JP3286372B2 - Pressure wave dispersion device in tubular passage for high-speed train - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tubular passage structure constructed as a pressure wave dispersion device in a tubular passage for a high-speed train. The early realization of the linear Shinkansen as a future high-speed mass transportation is desired, but how to reduce environmental noise is a major problem. Therefore, it is conceivable to avoid the noise problem as much as possible by running the train in mountainous areas and in tunnels. However, in densely populated areas, this is not the case, and it is necessary to make the train passages tubular to provide soundproofing. If this were realized, the train would travel in an ever-longer tubular path (hereinafter simply referred to as a tunnel) and at a higher speed.

[0002] Pressure fluctuations caused by running a train propagate as sound waves in a tunnel. At that time, since the tunnel plays a role of a kind of waveguide, the low-frequency pressure wave propagates to a distant place without being attenuated by the three-dimensional expansion of the space. When the pressure fluctuation increases with the increase in traveling speed, the waveform is deformed by the so-called nonlinear (finite amplitude) effect while the pressure wave propagates, and a shock wave is generated at an unexpected place far away from the train. The present invention is to prevent the above-mentioned shock wave from being generated and reduce noise by dispersing pressure waves generated by a high-speed train traveling in a tunnel.

[0003]

2. Description of the Related Art When the Sanyo Shinkansen was constructed, when a train entered a tunnel, a noise problem accompanied by a loud popping sound occurred at the exit of the tunnel. This is known as the micro-pressure wave problem. Currently, this problem has been alleviated to some extent by installing hoods at the entrances and exits of the tunnel and reducing the amount of air that the train brings into the tunnel. However, it has already been pointed out that at ultra-high speeds such as the linear Shinkansen, measures using only the hood are not sufficient.
There is a long-awaited need for new drastic methods. Accordingly, as one of the drastic measures, the applicant has installed a number of Helmholtz resonator rows (hereinafter simply referred to as resonator rows) around the tunnel and changed their natural (resonant) frequency to pressure. By setting according to the frequency of the wave,
Japanese Patent Application Laid-Open No. Hei 4
No. 353193.

[0004]

The mechanism by which a shock wave is generated is such that as the size of a pressure wave increases, the speed of propagation of the shock wave is no longer the speed of sound, but it is faster and increases with the size of the pressure wave. Therefore, at first, no matter how smooth the waveform of the pressure wave is, spatially, temporally,
Since the propagation speed at a high pressure is higher than the propagation speed at a low pressure, a 'stick-out' phenomenon occurs gradually as the waveform propagates. As this progresses further,
The pressure waveform gradient becomes very large, and a portion occurs as if it changes discontinuously. This is a so-called shock wave. When a shock wave appears, a high-frequency component is generated due to a sudden change in pressure, which is heard as a plosive sound. Also,
When a shock wave is emitted from the tunnel exit, the sound pressure at a point sufficiently far from the exit increases in proportion to the time derivative of the pressure before the exit, that is, the gradient. For this reason,
The generation of a shock wave with a waveform gradient of infinity causes a serious environmental noise problem. The present invention solves the above problems.

[0005]

The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described. That is, one or more closed vessels or closed cavities with a certain volume are embedded in the tunnel wall in the circumferential direction of the cross section of the tunnel, and a large number of them are installed in the direction of the passage. Open connection with tunnel. A container is a space that already has some shape before installation, whereas a cavity here is somehow (by providing a wall, lid, etc.)
Refers to the space created on the wall. What is important here, whether a container or a cavity, is that a closed space with a certain volume is ensured. Therefore, for the sake of simplicity, instead of being called a container or a cavity, it is often simply called a container. A feature of the present invention is not limited to the resonator already proposed, but may be any type of container. However,
They only need to satisfy the conditions regarding acoustic impedance described later.

A typical example of the container is a resonator already proposed. However, since the present device aims at the dispersion effect of the container, it can be made smaller than when it is used as an attenuation device. Therefore, it can be mounted inside the tunnel wall as shown in FIG. Another simple example is a 'quarter-wavelength tube' in which the shape of the cavity cross section is constant in the depth direction as shown in FIG. As a modification, a quarter-wave tube having a gentle curvature in the depth direction as shown in FIG. 3 is provided in the circumferential direction of the tunnel, or is attached in the length direction of the tunnel as shown in FIG. Is also good. Furthermore, a combination of these is also conceivable. In any case, bury some containers on the tunnel wall. At this time, the size of each container may be different, but for the sake of simplicity, a case where one kind of the same size container is attached at equal intervals d in the length direction of the tunnel is considered.

[0007] The effect of the row of containers appears through the following two parameters. One is K (= V / 2εAd; ε (<<), which is called “coupling coefficient” that indicates the size of the container and the mounting interval.
1)). Here, V is the 'real volume' of the container defined later, ε is the maximum value Δp of the fluctuation pressure of the pressure wave and the atmospheric pressure p
The value obtained by multiplying the ratio of _{0 by} the coefficient [(γ + 1) / 2γ] (where γ is the specific heat ratio of air and is 1.4). A is the cross-sectional area of the tunnel. If m same containers (m is a positive integer) are mounted in the circumferential direction of the tunnel, K is multiplied by m (equivalent to multiplying V by m or setting d to d / m). Another parameter is the 'tuning coefficient' Ω (= (ω ₀ / ω) ² ) defined by the square of the ratio of the natural (resonant) frequency ω ₀ of the container and the representative frequency ω of the sound wave. In the case of a resonator row, V is equal to the volume of the container except for the three parts of the throat, and the resonance frequency ω ₀ is known (Ba ₀ ² / L
V) given by ^1/2 . However, B is the effective length of the throat 3 the cross-sectional area of the throat 3 in the mounting portion of the tunnel, L is where the tube end correction, and a ₀ is the speed of sound. Also,
In the quarter wavelength tube shown in FIG. 2, assuming that the cross-sectional area is B and the effective depth after tube end correction is L, V is still equal to the volume BL of the container, and the smallest natural frequency ω ₀ is π
given by a ₀ / 2L.

[0008]

[Action] One way to prevent the generation of shock waves is to rapidly attenuate the pressure waves before they occur, which has already been proposed as an action of the pressure damping device. The other is, as in the present application, to suppress the occurrence of shock waves by 'dispersion'. When the intensity of the pressure wave increases, it is not sufficient to suppress the pressure wave by a mere damping effect. On the other hand, suppressing swelling by dispersion is an essential shock wave prevention method. The term “dispersion” means that the propagation speed of each of the frequencies constituting the pressure wave differs depending on the frequency. Of course, there is no such dispersion in a sound wave transmitted through a normal tunnel.

It is known in quantum mechanics that a wave of a mode called a Bloch wave newly appears in a wave system having a spatial periodic structure. The major feature is that the waves show dispersibility that depends on the periodic structure. The same applies to the case of sound waves propagating in a tunnel in which a row of containers is periodically attached, as is now considered. By attaching a container, dispersibility occurs while the sound waves are repeatedly reflected and transmitted. The dispersibility makes the propagation speed of each of many high-frequency components generated by the rise different, suppresses the steepness of the pressure waveform gradient, and prevents the generation of shock waves. Another characteristic of Bloch waves is that in certain frequency bands, a so-called 'stop band', in which waves cannot propagate, appears. The frequency component of the band is subject to a damping effect of a mechanism different from dissipation such as wall friction. If this stop band is used well, attenuation can be expected at the same time as dispersion, which is very convenient for preventing shock waves. In the following, in order to quantify the effect of the row of vessels, the sound wave propagation in the tunnel is formulated.

(Formulation) Linear dispersion relation of Bloch wave in tunnel The linear dispersion relation of Bloch wave is shown in order to know the propagation characteristics of sound wave in a tunnel with a periodically attached vessel. An infinitely long tunnel is fitted with equally sized containers of equal size at equal intervals. The characteristics of the container shall be characterized by the acoustic impedance defined below.
When the pressure at the container mounting portion is p, the fluctuating (excess) pressure p ′ (= p−p ₀ : p ₀ is atmospheric pressure) is Pe.
xp (−iωt) + c. c. Is changed at the angular frequency ω. Here, P is a complex amplitude, i is an imaginary unit, and t is time. Also, c. c. Represents the complex conjugate of the preceding term. It is assumed that the volume flow rate Bv of the air flowing into the container also changes to Qexp (−iωt) according to the pressure fluctuation. Here, B is the cross-sectional area of the container at the tunnel mounting portion, v is the flow velocity of the air flowing into the container, and Q is the complex amplitude. The ratio P / Q of the complex amplitudes gives the acoustic impedance Z. Generally, the acoustic impedance is a function of iω and is a complex number. The specific shape is, in the case of a resonator,

(Equation 1) Given by Here, ρ ₀ is the density of air in the static equilibrium state. In a quarter-wave tube, Z is

(Equation 2) Becomes

Each of the tunnels sandwiched between two adjacent containers has a number n (n is an integer, n = ...- 2,-).
1,0,1,2,. . . ), And the fluctuating pressure p ′ in the n-th tunnel is Φ (x) exp [i (qx−ω
t)] + c. c. There exists a solution that changes as follows. Here, x is a coordinate in the length direction of the tunnel, Φ (x) is a periodic function having a period d, and q is a wave number. These Φ and q are called the wave function and wave number of the Bloch wave. Wave number q
And the frequency ω are related by the following Bloch dispersion relation:

(Equation 3) Here, R is the acoustic impedance ρ ₀ a of the tunnel and Z
It is the ratio to ₀ / A:

(Equation 4) Now, when Z is sufficiently larger than the acoustic impedance of the tunnel, as is apparent from Equation 3, the second on the right side
The term becomes sufficiently small. Now, if R → ∞, q is ω /
a ₀ , which results in an ordinary sound wave dispersion relational expression having no dispersibility. This indicates that dispersibility does not occur when the high-frequency sound wave, in other words, the mounting interval d is too long compared to the wavelength of the sound wave. However, when R decreases, q deviates from ω / a ₀ , and the difference depends on the frequency, that is, shows a dispersion. q is generally real, but can also be complex depending on frequency. Note that this occurs even if the sound diffusion effect and the friction on the wall are completely ignored. At this time, the real part of q becomes an integral multiple of π / d, and even if q is a complex number, as can be seen from the definition, it substantially corresponds to the case of a pure imaginary number. Since the imaginary part of q represents the spatial decay of the wave, the wave cannot propagate and is only attenuated. Specific graphs of the Bloch wave dispersion relations are shown in FIGS. 5 and 6 for the case of the resonator array of FIG. 1 and for the case of the quarter-wavelength tube of FIG.
Shown in The numerical values used here are given in Examples 1 and 2 described later.

Physically, this attenuation is due to (i) resonance when the frequency of the sound wave is close to the natural frequency of the container, and (ii) the container mounting interval is an integral multiple of the half wavelength πa ₀ / ω of the sound wave. , And two due to the so-called Bragg reflection. As can be seen in FIGS. 5- (2) and 6- (2), at frequencies where the imaginary part of qd is not zero,
Since a wave cannot propagate, this frequency band is called a stop band as described above, and is distinguished from a pass band when q is a real number. Therefore, in a pressure wave including many frequency components, attenuation occurs selectively depending on the frequency. The width of the stop band is determined by the size of R, and the width of the stop band is small except for R, which is quite small, so that most frequency components pass. Therefore, in order to reduce the value of R, that is, to reduce Z, as can be seen from Equation 3, the resonance frequency at which Z = 0 is matched with the frequency of the sound wave (this is the same as that of the already proposed pressure wave damping device). The principle is to increase the sectional area B of the container mounting portion. However, increasing B requires a large container,
There is a problem when considering the economics of making the tunnel cross-sectional area as small as possible. Therefore, R cannot be reduced except in the vicinity of Z = 0. Therefore, instead of reducing R, it is conceivable to increase the effect by reducing the mounting interval d.

2. Propagation of low-frequency nonlinear sound waves Actually, low-frequency sound waves are directly related to shock wave formation after sound waves propagating in the tunnel. Since the wavelength is long enough, it is easy to realize a small mounting interval. At this time, it can be considered that the containers are distributed continuously. This situation corresponds to a case where ω / ω ₀ (or qd) is sufficiently smaller than 1 in the Bloch wave dispersion relational expression. The propagation characteristic of a Bloch wave is a case of a linear wave having a sufficiently small sound wave amplitude. When the amplitude becomes large enough to generate a shock wave, it is necessary to consider nonlinearity. Therefore, the propagation of low-frequency nonlinear sound waves is formulated below.

Under the continuous distribution approximation, the behavior of a nonlinear sound wave propagating in a tunnel in both directions is described by the following equation:

(Equation 5) Here, x and t are the coordinates and time in the length direction of the tunnel as defined above, and u is the velocity component in the x direction induced by the sound wave. On the other hand, a is the so-called local sound velocity, which is different from a ₀ , depending on the density ρ of air.

(Equation 6) Is defined by The right side of Equation 5 represents the effect of the container row. N is the number of containers attached per unit length of the tunnel, and is 1 / d (however, when m are attached in the circumferential direction, it is m / d). B is the cross-sectional area at the tunnel mounting portion of the container.

Since the volume V of each container is sufficiently smaller than the volume Ad of the tunnel per container mounting interval, each container does not significantly affect the sound wave traveling through the tunnel. In other words, the response of the vessel to the pressure fluctuation in the tunnel can be linearly approximated. At this time, the inflow velocity v at the vessel mounting part and the fluctuating pressure p ′ in the tunnel are obtained by using acoustic impedance.

(Equation 7) Are related by Here, Y is an acoustic admittance is the reciprocal of acoustic impedance, which is dimensionless in B / ρ ₀ a _0. I'm thinking about low-frequency sound waves.
Can be expanded in (-iω) as follows:

(Equation 8) Here, α and β are constants having dimensions of time and its third power. In fact, this development is based on the resonators and quarters already shown.
This is true in the case of a wavelength tube, and it can be said that this is quite general when the effect of dissipating sound waves due to friction or the like is ignored. In this application,
Although the container may have any shape, it is assumed that its acoustic admittance is limited to one that can be developed as shown in Expression 8 when the dissipative effect is ignored. This is a necessary condition.

Now, since (-iω) corresponds to the calculation of ∂ / ∂t, the volume flow rate Bv is given by the fluctuating pressure p 'as follows:

(Equation 9) Using this relationship in equation 5, paying attention to the propagation in the positive direction of the x-axis, using the relationship p'~ρ ₀ a ₀ u of fluctuating pressure p 'flow velocity u

(Equation 10) Can be approximated. Assuming now that the fluctuating pressure is sufficiently small,
When the linear dispersion relational expression is obtained by ignoring the nonlinear term of this equation, qd << 1 of the Bloch wave dispersion relational expression already described.
Is confirmed to match. To make Equation 10 more compact, the delay time θ [= ω (t−x
/ A ₀ ], coordinates X [= εω describing the far field of the tunnel
x / a ₀ ] is introduced instead of x, t. Here, ω is the representative frequency of the sound wave, and ε is the ratio of the previously defined maximum value Δp of the fluctuating pressure to the atmospheric pressure multiplied by (γ + 1) / 2γ. Further, [(γ + 1) / 2] u / a ₀ is converted to ε
f

[Equation 11] The so-called Corteweg-de-Fries (Kor
teweg-de Vries) equation (hereinafter simply K
−dV equation). Where the coefficients K and Γ are each given as follows:

(Equation 12) Here, since α has a unit of time, a ₀ α
Has a dimension of length, multiplied by the cross-sectional area B to give a volume. Ba ₀ α is defined as the 'real volume' V of the container. The specific values of K and Γ are

(Equation 13) Becomes Here, Ω is the square of the ratio between the natural frequency ω ₀ of the resonator already defined and the representative frequency ω of the sound wave. Also, 4
In the case of a one-wavelength tube

[Equation 14] Becomes

The nature of the solution of the K-dV equation has been very well studied. According to this, it is known that a sound wave no longer forms a shock wave but becomes a so-called soliton wave train in the form of a pulse wave. The specific waveform of each soliton is

(Equation 15) Where C is the soliton wave height and θ ₀ is the phase.
To determine the maximum value of C, the initial value problem of the K-dV equation must be solved. Then, the value of C may be larger than the maximum value of the initial value, but when splitting into several soliton trains, C is less than twice the initial value.
Looking at the waveform of Equation 15 from a function of time at a certain location where X is fixed, as can be seen from the definition of θ, (C / 12Γ)
The reciprocal of ^{1 /} 2ω gives the representative time interval (pulse width) of the pulse. In other words, (C / 12Γ) ^1/2 ω can be regarded as a 'representative frequency of a pulse'. From this, the pulse width becomes larger as C becomes larger or Γ becomes smaller.
Narrows. Therefore, how to set (C / 12Γ) ^1/2 becomes a problem. As it becomes larger than 1, the pulse width becomes gradually narrower, and when it becomes extremely narrow, the waveform gradient of the pressure wave becomes too large, and a new noise problem different from the shock wave may occur.

Finally, the generality of the expanded form of the acoustic admittance of Expression 8 assumed in the analysis will be described. Physically, it cannot occur when α = 0, but can occur exceptionally when β = 0 depending on the container shape. At this time, K-dV
An equation is derived in which the third derivative of the equation is replaced by the fifth derivative. Even with this solution, it is known that no shock wave is generated. Therefore, the shape of the container for preventing shock waves can be taken quite generally.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A pressure wave propagating in the far field in a tunnel is almost a plane wave over the cross section of the tunnel, and its frequency is expected to be a so-called 'low-frequency sound wave'. From physical considerations, the frequency is approximately a ₀ /, where λ is the train length, U is the train speed, and D is the (hydraulic) diameter of the tunnel.
It is estimated to be λ or U / D, and is considered to be at most a ₀ / D. On the other hand, the upper limit of the pressure level Δp / p ₀ is estimated to be χM / (1−M), where 比 is the ratio of the train sectional area to the tunnel sectional area. However, M is the Mach number of the train, which is U / a _0. Now, λ = 200
m, U = 150 m / s (540 km / s), D = 10
Assuming that m and χ = 0.1, the frequency is 10 Hz from 2-3 Hz.
It is a low-frequency sound wave of about 30 Hz and no more than 30 Hz at most. Also, the maximum sound level is 0.1
(172 dB SPL) should be expected. From the above estimation, the representative frequency ω of the pressure wave is calculated as 1
0π rad / s (5 Hz), and the pressure level is about 0.08, assuming an upper limit. From this, ε is set to 0.1. The pulse width can be up to three times the representative frequency (1
5Hz) Assuming that it is allowed, Γ ≧ 1/54 = 0.018
Must be set to 5. Hereinafter, some typical embodiments will be described.

Embodiment 1 An example of the resonator array shown in FIG. 1 is shown. Figure 1 shows the shape of each resonator.
(3), shown in FIG. 1- (4). The volume V of the cavity 2 is 4 m ³
If the cross-sectional area B of the throat 3 is 4π / 100 m ² (40 cm in diameter) and the effective length L of the throat 3 is 0.5 m, the natural frequency is approximately 14 Hz (closer to a rectangular parallelepiped of 2 mx 2 mx 1 m). When eight resonators (m = 8) are mounted in the tunnel circumferential direction and mounted at intervals of 4 m in the length direction (d = 4 m), the values of K and Ω are respectively K = 0.0.
51 / ε, Ω = 7.4, Γ = 0.069, which satisfies the design condition.

(Example 2) An example in which the quarter wavelength tube of FIG. 2 is attached is shown. Assuming that the sectional area B of the cavity 2 is 5 m ² and the effective depth L is 5 m, the volume V of the cavity 1 is 25 m ³ and the natural frequency is 17 Hz. Two quarter-wave tubes (m
= 2) When attached at 10 m intervals in the length direction (d = 10 m), the values of K and Ω are respectively K = 0.0
32 / ε, Ω = 11.6, Γ = 0.023, which satisfies the design condition.

(Embodiment 3) An example is shown in which a quarter-wave tube having the curvature shown in FIG. 3 is attached. Assuming that the sectional area B is 4 m ² and the effective depth L is 7 m, the volume V of the container is 28 m ³ and the natural frequency is about 12 Hz. When four quarter-wave tubes are mounted in the tunnel circumferential direction (m = 4) and in the length direction at 10 m intervals (d = 10 m), the values of K and Ω are respectively K = 0.071 / ε, Ω = 5.9, Γ = 0.10, which satisfies the design condition. In these three examples, the pressure level value was assumed to be the upper limit, ε = 0.1, but if it is lower than that, there is no problem since the value of K increases and the value of Γ also increases. .

[0023]

The pressure wave dispersion device according to the present invention has the effect of preventing the generation of shock waves, but cannot expect the effect of attenuating pressure waves. This is because most of the frequencies fall into the pass band because a low frequency of qd << 1 is considered. However, among the high-frequency components, components that fall into the stop band are attenuated, but the waves as a whole propagate along the tunnel without much attenuation. Therefore, in order to prevent the generation of a shock wave and to suppress the propagation of a pressure wave to a distant place, it is effective to make the stop band as wide as possible and positively use its damping effect. This is nothing but a combination with the already proposed pressure wave damping device. Figure 1 shows how to actually prevent shock waves and suppress the propagation of pressure waves to distant places.
The configuration shown in FIG. 7 in which the pressure wave dispersion device and the damping device are combined is considered to be optimal. Of course, the dispersing device is not limited to the resonator of FIG. 1 and may be combined with FIGS.

[Brief description of the drawings]

FIG. 1 shows an example in which eight same resonators are attached to a wall surface of a tunnel along a circumferential direction of a cross section thereof. Figure 1
(1) is a cross-sectional view of the tunnel, FIG. 1- (2) is a side view in the length direction of the tunnel, FIG. 1- (3) is a front view of the resonator,
FIG. 1- (4) is a side view, and FIG. 1- (5) is a sectional view of the air. The perspective part in FIG. 1- (3) is the opening.

FIG. 2 shows an example in which a cavity is provided on the wall surface of a tunnel to form a quarter wavelength tube. In the depth direction of the cavity (perpendicular to the length direction of the tunnel), if the cross-sectional shape is a uniform rectangle, the same cavity shall be mounted symmetrically at a position facing the tunnel wall. Figure 2- (1) shows the tunnel air and air.
FIG. 2 (b) is a side sectional view of the tunnel, and the hatched portion is an opening.

FIG. 3 shows an example in which four sets of the same quarter-wave tubes are gently bent along the circumferential direction of the tunnel cross section on the wall surface of the tunnel. FIG. 3- (1) is a cross-sectional view of the tunnel, FIG. 3- (2) is a side view of the tunnel, FIG.
(3) is a front view of each quarter wavelength tube, and FIG. 3- (4) is a side view thereof. The shaded area is open.

FIG. 4 shows four sets of quarter-wave tubes on the tunnel wall.
This is an example in which the length direction is set to match the length direction of the tunnel. In this case, a cavity is made in the wall by providing a groove with concrete and covering it with a lid. FIG. 4- (1) is a cross-sectional view at the air line and the eye line of the tunnel, and FIG. 4- (2) is a side view of the tunnel, where the hatched portion is open.

FIG. 5 is a linear dispersion relational expression of a Bloch wave in a tunnel according to the first embodiment. In FIG. 5- (1), the vertical axis represents the dimensionless frequency at the natural frequency ω ₀ of the resonator, and the horizontal axis represents the real part Re of the Bloch wave number qd dimensionless at the mounting interval d.
{Qd}. In FIG. 5- (2), the vertical axis indicates the frequency that is dimensionless at the natural frequency ω ₀ , and the horizontal axis indicates the imaginary part Im {qd} of the dimensionless Bloch wave qd. The frequency band in which the imaginary part exists is called a stop band, and the others are called pass bands. The stop band is formed by resonance of a resonator whose dimensionless frequency is close to 1, and by other Bragg reflection.

FIG. 6 is a linear dispersion relational expression of a Bloch wave in a tunnel according to the second embodiment. In FIG. 6- (1), the vertical axis indicates the dimensionless frequency at the lowest natural frequency ω ₀ of the quarter-wave tube, and the horizontal axis indicates the dimensionless Bloch wave number qd at the mounting interval d. Indicates the real part Re {qd}. In FIG. 6- (2), the vertical axis represents the frequency that has been made dimensionless at the natural frequency ω ₀ , and the horizontal axis represents the imaginary part Im ｛q of the dimensionless Bloch wave number qd.
d｝. In this case, all odd multiples of ω ₀ correspond to the natural frequency of the quarter-wave tube and coincide with the frequency at which Bragg reflection occurs. In this example, the stopband is ω ₀
It does not occur at even multiples of.

FIG. 7 shows a tunnel equipped with the resonator row shown in FIG.
This is an example in combination with a previously proposed pressure wave damping device. The damping device has a structure in which an auxiliary tunnel is provided in parallel with the main tunnel, and the inside of the auxiliary tunnel is partitioned by a partition wall at an appropriate interval, and the cavity and the tunnel are connected. FIG. 7- (1) is a cross-sectional view of the tunnel at the air line and the eye line, and FIG. 7- (2) is a bottom view of the damping device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tubular passage (tunnel) 2 Cavity 3 Throat 4 Main tunnel 5 Auxiliary tunnel for pressure wave damper 6 Cavity for pressure wave damper 7 Throat for pressure wave damper 8 Partition wall in auxiliary tunnel

Claims (1)

(57) [Claims] 1. A closed container having a fixed volume is embedded in a wall in a tubular passage 1 for a high-speed train, or a closed cavity having a fixed volume is provided, and the container or the cavity is formed.
As one unit, one surface of the one unit is opened and a tubular passage 1 is formed.
Communicating with each other in the circumferential direction of the tubular passage
A container row is constructed by connecting a plurality of units of cavities, and a tubular passage
1 Take a number of the container rows at a certain interval in the length direction.
Give, by generating a frequency dependent on the speed of propagation of the wave of each frequency constituting a pressure wave propagating tubular passage, to generate dispersibility in the pressure wave, to suppress the steep pressure waveform gradient, pressure waveform A pressure wave dispersing device in a tubular passage for a high-speed train, wherein a shock wave in which a pressure waveform changes discontinuously due to an increase in gradient is prevented.