JPH0110440Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a water flow guide for a cross-flow turbine that efficiently guides water flow to a runner without causing cavitation.

<Prior Art> Cross-flow water turbines, in which a water flow flows through a runner, are widely used to generate electricity using hydraulic power, such as water discharged from a plant. As shown in Fig. 6, which shows a typical structure of a cross-flow turbine, a runner 2 is formed into a cylindrical cage-like shape by radially arranging a large number of runner blades 1 each having an airfoil cross section. Casing 4 with runner shaft 3
At the outlet end of the inlet pipe 5 which is rotatably supported by the casing 4 and is connected to the casing 4 and provided on the upstream side of the runner 2, there is a curved plate-shaped water flow guide 6 that guides the water flow from the inlet pipe 5 into the runner 2. is provided. On the other hand, a water discharge pipe 7 connected to the casing 4 is provided on the downstream side of the runner 2, and the water flow that flows in from the inlet pipe 5 is guided by a water flow guide 6, flows through the runner 2, and rotates the runner 2. After that, the water is drained from the water discharge pipe 7. Note that 8 is a movable vane that adjusts the amount of water.

Here, since a gap A is inevitably created between the outer peripheral surface of the runner 2 and the tip of the water flow guide 6 due to the structure, water flow is prevented from falling from this gap A without passing through the runner 2. , it is necessary to aim for efficient use of hydropower. For this reason, conventionally, as shown in FIG. 7, a covering portion 6a extending close to the outer peripheral surface of the runner 2 is provided at the tip of the water flow guide 6.
The water flow flowing out from the gap A is guided into the runner 2 while preventing the water flow from scattering at the tip of the water flow guide 6.

<Problems to be solved by the invention> In the above conventional measures, although the water flow flowing out from the gap A is guided into the runner 2 to achieve efficient use of hydraulic power, the covering part 6a
Since a flow path B with an extremely narrow cross-sectional area is formed between the outer circumferential surface of the runner 2 and
The pressure of the water flow inside the tank had decreased, causing cavitation. The occurrence of such cavitation not only causes the runner blade 1 to vibrate and causes noise and vibration, but also shortens the life of the runner 2.

The present invention was devised in view of the above-mentioned conventional problems, and aims to provide a water flow guide for a cross-flow turbine that effectively prevents cavitation from occurring at the covering portion that efficiently guides the water flow into the runner. .

<Means and effects for solving the problems> The water flow guide of the cross-flow turbine according to the present invention has a covering part at the tip that runs close to the outer peripheral surface of the runner, and the covering part has a covering part that runs along the outer peripheral surface of the runner. A concave portion facing the water flow guide is formed over almost the entire width direction of the water flow guide, and the covering portion efficiently guides the water flow into the runner, and the concave portion is formed between the covering portion and the outer peripheral surface of the runner. This method effectively prevents cavitation by enlarging the cross-sectional area of the flow path and guiding a relatively high static pressure upstream of the flow path into the flow path, suppressing the pressure drop within the flow path. be.

<Example> An example of a water flow guide for a cross-flow turbine according to the present invention will be described based on the drawings. It should be noted that the same parts as those in the prior art described above are given the same reference numerals and detailed explanations will be omitted.

FIG. 1a is a sectional view showing the relationship between the water flow guide and the runner according to the first embodiment, and FIG. 1b is a drawing showing the tip of the water flow guide viewed from the direction of arrow X in FIG. 1a. As shown in the figure, a rectangular recess 11 is formed on the inner surface of the covering part 6a facing the outer peripheral surface of the runner 2, and this recess 11 faces the outer peripheral surface of the runner 2. The width of the recess 11 is the same as that of the water flow guide 6.
The length of the recess 11 extends slightly beyond the covering part 6a to the rear end side, and this recess 11 expands the cross-sectional area of the flow path B and extends the flow path B to the upstream side. It communicates with

According to the above configuration, the water flow flowing out from the gap A between the covering part 6a and the outer circumferential surface of the runner 2 is prevented from scattering by the covering part 6a, and the runner 2
At the same time, the cross-sectional area of the flow path B is expanded by the recess 11, and the relatively high static pressure on the upstream side is guided into the flow path B, so the pressure drop within the flow path B is suppressed. This prevents cavitation from occurring.

FIG. 2 is a drawing showing the tip of the water flow guide according to the second embodiment, seen from the same viewpoint as FIG. 1b.

As shown in the figure, a groove 12a extending in the width direction of the water flow guide is formed on the inner surface of the covering part 6a, and a plurality of grooves 12b communicating with this groove 12a and extending in the longitudinal direction of the water flow guide 6 are formed. However, a comb-shaped recess facing the outer peripheral surface of the runner 2 is formed as a whole. The groove 12a is formed over almost the entire width direction of the water flow guide 6a, and the groove 12b
extends slightly beyond the covering portion 6a to the upstream side along the flow direction of the water stream. Therefore, in this embodiment, similarly to the above embodiment, the covering part 6a
In addition to efficiently guiding the water flow into the runner 2,
Cavitation in the flow path B is effectively prevented by the grooves 12a and 12b.

3 to 5 are drawings showing the tip portions of the water flow guides according to the third to fifth embodiments in the same manner as in FIG. 2.

As shown in each figure, in these embodiments, a plurality of approximately triangular recesses 13 facing the outer peripheral surface of the runner 2 are formed on the inner surface of the covering portion 6a, and each recess 13 is formed on the inner surface of the covering portion 6a. The runner blade 1 is partitioned by a partition portion 14 that extends flush with the outer edge of the runner blade 1 and at an angle with respect to the direction in which the outer edge of the runner blade 1 extends. Therefore, in these embodiments, cavitation is effectively prevented and the water flow is efficiently guided into the runner 2 in the same way as in the above-mentioned embodiments, and the partition portion 14 provides the following effects. That is, as shown by the chain line in FIG.
Due to the rotation of the runner 2, the outer edge of the runner blade 1 passes diagonally through the partition part 14, so the pressure change that occurs when the runner blade 1 passes through the covering part 6a becomes gentler, which further increases the vibration of the runner blade. Occurrence is prevented. In addition, the recess 13
does not have to be triangular; for example, if it is V-shaped and inclined with respect to the outer edge of the runner blade 1, the same effect as described above can be obtained.

<Effect of the invention> According to the invention, a concave portion facing the outer circumferential surface of the runner is formed in the covering portion at the tip of the water flow guide over almost the entire width direction of the water flow guide, so that the contact between the covering portion and the outer circumferential surface of the runner is formed. Since the cross-sectional area of the flow path formed between the runners is enlarged, the water flow can be efficiently guided into the runner without causing cavitation.

[Brief explanation of the drawing]

Figures 1a and b relate to the first embodiment of the present invention, Figure 1a is a sectional view of the tip of the water flow guide, and Figure 1b is the tip of the water flow guide taken in the direction of the X arrow in Figure 1a. Figures 2 to 5 are drawings showing the tips of the water flow guides according to the second to fifth embodiments, respectively, from the same perspective as in Figure 1b, and Figure 6 is a diagram showing a typical cross flow water turbine. FIG. 7 is a partially cutaway overall perspective view showing the structure of the conventional water flow guide. In the drawing, 2 is a runner, 6 is a water flow guide, 6a is a covering part, 11, 13 are concave parts, 12a, 12
b is a groove, and B is a flow path.

Claims (1)

[Scope of utility model registration request] In a water flow guide for a cross-flow turbine that is located upstream of a runner that is rotationally driven by a water flow and has a covering part at its tip that runs close to the outer peripheral surface of the runner to guide the water flow into the runner. , a concave portion facing the outer circumferential surface of the runner and preventing cavitation of the flow path formed between the covering portion and the outer circumferential surface of the runner is provided in the covering portion over almost the entire width direction of the water flow guide. A water flow guide for a cross-flow turbine characterized by the following: