Abstrict Improved turbine comprising plural turbine blades supported by
a turbine rotor of a flow meter, each turbine blade having a rounded
leading edge, a feathered trailing edge, a convave top blade surface
and a convex bottom blade surface, the turbine blade tapered from
the leading edge to the trailing edge to form a hydrofoil shape
defined by empirical profile date.
Claims What is claimed is:
1. An improved turbine rotatingly supported in a fluid opening
of a meter housing of a flow meter, the flow meter mounted in a
fluid delivery line for dispensing fluids, the turbine comprising:
a turbine rotor;
a plurality of turbine blades supported by the turbine rotor, each
such turbine blade comprising:
a first end and a second end, the first end attached to the turbine
rotor with the blade extending outwardly therefrom, the second end
having a flattened surface with an aperture therein for receiving
a ferrous slug, the ferrous slug disposed within the aperture so
as to be flush with the flattened surface of the second end;
a rounded leading edge;
a feathered trailing edge;
a first blade surface concave in shape along the length of the
blade, the concave first blade surface disposed to receive fluid
flow thereagainst to rotate the turbine; and
an opposed second blade surface convex in shape along the length
of the blade, the blade tapered from the rounded leading edge into
the feathered trailing edge so that the blade has a hydrofoil shape.
2. Improved turbine blades mounted in a spaced relationship to
each other on a turbine rotor of a turbine, the turbine received
in a fluid opening of a meter housing of a flow meter, the flow
meter mounted in a fluid deliver line for dispensing fluids, each
turbine blade comprising:
a first end and a second end, the first end attached to the turbine
rotor with the blades extending outwardly therefrom, the second
having a flattened surface portion and including an aperture therein
for receiving a ferrous slug, the ferrous slug being disposed within
the aperture so as to be flush with the flattened surface portion
of the second end;
a rounded leading edge;
a feathered trailing edge;
a first blade surface, the first blade surface concave in shape
along the length of the blades, the concave first blade surface
receiving the force of fluid flow thereagainst to rotate the turbine
rotor; and
an opposed second blade surface, the second blade surface convex
in shape along the length of the blades, the blades, when viewed
end to end, are tapered from the rounded leading edge into the feathered
trailing edge and have a hydrofoil design.
3. The turbine blades of claim 2 wherein four such blades with
the first ends thereof attached to the turbine rotor at 90.degree.
separations between adjacent blades.
4. In a flow meter mounted in a fluid delivery line for dispensing
fluids, the flow meter having a turbine with a turbine rotor having
plural turbine blades extending therefrom and rotatably supported
in a fluid opening of flow meter along the centerlines along the
length of the flow meter opening and the centerline of the turbine
rotor being coincident, and wherein each turbine blade comprises:
a first end and a second end, the first end attached to the turbine
rotor with the blade extending outwardly therefrom;
a leading edge made up of a rounded nose, the front of the nose
disposed below the centerline of the turbine rotor when viewing
the blade end to end;
a feathered trailing edge;
a first blade surface, the first blade surface concave in shape
along the length of the blade, the concave first blade surface receiving
the force of fluid flow thereagainst and driving the turbine, the
concave first blade surface disposed above the centerline of the
turbine rotor when viewing the blade end to end; and
an opposed second blade surface, the second blade surface convex
shaped along the length of the blade, the convex second blade surface
disposed below the centerline of the turbine rotor and extending
upwardly above the centerline, the blade when viewed end to end
being tapered from the rounded leading edge into the feathered trailing
edge so that the blade profile forms a hydrofoil shape.
5. The turbine blades of claim 4 in which the second end of each
turbine blade has a flattened surface having a bore, the turbine
blade further comprising:
a ferrous slug disposed in the bore and flush with the flattened
surface of the turbine blade second end.
Description BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to fluid flow measurement,
and more particularly, but not by way of limitation, to turbine
blade improvements for a flow meter.
2. Brief Description of the Prior Art
Heretofore, the size and complexity of fluid flow meters precluded
the use of a flow meter which could be used and read at a point
of delivery when the fluid is being dispensed. Further, flow meters
with normal turbine blades used a flat blade profile of machined
metal which is expensive. Also, the high cost of existing self-contained
battery powered equipment limited this type of equipment for use
by the average consumer.
In the past there have been various types of flow meters with different
types of read-out counters and blade designs. These types of flow
meters are disclosed in the following U.S. Patents: U.S. Pat. Nos.
3329021 to Quesinberry, 3370465 to Belle, 3774448 to Gass
et al., 3823310 to Kalotay, et al., 4265127 to Onoda, 128338
to Van Anden, 3084545 to Waugh, 3238776 to Potter, 3757578
to Clinton, 3452593 to Lauter, Jr., 3534602 to Boyd, 3623835
to Boyd, 3945253 to Lui et al. and 4253341 to Ikeda et al.
None of the above-mentioned patents specifically discloses the
unique structure and advantages of the subject improved turbine
blade used in a turbine flow meter.
SUMMARY OF THE INVENTION
The present invention provides an improved turbine having turbine
blades mounted on a turbine rotor in spaced relationship to each
other, the turbine rotatingly supported in a fluid opening of a
flow meter housing mounted in a fluid delivery line for dispensing
fluids. Each blade of the turbine has a first end attached to the
turbine rotor and a second end flattened with an aperture therein
for receiving and retaining a ferrous metal slug. Each blade has
a rounded leading edge and a feathered trailing edge with a concave
top blade surface for receiving fluid flow thereagainst to rotate
the turbine. The bottom surface of each blade is convex in shape,
and each blade is tapered from the rounded leading edge into the
feathered trailing edge so as to form a hydrofoil shape.
One object of the invention is to provide an improved turbine having
turbine blades each of which has a profile which insures greater
fluid measurement accuracy of fluid delivered through a flow meter,
the design of the turbine blades empirically derived to determine
a straight line constant "K" factor, over a wide range
of flow rates, to insure accuracy of fluid delivered.
Another object of the subject invention is to eliminate the need
for machining flat profile turbine blades which is expensive. The
turbine blades may be molded using a plastic material and the like
with the normal flat profile of the blades modified to provide room
for ferrous metal slugs mounted in the ends thereof.
Other objects, advantages and features of the present invention
will become clear from the following detailed description of the
preferred embodiment when read in conjunction with the drawings
and the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a flow meter with turbine and stationary
shaft supports positioned for assembly in the meter.
FIG. 2 illustrates a side view of the turbine mounted on the stationary
shaft supports.
FIG. 3 is a front view of the turbine.
FIG. 4 illustrates a plot of a "K" factor (pulses per
unit measure) and flow rate (i.e. gpm)
FIG. 5 illustrates an enlarged end view of the turbine blade profile.
DETAILED DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a partially assembled flow meter designated by general
reference numeral 10. The flow meter 10 includes a meter housing
12 having a display cavity 14 for receiving a liquid crystal display
16 with a digital counter incorporated therein. The counter is not
shown in the drawing. The cavity 14 is also used for receiving electronic
counter controls therein. The meter housing 12 further includes
a fluid opening 18 therethrough with opposite ends 20 and 22 threaded
for coupling a delivery line. The direction of fluid flow is indicated
by arrows 24.
A turbine designated by general reference numeral 26 is disposed
inside the opening 18. The turbine 26 includes a turbine rotor 28
with a plurality of turbine blades 30 equally spaced around the
turbine rotor 28 and extending outwardly therefrom. In this figure
and FIG. 2 the turbine 26 is shown with four blades 30 attached
to the rotor 28 and at right angles to each other. Mounted in the
ends of the blades 30 are ferrous metal slugs 32. The turbine 26
further includes a turbine shaft 34 received therethrough and mounted
on support bearings 36. The support bearings 36 are received in
a pair of support bases 38 which are a part of a pair of shaft supports
40. Each of the two shaft supports 40 include a plurality of support
arms 42 extending outwardly from the support base 38 with the ends
of the support arms 42 secured to the sides of the fluid opening
18 and held therein by split rings 44 received in opposite ends
20 and 22 of the opening 18 of the meter housing 12.
In FIG. 2 the turbine 26 with shaft supports 40 are shown in a
side view removed from the meter housing 12. In this figure the
two support bases 38 are partially cutaway to expose fluid ports
45 therethrough. The fluid ports 45 receive fluid, flowing in the
direction of arrows 24 for acting as a washing and cooling agent
around and beside the turbine shaft 34 and shaft bearings 36. In
this side view an end to end profile of one of the turbine blades
30 with ferrous metal slug 32 is shown. The unique profile features
of the blade 30 are discussed in greater detail under the description
of FIG. 5.
As the turbine blades 30 rotate on the turbine 26 and turbine shaft
34 in the opening 18 the ferrous slugs 32 move adjacent the outer
periphery of the opening 18 and past a pickup coil having a magnet
mounted in the end thereof. The pickup coil and magnet are not shown
in the drawings. The pickup coil converts the magnetic pulses received
by the magnet to a readable electrical count which is sent to a
microprocessor. The microprocessor is part of the liquid crystal
display 16. The above-mentioned electrical controls are powered
by a pair of batteries received in the display cavity 14. The operation
of the pickup coil, magnet and electrical controls of the flow meter
10 are discussed more fully in U.S. application Ser. No. 826297
by the subject inventor. This structure, while very important, is
not part of the subject invention as described herein.
Referring now both to FIG. 3 which shows a front view of the turbine
26 with blades 30 and FIG. 5 which illustrates an enlarged end
to end view of one of the blades 30 each blade 30 has a leading
edge 46 made up of a rounded nose 48 which tapers upwardly into
a feathered trailing edge 50. Each blade 30 includes a first end
52 which is secured to the sides for the turbine rotor 26 and equally
spaced therearound. While four blades 30 are shown in FIGS. 1 2
and 3 it should be appreciated that any practical number of blades
30 could be used that are consistent with the critical demands required
in the accurate measurement of fluid flow through the flow meter
10. A second end 54 is flattened with an aperture or bore 56 therein
for receiving the metal slug 32. The end of the slug 32 is flush
with an outer edge or side 58 of the second end 54 and the side
58 is rounded as shown in FIG. 3 to correspond with the circumference
of the fluid opening 18.
In FIGS. 1 2 3 and 5 a centerline 60 is shown through the center
of the fluid opening 18 through the center of the turbine rotor
28 and through the center of the metal slug 32 in the blade 30.
The centerline 60 is shown as a point in FIG. 3. From reviewing
FIG. 3 and FIG. 5 it will be noted that the rounded nose 48 of the
leading edge 46 is below the centerline 60 with the top of the nose
48 merging into a concave top blade surface 62. The concave top
blade surface 62 flows upwardly into the feathered trailing edge
50. The bottom of the nose 48 flows slightly downward and then upwardly
into a convex bottom blade surface 64. The concave top blade surface
62 is disposed above the centerline 60 and receives the force of
fluid flowing in direction 24 to rotate the turbine 26. By positioning
the rounded nose 48 below the centerline 60 the angle of attach
in engaging the fluid is improved. When viewing the blade 30 end
to end as shown in FIG. 2 and FIG. 5 it will be noted that it has
a hydrofoil type shape with the concave top blade surface 62 and
the convex bottom blade surface 64 tapered upwardly at an angle
in the range of 40.degree. as shown.
FIG. 4 illustrates how the unique shape and design of the turbine
blades 30 influence the performance and accuracy of the amount of
fluid delivered by the flow meter 10. It has been found that the
shape of the blades 30 directly influence the "K" factor
(pulses per unit measure) over a certain flow range. The vertical
line in FIG. 4 shows flow rate from 0 to 40 gallons per minute.
Ideally the "K" factor should be a vertical line when
plotting the "K" factor vs. flow rate. But as a practical
basis, the "K" factor curve shown as line 66 is not a
vertical line and has some slope to it; also, at the low end the
line 66 has a "knee" shape.
From viewing FIG. 4 it can be appreciated that once the flow meter
10 has begun delivering fluid and at a volume greater than 2 gals.
per minute, the pulses per unit measured are plus and minus 1.5%
accurate. In this example the pulses number approximately 770 per
unit delivered. The straight line constant of the "K"
factor helps insure accuracy in the amount of fluid delivered into
a storage tank, through a pipeline and similar applications.
To obtain as near as possible the straight line constant of the
"K" factor, the shape of blade 30 was empirically derived
through trial and error. Once bench testing was complete, computer
aided design was used "to determine the shape of the blade
30."
The turbine blade design can be described using typical aircraft
wing terminology. The blade 30 when viewed end to end is a thick
subsonic highly cambered airfoil with a relatively small leading
edge radius. As mentioned above the blade angle is in a range of
40.degree. from the horizontal. The blade or airfoil also has a
trailing edge radius as opposed to a sharp or pointed trailing edge.
The concave top blade surface 62 acts as a positive-pressure area
while the convex bottom blade surface 64 acts as a suction-negative
pressure area. The camber line of the blade 30 is displaced below
the cord line and toward the convex bottom blade surface 64. When
viewing the blades 30 along the axis 60 as shown in FIG. 3 the
blades 30 provide a high solidity ratio which is typical in the
handling of fluids at subsonic speed.
As mentioned above, extensive testing of various blade designs
was conducted with fluids of different viscosities. The unique profile
of the blade 30 provided superior performance in a turbine used
with a flow meter to accurately and consistantly deliver and measure
a desired fluid quantity.
It is clear that the present invention is well adapted to carry
out the objects and to attain the ends and advantages mentioned
herein as well as those inherent in the invention. While presently
preferred embodiments of the invention have been described for the
purposes of this disclosure, numerous changes may be made which
will readily suggest themselves to those skilled in the art and
which are encompassed within the spirit of the invention disclosed
and as defined in the appended claims. |