to direct water from the
spilLway onto the blades of the wa-~er wheel so as to cause
xotational movement thereof; and~ electric generating means
drivingly connected to the water wheel.
In order that the invention may be more fully and
readily understood, one embodiment thereof will now be des-
cribed by way of example, with reference to the accompanying
drawings in which:
Figure l is a schematic side elevation, partly in phan-
~o tom, of an apparatus according to the invention;
Figure 2 is a view similar to Figure l~ with the 5Up-
port structure, generating means and drive gearing removed;
Figure 3 is a sectional view along line 3-3 of Figure
2; and
Figure ~ is a perspective view showing in detail a por-
tion of Figure 2~
The device illustrated comprises a water wheel~ gener-
ally designated lO~ which is mounted for rotation about an
axle 11 on a support structure, generally designated 12. Such
mounting is by conventional means, such as by journalling in
a bearing housing 13, which housing can be adjustably positioned
\ .
25~
on the support structure 12 by means of adjustment screws 14.
The water wheel 10 is composed of two annular side
panels 15 and a circumferential peripheral panel 16. The
side and circumferential panels 15,16 are formed of metal,
or other suitable material, and are joined at their common
edges by, for example, welding. It is also possible to con-
struct the wheel 10 with a unitary construction, as where
side and peripheral panels 15,16 are moulded as a single unit
from a lightweight, durable and water resistant material, such
as fibreglass. Axle 11 is mounted in any conventional fashion
at the centre of wheel 10. In the arrangement shown, axle 11
extends through the centre of side panels 15, and is rigidly
affixed to both panels, as by welding, with its free ends
journalled in housing 13. Other conventional mounting ar-
rangements are possible, so long as they allow for relativelyfree rotation of wheel 10 true to centre.
The wheel 10 has arranged around its entire circumfer-
ential periphery, that is upon the outer surface of panel 16,
a plurality of evenly spaced blades 17 of upwardly curved
cross-section. As shown, the blades 17 have a generally con-
cave cross-section with an outer edge 22. It is preferable,
for ease of fabri~ation, maintenance and replacement, that
blades 17 be made of a durable, lightweight, corrosion re-
sistant material, such as for example, aluminum or stainless
steel, and that they have a unit construc~ion. One form of
unit blade construction is readily apparent from Figures 3
and 4, where it will be seen that each blade 17 has an upper
flange 18 and a lower flange 19, drilled to accommodate fast-
ening means such as bolts 20. The upper flange 18 of a blade
30 17 overlaps the lower flange 19 o the blade 17 next above on
the wheel 10, with bolts 20 passing through the aligned holes
21 of the overlapping flanges 18,19, so as to fasten the
flanges 17 to the circumferential panel 16. All of the blades
17 extend axially to, but not beyond, the opposite side panels
.
~z~
-- 6
15 of wheel 10, and all curve in the same direction, that
being upwar~ly at the poxtion of the wheel 10 shown at the
right of Figure 2, which portion is in first contact with
the incoming water flow (shown as a solid arrow at the upper
right of Figure 1). The blades 17 must each he of sufficient
thickness to support a volume of water equal to the volume
defined by the space between two adjacent blades, between
imaginary radial outward projections of both side panels 10
and between the outer edge 22 of each blade 17.
A flow-duct~ generally designated 23, having two side
walls 24 and a floor 25, together defining a water retention
portion, generally designated 47, of generally U-shaped cross-
section, surrounds a peripheral portion of the water wheel 10,
beginning at the point of entry of the water onto the water
wheel (shown to the upper right o~ Figure 1) and ending at
the point of discharge of the water from the wheel 10 (shown
to the lower left of Figure 1) so as to enclose the blades 17
within the peripheral portion of the wheel 10 on three sides
of said blades. The flow-duct 23 is attached to the support
structure 12 by conventional supportin~ means (not shown).
The flow-duct 23 is fabricated from metal or other suitable
material and the two side walls 24 are preferably separated
throughout the water retention portion 47 by a distance just
sufficient to allow the circumferential periphery of the wheel
10 to rotate freely therebetween. The flow-duct 23 is con-
structed and positioned such that the clearance between thefloor 25 and the outer edges 22 of ~lades 17 is only that
necessary for the wheel 10 to freely rotate. The side walls
24 extend radially inwardly toward axle 11 such that they
peripherally cover at least the outer third of the radius of
wheel 10.
A spillway 26 of cement or metal, or other suitable
materials, is disposed at the upper end of the flow~duct 23.
The spillway 26 may open at the top, or, as shown, may be
` 35 enclosed on all sides. The spillway has a first higher
upstream en~ 27 adapted for fluid communication with the
waterway (not shown) and a second lower downstrea~ end 28
adapted to direct water from the spillway 26 onto the blades
17 of the water wheel 10 so as to cause rotational movement
thereof. The upstream end 27 is maintained at a higher level
than the downstream end 28 to racilitate water flow there-
between by means o~ conventional supporting means, such as
brackets 33 embedded in cement columns 29, which are in turn
anchored in ground 30. Similar cement columns 31 may be used
1~ to provide a firm base for mounting support beams 32, to
which beams support structure 12 is anchored in a conventional
manner.
The second end 28 is adapted to direct water from
spillway 26 onto blades 17 by overlying an intake plenum
15 portion 33 of flow-duct 23, which plenum portion 33 prefer
ably is fitted with guide vanes 34 which ser~e to minimize
turbulence in the transfer of the water from spillway 26 to
blades 17 and to structurally reinforce intake plenum por-
tion 33.
As has been previously outlined, the weight of water
flowing from the spillway 26 onto blades 17 causes wheel 10
to be unbalanced, generating a ro~ational torque on the wheel
10 which causes rotational movement of the wheel 10, being
clockwise rotational movement as seen in Figures 1 and 2.
A main spur gear 35 is rigidly affixed to side panel
15 in concentric arrangement with axle 11 so as to rotate
with wheel 10. Subsidiary gearing 36, acting through drive
belt 37, drivinyly connects water wheel 10 to electric gen-
erating means 38 mounted on support beams 32. The electric
generating means is of readily available conventional design.
In the preferred embodiment illustrated~ the retention
portion, defined by side walls 24 and floor 25, terminates
5~5
substantially at a point where the water dumped from the
blades 17 ceases to exert a rotational torque on wheel 10.
Such point is at the nadir of rotation, where the component
of force from the weight of the water is directionally straight
down ~i.e. parallel to the vertical). A discharge portion 38
of the flow-duct 23 preferably begins at the point where the
water retention portion 47 terminates. The floor 25 of the
flow-duct 23 slopes sharply downwardly at the discharge por-
tion 38 so as to facilitate quick discharge of the water from
the retention portion 47 at -the aforementioned point.
Sealing means adapted to lessen leakage of water from
between the water wheel L0 and the re~ention portion 47 of
the flow-duct 23, thus increasing the efficieny of the flow-
duct, are fitted on the side walls 24 of the flow-duct 23.
~s shown in Figure 3, the sealing means preferably comprises
sealing clamps, generally designated 39, constructed of, for
example, light-gage stainless steel, and are disposed, one
each, along the upper free edges 40 of the side walls 24 in
the water retention portion 47 of the flow-duct 23. The
clamps 39 have a generally U-shaped portion 41 adapted to
overlie and releasably grip said free edges 40 of the side
walls ~4 and a flange portion 42 extending downwardly and
axially inwardly toward the side panels 15 of water wheel 10.
The releasable gripping of the free edges 40 is accomplished
by means oE bolts 43 extending through outer wall 44 of clamp
portion 41, in screw-threaded engagement therewith, and through
side walls 24 of flow-duct 23 in screw-threaded engagement
therewith to contact inner wall 45 of clamp portion 41, such
that by adjusting the length of the secti~n of bolts 43 be-
30 tween the side walls 24 of flow-duct 23 and the inner wall 45
of clamp portion 41 of sealing clamp 39, the clearance between
the flange portion 42 of sealing clamp 39 and the side panels
15 of wheel lO can be variably adjusted. Preferably, the
flange portion 42 should be capable of adjustment to within
35 l/8"-3/16" clearance of the side panels 15. The use of light
, . ,
~2~Z~5
g
~age stainless steel or other flexible materials in the con-
struction of the sealing clamps 39 allows a degree of flexion
of the flange portion 42, if contacted by the side panels 15
during rotation of wheel 10.
.
To generate hydroelectric power using the apparatus
herein described, the following steps are followed. After
assembling the apparatus at a suitable site near a natural
or artificial drop in a waterway, water from the waterway is
channelled by any conventional means into a spillway 26. The
water flows along the spillway 26 onto upwardly curved blades
17 of the water wheel 10/ surrounded by flow-duct 23 as here-
inbefore described, thereby causing downward rotational move-
ment (i.e~ clockwise as seen in Figures 1 and 2~ of the water
wheel 10. The water is then exhausted from the water wheel
substantially at a point where it ceases to exert a downward
rotational torque on the water wheel (i.e. substantially at
the nadir o~ rotation). The rotational movement of the water
wheel 10 is used to drive electrical generating means 46 of
conventional design, either directly or through interconnec-
ting gear means.
While but one specific example of the present inven-
tion is herein shown and describedl it will be understood
that various changes in size, shape and arrangement of parts
may be made without departing from the spirit of the inven-
tion. For example, the spillway 26 used need not be as shown,but could, at least in part, be simply a passage through a
cement barrier wall, as for e~ample, a dam, where the dam is
used to enlarge or otherwise alter the waterway. Also, it
is desirable to have the electrical generating means 46
structurally isolated from the water wheel on its own base
separatel~ anchored in the ground 30, and driven from the
wheel 10 by interconnecting drive means, such as a drive
belt, capable of transmitting said drive without transmitting
vibrations from the wheel 10 to the generating means 46 9 or
vice versa.
