CN108843619B

CN108843619B - Double-volute structure of centrifugal pump

Info

Publication number: CN108843619B
Application number: CN201810690428.1A
Authority: CN
Inventors: 孙中国; 宋运璋; 席光
Original assignee: Xian Jiaotong University
Current assignee: Xian Jiaotong University
Priority date: 2018-06-28
Filing date: 2018-06-28
Publication date: 2020-05-22
Anticipated expiration: 2038-06-28
Also published as: CN108843619A

Abstract

The invention relates to the field of fluid machinery, in particular to a double-volute structure of a centrifugal pump, which comprises a volute, a volute chamber arranged in the volute and a diffusion pipe arranged at the outlet of the volute, wherein a separation tongue is arranged at the contact part of the volute and the diffusion pipe, a partition plate is arranged in the volute, the volute chamber is divided into two volute channels by the partition plate, the head end of the partition plate is a sharp corner, and the tail edge of the partition plate is a sharp corner. The sharp corner at the head end of the partition plate eliminates the defect that the radial force borne by the impeller is increased due to the fact that the existence of the partition tongue causes great difference in pressure distribution at the front ends of the two flow channels, the sharp corner at the tail edge of the partition plate overcomes the phenomenon that the traditional double-volute casing has serious flow loss and flow separation at the tail edge of the partition plate, the lift of fluid is improved, and therefore efficiency is improved.

Description

Double-volute structure of centrifugal pump

Technical Field

The invention relates to the field of fluid machinery, in particular to a double-volute structure applied to a centrifugal pump.

Background

The spiral case form of present research is mostly conventional single spiral case, because two spiral case structures can make the pump internal flow more symmetrical, and radial force compares in single spiral case structure and very weakens, and the operation of pump is more stable, therefore uses comparatively extensively.

The double volute form is symmetrically arranged by two separate flow passages, and the sum of two symmetrical throat areas is equal to the throat area of the single volute. The double volute casing has the characteristics that the radial force basically keeps balance, and the pump runs stably; the efficiency of the double-volute pump is similar to that of the single volute, the double-volute pump is lower than the single volute by l-1.5% under the optimal working condition, and is higher than the single volute by about 2% under the non-design working condition, and the high-efficiency range is wide; the double-volute is difficult to cast due to the double-layer flow channel, and the double-volute flow channel is not suitable for being used under the condition that the flow rate is less than 90mVh and is suitable for being applied to the condition of large flow.

When the centrifugal pump is operated under the condition of deviating from the design working condition and under the condition of zero flow, radial force is an alternating load for a pump shaft, and when the generated radial force is too large, vibration of the pump shaft can be caused, so that the vibration of the pump is caused, and the instability of the pump is increased. The balancing of the radial forces of centrifugal pumps is very important, especially for high flow high lift pumps. The conventional twin volute is theoretically capable of balancing the radial force well, but due to the presence of the diaphragm and the asymmetric pump body, the twin volute cannot balance the radial force completely in practice. Especially for a large-flow high-lift pump, under the working condition of lower than rated flow, even if the pump is provided with a double-volute structure, the radial force borne by the impeller is still larger. Under the designed working condition, the speed and the pressure of the fluid in the pressurized-water chamber around the impeller are uniform and symmetrical theoretically, so that the resultant force acting on the impeller is zero. In practice, however, the flow field is disturbed by the presence of fluid impact near the volute tongue, and the radial force experienced by the impeller is not zero. When the centrifugal pump operates under the condition of deviating from the designed flow, the volute line deviates from the streamline of the actual impeller outflow, so that the peripheral speed and pressure of the impeller are uneven and are asymmetrically distributed, the larger the deviation of the volute line from the designed flow is, the more serious the uneven and asymmetrical peripheral speed and pressure of the impeller is, and the higher the radial force is displayed. The double volute casing can eliminate radial force by dividing a flow channel outside the impeller, namely the volute casing, into two volute casings to form a symmetrical structure, but the influence of a special structure of the partition tongue on the radial force is not considered, the partition tongue is arranged at the front end of the first channel, the pressure distribution of the front ends of the two flow channels of the partition tongue is greatly different, and the radial force borne by the impeller is increased.

Disclosure of Invention

The invention aims to provide a double-volute structure of a centrifugal pump, which aims to solve the problem that a double-volute impeller in the prior art is subjected to large radial force.

The invention is realized by the following technical scheme:

the utility model provides a two spiral case structures of centrifugal pump, includes the spiral case, locate the volute in the spiral case and locate the diffusion tube of spiral case exit, spiral case and diffusion tube contact department are equipped with the partition tongue, are equipped with the baffle in the spiral case, and the baffle separates the spiral case into two spiral case passageways, and one side that the baffle is close to the diffusion tube is the trailing edge, and the opposite side is the head end, and the head end of baffle is the closed angle form, the closed angle summit is located the well cross-section of spiral case.

Furthermore, the sharp corner vertex at the head end of the clapboard and the isolating tongue are symmetrical about the center of the base circle of the volute.

Furthermore, the tail edge of the partition board is in a sharp angle shape, and the vertex of the sharp angle is positioned on the middle section of the volute.

Further, the sharp angle is an acute angle.

Furthermore, the size of the sharp angle of the head end of the clapboard is 50-60 degrees.

Furthermore, the size of the sharp angle of the tail edge of the clapboard is 40-50 degrees.

Further, the thickness of the sharp corner is 1/2 of the maximum thickness of the partition board.

Further, the separator has a roughness Ra <6.3 μm.

Compared with the prior art, the invention has the following beneficial technical effects:

the invention arranges a sharp corner with a certain angle at the first section of the clapboard, can eliminate the defect that the radial force borne by the impeller is increased due to the large difference generated by the pressure distribution at the front ends of the two flow channels caused by the existence of the baffle tongue to a certain extent, so that the flow field at the first end of the clapboard is more similar to the flow field near the clapboard, and the flow field of the whole volute is more symmetrical; the sharp corner of certain angle that the baffle trailing edge set up can be fine reduces the impact loss and the flow loss of basin in place, has improved the characteristic curve of centrifugal pump, has improved flow lift and efficiency. The invention can be applied to a high-flow high-lift centrifugal pump.

Drawings

FIG. 1 is a schematic structural view of a double volute of a centrifugal pump provided by the invention;

FIG. 2 is a relation between the radial force of the double-volute casing of the centrifugal pump provided by the invention and the flow rate under different angles of the sharp corner of the first-end partition tongue;

FIGS. 3a and 3b are flow charts of a double-volute of a centrifugal pump with a sharp-cornered head section and a sharp-cornered tail edge and a double-volute with a sharp-cornered head section only on a middle section, respectively, according to the invention;

FIG. 4 is a relationship between the head of the twin-volute casing of the centrifugal pump and the flow rate when the sharp angle of the trailing edge tongue is different;

FIG. 5 is a graph comparing the efficiency of the same centrifugal pump using the twin volute configuration of the present invention with a conventional twin volute;

FIG. 6 is a graph comparing fluid head for the same centrifugal pump using the twin volute configuration of the present invention with a conventional twin volute;

FIG. 7 is a graph comparing the average radial force experienced by a twin-volute and a conventional twin-volute impeller of the same centrifugal pump using the centrifugal pump of the present invention.

Wherein, 1-volute chamber, 2-baffle tongue, 3-baffle plate, 4-diffuser pipe, 5-volute.

Detailed Description

The present invention will now be described in further detail with reference to specific examples, which are intended to be illustrative, but not limiting, of the invention.

As shown in fig. 1, fig. 1 is a schematic diagram of a double-volute structure applied to a centrifugal pump, and includes a volute 5, a volute chamber 1 arranged in the volute 5, and a diffusion pipe 4 arranged at an outlet of the volute 5, wherein a partition tongue 2 is arranged at a contact position of an upper end of the volute 5 and the upper end of the diffusion pipe 4 and the volute 5, a partition plate 3 is arranged in the volute 5, the volute chamber 1 is divided into two volute channels by the partition plate 3, a head end of the partition plate 3 is a sharp corner, and a vertex of the sharp corner of the head end of the partition plate 3, the partition tongue 2 and a center of a base circle of the; the tail edge of the clapboard 3 is a sharp angle, the sharp angle vertex of the tail edge of the clapboard 3 and the separating tongue 2 are on the same straight line, the size of the sharp angle at the head end of the clapboard 3 is 50-60 degrees, and the size of the sharp angle at the tail edge of the clapboard 3 is 40-50 degrees.

Referring to fig. 2, the relationship between the radial force of the impeller in the double-volute of the centrifugal pump and the flow rate when the sharp angle of the front-end isolating tongue is different is shown. It can be seen from the figure that at the same flow rate, the radial force of the impeller tends to decrease at the leading end tip angle of the baffle plate 3 of 30 °, 40 ° and 50 °, increases at the leading end tip angle of the baffle plate 3 of 50 °, 60 ° and 70 °, and reaches a minimum value at 50 °, and it can be seen from the figure that the radial force of the impeller is less than 40 ° at the leading end tip angle of the baffle plate 3 of 60 °, so that the minimum value of the radial force of the impeller is taken between 50 ° and 60 °. Fig. 2 also illustrates that the defect that the radial force applied to the impeller is increased due to the large difference of the pressure distribution at the front ends of the two flow channels caused by the existence of the baffle tongue 2 can be eliminated to a certain extent by sharpening the head end of the baffle plate 3 in the invention.

Referring to fig. 3, fig. 3a and 3b are flow charts of the centrifugal pump double-volute and the conventional double-volute respectively on the middle section, and as can be seen from fig. 3(b), the flow loss of the conventional double-volute is serious at the trailing edge of the partition plate, flow separation occurs, and even a vortex is generated; the flow field at the position is improved and unnecessary flow loss is reduced by making the tail edge of the partition plate 3 into a certain angle, and as can be seen from fig. 3(b), the flow loss at the tail edge of the partition plate is serious, and the phenomenon of flow separation is obviously improved.

Referring to fig. 4, fig. 4 shows the relationship between the lift of the twin-volute of the centrifugal pump provided by the invention and the flow rate when the sharp angle of the tail edge tongue is different, and it can be seen from the figure that the fluid lift in the twin-volute of the centrifugal pump is maximum when the angle of the sharp angle of the tail edge of the partition plate 3 is 40-50 degrees when the flow rate is the same. This shows that the use of the sharpened trailing edge of the baffle 3 in the present invention effectively reduces flow losses and maximizes fluid head by setting the sharp angle of the trailing edge of the baffle 3 at 40-50.

Referring to fig. 5, 6 and 7, fig. 5, 6 and 7 are graphs comparing the efficiency, head and average radial force experienced by the impeller of a centrifugal pump twin-volute improved using the present invention with a conventional twin-volute, respectively, for the same centrifugal pump; the numerical simulation verifies that compared with the traditional double-volute, the radial force and the hydraulic performance of the double-volute of the centrifugal pump are obviously improved, and the hydraulic performance is not obviously different under the condition of small flow and rated flow, but under the condition of large flow, the efficiency and the lift of the double-volute pump of the centrifugal pump are higher than that of the traditional double-volute due to the improvement of the sharp corner at the tail edge of the partition plate on the flow; in the aspect of radial force, due to the existence of the sharp corner at the head end of the partition plate, the impeller of the centrifugal pump double-volute pump is obviously less in radial force than that of the traditional double-volute pump. Therefore, the centrifugal pump double-volute provided by the invention overcomes the defects of the traditional double-volute structure, improves the radial force borne by the impeller, and improves the efficiency under the condition of large flow.

Claims

1. The double-volute structure of the centrifugal pump is characterized by comprising a volute (5), a volute chamber (1) arranged in the volute (5) and a diffusion pipe (4) arranged at the outlet of the volute (5), wherein a separation tongue (2) is arranged at the contact part of the volute (5) and the diffusion pipe (4), a partition plate (3) is arranged in the volute (5), the volute chamber (1) is divided into two volute channels by the partition plate (3), one side, close to the diffusion pipe (4), of the partition plate (3) is a tail edge, the other side of the partition plate is a head end, the head end of the partition plate (3) is in a pointed angle shape, and the pointed angle is an acute angle; the thickness of the sharp corner is 1/2 of the maximum thickness of the clapboard (3); the vertex of the sharp corner is positioned on the middle section of the volute (5); the apex of the sharp corner at the head end of the clapboard (3) is symmetrical with the center of the base circle of the volute (5) of the isolating tongue (2); the tail edge of the clapboard (3) is in a sharp angle shape, and the vertex of the sharp angle is positioned on the middle section of the volute (5); the size of a sharp angle at the head end of the clapboard (3) is 50-60 degrees; the size of the sharp angle of the tail edge of the clapboard (3) is 40-50 degrees; the separator (3) has a roughness Ra <6.3 [ mu ] m.