JP2012132368A - Double suction type centrifugal liquid machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a double suction type centrifugal liquid machine that reduces water pressure pulsation.SOLUTION: The double suction type centrifugal liquid machine includes: a first suction opening Isucking a liquid; a second suction opening Ipositioned coaxially with the first suction opening Iand sucking a liquid trending in the opposite direction of the first suction opening I; a plurality of first blades 1 introducing a liquid into the first suction opening I; the same number of second blades 2 as the first blades 1, introducing a liquid into the second suction opening Iand an outlet O discharging in the radius direction the liquid sucked from the first and second suction openings Iand I. The first blades 1 and the second blades 2 are alternately arranged in a circumferential direction, and form liquid flow passages, respectively. The liquid introduced by the first blades 1 and the liquid introduced by the second blades 2 are joined together in the liquid flow passages, and are discharged from the outlet O.

Description

  The present invention relates to a double suction centrifugal fluid machine.

Conventionally, a double-suction centrifugal fluid machine is known (see Patent Documents 1 to 3 below).
For example, in a conventional double suction centrifugal fluid machine, as described in Patent Document 1 below, the outlet speed of the fluid at the discharge port varies as shown in FIG. 2 of Patent Document 1 below. Therefore, when this interferes with the tongue end (see Tp in FIG. 3A of Patent Document 1 below), a hydraulic pulsation occurs.
On the other hand, by increasing the number of blades as shown in FIG. 5 of the following Patent Document 1, the fluctuation of the outlet speed is reduced and the water pressure pulsation is also reduced as shown in FIG. 6 of the following Patent Document 1. be able to.

JP 58-13597 A JP 2008-008154 A Japanese Utility Model Publication No. 6-087694

  However, in the conventional double suction type centrifugal fluid machine, when the number of blades is increased as shown in FIG. 5 of the above-mentioned Patent Document 1, the structure becomes complicated, so that the manufacturing cost is greatly increased. There's a problem.

  In FIG. 5 of the above-mentioned Patent Document 1, the number of blades located outside in the radial direction is increased from the middle. However, when the number of blades is increased from the fluid inlet, When the flow path area at the suction port decreases and the flow velocity increases, cavitation, which is a phenomenon in which the static pressure decreases and the fluid vaporizes, is likely to occur. And when cavitation generate | occur | produces, there exists a problem that there exists a possibility of causing the performance fall and damage of both suction type | mold centrifugal fluid machines.

  In view of the above, an object of the present invention is to provide a double suction centrifugal fluid machine that can reduce hydraulic pulsation.

The double suction centrifugal fluid machine according to the first invention for solving the above-described problems is
A first inlet for inhaling fluid;
A second suction port for sucking a fluid located coaxially with the first suction port and facing in a direction opposite to the first suction port;
A plurality of first blades for introducing fluid into the first suction port;
The same number of second blades as the first blades for introducing fluid into the second inlet;
A double-suction centrifugal fluid machine comprising a first suction port and a discharge port for discharging fluid sucked from the second suction port in a radial direction;
The first blades and the second blades are alternately arranged in the circumferential direction to form a fluid flow path by the first blades and the second blades, and are guided by the first blades. And the fluid guided by the second blades merge in the flow path and are discharged from the discharge port.

A double-suction centrifugal fluid machine according to a second invention for solving the above problems is the double-suction centrifugal fluid machine according to the first invention.
The fluid introduced by the first blade is branched by encountering the second blade on the way, and the branched fluid is led to the first blade and the second blade and is discharged from the discharge port. Discharged,
The fluid introduced by the second blade is branched by encountering the first blade on the way, and the branched fluid is led to the first blade and the second blade and is discharged from the discharge port. It is characterized by being discharged.

A double suction centrifugal fluid machine according to a third aspect of the present invention for solving the above problem is the double suction centrifugal fluid machine according to the first aspect of the invention,
The shape of the ends of the first blade and the second blade at the discharge port is a shape other than the shape parallel to the axial direction.

  ADVANTAGE OF THE INVENTION According to this invention, the double suction type centrifugal fluid machine which can reduce a hydraulic pulsation can be provided.

It is sectional drawing and the perspective top view in the axial direction of the both suction type | mold centrifugal fluid machine which concern on 1st Example of this invention. It is sectional drawing and an expanded view in the axial direction of the double suction type centrifugal fluid machine which concerns on 1st Example of this invention. It is the side view which showed the shape of the discharge port of the fluid in the double suction type centrifugal fluid machine which concerns on 2nd Example of this invention.

Hereinafter, an embodiment for carrying out a double suction centrifugal fluid machine according to the present invention will be described with reference to the drawings.
As described above, it is effective to increase the number of blades in order to reduce the hydraulic pulsation in the double suction centrifugal fluid machine. However, when the number of blades is simply increased, the flow passage area of the suction port is reduced by the thickness of the blades, and there is a problem that cavitation tends to occur in the blades at the suction port portion.

  For this reason, a configuration in which the number of blades at the discharge port is increased by adding short blades (hereinafter referred to as splitters) that exist only near the outside in the radial direction between the blades is conventionally known. Since the structure is complicated, there is a problem that the manufacturing cost is greatly increased.

  Moreover, the structure shown by FIG. 6, 7 of the said patent document 2 is known as a conventional double suction type centrifugal fluid machine. In FIG. 7 of Patent Document 2, the blades are staggered in order to reduce hydraulic pulsation, but there is a central main plate (see, for example, the central main plate 200 in FIGS. 6 and 7 of Patent Document 2). Therefore, there is a problem that the performance improvement effect is poor. Moreover, in FIG. 6 of the said patent document 2, although an intermediate wall is eliminated for the performance improvement and the friction loss is reduced, there exists a problem that the reduction effect of a hydraulic pulsation is inferior.

For this reason, the double suction centrifugal fluid machine according to the present invention has a configuration in which two ordinary single suction centrifugal fluid machines are bonded together. As a result, the flow rate is almost doubled, and thrust generated in the axial direction can be canceled.
In the double suction type centrifugal fluid machine according to the present invention, the two main single suction type centrifugal fluid machines are not simply bonded together, but the flow is merged by removing the central main plate, and the blades are alternately arranged. The device is shared by arranging.
Thereby, according to the double suction type centrifugal fluid machine according to the present invention, it is possible to reduce the manufacturing cost while reducing the hydraulic pulsation by providing the splitter, and further to improve the performance by eliminating the central main plate. it can.

The double suction centrifugal fluid machine according to the first embodiment of the present invention will be described below.
FIG. 1 is a sectional view and a perspective plan view in the axial direction of a double suction centrifugal fluid machine according to a first embodiment of the present invention. 1A is a sectional view in the axial direction of a double suction centrifugal fluid machine according to the first embodiment of the present invention, and FIG. 1B is a double suction type according to the first embodiment of the present invention. It is a perspective top view of a centrifugal fluid machine. Moreover, in FIG. 1 (a) and FIG.1 (b), the arrow R has shown the rotation direction. In addition, arrows I, II, and III shown in FIG. 1B show examples of fluid flow.

As shown in FIG. 1A, the double-suction centrifugal fluid machine according to the present embodiment includes a first suction port I ₁ indicated by an arrow I ₁ as a fluid suction port and a second suction port indicated by an arrow I _2. A suction port I ₂ is provided, and a discharge port O indicated by an arrow O is provided as a fluid discharge port. In the dual suction centrifugal fluid machine according to the present embodiment, when fluid is sucked into the first suction port I ₁ and the second suction port I ₂ from the axial direction, the first suction port I ₁ and the second suction port I 2 are used. The fluid sucked from the suction port I ₂ is joined, and the joined fluid is discharged from the plurality of discharge ports O in the radial direction.

In the double suction centrifugal fluid machine according to the present embodiment, the first impeller 4 and the second impeller 3 form an outer shell. Between the first impeller 4 and the second impeller 3, the first blade 1 for sucking fluid from the first suction port I ₁ side and the fluid from the second suction port I ₂ side The second blade 2 for sucking in is installed. The first blade 1 and the second blade 2 are supported via a blade support portion 6 installed on the shaft portion 5.

  As shown in FIG. 1B, the double suction centrifugal fluid machine according to the present embodiment includes three first blades 1 and three second blades 2. The first blade 1 and the second blade 2 extend from the front to the rear in the rotational direction and have a curved shape so as to swell in the rotational direction. In the present embodiment, a case where three first blades 1 and three second blades 2 are provided will be described as an example. This can be realized in the same manner as long as the same number of first and second blades 2 are installed.

In the first suction port I ₁ , there are three first blades 1, and in the second suction port I _2, there are also three second blades 2, and the first blade 1 and the second blades 2. By combining the blades 2 so as to be alternately arranged, the discharge port O has six sheets including the first blade 1 and the second blade 2. For this reason, in the discharge port O, it will be in the situation equivalent to the case where six blades on one side are installed in the conventional double suction type centrifugal fluid machine.

  FIG. 2 is a sectional view and a developed view in the axial direction of the double suction centrifugal fluid machine according to the first embodiment of the present invention. 2A is a sectional view in the axial direction of the double suction centrifugal fluid machine according to the first embodiment of the present invention, and FIG. 2B is a double suction type according to the first embodiment of the present invention. It is an expanded view of a centrifugal fluid machine. Further, in FIG. 1A, an arrow R indicates a rotation direction. 2 indicate the same flow as the arrows I, II, and III shown in FIG. Further, A, A ', B, B', C, C ', D, and D' in FIG. 2 are A, A ', B, B', C, C ', D, and D' shown in FIG. It shows the same position.

As shown in FIG. 2B, in the double suction centrifugal fluid machine according to the present embodiment, the first blade 1 is guided from the first suction port I _{1 as} indicated by arrows I, II, and III. The fluid flows in. The fluid flow indicated by the arrow II encounters the second blade 2 on the way. Thereby, the 2nd blade | wing 2 has the same effect as the splitter in the conventional both suction type centrifugal fluid machine.

Further, as shown in FIG. 2B, in the double suction centrifugal fluid machine according to the present embodiment, the second suction port I ₂ is shown by the arrows I ′, II ′, III ′ as shown by the arrows I ′, II ′, III ′. The fluid flows in by being guided to the blade 2. Then, the fluid flow indicated by the arrow II ′ encounters the first blade 1 on the way. That is, the fluid introduced by the first blade 1 is branched when it encounters the second blade 2 on the way, and the branched fluid is guided to the first blade 1 and the second blade 2 and discharged from the outlet. The fluid discharged from O and introduced by the second blade 2 is branched while encountering the first blade 1 on the way, and the branched fluid is branched into the first blade 1 and the second blade 2. It is guided and discharged from the discharge port O. Thereby, the 1st blade | wing 1 will have the same effect as the splitter in the conventional both suction type centrifugal fluid machine.

By the way, the double suction type centrifugal fluid machine described in the above-mentioned patent document 3 is not simply bonding two single suction type centrifugal fluid machines, but two two suction type centrifugal fluid machines are fused. (See FIGS. 1B and 1C of Patent Document 3).
However, in the double suction centrifugal fluid machine described in Patent Document 3, the flow channel 1a and the flow channel 1b shown in FIGS. 1B and 1C of Patent Document 3 are three-dimensionally complicated. However, since the flow path 1a and the flow path 1b are not joined, the effect of improving the performance is poor. Note that FIG. 1A of Patent Document 3 corresponds to only the flow path 1a.

On the other hand, in the double suction centrifugal fluid machine according to the present embodiment, two single suction centrifugal fluid machines are essentially fused as shown in FIG. That is, a fluid flow path is formed by the first blade 1 and the second blade 2, respectively, and flows through the first suction port I ₁ indicated by arrows I, II, and III in FIG. The flow of the fluid and the flow of the fluid flowing in from the second suction port I ₂ indicated by arrows I ′, II ′, and III ′ in FIG. 2 are merged and discharged from the discharge port O. . Thereby, the flow rate of the fluid in each flow path is almost doubled, and the thrust generated in the axial direction can be canceled.

As described above, according to the double suction centrifugal fluid machine according to the present embodiment, since the number of blades at the discharge port O is large as in the case where the splitter is installed, the hydraulic pulsation can be reduced.
Similarly to the case where the splitter is installed, the number of blades in the first suction port I ₁ and the second suction port I ₂ is small, so that the occurrence of cavitation can be suppressed.
Further, by eliminating the central main plate, it is possible to reduce friction loss and improve performance.
In addition, the manufacturing cost can be halved compared to the case where two single suction centrifugal fluid machines in which a splitter is simply installed between the blades are bonded together.

The double suction centrifugal fluid machine according to the second embodiment of the present invention will be described below.
FIG. 3 is a side view showing the shape of a fluid discharge port in a double suction centrifugal fluid machine according to a second embodiment of the present invention. In FIG. 3, the wave of the speed fluctuation of the outlet speed of the fluid at the discharge port O is schematically indicated by a broken line. In FIG. 3, an arrow S indicates the axial direction, and an arrow R indicates the rotational direction.

As described above, the fluid outlet speed at the discharge port O fluctuates as shown in FIG. 2 of the above-mentioned Patent Document 1, and this is the tongue end (FIG. 3A of the above-mentioned Patent Document 1). ) (See Tp)), hydraulic pulsation occurs.
For example, when the shape of the discharge port O is the shape as shown in FIG. 3B of Patent Document 1, the phase difference in the axial direction in the wave of the speed fluctuation as shown by the broken line in FIG. Because there is no wave, the wave of speed fluctuation hits the tongue end all at once and a big water pressure pulsation occurs.

  On the other hand, according to the shape of the discharge port O in the double-suction centrifugal fluid machine according to the present embodiment, the phase of the velocity fluctuation wave in the axial direction is indicated by a broken line in FIGS. Since there is a difference in the timing at which the velocity fluctuation wave hits the tongue end, water pressure pulsation can be reduced.

  That is, in the double suction centrifugal fluid machine according to the present embodiment, the shape of the ends of the first blade 1 and the second blade 2 at the discharge port O is a shape other than the shape parallel to the axial direction. Since there is a difference in the timing at which the wave of velocity fluctuation hits the tongue end, the hydraulic pulsation can be reduced.

  Therefore, according to the double suction centrifugal fluid machine according to the present embodiment, in addition to the effect exhibited by the double suction centrifugal fluid machine according to the first invention, periodic water pressure pulsation can be reduced. Vibration can be reduced.

  The present invention can be used in, for example, a double suction centrifugal fluid machine.

DESCRIPTION OF SYMBOLS 1 1st blade | wing 2 2nd blade | wing 3 2nd impeller 4 1st impeller 5 Shaft part 6 Blade | wing support part I ₁ 1st inlet I ₂ 2nd inlet O O outlet

Claims (3)

A first inlet for inhaling fluid;
A second suction port for sucking a fluid located coaxially with the first suction port and facing in a direction opposite to the first suction port;
A plurality of first blades for introducing fluid into the first suction port;
The same number of second blades as the first blades for introducing fluid into the second inlet;
A double-suction centrifugal fluid machine comprising a first suction port and a discharge port for discharging fluid sucked from the second suction port in a radial direction;
The first blades and the second blades are alternately arranged in the circumferential direction to form a fluid flow path by the first blades and the second blades, and are guided by the first blades. And a fluid guided by the second blade join together in the flow path and are discharged from the discharge port. The fluid introduced by the first blade is branched by encountering the second blade on the way, and the branched fluid is led to the first blade and the second blade and is discharged from the discharge port. Discharged,
The fluid introduced by the second blade is branched by encountering the first blade on the way, and the branched fluid is led to the first blade and the second blade and is discharged from the discharge port. The double suction centrifugal fluid machine according to claim 1, wherein the double suction centrifugal fluid machine is discharged. 2. The double suction centrifugal fluid machine according to claim 1, wherein the shape of the end portions of the first blade and the second blade at the discharge port is a shape other than a shape parallel to the axial direction.

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