JP2022189718A - Design method of large-scale construction pump volute and the volute - Google Patents

Abstract

To provide a design method of a large-scale construction pump volute which can reduce pressure pulsation and a radial force at an operation of a pump, and can improve operation safety and stability at each opening condition of the pump, and the volute.SOLUTION: A large-scale construction pump volute includes a volute outlet, a diffusion segment (2), a throat part (3), a movable guide vane (5), a fixed guide vane (6), an outlet guide vane (7), and a partitioning tongue (8). A plurality of the fixed guide vanes are arranged at an external periphery of the movable guide vane, the outlet guide vane substantially tangentially contacts with a base circle D3 of an inlet of a pressurization water chamber, an inlet end of the outlet guide vane has a cross section I, a partitioning tongue end has a cross section II, the volute is an annular volute extending up to the cross section I from the cross section II in a flow direction, and circulation areas of the cross sections of a volute flow passage are substantially the same.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to the technical field of pump volutes for water use works and centrifugal pump volutes, and more specifically to a method of designing pump volutes for large-scale works and their volutes.

In recent years, China's water conservancy and hydropower projects have developed well, meeting China's power energy supply and demand requirements and laying a solid foundation for the implementation of China's sustainable development strategy. The volute is an important turbulence component of centrifugal pumps, and has a great influence on the efficiency index of pumps. When the fluid enters the volute from the impeller, a strong interaction occurs due to the small gap between the impeller and the partition tongue/tongue of the volute, resulting in high amplitude and low frequency in the partition tongue region of the conventional helical volute. result in pressure pulsations. In addition, since the geometric structure of the helical volute is asymmetrical, when the head and flow rate are high, large pressure pulsation and radial force are generated, resulting in large vibration and noise. affect. To this problem, Chinese Utility Model Publication No. CN201218236Y discloses a high-speed water pump volute, a continuous volute passage consisting of a circular volute bottom and a continuous sidewall of a flat volute with an involute or Archimedean spiral, a pump water inlet and a a volute provided with a water outlet, the center of the volute is a water inlet, the continuous side wall is a water stop plate, which increases the lifting height and water flow rate, is light in weight and corrosion resistant; It is characterized by easy manufacturing and low cost. Chinese Patent Application Publication No. CN111894903A discloses the volute and design method of a serialized single-stage centrifugal pump, when designing different flow rates and the same impeller outer diameter, the axial wall of the pump body close to the pump cover side The thickness can be the same and the pump cover can be designed with a universal shape. The pressurized water chamber uses an axially asymmetric cross-section, with the center line as the reference, the cross-section near the pump cover side is rectangular, and the other side is a right-angled trapezoid, effectively reducing the degree of perturbation of the rotating shaft, Improves sealing reliability and reduces pump vibration. In this way, the production efficiency is improved, the mechanical strength is improved, and the pressure pulsation is reduced to some extent, but the pressure head and efficiency of the pump are low when the trapezoidal or rectangular cross section is used. Therefore, it is necessary to design a pump volute structure for large-scale irrigation works that can be widely applied, has small pressure pulsation, has stable radial force, and can be operated efficiently.

A conventional volute structure includes a volute body with water flow passages provided therein, the water flow passages generally consisting of a pressurized water chamber and a diffusion segment. The starting end of the pressurized water chamber is the partition tongue, the connection point between the pressurized water chamber and the diffusion segment is the throat, and the outlet of the diffusion segment is the pump body outlet. A conventional pressurized water chamber has a set of cross-sections that are based on the design base circle outside the outer circle of the impeller and that increase from the partition tongue portion toward the throat portion of the inlet of the diffusion segment of the pump along the rotational direction of the impeller. The cross-section of the pressurized water chamber, which is constructed in conjunction, uses an eccentric elliptical, trapezoidal or semicircular arc-shaped cross-section to improve the pressure head and efficiency of the pump.

Chinese Utility Model Publication No. CN201218236Y

The present invention solves the deficiencies of the prior art by reducing the pressure pulsation and radial force during operation of the pump, and improving the operational safety and stability of the pump in each operating condition. It is an object of the present invention to provide a method of designing a construction pump volute and its volute.

In order to achieve the above objects, the technical solutions used in the present invention are as follows.

Volute outlet (1), diffusion segment (2), throat (3), fixed multi-channel (4), movable guide vane (5), fixed guide vane (6), outlet guide vane (7), partition tongue / A diffusion segment is provided at the outlet end of the pressurized water chamber, comprising a tongue (8), and a channel gap (9), the outlet end of the diffusion segment having a volute outlet, between the pressurized water chamber and the diffusion segment. The connecting part is the throat part, and a diffuser is provided on the outer periphery of the impeller, the diffuser includes a plurality of movable guide vanes distributed in the circumferential direction, and a partition tongue is configured between the diffusion segment and the volute wall. A volute for a large construction pump, a plurality of fixed guide vanes (6) are provided on the outer periphery of a movable guide vane (5), and the fixed guide vanes partition the volute flow path into fixed multi-flow paths and exit The median/axis of the guide vanes is collinear/parallel to the median/axis of the diffusion segment, the outlet guide vanes are approximately tangent to the base circle D3 of the inlet of the pressurized water chamber, the outlet ends of the stationary guide vanes and the diameters adjacent thereto. There is a channel gap (9) between the inlet end of the fixed guide vane on the direction inner side or the base circle D3 of the inlet of the pressurized water chamber, the inlet end of the outlet guide vane has section I and the dividing tongue end has section II and the volute is an annular volute from section II to section I in the flow direction, and the flow area of the cross section of the channel of the volute is approximately the same.

Further, the volute employs an annular volute of substantially eccentric elliptical cross-section, wherein the length of the eccentric long portion of the ellipse is 2 to 4 times the size of the short portion of the ellipse in the major axis direction of the ellipse.

Further, the fixed guide vane (6) is an arc-shaped guide vane, and the fixed guide vanes have different centric angles, and the centric angle increases from section II to section I in the flow direction, and the flow From section II to section I in the direction, the downstream centroid angle is 1.05-1.25 times the upstream centroid angle.

Furthermore, the channel gap (9) increases in the flow direction from section II to section I, and from section II to section I in the flow direction, the downstream channel gap is 1.05 of the upstream channel gap. ~1.2 times.

Furthermore, said fixed guide vane (6) has a downstream end/tailing edge (61), the downstream end being tapered or arcuate, the downstream end having a first concave groove (62) and a first 2 grooves (63), a plurality of first grooves are provided on the radial inner surface of the downstream end, a plurality of second grooves are provided on the radial outer surface of the downstream end, 1 concave groove, the second concave groove has a semi-circular structure

Further, the number of the first grooves (62) is greater than the number of the second grooves (63), and the number of the first grooves is 1.5 to 3.0 of the number of the second grooves. Double.

Further, the diffusion segment is a pump body outlet, the area of the water flow passage increases as the diffusion segment goes from the throat to the volute outlet, the cross section of the diffusion segment includes a shape consisting of a rectangle and/or an arc, and the throat The cross-sectional shape of the pressurized water chamber at the position is the same as and overlaps the end face shape of the diffusion segment, the structure ensuring a smooth transition between the water chamber and the diffusion segment.

A method for designing a volute for a large construction pump, which uses an annular volute structure with fixed guide vanes and movable guide vanes, and according to predetermined operating conditions, based on the volute velocity coefficient method, the base circle of the inlet of the pressurized water chamber Geometric parameters of the volute, including the diameter D ₃ , the inlet width B ₃ of the pump pressurized water chamber, the radius R of the outer contour of the volute chamber, the number of movable guide vanes Z ₁ , the number of fixed guide vanes Z ₂ and the divergence angle θ. to determine

Step ( ₁ ) of designing the base circle diameter D3 of the inlet of the pressurized water chamber, such that D3 ₌ D2 _{+ 2b2} ,

In the formula,
b ₂ - radius of the movable guide vane, mm;
D ₂ - external diameter of the pump impeller, mm;
D ₃ - is the base circle diameter of the inlet of the pump pressurized water chamber, mm, step (1);
Step ( ₂ ) of designing the inlet width B3 of the pump pressurized water chamber such that B3=B2 _{+ 0.05D3 ,}

のように、ボリュートチャンバーの外輪郭線の半径Ｒを設計するステップ（３）であって、 In the formula,
B ₂ - axial width of pump impeller outlet, mm;
D ₃ - base circle diameter of the inlet of the pump pressurized water chamber, mm;
B ₃ - the inlet width of the pump pressurized water chamber, mm, step (2);

Step (3) of designing the radius R of the outer contour of the volute chamber as

In the formula,
A _I - is the area value of the I cross section of the volute, mm;
R - the radius of the outer contour of the volute chamber, mm, step (3);
Step (4) of designing the number of movable guide vanes Z ₁ such that Z ₁ =8 to 14,

In the formula,
Z ₁ - is the number of movable guide vanes, step (4);
Step (5) of designing the number of fixed guide vanes Z ₂ such that Z ₂ =3 to 5,

のように、拡散セグメントの拡散角を設計するステップ（６）であって、 In the formula,
Z ₂ - is the number of fixed guide vanes, step (5);

Step (6) of designing the diffusion angle of the diffusion segment as:

In the formula,
A _I - is the area value of the I cross section of the volute, mm;
D _S - the diameter of the volute outlet, mm;
L - the length of the diffusion segment of the volute, mm;
θ - the divergence angle, in degrees;
A method for designing a volute of a pump for large-scale construction, comprising a step (6) of setting θ to 6° to 12°.

The present invention has the following beneficial technical effects.
(1) Using the structure of an annular volute, the annular volute has a symmetrical vortex flow path and a large gap between the partition tongue and the impeller outlet, compared with the traditional spiral volute; By using an annular volute instead of a conventional volute, the pressure pulsation and radial force of the pump can be reduced and the operational stability can be improved. The gap between the impeller circumference and the volute partition tongue is increased, the advantage of which is that the impact of the water flow on the volute partition tongue is reduced and the gap between the partition tongue and the impeller is increased, thus reducing the pressure pulsation and overall Radial forces can be reduced.

(2) By further designing, the fixed guide vanes have different centric angles, and the centric angles increase from section II to section I in the flow direction. The channel gap increases in the direction of flow from cross-section II toward the other cross-sections. Further reduce the pressure pulsation and radial force during operation of the pump, reduce the corner vortex at the outlet of the fixed guide vane, reduce the pressure fluctuation and pressure loss in the annular volute, and improve the operational safety under each operating condition of the pump. It can improve performance and stability. The present invention further reduces the corner vortex at the fixed guide vane outlet through the design of the first recessed groove, the second recessed groove, and reduces the pressure fluctuation and pressure loss of the annular volute, thereby Driving safety and stability under driving conditions can be improved.

(3) By providing two rows of guide vanes (movable guide vanes, fixed guide vanes) in the volute, the high-speed liquid shaken off from the impeller is collected and uniformly distributed to the inlet of the next stage impeller or the discharge chamber. and convert some of the kinetic energy of the liquid into pressure energy in the guide vanes, thereby improving the efficiency of the pump. The use of two rows of guide vanes significantly improves hydraulic performance compared to no fixed guide vanes or a single row of fixed guide vanes. Considering that the cross section of the volute uses an eccentric elliptical cross section, we analyzed the influence of the cross section shape on the hydraulic performance of the centrifugal pump. It can be seen that the rectangle gives a higher pump pressure head.

FIG. 1 is a structural schematic diagram of the annular volute of the pump of the present invention. FIG. 2 is a comparison diagram of a locality of an annular volute and a locality of a helical volute, where (a) is an annular volute and (b) is a helical volute. FIG. 3 is a comparison diagram of a cross section of a helical volute and a cross section of an annular volute (A is a helical volute, B is an annular volute). FIG. 4 compares the performance of an annular volute pump with that of a helical volute pump. FIG. 5 is a schematic diagram of the local expansion structure of another embodiment of the fixed guide vane of the present invention.

In order to make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions of the embodiments of the present invention together with the drawings of the embodiments of the present invention. explain. Apparently, the described embodiments are some, but not all embodiments of the present invention. According to the embodiments of the present invention, all other embodiments obtained by persons skilled in the art without creative work fall within the protection scope of the present invention.

The present invention will be described in more detail below with reference to the drawings.

As shown in FIGS. 1-2, a volute outlet 1, a diffusion segment 2, a throat 3, a fixed multichannel 4, a movable guide vane 5, a fixed guide vane 6, an outlet guide vane 7, a partition tongue/tongue 8, and a flow passage gap 9, a diffusion segment 2 is provided at the outlet end of the pressurized water chamber, the outlet end of the diffusion segment 2 has a volute outlet 1, and the connection between the pressurized water chamber and the diffusion segment 2 is the throat 3, a diffuser is provided on the outer periphery of the impeller, the diffuser comprises a plurality of movable guide vanes 5 distributed in the circumferential direction, and a partition tongue 8 is configured between the diffuser segment 2 and the volute wall. A method of designing a pump volute for construction work and its volute, wherein a plurality of fixed guide vanes 6 are provided on the outer periphery of a movable guide vane 5 for partitioning the volute channel into fixed multi-channels 4, and an outlet guide vane 7 The median/axis is collinear/parallel to the median/axis of the diffusion segment 2, the outlet guide vanes 7 are substantially tangent to the base circle D3 of the inlet of the pressurized water chamber, the outlet ends of the fixed guide vanes 6 and adjacent thereto. There is a channel gap 9 between the inlet end of the radially inner fixed guide vane 6 or the base circle D3 of the inlet of the pressurized water chamber, the inlet end of the outlet guide vane 7 has a cross section I, and the end of the partition tongue 8 is It has a cross-section II and is characterized in that the volute is an annular volute from cross-section II to cross-section I in the direction of flow, and the flow area of the cross-section of the flow path of the volute is the same.

Furthermore, as shown in FIG. 3, the volute uses an annular volute B with a substantially eccentric elliptical cross section, and the size of the long eccentric portion of the ellipse in the long axis direction (X-axis direction) of the ellipse is 2 to 4 times the size of the short portion, preferably 2.5 times.

Furthermore, the fixed guide vanes 6 are arcuate guide vanes, and the fixed guide vanes 6 have the same or different centric angles. Preferably, the fixed guide vanes 6 have different angles of centricity, the angles of centricity increasing from section II to section I in the flow direction. Specifically, from section II to section I in the flow direction, the downstream centroid angle is 1.05 to 1.25 times the upstream centroid angle.

Furthermore, the channel gap 9 increases from cross-section II to cross-section I in the flow direction. Specifically, from section II to section I in the flow direction, the downstream channel gap 9 is 1.05 to 1.2 times the upstream channel gap 9 .

As shown in FIG. 1, the volute has approximately the same cross-sectional flow area from cross-section II to cross-section I in the flow direction, and then the gap between the impeller outer circle and the volute partition tongue 8 is The advantage is that the impact of solid particles on the volute tongue is reduced and the gap between the partition tongue and the impeller is increased, thus reducing pressure pulsations and overall radial forces.

The diffusion segment 2 is a pump body outlet, the diffusion segment has a water flow passage area that increases from the throat portion 3 toward the volute outlet 1, and the cross section of the diffusion segment includes a rectangular and/or arc shape. The cross-sectional shape of the pressurized water chamber at the throat 3 is the same as and overlaps the end face shape of the diffusion segment 2, which structure ensures a smooth transition between the pressurized water chamber and the diffusion segment.

As shown in FIG. 2, compared to conventional helical volutes, annular volutes have a larger and more uniform cross-sectional area of flow. A small volute cross-sectional area results in a hump peak in the pump head curve, resulting in surge in the pipe system. At rated operating conditions, hydraulic performance decreases slightly as the swept area of the volute increases. A large volute flow area improves hydraulic performance when pump operation deviates from rated operating conditions, and the high efficiency region widens as the volute flow area increases.

The volute is advantageous in reducing pressure pulsations in the volute by using a substantially eccentric elliptical cross-section rather than using a conventional trapezoidal or semi-circular volute cross-section.

By using annular volutes, as shown in FIG. 4(a), radial forces can be reduced in the low flow range; Higher lift and efficiency result. With these volutes, the large tip clearance reduces the interaction between the impeller blades and the volute partition tongue, thus making the pressure distribution around the impeller more uniform. As designed, due to the non-uniform pressure distribution around the impeller due to the constant cross-sectional area volute, the minimum radial force point is at low flow rather than the design flow.

The radial force distribution in FIG. 4(b) is shown as squares, which correspond to the angles of the impeller blades. In addition, as the flow increases, the square rotates clockwise, and the increase in the flow area of the volute can reduce the magnitude of the radial force acting on the shaft, especially under nominal and large flow conditions. , the vibration of the pump can be reduced, thereby improving the operational stability of the pump.

As shown in FIG. 4(c), it can be seen from the polygonal line distribution of the fluctuation strength coefficient in the annular volute that the coefficient generally increases as the flow rate increases. Also, all of the lines show four peaks, consistent with the number of impeller blades, the equivalent deflection angle of the four peaks is 90°, and the maximum pressure pulsation is about 30° after the partition tongue of the volute. , implying that the interaction between the impeller trailing edge and the volute partition tongue is responsible for the pressure pulsation at the volute. Also, increasing the flow area of the volute reduces pressure pulsations in the volute regardless of pump operating conditions.

Preferably, by further design, the stationary guide vanes 6 have different centric angles, which increase from section II to section I in the flow direction. The channel gap 9 increases from the cross section II to the cross section I in the flow direction. Further reduce the pressure pulsation and radial force during operation of the pump, reduce the corner vortex at the outlet of the fixed guide vane, reduce the pressure fluctuation and pressure loss in the annular volute, and improve the operational safety under each operating condition of the pump. It can improve performance and stability.

As shown in FIG. 5, in one embodiment, the stationary guide vane 6 has a downstream/trailing edge 61, the downstream/trailing edge 61 being tapered or arcuate, and the downstream edge 61 being It has a first groove 62 and a second groove 63 , the plurality of first grooves 62 are provided on the radial inner surface of the downstream end 61 , and the plurality of second grooves 63 are provided on the downstream end 61 . provided on the radially outer surface of the The first groove 62 and the second groove 63 have a semicircular structure. By designing the first recessed groove 62, the second recessed groove 63, the corner vortex at the fixed guide vane exit is further reduced, and the pressure fluctuation and pressure loss of the annular volute are reduced, thereby improving the pump performance. Improve driving safety and stability in each driving condition.

Furthermore, the number of the first grooves 62 is greater than the number of the second grooves 63, and preferably the number of the first grooves 62 is equal to the number of the second grooves 63, 1.5 to 3.5. 0 times.

A method for designing a volute for a large construction pump, which uses an annular volute structure with fixed guide vanes and movable guide vanes, and according to predetermined operating conditions, based on the volute velocity coefficient method, the base circle of the inlet of the pressurized water chamber Geometric parameters of the volute, including the diameter D ₃ , the inlet width B ₃ of the pump pressurized water chamber, the radius R of the outer contour of the volute chamber, the number of movable guide vanes Z ₁ , the number of fixed guide vanes Z ₂ and the divergence angle θ. to determine

Step ( ₁ ) of designing the base circle diameter D3 of the inlet of the pressurized water chamber, such that D3 ₌ D2 _{+ 2b2} ,

In the formula,
b ₂ - radius of the movable guide vane, mm;
D ₂ - external diameter of the pump impeller, mm;
D ₃ - is the base circle diameter of the inlet of the pump pressurized water chamber, mm, step (1);
Step ( ₂ ) of designing the inlet width B3 of the pump pressurized water chamber such that B3=B2 _{+ 0.05D3 ,}

のように、ボリュートチャンバーの外輪郭線の半径Ｒを設計するステップ（３）であって、 In the formula,
B ₂ - axial width of pump impeller outlet, mm;
D ₃ - base circle diameter of the inlet of the pump pressurized water chamber, mm;
B ₃ - the inlet width of the pump pressurized water chamber, mm, step (2);

Step (3) of designing the radius R of the outer contour of the volute chamber as

In the formula,
A _I - is the area value of the I cross section of the volute, mm;
R - the radius of the outer contour of the volute chamber, mm, step (3);
Step (4) of designing the number of movable guide vanes Z ₁ such that Z ₁ =8 to 14,

In the formula,
Z ₁ - is the number of movable guide vanes, step (4);
Step (5) of designing the number of fixed guide vanes Z ₂ such that Z ₂ =3 to 5,

のように、拡散セグメントの拡散角を設計するステップ（６）であって、 In the formula,
Z ₂ - is the number of fixed guide vanes, step (5);

Step (6) of designing the diffusion angle of the diffusion segment as:

In the formula,
A _I - is the area value of the I cross section of the volute, mm;
D _S - the diameter of the volute outlet, mm;
L - the length of the diffusion segment of the volute, mm;
θ - the divergence angle, in degrees;
and step (6) with θ between 6° and 12°.

In order to reduce the volume of the pump and the diameter of the discharge pipe, reduce the loss of the pipe, thereby reducing the lift of the pump, reducing the power of the pump, saving energy and reducing operating costs, the discharge caliber can be less than the inlet diameter. After rudimentary determination of the diameter of the outlet of the pump, it is rounded according to the standard pipe diameter series. In order to reduce the size of the pump, the diffusion tube/diffusion segment height L should be as small as possible while ensuring diffusion angle, machining and bolting.

The present invention has the following beneficial technical effects.

(1) Using the structure of an annular volute, the annular volute has a symmetrical vortex flow path and a large gap between the partition tongue and the impeller outlet, compared with the traditional spiral volute; By using an annular volute instead of a conventional volute, the pressure pulsation and radial force of the pump can be reduced and the operational stability can be improved. The gap between the impeller circumference and the volute partition tongue is increased, the advantage of which is that the impact of the water flow on the volute partition tongue is reduced and the gap between the partition tongue and the impeller is increased, thus reducing the pressure pulsation and overall Radial forces can be reduced.

(2) By further designing, the fixed guide vanes have different centric angles, and the centric angles increase from section II to section I in the flow direction. The channel gap increases in the direction of flow from cross-section II toward the other cross-sections. Further reduce the pressure pulsation and radial force during operation of the pump, reduce the corner vortex at the outlet of the fixed guide vane, reduce the pressure fluctuation and pressure loss in the annular volute, and improve the operational safety under each operating condition of the pump. It can improve performance and stability. The present invention further reduces the corner vortex at the fixed guide vane outlet through the design of the first recessed groove, the second recessed groove, and reduces the pressure fluctuation and pressure loss of the annular volute, thereby Driving safety and stability under driving conditions can be improved.

(3) By providing two rows of guide vanes (movable guide vanes, fixed guide vanes) in the volute, the high-speed liquid shaken off from the impeller is collected and uniformly distributed to the inlet of the next stage impeller or the discharge chamber. and convert some of the kinetic energy of the liquid into pressure energy in the guide vanes, thereby improving the efficiency of the pump. The use of two rows of guide vanes significantly improves hydraulic performance compared to no fixed guide vanes or a single row of fixed guide vanes. Considering that the cross section of the volute uses an eccentric elliptical cross section, we analyzed the influence of the cross section shape on the hydraulic performance of the centrifugal pump. It can be seen that the rectangle gives a higher pump pressure head.

The above-described embodiments are illustrative of the present invention and are not limitations on the present invention, and various alterations, modifications, substitutions and variations of these embodiments may be made without departing from the principles and spirit of the present invention. It is understood that the protection scope of the present invention is limited by the appended claims and their equivalents.

Volute outlet 1, diffusion segment 2, throat 3, fixed multi-channel 4, movable guide vane 5, fixed guide vane 6, outlet guide vane 7, partition tongue/tongue 8, channel gap 9, D2 impeller outer diameter , the base circle diameter of the inlet of the D3 pressurized water chamber, the radius of the contour line of the R volute chamber, the downstream edge/trailing edge 61, the first groove 62, the second groove 63.

Claims (8)

Volute outlet (1), diffusion segment (2), throat (3), fixed multi-channel (4), movable guide vane (5), fixed guide vane (6), outlet guide vane (7), partition tongue / A diffusion segment is provided at the outlet end of the pressurized water chamber, comprising a tongue (8), and a channel gap (9), the outlet end of the diffusion segment having a volute outlet, between the pressurized water chamber and the diffusion segment. The connecting part is the throat part, and a diffuser is provided on the outer periphery of the impeller, the diffuser includes a plurality of movable guide vanes distributed in the circumferential direction, and a partition tongue is configured between the diffusion segment and the volute wall. It is a volute for large construction pumps,
A plurality of fixed guide vanes (6) are provided around the outer circumference of the movable guide vanes (5), the fixed guide vanes divide the volute channel into fixed multi-channels, and the median/axis of the exit guide vanes are diffusion segments collinear/parallel to the median/axis line, the outlet guide vane is substantially tangent to the base circle D3 of the inlet of the pressurized water chamber, the outlet end of the fixed guide vane and the inlet end of the adjacent radially inner fixed guide vane or There is a channel gap (9) between the base circle D3 of the inlet of the pressurized water chamber, the inlet end of the outlet guide vane has a cross section I, the dividing tongue end has a cross section II, the volute is in the flow direction A volute for a large construction pump, characterized in that the section II to section I is an annular volute, and the cross-sectional flow areas of the volute flow passages are substantially the same. The volute uses an annular volute with a substantially eccentric elliptical cross-section, and in the major axis direction of the ellipse, the size of the long eccentric part of the ellipse is 2 to 4 times the size of the short part of the ellipse. The volute of the pump for large-scale construction work according to claim 1. Said fixed guide vane (6) is an arc-shaped guide vane, the fixed guide vane has different centric angles, the centric angle increases in the flow direction from section II to section I, and in the flow direction The volute of large construction pump according to claim 2, characterized in that from section II to section I, the downstream centroid angle is 1.05-1.25 times the upstream centroid angle. The channel gap (9) increases in the direction of flow from cross-section II to cross-section I, and from cross-section II to cross-section I in the flow direction, the downstream channel gap is 1.05 to 1.05 to 1 of the upstream channel gap. 4. The volute of a large construction pump according to claim 3, characterized in that it is .2 times. Said fixed guide vane (6) has a downstream/tailing edge (61), the downstream end being tapered or arcuate, the downstream end having a first concave groove (62) and a second A plurality of first grooves are provided on the radially inner surface of the downstream end, and a plurality of second grooves are provided on the radially outer surface of the downstream end. 5. The volute of a pump for large-scale construction according to claim 4, wherein the concave groove and the second concave groove have a semi-circular structure. The number of the first grooves (62) is greater than the number of the second grooves (63), and the number of the first grooves is 1.5 to 3.0 times the number of the second grooves. The volute of the large construction pump according to claim 5, characterized in that there is a volute. The diffusion segment is a pump body outlet, the area of the water flow passage increases as the diffusion segment goes from the throat to the volute outlet, the cross section of the diffusion segment includes a rectangular and/or arc shape, and is at the throat position. Large construction according to claim 5, characterized in that the cross-sectional shape of the pressurized water chamber of is the same as and overlaps the end face shape of the diffusion segment, said structure ensuring a smooth transition between the pressurized water chamber and the diffusion segment volute of the pump. Using an annular volute structure with fixed guide vanes and movable guide vanes,
Depending on the given operating conditions, based on the volute velocity factor method,

The basic circle diameter D ₃ of the inlet of the pressurized water chamber, the inlet width B ₃ of the pump pressurized water chamber, the radius R of the contour line of the volute chamber, the number Z ₁ of the movable guide vanes, the number Z ₂ of the fixed guide vanes, and the diffusion angle θ. determine the geometric parameters of the containing volute,
Step ( ₁ ) of designing the base circle diameter D3 of the inlet of the pressurized water chamber, such that D3 ₌ D2 _{+ 2b2} ,
In the formula,
b ₂ - radius of the movable guide vane, mm;
D ₂ - external diameter of the pump impeller, mm;
D ₃ - is the base circle diameter of the inlet of the pump pressurized water chamber, mm, step (1);
Step ( ₂ ) of designing the inlet width B3 of the pump pressurized water chamber such that B3=B2 _{+ 0.05D3 ,}
In the formula,
B ₂ - axial width of pump impeller outlet, mm;
D ₃ - base circle diameter of the inlet of the pump pressurized water chamber, mm;
B ₃ - the inlet width of the pump pressurized water chamber, mm, step (2);

Step (3) of designing the radius R of the outer contour of the volute chamber as
In the formula,
A _I - is the area value of the I cross section of the volute, mm;
R - the radius of the outer contour of the volute chamber, mm, step (3);
Step (4) of designing the number of movable guide vanes Z ₁ such that Z ₁ =8 to 14,
In the formula
Z ₁ - is the number of movable guide vanes, step (4);
Step (5) of designing the number of fixed guide vanes Z ₂ such that Z ₂ =3 to 5,
In the formula
Z ₂ - is the number of fixed guide vanes, step (5);

Step (6) of designing the diffusion angle of the diffusion segment as:
In the formula
A _I - is the area value of the I cross section of the volute, mm;
D _S - the diameter of the volute outlet, mm;
L - the length of the diffusion segment of the volute, mm;
θ - the divergence angle, in degrees;
The method for designing a volute of a large construction pump according to claim 1, characterized by comprising a step (6) of setting θ to 6° to 12°.

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