[0001] This invention relates to equipment designed for pumping fluids and can be used in
industry, agriculture and in household.
[0002] There is a known centrifugal pump impeller, containing vanes with curvature in one
plane [
CN2204344, priority date 2.08.1993, publication date 2.08.1995, MPC: FO4D 07/04].
[0003] There exists a centrifugal pump impeller, containing vanes with curvature in one
plane [
CN205779755, priority date 19.05.2016, publication date 7.12.2016; MPC: FO4D 13/06].
[0004] The centrifugal pump impeller with vanes curving in one plane, with an angle between
the line tangent to the trailing edge of a vane and the line tangent to the circumference
of the impeller in the 15°-27° range.
15 - 27 range [
CN204152837); priority date 15.10.2014; publication date 11.02.2015; MPC: F04D 29/24] was chosen
for this invention as its prototype.
[0005] The drawback of the prototype is that fluid moves slowly at the impeller outlet due
the small angle between the line tangent to the trailing edge of a vane and the line
tangent to the circumference of the impeller. Increasing that angle would result in
hydrodynamic losses and would reduce the efficiency coefficient of the impeller, which
impairs service characteristics of the centrifugal pump.
[0006] The technological problem this invention aims to solve, is improving exploitation
characteristics of centrifugal pumps.
[0007] The technological result achieved by this invention is a greater centrifugal pressure
generated, while the efficiency coefficient of the centrifugal pump impeller is not
affected.
[0008] The essence of the invention is as follows.
[0009] Proposed a centrifugal pump impeller, characterized by the angle between the line
tangent to the trailing edge of a vane and the line tangent to the circumference of
the impeller being located in the 40°-90° range, while the shape of a vane corresponds
to a second-order surfaces, which permits the vanes to be inclined towards the impeller
rotation direction and stretched towards the impeller eye.
[0010] The centrifugal pump impeller can be manufactured by either casting or spot welding
and can be either flat or concave.
[0011] The impeller includes the main and cover discs and vanes. The impeller has an inlet
(eye) in the central part and an outlet on the side (butt) surface. The impeller carries
radial working channels between the vanes, running from the eye to the outlet. The
vanes are designed to generate a centrifugal force and transform mechanical energy
of the impeller to hydrodynamic energy of the fluid. Each vane has a leading and a
trailing edge.
[0012] The trailing edges of the vanes cast out the fluid from the radial working channels.
The trailing edges are located at the impeller outlet. The angle between the line
tangent to the vane trailing edge and the line tangent to the circumference of the
impeller is located in the 40°-90° range, which increases the circumferential component
of absolute velocity at the ends of the vanes. Having that angle less than 40° does
not increase the centrifugal force, while having that angle above 90° might result
in hydraulic resistance becoming too high, thus impairing efficiency and making the
impeller wear out faster. To increase the centrifugal force to a maximum, the angle
between the line tangent to the trailing edge of a vane and the line tangent to the
circumference of the impeller must be in the 80°-90° range.
[0013] The shape of the vanes is represented by second-order surfaces, which means that
any section of a vane along any plane has a curvature, which makes it possible to
have the vanes inclined towards the rotation direction of the impeller as well as
their maximum stretching towards the eye of the impeller. The second-order surface
can be profiled by calculating triangles of velocity for a large number of sections,
taking into account the chosen angles between the lines tangent to the trailing and
leading edges of the vanes on the one hand and the lines tangent to the circumferences
of the impeller on the other hand.
[0014] In addition, to reduce hydrodynamic resistance and increase the efficiency coefficient
of the impeller, the leading edge of a vane can be placed as close to the eye of the
impeller as possible, while the angle between the line tangent to the leading edge
of a vane and the line tangent to the circumference of the impeller can be chosen
in the 10-25° range.
[0015] To achieve a greatest possible reduction of hydrodynamic resistance and increase
the centrifugal force without affecting efficiency of the impeller, the angle between
the line tangent to the leading edge of a vane and the line tangent to the circumference
of the impeller can be chosen in the 12°-15° range, while the angle between the line
tangent to the trailing edge of a vane and the line tangent to the circumstance of
the impeller can be chosen in the 80°-90° range.
[0016] In addition, to increase the centrifugal force as well as stiffness and strength
and to improve anti-cavitation characteristics of the impeller, the latter may contain
one or more rows of auxiliary vanes, which can be of the same shape as the main vanes.
The trailing edges of the auxiliary vanes in relation to the trailing edges of the
main vanes can be placed at the same distance from the rotation axis of the impeller.
The length of the auxiliary vanes of the first row can measure 40-60% of the length
of the main vanes, while the auxiliary vanes of the consecutive rows can measure 40-60%
of the length of the vanes of the preceding rows, which ensures their lowest hydrodynamic
resistance to the flow of fluid. The angle between the line tangent to the trailing
edge of an auxiliary vane and the line tangent to the circumference of the impeller
can be chosen in the 40°-90° range, which also drives up the centrifugal force. Also,
the use of auxiliary vanes improves the weight and size characteristics of the impeller
because the number and thickness of main vanes can be reduced. It also affords having
impellers manufactured out of polymer materials.
[0017] This invention possesses the previously unknown in set of essential technological
characteristics, characterised by the following:
- the angle between the line tangent to the trailing edge of a vane and the line tangent
to the circumference of the impeller is in the 40° to 90° range, which increases the
circumferential component of absolute velocity at the impeller outlet and increases
the dynamic component of the centrifugal force generated by the impeller.
- the vanes are shaped as second order surfaces, which permits having the vanes inclined
towards the impeller rotation direction and stretched towards the eye of the impeller,
which means that the leading edges of the vanes can be placed as close to the eye
of the impeller as possible, and this reduces hydrodynamic resistance and improves
cavitation resistance of the impeller.
[0018] Thus, the set of new features of this invention increases the dynamic component of
the centrifugal force, reduces hydrodynamic resistance and improves cavitation resistance
of the impeller, thus achieving the desired technological goals: increasing the centrifugal
force without affecting the efficiency coefficient of the impeller and improving service
characteristics of centrifugal pumps. The new important characteristics of this invention
suggest that it meets the "novelty" and "level of invention" criteria of patentability.
[0019] This model can be manufactured from available materials, using commonly used methods,
which means that this invention meets the "industrial applicability" criterion of
patentability.
[0020] The invention is illustrated with the following drawings.
Fig. 1. An outline drawing (plan view) of the impeller of a centrifugal pump; indicated
are the angle between the line tangent to the trailing edge of a vane and the line
tangent to the circumference of the impeller and the angle between the line tangent
to the leading edge of a vane to the line tangent to the circumference of the impeller.
Fig. 2. The centrifugal pump impeller, view from the left, a longitudinal section.
Fig. 3. The centrifugal pump impeller, plan view, a cross section.
Fig. 4. The centrifugal pump impeller with auxiliary vanes as seen from the left,
a longitudinal section.
Fig. 5. The centrifugal pump impeller with auxiliary vanes, a plan view, a cross section.
Fig. 6. The centrifugal pump impeller with auxiliary vanes, a three-dimensional model,
an axonometric view.
Fig. 7. The centrifugal pump impeller with auxiliary vanes, a three-dimensional model,
view from the left.
Fig. 8. A vane of the centrifugal pump impeller, shaped as a second-order curve; a
general view.
[0021] The centrifugal pump contains an impeller with an eye and an outlet, which includes
the main disk 1, the cover disk 2 and the vanes 3 shaped as a second-order curve,
which makes it possible to have the vanes inclined towards the impeller rotation direction
and their stretching towards the impeller eye. The β
1 angle between the line tangent to the trailing edge of a vane and the line tangent
to the circumference of the impeller is 90°, while the β
2 angle between the line tangent to the leading edge of the vane and the line tangent
to the circumference of the impeller is 12°.
[0022] The invention operates as follows.
[0023] The centrifugal pump is immersed in a fluid, and its impeller starts to rotate. The
fluid is sucked through the eye of the impeller and, skirting the leading edges of
the vanes 3, placed at the β
2 angle at a minimum hydrodynamic resistance, moves along the second-order curves of
the vanes 3, interacts with the trailing edges of the vanes 3, placed at the β
1 angle, and- acquiring a maximum absolute velocity- leaves the impeller. This achieves
the desired technological result: increasing the centrifugal force without impairing
the efficiency coefficient of the impeller and improving exploitation characteristics
of the centrifugal pump.
1. The impeller of a centrifugal pump, characterised by the angle between the line tangent to the trailing edge of the vanes and the line
tangent to the circumference of the impeller being in the 40°-90° range, while the
shape of the vanes corresponds to second order-surfaces, which enables the vanes to
inclined towards the impeller rotation direction and stretched towards the eye of
the impeller.
2. The impeller of a rotary pump as in claim 1, characterised by the angle between the line tangent to the trailing edge of a vane and the line tangent
to the circumference of the impeller being in the 80°-90° range.
3. The impeller of a rotary pump as in claim 1, characterised by the angle between the tangent to the leading edge of a vane and the line tangent
to the circumference of the impeller being within the 10°-25° range.
4. The impeller of a rotary pump as in claim 3, characterised by the angle between the line tangent to the leading edge of a vane and the line tangent
to the circumference of the impeller being within the 12°-15° range and the angle
between the line tangent to the trailing edge of a vane and the line tangent to the
circumference of the impeller being within the 80°-90° range.
5. The impeller of a rotary pump as in claim 1, characterised by containing a row of auxiliary vanes.
6. The impeller of a rotary pump as in claim 5, characterised by the length of the auxiliary vanes being 40-60% of the length of the main vanes.
7. The impeller of a rotary pump as in claim 5, characterised by the angle between the line tangent to the outlet end of the auxiliary vanes and the
line tangent to the circumference of the impeller being in the 40°-90° range.
range.
8. The impeller of a rotary pump as in claim 5, characterised by containing an additional row of auxiliary vanes.
9. The impeller of a rotary pump as in claim 8, characterised by the length of the additional auxiliary vanes being 40-60% of the length of auxiliary
vanes.