JPS6135399B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a mixed flow pump, and particularly to an improvement in the flow path between guide vanes.

[Conventional technology]

The structure of a conventional mixed flow pump of this type will be explained with reference to FIGS. 2 to 9. In FIG. 2, 1 is a casing, and 2 is an impeller housed in the casing 1, which is fixed to a rotating shaft 3 and rotated by a prime mover (not shown). Reference numeral 4 denotes guide vanes arranged behind the impeller 2, and arranged between the casings 5 and 6.

As the impeller 2 rotates, water is sucked in from the suction port a and energy is given by the impeller 2.
The dynamic pressure of the water through the guide vane 4 is converted into static pressure and is discharged from the discharge port b in the axial direction.

FIGS. 3a and 3b show developed views of the tip side 4' and hub side 4'' of the guide vane 4, and FIG. This is a schematic perspective view.As described above, the guide vanes 4 constitute a curved diff user that restores pressure to the flow while being accompanied by three-dimensional bending.

In addition, the Utility Public Policy Act 1977- related to this type of equipment
No. 15480 is mentioned.

[Problem that the invention seeks to solve]

As shown in Fig. 5, the shape of the A-A' cross section perpendicular to the axis 3' includes point E slightly downstream from the point where the distance from the hub surface 6 to the rotation axis 3' is maximum. It is shown in FIG. That is, the surface 6a of the hub surface of the inter-blade flow path in the AA' cross section is normally formed by a circular arc with a radius R.

On the other hand, since the flow flows along the flow path, it is necessary to consider the cross-sectional shape perpendicular to the flow path when expanding the flow path area, which has an important effect on flow separation. Therefore, as shown in Figures 3 and 4, a cross section perpendicular to the flow path including the above-mentioned point E is
Think DEFG. In this cross section, as shown in Figure 5, the distances of the E and F points of the hub are different from the axis,
RE>RF.

On the other hand, the distances from the axis of points D and G on the chip side are approximately the same. Therefore, the cross-sectional shape of DEFG is as shown in FIG. That is, compared to the arcuate surface EF' which is concentric with the approximately arcuate DG surface, the EF surface is located on the axis 3' side and has a larger area near point F. In other words, the area near point F increases greatly, and the flow tends to separate in this vicinity. The problem is that flow separation increases losses and reduces pump efficiency.

Therefore, as shown in Fig. 8, the change in blade angle is made gradual to reduce the distance that point F moves in the axial direction from point F'.
A method can be considered to reduce the expansion of the flow path area. However, if this is done, the length of the blade becomes longer as shown by the broken line in FIG. 8, resulting in an increase in the size of the pump.
Furthermore, as shown by the broken line in Figure 9, even if the change in the hub surface of the meridional flow path shape is made gradual to reduce the expansion of the flow path area, the axial distance and the outer diameter on the chip side will inevitably increase. This also means that the pump will be larger. Increasing the size of the pump is a problem because it increases manufacturing costs.

An object of the present invention is to improve the performance of a pump by preventing separation of the guide vanes without increasing the axial distance of the guide vanes.

[Means for solving problems]

The above-mentioned problem: By forming the hub surface of the inter-vane flow path, which has a cross section perpendicular to the rotational axis, into an inclined surface that becomes farther from the rotational axis as it goes from the concave side to the convex side of the guide vane. resolved.

[Effect]

Rapid expansion of the flow path on the convex side of the guide vane is alleviated and flow separation is suppressed, so that a highly efficient guide vane can be obtained.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

In the figures, the same reference numerals as in FIGS. 2 to 9 represent the same parts. From the hub surface 6a of the inter-vane flow path constituted by the guide vane 4, especially from the vicinity where the hub surface 6a begins to face radially inward to the flow path outlet, the concave side 4b of the guide vane directs the convex side 4a. A smooth inclined surface 6b is formed so as to be farther away from the rotation axis. The rest is the same as the conventional one.

Since this invention has the above configuration, points E and F at the intersection of the hub surfaces of the convex side 4a and the concave side 4b in the cross section C-C', which is a cross section perpendicular to the flow path shown in FIG. Since the distance R from the axis can be made equal and the rapid expansion of the flow path area near point F can be slowed down, flow separation can be suppressed without increasing the axial distance of the guide vane casing. be done. Thereby, a highly efficient guide vane can be realized.

〔Effect of the invention〕

As explained above, this invention forms the hub surface of the inter-vane flow path into an inclined surface that is farther from the rotation axis as it goes from the concave side of the guide vane to the convex side. Since the sudden expansion of the flow path is alleviated and separation of the flow is suppressed, a highly efficient guide vane can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of the flow path between the blades perpendicular to the rotation axis of the guide vanes of the mixed flow pump of the present invention, and Figs. 2 to 9 are diagrams illustrating a conventional mixed flow pump. 3A and 3B are developed views of the tip side and hub surface of the guide vanes in FIG. 2; FIG. Figure 5 is a schematic cross-sectional view of the guide vane section, Figure 6 is a cross-sectional view taken along line A-A' in Figure 5, Figure 7 is a cross-sectional view perpendicular to the rotation axis of the guide vane flow path, and Figure 8 is Figure 3. FIG. 9 is a developed view of the guide vane when the angle change of the vane is made gradual, and FIG. 3... Rotating shaft, 4... Guide vane, 4a... Convex side of guide vane, 4b... Concave side of guide vane, 6a... Channel hub surface between guide vanes, 6b... Inclined surface. 〓〓〓〓〓

Claims (1)

[Claims] 1 In the inter-vane flow path composed of guide vanes,
The hub surface of the inter-blade flow path having a cross section perpendicular to the rotation axis is formed into an inclined surface that becomes farther from the rotation axis as it goes from the concave side to the convex side of the guide vane. flow pump.