JPH0362278B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a soundproofing device for a water outlet of a water turbine, etc., which prevents infrasound generated from the water outlet of a dam or weir having an underdrain from being radiated into the atmosphere. Regarding.

In general, it is well known that so-called infrasound, which has a low frequency and cannot be heard, is generated from the water outlets of hydroelectric power plants, etc., and has a negative impact on the living environment. The generation of infrasound has rarely been a problem when hydroelectric power plants are built deep in the mountains and private homes are far away, as in the past. However, recently, power plants are being built next to private houses, or private houses are often coming closer to power stations, and as a result, the above-mentioned generation of infrasound becomes a problem. Cases have often arisen.

To explain the water discharge route of a conventional general power plant with reference to FIG. 1, the water discharged from the water turbine 1 is as follows:
Through the suction pipe 2 and the water outlet 3, the water is led to the water discharge channel 5 provided on the outside of the building wall 4.
The cross section with the top open is shaped like an inverted V-shape. In the figure, 6 indicates the position of the water surface and GL indicates the position of the ground surface.

In the water discharge route as described above, ultra-low frequency pulsations generated due to various causes propagate through the water of the suction pipe 2 from the outlet of the water turbine 1, reach the water discharge opening 3a, and are At the point where it first comes into contact with the air, it is converted into vibrations of the air above the water surface 6 and radiated into the air as infrasound. The infrasound emitted into the air then propagated through the atmosphere and affected nearby houses.

In view of the above points, the object of the present invention is to provide a soundproofing system for a water outlet of a water turbine, etc., which attenuates infrasound generated from the water outlet of a water turbine, etc. at the water outlet and prevents it from being radiated into the atmosphere. We are in the process of providing equipment.

In order to achieve the above object, the first aspect of the present invention is to form a cavity above the water surface at the water outlet of the waterway, consisting of an air layer constituted by the water surface, the waterway side wall, the building wall, and the cover. The cavity is formed by a building wall and a sound-deadening chamber, each of which has an insertion portion projecting horizontally inward on a wall that forms part of the cover and faces the building wall. ,
In addition, the second invention is at the water outlet of the waterway,
Forming a cavity above the water surface consisting of an air layer made up of the water surface, waterway side walls, building walls, and cover,
The cavity is formed by a resonance chamber having an opening at a certain height above the water surface directly above the waterway outlet and having a predetermined length in the vertical or horizontal direction from the opening, The third invention is
At the water outlet of the waterway, a cavity is formed above the water surface by the water surface, the waterway side wall, the building wall, and the cover, and the cavity is made up of an air layer that forms part of the cover and faces the building wall. It is characterized by the fact that the matching end walls are constructed with walls whose tips are submerged in water, creating a sealed cavity.

Embodiments of the present invention will be described below with reference to FIGS. 2 to 6.
This will be explained with figures.

FIGS. 2A and 2B are a longitudinal cross-sectional view and a cross-sectional view showing a first embodiment of the present invention. In this example,
A spillway 5 with a U-shaped cross section is laid outside the building wall 4 where the water turbine 1 is installed, and is connected to the building wall 4 around the water outlet opening 3a, with an air layer on the top and both sides of the spillway 5. Covers 8a and 8d are provided so that air layers 7a and 7c are formed, and these air layers 7a,
A muffling chamber 9 is formed by 7c, and a tail pipe 10
A cover 8b is formed lower than the cover 8a so that an air layer 7b is also formed above the portion corresponding to the cover 8a.
is provided, and the cover 8b, the water surface 6 and the waterway side wall 5
A conduit is formed by a.

In this embodiment, in particular, the building wall 4 and the vertical wall portion 8c of the cover 8a in the silencing chamber 9 are provided with insertion portions 21 that protrude toward the internal silencing chamber 9, further promoting the silencing effect. In order to do this, the inner wall surface of the sound deadening chamber 9 is lined with a sound absorbing material 22.

According to this embodiment, pulsations generated due to various causes associated with the operation of the water turbine are first converted into vibrations of the air above the water surface at the water outlet, and are radiated into the air as infrasound. After the infrasound passes through the building wall 4, it is gradually attenuated by reflection and interference in the silencing chamber 9, which is continuously formed above and to the side of the spillway 5.

In this embodiment, the insertion part 21 is provided in a protruding manner at a position corresponding to the entrance of the silencing chamber 9 as described above, so that the air layer above the water surface 6 of the discharge channel 5 and the air layer in the silencing chamber 9 are partially partitioned through the insertion part 21, thus promoting sound reflection and interference within the sound deadening chamber 9, and furthermore, the sound deadening chamber 9 is lined with a sound absorbing material 22. Together with this, the sound deadening effect within the room 9 is further promoted.

Therefore, infrasound emitted from the water outlet is effectively reduced.

FIGS. 3A and 3B are a vertical cross-sectional view and a cross-sectional view showing a second embodiment of the present invention. In this example,
Particularly, right above the water outlet opening 3a, an opening 23 is provided below at a certain interval from the water surface 6 in a part of the cover 8a which covers the upper part of the water surface 6 of the water outlet 5 with an air layer interposed therebetween. It is characterized by a resonance chamber 24 having a predetermined length in the vertical direction from the opening, and downstream from the resonance chamber 24, from the water surface 6, the waterway side wall 5a, and the cover 8b. A tail tube 10 is formed.

According to this embodiment, pulsations generated due to various causes associated with the operation of the water turbine are converted into vibrations of the air on the water surface directly above the water outlet after exiting the water outlet opening 3a, and are generated as infrasound. The infrasound is emitted into the air, but since a resonance chamber 24 is formed just above the water surface 6 of the water outlet opening 3a, the infrasound emitted into the air is radiated into the resonance chamber 24. The infrasound enters the resonance chamber 24 from the entrance 23 and resonates in the resonance chamber of a predetermined length that has a certain relationship with the wavelength of the infrasound, and the amplified sound energy is transmitted through the opening 23. The infrasound is attenuated by canceling out the incoming sound, and is then radiated into the atmosphere through the tail pipe 10.

Therefore, the sound radiated into the atmosphere is
Almost no infrasound is included.

FIGS. 4A and 4B are a vertical cross-sectional view and a cross-sectional view showing a third embodiment of the present invention. In this example,
The resonance chamber 24 in the second embodiment is installed horizontally. That is, a resonance chamber 24 having an opening 23 in the cover directly above the water outlet opening 3a and having a predetermined length in the horizontal direction is located in the extension 8b' of the cover 8b forming the upper wall of the tail pipe 10. It is formed along and above it.

According to this embodiment, as in the second embodiment, pulsations generated due to various causes during the operation of the water turbine are converted into vibrations of the air on the water surface directly above the water outlet opening 3a, and The emitted infrasound is
The sound energy enters from the entrance 23 of the resonance chamber 24 and generates resonance in the process of returning to the end wall 8c, and the energy amplified by the resonance acts to cancel out the sound entering from the opening 23. It is attenuated and radiated into the atmosphere through the tail pipe 10. Therefore, the sound radiated into the atmosphere contains almost no infrasound.

Further, this resonance chamber 24 is a cover 8b of the tail pipe 10.
Since the structure is formed parallel to the second embodiment, the structure can be made lower and more compact than that of the second embodiment, and it is also relatively easy to manufacture.

FIGS. 5A and 5B are a vertical cross-sectional view and a cross-sectional view showing a fourth embodiment of the present invention. In the first to third embodiments, the cavity formed above the water surface of the water outlet communicates with the air layer 7b of the tail pipe 10, whereas in this embodiment, the cavity formed above the water surface of the water outlet communicates with the air layer 7b of the tail pipe 10. The tip of the end wall 8c, which constitutes a part and faces the building wall 4, is extended until it is submerged in water, and a sealed cavity 25 is formed inside.

Therefore, according to this embodiment, as above,
Pulsations caused by various causes are caused by water discharge opening 3.
This radiated ultra-low frequency is converted into air vibrations on the water surface at the part a, that is, the part that comes into contact with the air first, the part of the sealed cavity 25 that contacts the building wall 4, and is radiated as infrasound. The sound of waves is a closed cavity 2
The water that travels downstream on the water surface 6 from the area near the building wall 4 of No. 5, reflects off the end wall 8c, and returns.
As mentioned above, the infrasound acts to cancel out the newly emitted infrasound, resulting in a so-called anti-resonance state and being reduced. Furthermore, the sound is insulated by the walls of the sealed cavity 25, so it propagates into the atmosphere. Infrasound is reduced.

FIGS. 6A and 6B are a longitudinal sectional view and a transverse sectional view showing a fifth embodiment of the present invention. This embodiment is a modification of the fourth embodiment (FIG. 5), in which the wall of the culvert 26 in the spillway section is used as the upper wall of the sealed cavity 25, and the water surface 6, the side wall 5a of the spillway, and the building wall 4 are A sealed cavity 25 is formed by the end wall 8c facing the end wall 8c.

According to this embodiment, the emission of infrasound caused by the operation of the water turbine is reduced by creating an anti-resonance state in the same manner as in the fourth embodiment, and is further sound-insulated by the wall of the sealed cavity 25, and is In addition to reducing infrasound propagating inside, the use of a culvert to cover the sealed cavity 25 has the effect of reducing construction costs accordingly.

In addition, in each of the above embodiments, the sound deadening chamber, the tail pipe,
Although each section of the sealed cavity etc. was formed into an inverted V-shape,
It may be rectangular, semicircular, or crescent shaped, and the sealed cavity may be provided with an air vent as necessary. Furthermore, the silencing effect can be promoted by appropriately partitioning the silencing chamber, the tail pipe, and the sealed cavity parallel to the flow direction. It is also possible to line the inside of the sound-absorbing chamber with a sound-absorbing material to reduce medium and high frequency sounds.

Further, the relationship between the dimensions of the cavity (resonance chamber, sealed cavity, etc.) and the frequency of infrasound in each of the above embodiments for the purpose of noise reduction is approximately expressed by the following theoretical formula.

In Fig. 2, the effective length L including the corrected length of the silencing chamber cavity and the tail pipe is L = 1/4 c/f (2n-1) (1) where, L: of the silencing chamber cavity. Length and tail tube length (effective length) (m) f; Frequency of infrasound (Hz) c; Speed of sound of infrasound (m/s) n: Expressed as an integer.

In addition, in Figures 3 and 4, the effective length L including the length of the resonance chamber (i.e. side branch) and the correction length of the tail tube is L = 1/4 c/f (2n-1). L: Length of side branch and length of tail tube (effective length) (m) f: Frequency of infrasound (Hz) c: Speed of sound of infrasound (m/s) n: Integer It is expressed as

In Figures 5 and 6, the length L of the sealed cavity is L=1/4 c/f(2n-1) Here L: Length of sealed cavity (m) f; Frequency of infrasound (Hz) c; Sound speed of infrasound (m/s) n; integer It is expressed as

As explained above, according to the first aspect of the present invention, a cavity consisting of an air layer constituted by the water surface, the channel side wall, the building wall, and the cover is formed above the water surface by the building wall and the cover. By forming a part of the building wall and the opposite wall with a silencing chamber with an insertion part that protrudes horizontally upward and inward, the air layer above the water surface of the spillway and the silencing chamber are formed. The air layer is partially partitioned off through the insertion part, thus promoting sound reflection and interference within the sound deadening chamber, and effectively reducing infrasound emitted from the water outlet. Ru.

Further, according to the second invention, the cavity is
By having an opening at a certain height above the water surface directly above the waterway water outlet and forming it with a resonance chamber having a predetermined length in the vertical or horizontal direction from the opening, air can be drawn from the water outlet opening. The infrasound emitted inside resonates within the resonance chamber, and the amplified sound energy acts to cancel out the sound entering from the opening and attenuates. Infrasound emitted from the infrasound is effectively reduced.

Further, according to the third invention, the cavity is
The end wall, which forms part of the cover and faces the building wall, is constructed of a wall whose tip is submerged in water to form a sealed cavity, so that pulsations caused by various causes can be absorbed into the sealed cavity. The infrasound that is converted into vibrations of the air above the water surface and radiated travels downstream on the water surface from the area near the building wall of the sealed cavity, and is reflected by the end wall and returned. This acts to cancel out the newly emitted infrasound, creating a so-called anti-resonance state and reducing the infrasound that propagates into the atmosphere. Reduced.

[Brief explanation of drawings]

Figure 1 shows the discharge channel of a typical power plant, where A is a vertical cross-sectional view, B is a cross-sectional view taken along A-A in Figure A,
Figures 2 to 6 show the first to fifth embodiments of the soundproofing device for a water turbine water outlet according to the present invention, and A in each of these figures is a longitudinal sectional view, and B in each figure is a respective figure in A. It is an AA sectional view of. 1...Waterwheel, 3...Waterway outlet, 4...Building wall, 5...Traceway, 5a...Traceway side wall, 8a~
8d...cover, 9...muffling chamber, 24...resonance chamber,
25... Sealed cavity.

Claims (1)

[Claims] 1. At the water outlet of a waterway, there is a water surface above the water surface,
A cavity consisting of an air layer is formed by the waterway side wall, the building wall, and the cover, and the cavity is connected to the building wall and the wall that is part of the cover and faces the building wall,
1. A soundproofing device for a water outlet, characterized in that it is formed by sound-deadening chambers each having an insertion portion that projects horizontally inward. 2. At the water outlet of the waterway, the water surface is above the water surface,
A cavity consisting of an air layer is formed by the waterway side wall, building wall, and cover, and the cavity has an opening at a certain height above the water surface directly above the waterway outlet, and is perpendicular to the opening. 1. A soundproofing device for a water outlet, characterized in that it is formed by a resonance chamber having a predetermined length in the vertical or horizontal direction. 3 At the water outlet of the waterway, the water surface is above the water surface,
A cavity consisting of an air layer is formed by the waterway side wall, the building wall, and the cover, and the end wall forming a part of the cover and facing the building wall,
A soundproofing device for a water outlet characterized by having a sealed cavity formed by a wall whose tip is submerged in water.