JPH07279897A - Variable rotor blade diagonal flow pump and discharge pump and circulating pump - Google Patents

Abstract

PURPOSE:To facilitate the machining of a conical hub surface by specifying the angle between the generatrix of a conical hub surface of a diagonal flow impeller and the center line of the stem shaft of a rotor blade so as to obtain a rightward downward G-H characteristic curve with no flection point over the entire blade angle of the rotor blade. CONSTITUTION:The hub surface 1a of a rotor blade diagonal flow impeller 1 and the hub side end face 2b of a rotor blade 2 of the impeller 1 are conical, the angle 6 between the generatrices of the hub surface 1a and the hub side end face 2b and the center line of the stem 21 of the rotor blade 2 is set to an angle of 90 deg. so that they are orthogonal to each other. Accordingly, a discharge volume (Q)-total head (Q) characteristic curve having no flection at a design total blade angle of the rotor blade 2 of the rotor blade diagonal flow impeller 1 and rightward downward inclined, can be obtained, and the impeller hub surface 1a and a casing liner inner surface 4a can be easily machined, thereby it is possible to lower the manufacturing cost.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a movable vane mixed flow pump, a drainage pump, and a circulating water pump applied to a large-sized drainage pump, a circulating water pump in a thermal power plant, and the like.

[0002]

2. Description of the Related Art As a vertical cross-sectional view illustrating the structure of a conventional movable blade mixed flow pump, as shown in FIG.
FIG. 10 shows the one described on page 121, issued by Nippon Kogyo Publishing Co., Ltd., January 1991. This movable vane mixed flow pump is composed of a movable vane mixed flow impeller 1, a diffuser 3, a suction bell mouth 4, a casing liner 5, etc., and a hub surface 1a of the movable vane mixed flow impeller 1 and a blade 2 of the impeller 1. Casing liner side end face 2a and hub side (root) end face 2 of
b, the inner surface 5a of the casing liner 5 is formed by a part of a spherical surface.

Furthermore, in another conventional example, there is JP-A-60-17.
299, JP-A-60-73094, JP-A-5-20.
There is No. 2899. The movable vane mixed flow pump described in JP-A-60-17299 is a movable vane mixed flow pump in which both the outer circumference of the blade and the surface of the hub are formed into a spherical shape. When viewed from the center in the flow direction, they are displaced rearward on the impeller rotation axis. Further, in the movable vane mixed flow pump described in JP-A-60-73094, an arc having a center in a region excluding the impeller rotation axis on the downstream side of the impeller rotation axis within a plane including the impeller rotation axis. The hub surface is formed as a rotation surface (including a conical surface) having a similar curve as a generatrix.

The non-interfering pump described in Japanese Patent Laid-Open No. 5-202899 is a propeller pump impeller including a hub and a plurality of rotatable vanes attached to the hub and having a leading edge set back in the flow direction. The cross-section of the hub increases conically in this flow direction, and these vanes are designed so that their cross-sectional shape, that is, their chord is constant or increases in the circumferential direction, The rotation axis of is located near the center of each cross section,
The impeller minimizes the respective distances between the axis of rotation and the leading and trailing edges so that translation of these components is minimized as it rotates the vane about its axis.

[0005]

In the above-mentioned prior art, the hub surface of the movable vane impeller of the movable vane mixed flow pump, the casing liner side tip surface and the hub side end surface of the impeller blade, and the inner surface of the casing liner are spherical. However, there is a problem that the spherical surface of these parts is not easy to process and the manufacturing cost is high. Further, as shown by the solid line in FIG. 6, in the performance curve flow rate (discharge amount) Q-total head H characteristic of the conventional movable blade mixed flow pump, the blade angle of the movable blade (blade attachment angle, blade opening)
When ψ is made smaller than the reference wing angle ψ ₀ and the wings are entrained,
At a certain small blade angle ψ _-2 , there may be an inflection point in the pump Q-H characteristic that rises to the right, and if such an inflection point occurs, stable pump operation may become difficult. There was a problem.

An object of the present invention is to solve the above-mentioned problems of the prior art and to obtain a downward-sloping Q-H characteristic without an inflection point at all blade angles of the movable blade of a movable blade mixed flow impeller. It is an object of the present invention to provide a movable vane mixed flow pump, a drainage pump, and a circulating water pump that can easily process an impeller hub surface or a casing liner inner surface to reduce manufacturing costs.

[0007]

In order to achieve the above object, the movable vane mixed flow pump, drainage pump and circulating water pump of the present invention have a hub surface shape of the movable vane mixed flow impeller in a casing liner. In the case of a movable blade mixed-flow pump in which the conical surface and the casing liner end surface shape of the movable blade of the impeller are spherical surfaces, the inside of the hub is defined by the angle between the generatrix of the conical surface of the hub surface and the movable blade stem axis center line. The upstream angle is 90
Or 90 degrees or more.

The movable blade mixed flow impeller is formed into a conical surface so that the end surface of the movable blade on the hub side fits the impeller hub surface at the design reference blade angle, and the blade stands at a large blade angle from the reference blade angle. The hub surface portion of the movable blade facing the hub side end surface is formed into a concave ellipsoidal surface so that the hub side end surface of the blade does not contact the impeller hub surface without a gap when the blade surface is contacted. Further, a portion where the hollow surface of the hub surface portion formed on the hollow ellipsoidal surface and the conical surface of the hub surface are connected is formed by a smooth curved surface. Furthermore, the inner surface of the casing liner facing the casing liner side end surface formed on the spherical surface of the movable blade mixed flow impeller is formed by a plurality of conical surfaces.

[0009]

In the movable blade mixed flow pump, drainage pump and circulating water pump described above, the conical surface of the hub surface of the movable blade mixed flow impeller facilitates machining, and the generatrix of the conical surface and the movable blade stem axis center. The angle formed by the line can be selected so that the angle on the upstream side inside the hub is 90 degrees or 90 degrees or more.

In addition, the movable blade mixed flow impeller has a conical surface as the impeller hub surface and is formed so that the end surface of the blade on the hub side at the design standard blade angle matches the conical surface of the impeller hub, and Even if the blade angle is set to be slightly larger than the blade angle, part of the hub surface is an ellipsoidal surface so that the end surface of the blade on the hub side faces without contacting the impeller hub surface, so leakage flow from the gap is minimized. Thus, the conventional Q-H characteristic is secured. When the blade angle is set to be smaller than one of the reference blade angles, the inflection point occurs in the conventional Q-H characteristic because the blade flow is rapidly separated in the flow rate Q low flow rate region and the blade is regenerated on the blade. This is because the area of stall without adhering becomes wider and the total head H is lowered. Therefore, in this movable vane mixed flow impeller, if the gap between the conical surface of the impeller hub and the end surface of the blade on the hub side is increased when the blade angle is smaller than the reference blade angle, the blade pressure surface moves from the blade pressure surface to the suction surface. The leakage flow toward the blade becomes large, and the separation of the flow of the blade gradually starts from a region having a relatively large flow rate, and the sudden separation is suppressed and the region of stalling is narrowed to prevent a sharp drop in the head. Then, when the flow rate Q becomes smaller, a backflow portion is generated at the impeller inlet and the total head H rises again. As a result, a right-down QH characteristic without an inflection point is obtained. In addition, if the inner surface of the casing liner facing the casing liner side end surface formed on the spherical surface of the blade of the movable blade mixed flow impeller is formed with a plurality of conical surfaces, the machining cost can be reduced and the spherical surface is formed. The characteristics almost equal to are obtained.

[0011]

Embodiments of the present invention will be described below with reference to FIGS. 1 to 9. FIG. 1 shows a first embodiment of a movable vane mixed flow pump according to the present invention.
It is a longitudinal cross-sectional view showing an embodiment of. In FIG. 1, the hub surface (hub surface) 1a of the movable blade mixed flow impeller 1 and the hub-side end surface 2b of the movable blade 2 of the impeller 1 facing the same are conical surfaces. The angle θ formed by the generatrix of the conical surface of the end surface 2b and the stem axis center line X of the stem 21 of the movable blade 2 is formed so as to be orthogonal to each other at 90 degrees. The casing liner-side tip surface 2a of one movable blade 2 has a spherical shape, and the casing liner-side tip surface 2a of the movable blade 2 on the inner surface of the suction casing 4 in which the suction bell mouth and the casing liner are integrally formed. The inner surface portion 4a of the casing liner that faces it is also spherical. The diffuser 3 is located downstream of the suction casing 4. In FIG. 1, the angle θ between the generatrix of the conical surface of the hub surface 1a and the hub-side end surface 2b and the stem axis center line X of the movable blade 2 is 9
Although it is set to 0 degrees, the angle formed by the generatrix of the conical surface of the hub surface 1a and the hub-side end surface 2a and the stem axis center line X of the movable blade 2 on the upstream side inside the hub is also 90 degrees or more. Shall be included. This movable vane mixed flow pump can be used as a large-scale drainage pump or a circulating water pump in a thermal power plant or the like.

FIG. 2 is a partial three-dimensional view of the movable blade mixed flow impeller of FIG. In FIG. 2, the movable blade mixed flow impeller 1 has a design reference blade angle, and the hub-side end surface 2b of the movable blade 2 is the impeller hub surface 1a.
When the movable blade 2 is erected at a large blade angle from the reference blade angle, the hub-side end surface 2b of the blade 2 does not contact the impeller hub surface 1a and there is no gap. The face of the impeller hub 1a facing the hub-side end face 2b of the movable blade 2 is recessed so as to face each other, and the ellipsoidal faces 1b, 1c are formed.
To form. Also, the hollow ellipsoidal surface 1 of the impeller hub surface 1a
Portions connecting the concave surfaces of b and 1c and the conical surface of the hub surface 1a are formed by smooth curved surfaces 1d and 1e. Figure 2
In the figure, the movable blade 2 is shown in a state in which the blade angle (blade attachment angle, blade opening) ψ is reduced by revolving in the impeller rotation direction.

FIG. 3 is a view of the movable vanes of the movable vane mixed flow impeller of FIG. In FIG. 3, the movable impeller 1 of FIG.
When the movable blade 2 of is viewed from the A direction (stem axis centerline X direction), and the blade angle ψ is the design reference blade angle ψ _{0 in the} reference state,
Larger blade angle ψ ₊ (ψ ₊
> Ψ ₀ ) shows the state of the blade 2 when the blade angle is small ψ ₋ (ψ ₋ <ψ ₀ ) when the blade is revolved in the impeller rotation direction.

FIGS. 4A and 4B are sectional views of the movable vane mixed flow impeller of FIG. 4 (a) and 4 (b), FIG. 4 (a) is a sectional view of the impeller 1 and the movable blade 2 of FIG. When the blade 2 has the design reference blade angle ψ ₀ , the hub-side end surface 2b of the blade 2 is almost in contact with the hub surface 1a of the impeller 1, and the surface shape of the concave ellipsoidal surface 1b is such that the blade angle ψ becomes large. Set 2 in the direction of the impeller rotation axis to increase the blade angle ψ
₊ (Ψ ₊ > ψ ₀ ), the hub-side end surface 2b of the blade 2 is formed into an ellipsoidal shape of the locus surface when the blade 2 rotates, and the hollow ellipsoidal surface 1b has the designed maximum blade angle ψ _+1. Is set so that the hub-side end surface 2b of the blade 2 does not come into contact with the impeller hub surface 1b and does not move until there is a gap. Further, the part where the concave ellipsoidal surface 1b formed in a part of the hub surface 1a of the impeller 1 and the conical surface of the impeller 1a are connected is formed as a smooth concave end surface. When the blade 2 is swung in the impeller rotation axis direction so as to reduce the blade angle ψ to a smaller blade angle ψ ₋ (ψ ₋ <ψ ₀ ), the hub-side end surface 2b of the blade 2 and the impeller hub surface 1a. A gap δ ₁ is formed at the inlet of the flow of the blade 2.

FIG. 4B shows a partial cross-sectional shape of the hub-side end surface 2b of the blade 2 of FIG. 4A. In FIG. 4 (b), the inlet side of the flow of the blade 2 of the hub-side end surface 2b of the blade 2 of FIG. 4 (a) is rounded at an angle where both the suction surface 2e and the hub-side end surface 2 (b) intersect. ₁ is attached, and corresponds to the smooth end face of the recess ellipsoidal surface 1b in FIG. 4 (a).

5A and 5B are sectional views of the movable vane mixed flow impeller of FIG. 4 (a) and 4 (b), FIG. 5 (a) is a cross-sectional shape of the impeller 1 and the movable blade 2 of FIG. Is the design reference blade angle ψ ₀ , the hub-side end surface 2b of the blade 2 is almost in contact with the hub surface 1a of the impeller 1, and the surface shape of the recessed ellipsoidal surface 1b is such that the blade 2 becomes large.
With a larger blade angle ψ ₊ (ψ ₊ ＞
ψ ₀ ), the hub-side end surface 2b of the blade 2 is formed into an ellipsoidal shape of the locus surface when rotationally moved, and the hollow ellipsoidal surface 1b is set until the blade 2 is set to the designed maximum blade angle ψ _+1. It is formed so that the hub-side end surface 2b of the blade 2 does not come into contact with the impeller hub surface 1b and does not move, and there is no gap. Also, a hollow ellipsoidal surface 1b formed in a part of the hub surface 1a of the impeller 1.
The part where the conical surface of the impeller 1a and the conical surface are connected to each other is formed as a smooth end surface of the recess. In addition, the wing 2 is set so that the wing angle ψ becomes smaller.
A smaller blade angle lay to the impeller rotation axis direction ψ _- (ψ _-
<Ψ ₀ ), a gap δ ₂ is formed on the outlet side of the flow of the blade 2 between the hub-side end surface 2b of the blade 2 and the impeller hub surface 1a.

FIG. 5B shows a partial cross-sectional shape of the hub-side end surface 2b of the blade 2 of FIG. 5A. In FIG. 5 (b), a hub side end surface 2b of the blade 2 of FIG. 5 (a) is provided with a circle R _{2 at} the corner where the pressure surface 2f and the hub side end surface 2b intersect on the outlet side of the flow of the blade 2. And the concave ellipsoidal surface 1b of FIG. 5 (a).
Corresponds to the smooth concave end face of.

FIG. 6 is an example of QH characteristics of the movable vane mixed flow pump of FIG. In FIG. 6, an example of the flow rate (discharge amount) Q-total head H characteristic of the movable vane mixed flow pump of the conventional example of FIG. 10 is shown by a solid line, and the movable vane of one embodiment of the present invention different from the conventional example of FIG. An example of the characteristic of the mixed flow pump QH is shown by a broken line. The QH characteristics of the movable vane mixed flow pump having the movable vane mixed flow impeller 1 having the configuration of the embodiment of the present invention described above with reference to FIGS. 1 to 5 are shown in FIG. With the reference blade angle ψ ₀ and the larger blade angle ψ ₊ and up to the maximum designed blade angle ψ ₊₁ , the QH characteristics (solid line) of the movable blade mixed flow pump of the conventional example of the movable blade mixed flow impeller are the same. is there. This is because in this embodiment the pump is designed so that the same Q-H characteristic is obtained in the conventional example pumps in the design reference blade angle [psi _0, also designed maximum blade angle [psi ₊₁ when from the large blade angle [psi ₊ This Up to FIG. 4 (a) and FIG.
As illustrated in (a), the gap between the hub-side end surface 2a of the movable blade 2 and the hollow ellipsoidal surface of the impeller hub surface 1a including the front edge portion 2c and the rear edge portion 2d is the reference blade angle ψ _0. This is because the depression depth of the depression ellipsoidal surface is sufficiently smaller than the height (flow passage width) of the blade 2, and therefore the increase in the flow loss due to the formation of the depression ellipsoidal surface is extremely small.

On the other hand, the blade angle ψ of the blade 2 is set to the design reference blade angle ψ.
_{When the} blade angle ψ ₋ is smaller than ₀ and is smaller than the blade angle ψ ₋₁ , for example, the QH characteristic example of FIG. The reason for this is that, as described above, when the blade angle ψ of the movable blade 2 is set to a blade angle ψ ₋ smaller than the design reference blade angle ψ ₀ as shown in FIGS. 4 (a) and 5 (b), the hub side of the blade 2 is formed. Between the end surface 2b and the conical surface of the impeller hub surface 1a, a gap δ ₁ and a gap δ ₂ are formed on the inlet side of the flow of the blade 2, respectively.
_1. Leakage flow is generated through the gap δ ₂ and the flow separation in the blade 2 in the low flow rate region is relatively large.
Gradually starts from the region of (1), and thus abrupt separation of the flow is suppressed, the region of stall in the flow passage is narrowed, and a sudden decrease in the total head H is prevented. When the flow rate Q becomes smaller, backflow to the inlet side of the impeller occurs, and the total head H rises again. As a result, there is no inflection point, and Q-H descends to the right.
Characteristic is obtained and stable operation of the movable blade mixed flow pump is performed.

FIG. 7 is a longitudinal sectional view showing a second embodiment of the movable vane mixed flow pump according to the present invention. In FIG. 7, the hub surface (hub surface) 1a of the movable blade mixed flow impeller 1 and the hub side end surface 2b of the movable blade 2 of the impeller 1 facing the hub surface (hub surface) 1a are conical surfaces. The angle θ between the hub inner surface and the stem axis center line X of the movable blade 2 formed by the generatrix of the conical surface of the end surface 2b is set to 90 degrees or less. By doing so, the flow passage width B ₁ ′ at the impeller inlet portion becomes larger than the flow passage width B ₁ at the impeller inlet portion shown in FIG. Then, the cavitation performance of the mixed flow pump is determined by the flow passage area at the impeller inlet. The larger the flow passage area, the smaller the meridional flow velocity, and the smaller the pressure drop in the blade 2 and the less cavitation performance. However, since the flow path area is proportional to the flow path width B ₁ ′, the second embodiment of FIG. 7 is superior to the flow path width B ₁ of the first embodiment of FIG. Excellent cavitation performance can be obtained. This movable vane mixed flow pump can be used as a large-scale drainage pump or a circulating water pump in a thermal power plant or the like.

FIG. 8 is a diagram of a velocity triangle at the outlet of the movable blade mixed flow impeller of FIG. In FIG. 8, regarding the impeller outlet flow path width (impeller outlet width) B ₂ , in the example in which both the casing liner inner surface and the hub surface of the conventional impeller of FIG. 10 are spherical, the impeller inlet flow Road width (impeller entrance width)
And the impeller outlet passage width (impeller outlet width) are the same, but in the second embodiment of FIG. 7, the impeller outlet passage width (impeller outlet width) B ₂ ′ is set to the impeller inlet. 'it is possible to set smaller than, Deguchiko meridional velocity at velocity triangle of the impeller exit in Figure 8 if so, Cm ₂ from Cm _2' part flow path width (impeller inlet width) B ₁ increases to Since the outlet outflow angle increases from β ₂ to β ₂ ′, the blade outlet angle β _b2 (FIG. 3) of the impeller 1 set in proportion to the outlet outflow angle β ₂ is the value of the conventional example of FIG. 10. Can be set larger. Then the length of the blade 2 is Sadamari depending on blade outlet angle beta _b2, as blade outlet angle beta _b2 is greater blade length is shortened, the wing in the movable blade 2 is attached to a stem, blade inlet Since the blade outlet portion is overhanging from the stem, it is preferable that the blade be appropriately short in view of the strength of the blade. Therefore, when the impeller outlet width B ₂ ′ is reduced, the blade 2 can be shortened, and the movable blade 2 excellent in strength can be realized.
In the velocity triangle at the outlet of the impeller of FIG. 8, the flow velocities w ₂ ′ and u ₂ are the impeller peripheral velocity, and C ₂ and C ₂ ′ are the absolute velocity of the flow (composite velocity).

FIG. 9 is a vertical sectional view showing a third embodiment of the movable vane mixed flow pump according to the present invention. In FIG. 9, the movable blade mixed flow impeller 1 is the same as that of the first embodiment of FIG. 1, and it faces the casing liner side tip surface formed on the spherical surface of the blade 2 of the movable blade mixed flow impeller 1. The shape of the inner surface 4a of the casing liner of the suction casing 4 is the busbar F
And two conical surfaces that are the generatrix G. By doing so, the inner surface 4a of the casing liner can be machined significantly more easily than the conventional spherical surface machining, and the machining cost can be reduced. Although the inner surface 4a of the casing liner is formed of two conical surfaces in FIG. 9, it may be formed of a plurality of conical surfaces in general. This movable vane mixed flow pump can also be applied to the movable vane mixed flow pump of FIG. 1 or FIG. The movable blade mixed flow pump can be used as a large-sized drainage pump or a circulating water pump in a thermal power plant.

[0023]

According to the present invention, in the movable vane mixed flow pump, the Q at all design blade angles of the movable vanes of the movable vane mixed flow impeller is obtained.
With the -H characteristic, a QH characteristic with a right downward slope without an inflection point can be obtained, which facilitates stable pump operation, and facilitates machining of the hub surface of a movable blade mixed flow impeller or the inner surface of a casing liner. This has the effect of reducing the processing cost of the product.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing a first embodiment of a movable vane mixed flow pump according to the present invention.

FIG. 2 is a partial three-dimensional view of the movable blade mixed flow impeller of FIG.

3 is a view of a movable blade of the movable blade mixed flow impeller of FIG.

FIG. 4 is a sectional view of the movable vane mixed flow impeller of FIG.

5 is a sectional view of the movable vane mixed flow impeller of FIG. 2 as viewed in the direction of arrow C. FIG.

FIG. 6 is a QH characteristic example diagram of the movable vane mixed flow pump of FIG. 1.

FIG. 7 is a longitudinal sectional view showing a second embodiment of the movable vane mixed flow pump of the present invention.

8 is a diagram of a velocity triangle at the outlet of the movable vane mixed flow impeller of FIG. 7. FIG.

FIG. 9 is a vertical sectional view showing a third embodiment of the movable vane mixed flow pump of the present invention.

FIG. 10 is a vertical cross-sectional view illustrating a conventional movable blade mixed flow pump.

[Explanation of symbols]

 1 Movable Blade Mixed Flow Impeller 1a Hub Surface 1b, 1c Dimple Ellipsoidal Surface 2 Movable Blade 3 Diffuser 4 Suction Casing

Claims (8)

[Claims] 1. A movable blade mixed flow pump in which a hub surface shape of a movable blade mixed flow impeller in a casing liner is a conical surface, and a casing liner-side end surface shape of a movable blade of the impeller is a spherical surface. A movable-blade mixed-flow pump in which the angle between the generatrix of the conical surface of the hub surface of the blade impeller and the stem axis center line of the movable blade is 90 degrees or more on the upstream side of the hub. 2. A movable vane mixed flow pump in which a hub surface of a movable vane mixed flow impeller in a casing liner has a conical surface and a tip end surface of a movable vane of the impeller has a spherical surface. A mixed-blade impeller is formed on a conical surface so that the end surface of the movable blade on the hub side matches the impeller hub surface at the design reference blade angle, and when the blade is set to a large blade angle from the reference blade angle, A movable-blade mixed-flow pump in which a portion of the hub surface of the movable blade facing the hub-side end surface is formed into a concave ellipsoidal surface so that the hub-side end surface does not contact the impeller hub surface with almost no gap. 3. The movable vane mixed flow pump according to claim 1, wherein the movable vane mixed flow impeller is formed into a conical surface such that the end face of the movable vane on the hub side matches the impeller hub face at a design standard blade angle. The hub on which the hub-side end surface of the movable blade faces so that the hub-side end surface of the vane faces the impeller hub surface with almost no gap when the blade stands up from the reference blade angle to a large blade angle. A movable vane mixed flow pump with a hollow surface that is formed into an ellipsoidal surface. 4. The movable vane mixed flow pump according to claim 2, wherein a portion where the hollow surface of the hub surface formed on the hollow ellipsoidal surface and the conical surface of the hub surface are connected to each other is formed by a smooth curved surface. 5. A movable-blade mixed-flow pump in which the inner surface of a casing liner facing the casing-liner-side tip surface formed on the spherical surface of the blade of a movable-blade mixed-flow impeller is formed with a plurality of conical surfaces. 6. The inner surface shape of a casing liner facing the casing liner side end surface formed on the spherical surface of the blade of a movable blade mixed flow impeller is formed by a plurality of conical surfaces. The movable blade mixed flow pump described in. 7. A drainage pump using the movable vane mixed flow pump according to any one of claims 1 to 6. 8. A circulating water pump for use in a power plant or the like, which uses the movable vane mixed flow pump according to any one of claims 1 to 6.