JPS59187918A - Power-reducing work - Google Patents

Abstract

PURPOSE:To easily reduce and maintain the setting space of a tank by specifically designating the shape of a driving channel to a box-like power-reducing tank on the downstream of a jet stream outlet and also the height of a diversion channel floor from the box-like power-reducing tank. CONSTITUTION:A water driving channel 6 in the downstream of a jet stream outlet 1 is shaped into a box form surrounding the upper and lower faces and both sides. On the upper wall 6a, a slope suitable for collision of jet water from the outlet 1 and incoming of the jet water into a power-reducing tank 7 while widening its width in a flat form is provided, and the slope of the lower wall 6b is made to be more gentle than the wall 6a. An air supply tube 8 opening in the open air is connected to the upper part of the wall 6a. The height of ceiling face 7a of the tank 7 is made higher than the center height of the outlet 1, the bottom 7b is formed below the lower edge of the opening of the water driving channel 6, and an exhaust tube 9 opening to the open air is connected to a chamber 7c. The height of the roadbed 4a of a diversion channel 4 is set up such that the surface 4b of effluent water from the tank 7 becomes lower than the center height of the outlet 1.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a system for reducing the force of water discharged into a spillway from a jet stream outlet such as a high-pressure gate provided at the lower part of a dam.

When water is sprayed to adjust the water level in a dam from a jet stream outlet such as a high-pressure gate installed at the bottom of the dam, if it is directly sprayed into the spillway, the force of the water will cause damage to the spillway. This can cause problems such as scouring of the roadbed and side banks, and sediment and rocks being washed downstream and accumulating.
A force reducing section is provided between the jet stream outlet and the water spillway to reduce the force of the ejected water stream and discharge the water into the waterway.

Conventionally, there have been two types of deenergizing systems for water ejected from a jet stream outlet such as a high-pressure gate: an air discharge type as shown in Figure 1, and an underwater discharge type as shown in Figure 2. It is used.

In the air discharge type shown in Fig. 1, when a gate valve 2 is provided at the jet stream outlet 1, the gate will not be submerged in water, which is advantageous for corrosion prevention and maintenance. It has the advantage of having little effect on the door grooves and doors, but if you use a water-jump type energy-reducing top (not shown in Figure 1), due to its function, there will be a large amount of damage in front of the jet stream outlet 1, especially in the length direction. There is a problem in that it requires a large space 3 and is subject to significant restrictions on the design of the discharge equipment. Reference numeral 4 in the figure is a water discharge channel.

The underwater discharge type shown in Fig. 2 is designed to make the energy reduction system more compact, and a box-shaped energy reduction tank 5 is provided between the jet stream outlet 1 and the discharge channel 4. Exit 1 opens into the water. ``This method is more compact than the aerial discharge jump type due to energy loss, but the jet flow nozzle 1
If a gate valve 2 is installed to adjust the flow rate in 1
Although it has been used for small-diameter types, it is currently difficult to apply it to items with large diameters and high water pressure. Additionally, this method has the disadvantage that the gate is constantly submerged in water, making it difficult to take countermeasures against corrosion and to maintain it.

The present invention eliminates the two drawbacks of energy reduction in conventional types, eliminates hydraulic problems such as the influence of radiated water on the gate, requires less installation space, and is compatible with large and small diameters. It is an object of the present invention to provide a jet flow energy reducer that can be applied regardless of the jet and the flow outlet.

Hereinafter, the present invention will be explained based on embodiments shown in the drawings.

FIG. 3 is a diagram showing an embodiment of the present invention. The energy reduction in this embodiment is constructed by providing in this order a water guide portion 6 with an inclined front and a box-shaped energy reduction tank 7 between the jet stream outlet 1 and the discharge channel 4. There is.

Water guide part 6il-1: It has a box shape with walls on the top, bottom, and both sides, and the top wall 6a has a jet stream outlet 1.
An appropriate angle of 45° is suitable for the radiated water to impinge obliquely and flow into the energy-reducing tank 7 while becoming flat and wide along that surface. Lower wall or bottom surface 61 of water guide portion 6) Ir, L
, although the slope is smaller than that of the J-face wall 6a.
The distance between the two faces i and 6a is set so that 6kL of water along the upper wall 6a can sufficiently entrain the water stagnant at the downstream part of the jet stream outlet 1.

An air supply pipe 8 that is open to the atmosphere is connected to the upper part of the two walls of the water conduit 6.

Next, the height of the ceiling surface 7a of the box-shaped deenergization tank 7 is set at a position slightly higher than the center height of the jet flow outlet 1, and the bottom surface 7b is set at a position that is slightly higher than the height of the center of the jet flow outlet 1, and the bottom surface 7b is set at a position equivalent to the lower edge of the opening of the water guide section 6. It is located below. Further, a chamber 7C is provided at the rear of the ceiling surface 7a, and an exhaust pipe 9 that is open to the atmosphere is provided on the top surface of the chamber 7C.
There is a connection point -C.

De-energized Ti! I 77') The upper edge of the outlet to the discharge channel 4 matches the height of the deterioration tank ceiling surface 7a, and the lower edge, that is, the height of the subgrade 4a of the discharge channel 4, The water surface 4b of the more flowing water stream is set to be lower than the center elevation of the jet stream outlet 1.

Since this energy reduction is configured as shown in 2 below, the water stream injected from the jet stream outlet 1 obliquely collides with the upper wall 6a of the water guide section, and becomes flat while widening laterally.
The water flows into the energy reducing tank 7 along the flow path, and at this time, the water remaining on the lower surface of the water guide section 6 downstream of the jet stream outlet 1 is entrained into the energy reducing tank 7.

As a result, the jet stream outlet can be maintained so as not to be submerged in water while in use, and the hydraulic influence on the gate groove and door can be eliminated. Further, since the height of the water surface 4b of the water discharge channel 4 is set to be lower than the centerline elevation of the jet stream outlet 1, water can be discharged without any problem at any opening degree of the gate.

Since the water guide portion 6 is connected to an air supply pipe 8 that is open to the atmosphere, it is possible to prevent a pressure drop downstream of the jet outlet 1 due to air entrainment of the water stream jetted out from the jet stream outlet 1. Further, since the chamber 7C at the upper part of the energy reducing tank 7 is connected to the exhaust pipe 9 which is open to the atmosphere, the air carried by the water flow flowing into the energy reducing tank 7 from the water guide section is removed from the chamber 7.
c, and is discharged into the atmosphere from the exhaust pipe 9, which has the effect of reducing the apparent flow rate (amount of water + entrained air) at the upper exit and smoothing the flow rate.

It has been confirmed from the results of hydraulic experiments that the structure according to the present invention described above has the above-mentioned effectiveness and has sufficient potential for practical use.

As described above, according to the present invention, the discharge state of the jet stream outlet can be maintained in the air discharge state, and hydraulic problems with respect to the gate can be avoided. By combining it with a tank, it is possible to achieve practical effects such as making it possible to make the installation space on the energy-reducing device more compact.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view showing an example of a conventional air-release spring type energy reducer, Fig. 2 is a longitudinal sectional view showing an example of a conventional underwater water-release type energy reducer, and Fig. 3 is a longitudinal sectional view showing an example of a conventional underwater water-release type energy reducer. FIG. 3 is a longitudinal cross-sectional view showing the above embodiment. 1...Jet stream spout 4...Discharge channel 4a...
Discharge channel floor 4b...Discharge channel water surface 6 at outlet of energy dissipating ball...Water guide section 6a...Water guide section upper surface wall 61)...Water guide lower surface wall 7...Box-shaped energy dissipating tank

Claims (1)

[Claims] Under the condition of reducing the force of the water discharged from the jet stream outlet provided at the bottom of the pipe, etc., into the water discharge channel, It consists of a water guide section whose surface is surrounded and is inclined toward the oil rise, and a box-shaped energy reduction tank, which are installed in this order. The lower wall has an inclination angle smaller than the upper surface M'1', and the vertical distance between it and the upper wall is The spacing is set so that the water flowing along the top wall carries away the stagnant water downstream of the jet stream outlet, and the height of the discharge channel floor at the position connected to the energy reducing tank is set to A power-reduction system characterized by being arranged so that the water surface of the water flowing out of the power tank is lower than the center elevation of the jet flow outlet.