JPH02140466A - Turning suppression fins for bent suction pipes - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a swirl suppression fin for a bent suction pipe.

[Conventional technology]

In general, the direction of water flowing out from the runners of fixed-blade turbines such as Francis turbines and propeller turbines is almost in the direction of the rotational axis of the runner under normal operating conditions, but when the load is greater than that, the direction of water flowing out from the runners is in the opposite direction of rotation. It flows out with a swirling component, and when the load is small, it flows out with a swirling component in the same direction as the rotation. For this reason, a swirling flow with a certain boundary is generated near the center of the bent suction pipe, and when the pushing water pressure is low (when the water level of the spillway is low), the pressure in the center becomes low and a cavity is formed. This excess center is often relatively stable under overload, but under partial load it becomes a tornado and swings around inside the bent suction pipe. If this phenomenon becomes severe, it may induce vibrations of the penstock (if it resonates with the iron pipe), vibrations of the power plant building, and power fluctuations.As a countermeasure to these problems, fins are installed in the water flow direction of the bent suction pipe to suppress swirling flow. may be installed.

Conventionally, swirl suppressing fins installed on water turbine bent suction pipes have been described in Technical Report of the Institute of Electrical Engineers of Japan (Part 1) No. 142 (3) (January 1980), Page 3, No. 1. As shown in FIG. 2, it was customary to arrange the tube in a symmetrical position with respect to the curved plane of the curved suction tube.

In other words, No. 8 shows a conventional example of a water turbine bent suction pipe.
As shown in FIGS.

The rotation suppressing fins 2 (2A to 2D) of the curved suction pipe 1 are arranged symmetrically with respect to a plane 3 that includes the runner rotation axis and passes through the center of the curved suction pipe outlet surface.

In Fig. 8, R is the runner rotation direction, and 5 is the runner rotation direction R around the runner rotation axis from the side that is not downstream of the plane that includes the runner rotation axis and passes through the center of the curved suction pipe outlet surface. This is the measured angle O. Also, in Fig. 9, 2E is the rotation suppressing fin 2 (2A, 2B, 2C, 2D)
This is the vortex center formed in the wake of the vortex.

[Problem to be solved by the invention]

The swirl suppression fin suppresses swirl and at the same time creates a new vortex center in the wake of the fin.

As shown in FIG. 9 above, this vortex center flows along the wall surface of the suction pipe while rotating along with the swirling flow.

Conventional fin placement did not take into account the effect of the vortex center in the wake of this fin, so when the vortex center bends and touches the wall surface of the suction pipe, it is necessary to protect the concrete that forms the wall surface and the concrete. There was a problem in that the steel plate liners installed in the pipes were strongly vibrated, causing serious damage to them. Particularly, when the water contains dirt and sand, the dirt components accelerate the impact on the wall surface, causing extremely serious damage to the wall surface of the suction pipe, which has become a major problem.

The present invention has been made in view of the above points, and it is an object of the present invention to provide a turning suppression fin for a curved suction pipe that can prevent damage to the wall surface of the curved suction pipe.

[Means to solve the problem]

The above purpose is to install a fin at an angle of 70 degrees or more and 230 degrees, measured in the runner rotation direction around the runner rotation axis from the side that is not downstream of a plane that includes the runner rotation axis and passes through the center of the bent suction pipe outlet surface. This can be achieved by placing it in an area other than the following areas.

[Effect]

The angle of the rotation suppressing fin measured in the runner rotation direction around the runner rotation axis from the side that is not downstream of the plane that includes the runner rotation axis and passes through the center of the bent outlet pipe exit surface is 7.
Since it is arranged in an area other than the range of 0 degrees or more and 230 degrees or less, the vortex center generated by the rotation suppressing fin and flowing while swirling inside the bent suction pipe will not reach the low pressure area at the inner periphery of the bend part of the bent suction pipe. This prevents the vortex core from bending and damaging the wall of the suction pipe.

In this way, the rotation suppressing fin should be placed around the runner rotation axis from the direction other than the downstream side of the plane that includes the runner rotation axis and passes through the center of the bent suction pipe outlet surface, so that the angle measured in the runner rotation direction is 70 degrees or more. By arranging it in a region other than the region below the degree, the desired purpose can be achieved, which will be explained next.

Generally, the mainstream inside a bent suction pipe has the property of a so-called potential flow. That is, the flow velocity is high at the inner circumference of the bend (therefore, the static pressure is low), and the flow velocity is slow at the outer circumference of the bend (therefore, the static pressure is high). Therefore, the static pressure on the wall of the bent section of the bent suction pipe is as shown in Figure 10, where the horizontal axis is the angle θ and the vertical axis is the static pressure on the suction pipe wall. .

According to the results of model experiments, the vortex center of the fin wake develops most strongly at the inner periphery of the bend of the bent suction pipe, in the area with low static pressure (between 100 degrees and 260 degrees in terms of angle θ). Strongly hit the wall of the suction pipe. In the high pressure area other than the low pressure area 6 in the inner peripheral part of the bend part, the vortex center of the fin wake does not develop significantly, and the impact on the wall surface is small. In addition, during partial load operation of a water turbine, the flow in the bent suction pipe has a swirling component in the direction of rotation of the runner, so the vortex center generated from the fin rides on this mainstream, and from the time it leaves the fin until it reaches the bend. It was confirmed that the runner rotated by 30 degrees in the runner rotation direction. Therefore, in the present invention, the fin has an angle of 70 degrees or more and 230 degrees, measured in the runner rotation direction around the runner rotation axis from the side that is not downstream of the plane that includes the runner rotation axis and passes through the center of the curved suction pipe outlet surface. It is now placed in areas other than the following areas. By doing this,
It is possible to obtain a turning suppression fin for a curved suction pipe that makes it possible to prevent damage to the wall surface of the curved suction pipe.

This is also clear from what is shown in FIG. In this figure, the horizontal axis includes the runner rotation axis, and the angle 0 measured in the runner rotation direction around the runner rotation axis from the side other than the downstream side of the plane passing through the center of the curved suction pipe outlet surface is taken, and the vertical axis is 0. This figure shows the path of the vortex core emitted from the fin, taking the length along the suction pipe. As is clear from the figure, the vortex center 2E emitted from the fins 2 arranged in the region where 0 is smaller than 70 degrees is within the region of θ = 1oO degrees at the bend even if rotated by 30 degrees, and the pressure is low. Area 6
has not been reached. Therefore, this vortex center does not develop to a large extent and does not damage the wall surface of the single-curved suction pipe.

Furthermore, when the vortex center 2E emitted from the fins 2 arranged in the area where θ is larger than 230 degrees rotates 30 degrees, it reaches the area where θ=260 degrees or more at the bend part, so this vortex center 2E also bends and the suction pipe wall surface In other words, from θ=70 degrees to 230 degrees, the fin prohibition zone 7
The other area becomes a fin arrangement zone 8.

〔Example〕

The present invention will be explained below based on the illustrated embodiments. An embodiment of the present invention is shown in FIGS. 1-3.

Note that parts that are the same as those in the conventional system are given the same reference numerals, and therefore their explanations will be omitted. In this example, the rotation suppressing fins 2Ao and 2Bo were measured in the runner rotation direction R around the runner rotation axis from the side that is not downstream of the plane that includes the runner rotation axis and passes through the center of the curved suction pipe outlet surface 3. The angle is 70 degrees or more23
It was placed in an area other than the area below 0 degrees.

By doing this, the rotation suppressing fin 2Ao.

The swirling of the bent suction pipe that causes the vortex core generated from 2Bo and flows while rotating inside the bent suction pipe 1 from reaching the low pressure area IA on the inner circumference of the bend part, making it possible to prevent damage to the wall surface of the bent suction pipe. Suppression fins 2Ao and 2Bo can be obtained.

That is, the rotation suppressing fins 2Ao are placed at symmetrical positions at an angle of 0 measured in the runner rotation direction R around the runner rotation axis on the side that is not on the downstream side of a plane that includes the runner rotation axis and passes through the center of the curved suction pipe outlet surface.

In this embodiment in which two 2Bos are arranged, the angle θ is set to 50 degrees or more and 70 degrees or less. The mounting angle of one fin 2Ao of these fins 2Ao and 2Bo is 70 degrees or less, and at the same time, the mounting angle of the other fin 2B.

The mounting angle θ is 230 degrees or more. Therefore, as shown in FIG. 11 above, both of these fins 2Ao and 2Bo are outside the forbidden zone of the fins 2Ao and 2Bo, so the vortex center generated in the wake of the fins 2Ao and 2Bo is bent and sucked out. It does not enter the low pressure area IA on the inner peripheral side of the bend part of the pipe 1, and does not cause damage to the wall surface of the one-bent suction pipe.
Moreover, since the two fins 2Ao and 2Bo are arranged symmetrically, no uneven flow is generated in the bent suction pipe.

In this way, according to the present embodiment, the core generated from the rotation suppressing fins does not reach the low pressure region of the inner circumference of the bend of the bent suction pipe, so the core does not damage the wall surface of the curved discharge pipe. .

Another embodiment of the invention is shown in FIG.

In this embodiment, rotation suppressing fins 2 Ao, 2 Bo, 2
C.

The angle θ measured in the runner rotation direction R around the runner rotation axis from the side other than the downstream side of the plane that includes the runner rotation axis and passes through the center of the bent suction pipe outlet surface is 50 degrees or more7
0 degrees or less and the symmetrical position of 50 degrees or more and 70 degrees or less
It was arranged at a position of 30 degrees or more and 250 degrees or less, and a position rotated 90 degrees in the runner rotation direction R from 230 degrees or more and 250 degrees or less.

By doing so, the effect of suppressing turning becomes greater than in the above-described case where there are two fins.

That is, two rotation suppressing fins 2Ao are placed at a symmetrical position YY' at an angle of 0 measured in the runner rotation direction R from the side other than the downstream side of the surface 3 that includes the runner rotation axis and passes through the center of the curved suction pipe outlet surface. 2B.

is placed. This angle 0 is set to be greater than or equal to 50 degrees and less than or equal to SO degrees, as in the case described above. Furthermore, 0 = 230 degrees or more 25
Another fin 2CO was installed at a position rotated 90 degrees in the runner rotation direction R from the fin 2Bo installed at 0 degrees or less. These three fins 2Ao, 2Bo, and 2Co are all installed at a position where O is 70 degrees or less or 230 degrees or more, so the fins 2Ao, 2Bo,
2G.

The wake flow will not damage the wall surface of the bent suction pipe.

5 to 7 show still another embodiment of the present invention. In this embodiment, the bent suction pipe 1a is formed into an S-shape. In this case as well, by arranging the fins 2Ao, 2Bo as shown in FIG.
You can get 2Bo.

〔Effect of the invention〕

As described above, the present invention prevents damage to the wall surface of the curved suction tube, thereby making it possible to obtain a turning suppression fin for the curved suction tube that can prevent damage to the wall surface of the curved suction tube.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing the fin arrangement of an embodiment of the swirl suppressing fin of a bent suction pipe of the present invention, and FIG.
3 is a sectional view taken along the Y-Y' line in FIG. 1, and FIG. 4 is a fin arrangement of another embodiment of the swirl suppressing fin for a bent suction pipe of the present invention. 5th plan view showing
The figure is a plan view showing the fin arrangement of still another embodiment of the swirl suppressing fin for a bent suction pipe of the present invention, FIG. 6 is a cross-sectional view taken along the line xx' in FIG. 5, and FIG. 5 is a sectional view taken along the Y-Y' line in FIG. 5, and FIG. 8 is a plan view showing the arrangement of the rotation suppressing fins of a conventional curved suction pipe. Fig. 9 is a cross-sectional view taken along the line xx' in Fig. 8, Fig. 10 is a characteristic diagram showing the relationship between the angle θ and the static pressure on the wall surface of the suction pipe, and Fig. 1
FIG. 1 is a characteristic diagram showing the relationship between the angle θ and the length along the suction pipe. 1, la-bent suction pipe, 2.2Ao, 2Bo. 2Co...Turn suppression fin, 2E...Seishin, 3...
・A plane that includes the runner rotation axis and passes through the center of the curved suction pipe outlet surface, 5 (θ)... Runner from the side that is not downstream of the plane that includes the runner rotation axis and passes through the center of the curved suction pipe exit surface. Angle measured in the runner rotation direction around the rotation axis, 6...Low pressure area on the inner periphery of the bend. Bakuzu clear 1 setting 7: Angle Hakushu Feng 6 Ward 30 Culture 4 Fig. 2 Co-OEFp profit 7 Tail 8 Fig. 9: JE-: $1!

Claims (1)

[Scope of Claims] 1. A diverging flow path connected to the outlet of the fixed-blade hydraulic runner, where the flow velocity at the outlet is slower than the flow velocity at the inlet, and an enlarged flow channel extending from at least the runner outlet in the direction of the runner rotation axis; The runner rotation axis continues from the runner outlet of the water turbine bent suction pipe, which is composed of a bend portion that turns the flow direction of the expanded flow path away from the runner rotation axis direction, and an expansion flow path that guides the water flow whose direction has changed at this bend portion. On the inner wall surface of the expanding channel extending in the direction of
In a swirl suppression fin for a curved suction pipe that is installed in the flow direction and suppresses swirling of the flow, the fin is moved around the runner rotation axis from a plane that includes the runner rotation axis and passes through the center of the curved suction pipe outlet surface. A swirl suppression fin for a bent suction pipe, characterized in that it is arranged in an area outside the range of 70 degrees or more and 230 degrees or less in the runner rotation direction. 2. The angle of the rotation suppressing fin is 50 degrees or more and 70 degrees.
23 degrees or less, and the symmetrical position of 50 degrees or more and 70 degrees or less
The swirl suppression fin for a bent suction pipe according to claim 1, which is arranged at an angle of 0 degrees or more and 250 degrees or less. 3. The angle of the rotation suppressing fin is 50 degrees or more and 70 degrees.
23 degrees or less, and the symmetrical position of 50 degrees or more and 70 degrees or less
The rotation suppressing fin of a bent suction pipe according to claim 1, which is arranged at a position of 0 degrees or more and 250 degrees or less and a position rotated 90 degrees in the runner rotation direction from 230 degrees or more and 250 degrees or less. 4. The swirl suppression fin for a bent suction pipe according to claim 1, wherein the bent suction pipe is formed in an S-shape. 5. Claim 1, wherein the fins are provided so that the vortex does not collide with the inner wall surface of the expanded flow path.
Turning suppression fins for bent suction pipes as described in 2.