JPS5918553B2 - runner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a runner, and more particularly to a runner in which the shape of the leading edge curve of the vane during pump operation is improved to reduce the drift phenomenon within the runner that occurs during low flow rate operation.

In general, a Francis-type runner has a crown 1, a band 2, and a blade 3 integrally constructed as shown in FIG.

The blade 3 is shown on I-I in FIG. ■～■・・・・・・,v-
■As shown in the cross section, on the flowing water surface during rated operation, blade elements '1x-x are designed for each cross section as shown in Figure 2, and I to I, II to ■ in Figure 1,... ..., V
It is formed as a continuum of wing elements 4I to 4v along ~■.

Although the shapes of the blade elements 4I to 4■ are not shown, similar to the blade element 4 shown in FIG. 2, the respective cross sections along lines I-X-I, . The design is made for.

In this case, each blade element 4I to 4■ forming one blade 3
Due to manufacturing reasons, the leading edge curve 5 during pump operation shown in FIG. 1 is arranged in the circumferential direction as shown in FIG.
It is designed to lie on a plane passing through the axis of rotation.

However, the runner designed in this manner generates severe water pressure pulsations at a flow rate of around 60 to 65% of the rated value (head of around 120 to 130%).

In large-capacity machines, this pulsating energy is so strong that it vibrates not only the main machine but also the power plant building, making it difficult to operate at turbine loads and pump lifts corresponding to the pulsating range.

As a result of the inventor's experiments, the above-mentioned water pressure pulsation is caused by: - During the flow in the runner in the low flow region of the pump, an ultra-low pressure region occurs locally, causing a partial flow, and the band of the leading edge curve 5 of the blade 3. It has become clear that this is due to backflow occurring on the side and on the crown side of the trailing edge 7 of the blade 3.

considered to be a thing. In order to explain this phenomenon, the flow of water in the runner under various operating conditions is as shown in Figure 4. Each figure shows the flow inside the runner during operation.

As is clear from these figures, a drifting phenomenon is observed in FIGS. 4A and 4C, and it is considered that the energy level of the flow has lost its balance in the portion where the drifting has occurred.

An object of the present invention is to provide an economical and highly reliable runner that reduces the drifting phenomenon in the runner that occurs during low flow rate operation, thereby reducing vibration and noise in the equipment building.

Hereinafter, an embodiment of the lunch according to the present invention will be described with reference to the drawings.

According to the present invention, blade elements 4I to 4■ of each design cross section of the blade 3
are arranged in the circumferential direction so that the vane elements 4I on the band 2 side are located forward in the pump rotational direction relative to the vane elements 4V on the crown 1 side.

As a result, the shape of the leading edge curve 5 of the blade 3 is different from the conventional one in its circumferential distribution, as shown by reference numeral 5' in FIG.
The inner diameter portion is formed so as to be relatively located at the rear.

The cross-sectional shape of the blade 3 constructed in this manner is shown in FIG. 6 in comparison with a conventional blade.

In FIG. 6, sections corresponding to the A-A cross sections in FIGS. 3 and 5 are shown by broken lines and solid lines, respectively.

As is clear from the figure, both occupies the same position R on the crown 1 side, but they occupy different positions R on the band 2 side.
They terminate at two positions p/ and Q/, respectively.

Comparing the energy level of the fluid between the conventional one and the one according to the invention, the point P' on the vane 3 of the invention
And the point Q' on the conventional blade 3 is P in FIG.
This corresponds to point Q, and the energy level at point P' is higher, and as a result, the occurrence of drifting as shown in FIG. 4 can be prevented.

FIG. 7 is a diagram comparing the characteristics of the runner according to the present invention and the conventional runner. In the figure, the solid line indicates the runner according to the invention, and the broken line indicates the conventional runner.

As is clear from the figure, the water pressure pulsation is significantly reduced at the same flow rate, and the region where the maximum pulsation value occurs also shifts to the high head and low flow rate side, and at low flow rates, the absolute amount of pulsation energy decreases. The maximum value of water pressure pulsation is also reduced.

On the other hand, in operation near the rated flow rate, the flow fills the runner and there is no local low pressure area, so the flow rate across the design cross section I-V is low and slow over time. It is.

Therefore, the flow within the runner is secondarily affected by the present invention, but the difference in performance can be said to be slight.

As described above, according to the present invention, the shape of the leading edge curve of the runner blade during pump operation is such that its distribution in the circumferential direction is relative to the front in the rotational direction of the pump at the outer diameter portion, and backward relative to the inner diameter portion. By forming the pipe so that it is located at the same position, it is possible to shift the vibration and noise phenomena that tend to occur during low flow rate operation due to drifting phenomena in the runner to a lower flow rate region, and to reduce the maximum value. be.

Therefore, when the runner according to the present invention is used as a pump or water turbine, it is possible to reduce vibration and noise phenomena in the specified operating range, and expand the range of possible continuous operation.
Efficiency during low flow pump operation can be improved.

Further, when the runner according to the present invention is used in a Francis turbine, effects such as a marked improvement in efficiency during low flow rate operation can be expected.

[Brief explanation of the drawing]

Figure 1 is a longitudinal cross-sectional view showing a Francis-type runner, Figure 2 is a diagram showing the shape of the blade element taken along line X-X in Figure 1, and Figure 3 is a plan view of a conventional runner as seen from the pump inlet side. , Figure 4a
, b, and c are diagrams showing the flow inside the runner under various conditions; FIG. 5 is a plan view of the runner of the present invention viewed from the pump inlet side;
FIG. 6 is a sectional view showing a comparison of the cross-sectional shape of the blade in the longitudinal section of the runner with that of a conventional blade, and FIG. 7 is a comparative characteristic diagram of the runner. 1... Crown, 2... Band, 3... Feather, 4
... wing element, 5 ... leading edge curve, 7 ... trailing edge.

Claims (1)

[Claims] 1. In a runner consisting of a crown, a band, and a vane, the shape of the leading edge curve of the vane during pump operation is such that its distribution in the circumferential direction is relative to the front in the rotational direction of the pump at the outer diameter part, and backward relative to the inner diameter part. A runner characterized by being formed so as to be located at a specific position.