JPS6245977A - Semispiral type kaplan turbine - Google Patents

Abstract

PURPOSE:To improve the efficiency of a water wheel and reduce noise and vibration by reducing the load applied onto a main vane by varying the shape of the sectional surface or arrangement of the main vane on the inflow side in the vicinity of the nose of a stay vane, thus preventing exfoliation of the stream on the surface of the stay vane. CONSTITUTION:A Kaplan turbine has a passage for the inflow of the water which flows in a semispiral casing 1 into a runner vane 4, passing through a stay vane 2 consisting of a plurality of main vanes and a guide vane 3, and the top edge of the nose of the casing 1 intrudes into the stay vane 2. With such constitution, the load applied onto a main vane is reduced by varying the sectional shape or arrangement of the inflow-side main vane in the vicinity of the nose of the stay vane 2,and the exfoliation of stream on the surface of the stay vane 2is prohibited. For instance, a plurality of main vanes on the inflow side close to the casing nose 1N of the stay vane 2 are formed into longer vanes 2a-2c, longer than the main vane 2 in other parts.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a structure for preventing separation of water flow generated in the stay vane near the casing nose of a semi-spiral Kaplan water turbine.

[Prior art and its problems]

Figure 5 is a longitudinal sectional view of a semi-spiral Kaplan water turbine, Figure 6 is a sectional view taken along the line A-A in Figure 5, and Figure 7 is a P in Figure 6.
It is a detailed view of the location. In the figure, 1 is a semi-spiral casing, IN is a casing nose, 2 is a stay vane consisting of a plurality of main wings, 3 is a guide vane, 4 is a runner vane, and the solid arrow indicates the direction of water flow. As is clear from FIG. 6, conventional stay vanes are generally arranged in the same cross-sectional shape in the circumferential direction. and stay vane 2
Inflow angle to? 's□l varies greatly depending on the position of the stay vanes 2 arranged on the circumference, as shown in the curve diagram of FIG. Particularly in the vicinity of the casing nose, as shown in FIG. 7, the water flows in approximately from the radial direction (i.e., rsoI-00) and the flow of water is greatly bent by the stay vane 3. In such a case, as shown in FIG. 7, flow separation S occurs on the surface of the stay vane 2 over a wide range from ψ#00 to 80° near the casing nose of the vehicle.

If the turbine is operated in such a state where the flaking S occurs, the efficiency of the water turbine decreases on the order of 1 to 2 inches, and the noise and vibration caused by cavitation also increase.

[Purpose of the invention]

In view of the above-mentioned circumstances, an object of the present invention is to prevent flow separation and cavitation on the stay vane surface by changing the shape and arrangement of the main blade of the stay vane of a semi-spiral Kaplan water turbine.

[Key points of the invention]

The key point of this invention is to set the inlet angle of the main wing near the casing nose of the stay vane, where separation is likely to occur, to the inlet angle rso'
In order to reduce the angle of incidence of the flow on each main blade in the circumferential direction according to the The goal is to prevent it.

[Embodiments of the invention]

FIG. 1 shows a first embodiment of the present invention, in which a plurality of main wings on the inflow side near the casing nose IN of the stay vane are made long wings 2a, 2b, and 2C and are made longer than the main wings 2 in other parts. It is. In this case, since the long blade closest to the casing nose IN has the largest blade load, it is necessary to make the blade span the longest.

FIG. 2 shows a second embodiment of the present invention, in which an intermediate blade 2d is provided at the inlet portion of the main wing 2 on the inflow side near the casing nose IN to reduce the blade load on the main wing and prevent water flow separation. It is intended to prevent

FIG. 3 shows a third embodiment of the invention, in which a slit 2e is provided on the inlet side near the casing nose IN.

By providing the slitted blade 2e having the slitted blade i2e, the blade load on the main wing of the slitted blade i2e is reduced and flow separation is prevented.

FIG. 4 shows a fourth embodiment of the present invention, in which the main blade on the inflow side near the casing nose IN is made of double blades 2t, so that the blade load on the main blade of the double blade 2f is reduced and the flow is improved. This prevents peeling.

〔Effect of the invention〕

In the present invention, the blade load on the main blades is reduced by changing the shape and arrangement of the main blades of the stay vanes, thereby preventing flow separation that occurs on the stay vane surfaces, improving water turbine efficiency, and reducing noise and vibration.

[Brief explanation of drawings]

Fig. 1 is a sectional view of a long blade of a semi-spiral Kaplan water turbine which is a first embodiment of the present invention, and Fig. 2 is a sectional view of an intermediate blade of a semi-spiral Kaplan water turbine which is a second embodiment of the invention. 3 is a cross-sectional view of a slitted blade of a semi-spiral type Kaplan turbine according to a third embodiment of the present invention, and FIG. 4 is a cross-sectional view of a semi-spiral type Kaplan turbine according to a fourth embodiment of the present invention. A cross-sectional view of the heavy blades, Figure 5 is a longitudinal cross-sectional view of a conventional Semis Viral type Kaplan turbine, Figure 6 is a cross-sectional view taken along the line A-A in Figure 5, and Figure 7 is a cross-sectional view of point P in Figure 6. The detailed view, FIG. 8, is a diagram showing the change in the inflow angle γ"so to the stay vane with respect to the circumferential angle ψ of the nose in FIG. 6. l: Semi-spiral casing, IN: nose, 2 Nisty vanes (main wing) , 2a12b, 2C: long wing, 2d:
Intermediate blade, 2e blade with nislit, 2f: double blade, 3
Guide vane, 4: Runner Fig. 3 Fig. 4

Claims (1)

[Claims] 1) The semi-spiral casing has a structure in which the water flowing inside the semi-spiral casing has a path through which it passes through stay vanes and guide vanes made up of a plurality of main wings and flows into the runner vanes, and the nose tip of the casing enters the stay vanes. In a certain semi-spiral type Kaplan turbine; the cross-sectional shape of the main blade on the inlet side near the nose of the stay vane is changed, or the arrangement of the main blade on the inflow side near the nose is changed to reduce the blade load on the main blade, thereby reducing the flow on the stay vane surface. A semi-spiral type Kaplan water turbine that is characterized by preventing flaking. 2) In the product described in claim 1, a plurality of main wings near the nose portion of the stay vane are extended toward the outer periphery to form long wings, and furthermore, the main wings are made successively longer as they get closer to the nose portion. The characteristic semi-spiral type Kaplan water turbine. 3) A semi-spiral Kaplan water turbine according to claim 1, characterized in that intermediate blades are provided between each of the plurality of main blades near the nose portion of the stay vane. 4) The semi-spiral Kaplan water turbine according to claim 1, wherein the plurality of main wings near the nose of the stay vane are blades with slits. 5) The semi-spiral Kaplan water turbine according to claim 1, wherein the plurality of main blades near the nose of the stay vane are double blades.