JPH0684750B2 - Water wheel - Google Patents

Description

TECHNICAL FIELD The present invention relates to a guide vane for a water turbine.

[Problems to be solved by the invention]

A conventional water turbine will be described with reference to FIGS. The guide vane 01 of the water turbine is for allowing a proper flow rate to flow into the runner vane 02 at an appropriate angle, and is greatly related to the performance of the water turbine. Further, the guide vane 01 is rotated about the rotation support shaft center 04 by the operation mechanism 03 so that the opening degree is adjusted from fully closed to fully open. In general, the casing of a water turbine is often manufactured in separate pieces, so guide vanes are used.
01 is usually about 16, 20, 24. On the other hand, the number of guide vanes 01 is required to be small due to manufacturing cost constraints.

Figure 3 shows the guide vanes in the conventional Francis turbine.
When 01 is 16 in total, FIG. 4 is a plan view of the guide vane 01 when it is 12 and FIG. 5 is an explanatory view of the flow out of the guide vane 01 in the case of 12 and is shown in FIG. In order to open the guide vanes 01 and cause a certain flow rate to flow into the runner vanes 02 of the unillustrated runner, the total port area a of the guide vanes 01 must be the same regardless of the number of guide vanes 01. I have to. However, if the number of guide vanes 01 is smaller when the port areas are the same, the camber line 05 of the guide vanes 01 becomes the runner center line 06.
Since the angle θ formed by is large, it becomes difficult for the flow exiting the guide vane 01 to flow into the runner vane 02 at an appropriate angle. In other words, if the number of guide vanes 01 is reduced to 12 in order to reduce the manufacturing cost, the flow velocity triangle coming out of the guide vane 01 and the flow velocity triangle at the inlet of the runner vane 02 are also at the maximum efficiency point. Since they do not match, there is a problem that the turbine efficiency decreases.

[Means for solving problems]

The water turbine according to the present invention is provided with 12 guide vanes for the purpose of solving the above-mentioned problems and maintaining the performance even when the number of guide vanes is reduced to 12, and the radius of curvature of the camber line of the guide vanes is provided. Is 0.5 to 1.0 times the pitch circle diameter of the guide vane, and is curved toward the runner side.

[Action]

In other words, the guide vane line is abolished from the conventional straight line and is curved toward the runner side while keeping an arc of one radius of curvature, and the angle formed by the guide vane line with the runner center line is I'm making it small. If the radius of curvature is made too small, the hydraulic loss of the guide vanes increases, but if the diameter of the circle with the center of the rotation support shaft of each guide vane on its circumference is the pitch diameter Dg of the guide vanes, the guide vanes will have In case of 12 sheets, the radius of curvature R of the camber line is 0 of the pitch circle diameter Dg of the guide vane.
5 times to 1.0 times, that is, R = (0.5 to 1.0) Dg is totally excellent, and the velocity triangle of the flow coming out of the guide vanes and the velocity triangle of the flow at the inlet of the runner vanes are at the maximum efficiency point. In agreement, the maximum efficiency of the water turbine is improved.

In this case, the opening from the fully closed to fully open guide vanes is about 10% narrower than the case where the line is straight, so the flow velocity triangles from the guide vanes and the runner vane inlet The range where the flow velocity triangle coincides is widened, improving the turbine efficiency overall, and the guide vane operating mechanism can be made smaller. Generally, there is a no-load opening when the guide vane is slightly opened from the fully closed state, but the flow leaving the guide vane with the guide vane slightly opened from the fully closed state is outside the runner. Since it is directed inward from the direction, the no-load rotation speed can be obtained with a smaller flow rate compared to when the camber line is straight. Further, since the camber line of the guide vane is formed by one arc, the manufacturing is not particularly complicated as compared with the case where the camber line is linear.

〔Example〕

The configuration and operation of the present invention will be specifically described based on an embodiment shown in FIGS. 1, 2, and 6. FIG. 1 is a plan view of the guide vane 1 in the case where there are 12 guide vanes 1 in total in the Francis turbine according to the present invention, and FIG. 2 is an explanatory view of the flow out of the guide vane 1, In the figure, the guide line 5 of the guide vane 1 is abolished from the conventional straight line and is curved toward the runner side while keeping an arc having a radius of curvature R. The guide line 5 of the guide vane 1 is the runner. The angle θ formed with the center line 6 of is reduced. The twelve guide vanes 1 are each rotated by an operating mechanism 3 about a rotation support shaft center 4, and the opening degree is adjusted from fully closed to fully open. The rotation support shaft centers 4 of the guide vanes 1 are arranged at equal pitches on a circle concentric with the rotation center 7 of the runner, and this circle is called a pitch circle 8 of the guide vanes 1.

The radius of curvature R of the camber line 5 when the number of the guide vanes 1 is 12 will be described with reference to FIG. Figure 6 shows
The horizontal axis is the ratio α (= R / Dg) of the radius of curvature R of the canber line 5 of the guide vane 1 to the diameter Dg of the pitch circle 8 and the vertical axis is the streamline from the outlet of the guide vane 1 to the inlet of the runner vane 2. FIG. 3 is a diagram showing the relationship between the two at the maximum efficiency point of the runner by taking the deviation angle from the streamline of. The horizontal axis means that the greater the value of α, the more gradual the warp of the camber line 5, and the smaller the value, the steeper the curve. The vertical axis shows the deviation angle. It means that the performance is excellent. The two curves in the figure show the deviation angles of the flow lines at the guide vane 1 outlet and the runner vane 2 inlet at the maximum efficiency point of the runner in the high and low head turbines. Note that the curve for the middle head turbine is omitted because it is in the middle of the above two curves.

From the figure, α = 0.5 ~ for both high head and low head turbines.
The deviation angle is small in the range of 1.0, that is, if the camber line 5 having the radius of curvature in this range is adopted, the hydraulic performance of the water turbine is not impaired. Also, the radius of curvature R
If the value is too small, the hydraulic loss of the guide vanes 1 increases, but when the number of guide vanes 1 is 12, the radius of curvature R = (0.5 to 1.0) Dg of the camber line 5 is comprehensively excellent. As shown in (1), the velocity triangle of the flow exiting the guide vane 1 and the velocity triangle of the flow at the inlet of the runner vane 2 are substantially coincident with each other at the maximum efficiency point, and the maximum efficiency of the turbine is improved.

In this case, the opening of the guide vane 1 from fully closed to fully open is about 10% narrower than the case where the camber line 5 is straight, so the flow velocity triangle coming out of the guide vane 1 and the runner vane 2 The range in which the velocity triangle of the flow at the inlet coincides is widened, the turbine efficiency is generally improved, and the operating mechanism 3 of the guide vane 1 can be downsized. In general, there is a no-load opening at a slightly opened position of the guide vane 1 from the fully closed state, but the flow leaving the guide vane 1 at a slightly opened position of the guide vane 1 from the fully closed state. Is directed from the outer side to the inner side of the runner, so that the no-load rotation speed can be obtained with a smaller flow rate than in the case where the camber line 5 is linear. Further, since the camber line 5 of the guide vane 1 is formed by one arc, the manufacturing is not particularly complicated as compared with the case where the camber line 5 is linear.

[Effects of the Invention] Due to such a configuration and operation, even if the number of guide vanes is reduced to 12, the flow leaving the guide vanes flows into the runner vanes at an appropriate angle as in the case of 16 or more guide vanes. So
The performance of the water turbine is maintained and the manufacturing cost is reduced.

[Brief description of drawings]

FIG. 1 is a plan view of a guide vane in the Francis type turbine according to the present invention when there are 12 guide vanes in total, FIG. 2 is an explanatory view of a flow out of the guide vane, and FIG. Guide vanes in Francis turbine
In the case of 16 sheets, FIG. 4 is a plan view of the guide vane in the case of 12 sheets, FIG. 5 is an explanatory view of the flow out of the guide vane in the case of 12 sheets, and FIG. 6 is related to the present invention. FIG. 6 is a relationship diagram between a radius of curvature of a camber line and a deviation angle. 1 …… Guide vane, 2 …… Runner vane, 4 …… Center of rotation support shaft of guide vane, 5 …… Kimber line, 8 ……
Guide vane pitch circle.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-51-72847 (JP, A) Actual development: A-58-144079 (JP, U) JP-B-58-7830 (JP, B2) Turbine and pump Turbine Ishii Yasuo Den Densho Shoin P. 49-64 P. 76-P. 94

Claims (1)

[Claims] 1. A water turbine comprising twelve guide vanes, wherein the radius of curvature of the guide line of the guide vanes is 0.5 to 1.0 times the pitch circle diameter of the guide vanes and is curved toward the runner. .