JP2000266627A - Method for generating simulated leakage sound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate the analysis of leakage sound in a piping system, etc. SOLUTION: A leakage sound of a conduit 1 is simulatively generated by a shaker 2. The shaker 2 is driven by a transmitter 3 with a signal source of a noise, etc. The vibrations added to an outer wall surface of the conduit 1 by the shaker 2 propagate the outer wall surface of the conduit 1 and are detected by a sensor 5. The waveform detected by the sensor 5 is compared with that of previously recorded real leakage sound, and the frequency components of a signal for driving the shaker 2 is regulated so that the detected waveform may approach that of leakage original sound. By using the regulated transmitter 3, it is possible to generate simulative leakage sound easily by the shaker 2 from the outside of the conduit 1 and to perform leakage sound analysis on the conduit 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for generating a simulated leak sound used for analyzing the behavior of a leak sound in a piping system or the like in which a fluid cannot actually leak.

[0002]

2. Description of the Related Art In a piping system such as a pipeline or a container for handling a fluid, it is necessary to monitor the piping system so that leakage does not occur. The determination as to whether or not leakage has occurred can be made, for example, from fluctuations in the pressure or flow rate of the fluid. However,
When the amount of leakage is relatively small, the variation is small,
Further, since the fluctuation does not necessarily occur only due to leakage, it is not always easy to determine that leakage has occurred from changes in pressure or flow rate.

If the fluid is leaking, a specific sound is generated at the leaking portion, propagates through an outer wall such as a piping system, and can be detected even at a location far away from the leaking point. However, for example, most of the city gas piping systems are buried underground, and it is necessary to accurately specify a leak location based on detection of leak sound. In order to accurately specify the leak location, it is necessary to further analyze the behavior of the leak sound.

[0004] Due to the analysis of leakage noise from a piping system or the like, it is impossible to leak a fluid such as city gas from an actual piping system. In such a piping system, a sound similar to a leak sound is generated by a method of attaching a valve and adjusting the nozzle opening of the valve, and the sound is analyzed.

[0005]

Conventionally, in the analysis of leakage sound from a piping system, a valve is attached to the piping system, and the sound generated when a fluid passes through the valve inside the piping system is reduced to the leakage sound. Instead of analyzing the behavior of the leak sound, this method requires the work of mounting the valve inside the piping system, especially the work of mounting on a live pipe such as city gas used for transporting fluid. It is difficult. Also, the sound generated from the valve does not always coincide with the leaked sound, and the path from when the sound is generated to when it is transmitted to the outer wall of the piping system is not necessarily the same as when leaking directly from the outer wall. Instead, the frequency component of the sound that eventually propagates along the outer wall may be different from the actual leaked sound.

An object of the present invention is to provide a method for generating a simulated leaked sound that can easily generate a simulated leaked sound when analyzing the behavior of the leaked sound from a piping system or the like.

[0007]

According to the present invention, a vibration exciter is mounted on an outer wall surface of a pipe or a vessel, and the vibration exciter is mounted on the outer wall of the pipe or the vessel. This is a method for generating a simulated leaked sound, wherein the simulated leaked sound is generated in a simulated manner by excitation by electrically driving.

According to the present invention, a leak sound of a fluid from a pipe or a vessel handling a fluid is simulated by vibration applied to a pipe or an outer wall surface of the vessel from a vibration exciter. Since the vibration exciter is electrically driven, it is possible to adjust the frequency component of the drive signal so that the simulated leaked sound approaches the actual leaked sound. Simulated leak noise can be generated simply by attaching the vibration exciter to the pipeline or the outer wall surface of the container, so rather than mounting a valve inside the piping system,
Preparations for the generation of the simulated leaked sound can be easily made. When installing the vibration exciter, there is no effect on the handling of fluid inside the pipeline or inside the vessel. Can be generated.

Further, the present invention monitors a sound generated by the excitation by the vibration exciter and propagating on the outer wall surface, and propagates the outer wall surface at the time of actual leakage in which a waveform of the sound is recorded in advance. The frequency component of an electric signal for driving the vibration exciter is adjusted so as to approximate a waveform of a sound to be played.

According to the present invention, the frequency component of the driving electric signal applied to the vibration exciter is adjusted, and the waveform of the sound generated by the excitation by the vibration exciter and transmitted through the outer wall surface is recorded in advance. Since the waveform of the sound propagating on the outer wall surface at the time of the actual leak is approximated, the behavior of the leak sound can be analyzed in a state close to the actual leak sound. The waveform of the sound propagating on the outer wall surface at the time of the actual leak can be reduced from the pipe to be analyzed if the actual fluid leaks through the same pipe as the pipe to be analyzed. The same sound can be recorded without actually leaking the fluid.

[0011]

FIG. 1 shows a state in which a leaked sound is simulated in an embodiment of the present invention. In the present embodiment, it is assumed that leakage noise is analyzed by the conduit 1 used for a city gas piping system. The vibrator 2 is brought into contact with the outer peripheral portion of the conduit 1, and the vibration generated by the vibrator 2 is applied to the outer peripheral portion of the conduit 1. An electric signal for driving the vibrator 2 is generated by the transmitter 3. The level of the electric signal output from the transmitter 3 can be adjusted by the sound pressure adjuster 4. The frequency component of the driving signal generated from the transmitter 3 is analyzed and adjusted so that the waveform of the sound transmitted by the outer wall surface of the conduit 1 and detected by the sensor 5 becomes closer to the actual leaked sound.

FIG. 2 shows a state in which an actual leaked sound is recorded. As the test conduit 10, a tube equivalent to the conduit 1 in FIG. 1 is used. A leak hole 11 is previously formed in the test conduit 10. When a fluid similar to the fluid flowing in the conduit 1 of FIG. 1 flows through the test conduit 10, a leak sound is generated from the leak hole 11 by the sensor 5. Performs spectrum analysis, etc. For example, in the case of a heat supply pipe or a superheated steam pipe that supplies a high-temperature fluid, it is difficult to perform drilling in a live pipe state. However, it is relatively easy to use the test conduit 10 but to set the temperature of the fluid to room temperature to generate a leak sound. The propagation state of the leaked sound is little changed by the temperature, and even if the temperature condition is slightly different, a leaked sound close to the actual one can be obtained.

FIG. 3 shows a schematic electrical configuration of the transmitter 3 for adjusting the frequency spectrum component of the simulated leaked sound while analyzing the leaked sound with the transmitter 3 of FIG. Exciter 2
Is basically generated by the random noise generation circuit 20. Random noise generation circuit 20
Generates uniform white noise over a wide range of frequency components. The frequency component of the signal generated from the random noise generation circuit 20 is adjusted by the graphic equalizer 21. The output of the graphic equalizer 21 drives the vibrator 2 via the sound pressure adjuster 4 of FIG.
The vibration applied to the outer periphery of the conduit 1 by the vibrator 2 propagates along the outer peripheral surface of the conduit 1 and is detected by the sensor 5. The output of the sensor 5 is input to a spectrum analyzer 22 provided in the transmitter 3. The spectrum analyzer 22 converts the input real-time domain signal into a frequency domain signal. For this conversion, FFT processing or the like is used. The input signal converted into a signal in the frequency domain by the spectrum analyzer 22 is displayed on the display 23.
Displayed above.

In this embodiment, the leaked original sound recorded in advance in the configuration as shown in FIG. 2 is also displayed on the display 23 via the spectrum analyzer 22. The frequency spectrum of the leaked original sound analyzed by the analyzer 12 as shown in FIG. 2 is stored in the original sound memory 24, for example, and can be displayed on the display 23 together with the leaked sound detected by the sensor 5 by the spectrum analyzer 22 at any time. deep. The graphic equalizer 21 is, for example, 1
With the frequency at every third octave as a center, the level of the frequency component can be relatively changed.

FIG. 4 shows the display 23 of FIG. 3 displaying a leaked original sound shown in practice and a simulated leaked sound shown by a broken line. By the adjustment by the graphic equalizer 21, the simulated leaked sound can be made closer to the leaked original sound.
In this case, the leaked sound was recorded by flowing cold water through the test conduit 10 of FIG. 2 at a pressure of 8.5 kgf / cm ² to form a leak hole 11 having a hole diameter of 3 mm.

FIG. 5 shows a procedure for adjusting the frequency component of the simulated leaked sound in the present embodiment. When the target conduit 1 shown in FIG. 1 is determined in step s1, the conduit 1 in step s2 is determined.
The leaked original sound is recorded using the test conduit 10 shown in FIG. The recorded leaked original sound is stored in the original sound memory 2 shown in FIG.
In step s3, preparation for generating a simulated leaked sound, such as mounting of the vibrator 2, the transmitter 3, the sound pressure regulator 4, and the sensor 5 on the conduit 1 as shown in FIG. 1, is performed. In step s4, the vibrator 2 is driven by the electric signal from the transmitter 3, and the sensor 5 detects sound propagating on the outer peripheral surface of the conduit 1, and performs a simulated leaked sound analysis. In step s5, FIG.
As shown in (1), it is determined whether the simulated leaked sound matches the leaked original sound. When it is judged that the degree is low,
At step s6, the graphic equalizer 21 is adjusted so that the simulated leaked sound approaches the leaked original sound. The adjustment result of step s6 is confirmed again in step s5,
When the state almost matches, or the state of no more matching even if the adjustment is made, the adjustment is terminated in step s7.

FIG. 6 shows that when the leak hole 30 is formed in the conduit 1, the sensors 31 and 32 are arranged at an interval L, and based on the leak sound detected by the sensors 31 and 32, the leak hole 3 is detected.
3 shows a configuration for calculating the position of 0. Although the leak sound generated from the leak hole 30 is generated with a waveform close to random noise, the instantaneous waveforms are different from each other. Focusing on the characteristics of the instantaneous waveform, ΔL = Δt × v, which is the product of the time difference Δt transmitted from the leak hole 30 to the two sensors 31 and 32 and the sound propagation speed v, is represented by the two sensors 31 and 32
From the distance to the position of the leak hole 30. FIG.
In the example, although the leak hole 30 is shown in a state close to the sensor 31, even when the leak hole 30 is close to the sensor 32,
A similar idea holds. In the case of FIG. 6, it is understood from the sensor 31 that the leak position is a position on the sensor 32 side by (L−ΔL) / 2.

As described above, in order to estimate the position of the leak hole 30 based on the arrival time difference of the leak sound as shown in FIG.
It is necessary to detect the arrival time difference Δt between 1 and 32. Such detection is called a "correlation method". The actual leaked sound is not white noise in which the frequency component is uniformly contained, but has a certain degree of bias in the frequency component. Also,
When propagating along the outer wall surface of the conduit 1, the propagation speed also has frequency dependence. For this reason, the transmitter 3 shown in FIG. 6 in which a simulated leaked sound close to an actual leaked sound is generated by the transmitter 3 for electrically driving the vibrator 2 as in the present embodiment and the data processing is performed by the correlation method. It is necessary to sufficiently confirm and adjust the operation of 33.

[0019]

As described above, according to the present invention, a pseudo leaked sound is generated outside using an electrically driven vibration exciter and is given as vibration to the outer wall surface. Analysis of the behavior can be performed in the same manner as the leak sound generated by the leak from the outer wall surface. Even when the fluid is being handled inside the pipe or the container, a leak sound can be generated irrespective of the handling state.

Further, according to the present invention, the frequency component of the electric signal for driving the vibration exciter is adjusted so as to approximate the waveform of the sound propagating on the outer wall surface at the time of actual leakage, so that the behavior of the leakage sound Can be accurately analyzed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic electrical configuration for generating a simulated leaked sound according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a schematic electrical configuration for recording a leaked original sound in the embodiment.

FIG. 3 is a block diagram showing an electrical configuration related to the transmitter 3 of FIG.

FIG. 4 is a graph showing a simulated leaked sound and a leaked original sound displayed on a display 23 of the transmitter 3 of FIG. 3;

FIG. 5 is a flowchart showing a procedure of adjusting a frequency spectrum of a simulated leaked sound in the present embodiment.

FIG. 6 is a diagram showing a basic concept of leak position detection by a correlation method that needs to be adjusted using a simulated leak sound generated in the present embodiment.

[Explanation of symbols]

 Reference Signs List 1 conduit 2 shaker 3 transmitter 5, 31, 32 sensor 10 test conduit 11 leak hole 12 analyzer 20 random noise generating circuit 21 graphic equalizer 22 spectrum analyzer 23 display 30 leak hole 33 processor

Claims (2)

[Claims] The present invention relates to a vibration exciter attached to an outer wall surface of a pipeline or a container and electrically driven to operate the vibration exciter. A method for generating a simulated leaked sound, wherein the simulated sound is generated by shaking. 2. A sound generated by excitation by the vibration exciter and propagated on the outer wall surface is monitored, and a sound waveform transmitted on the outer wall surface at the time of actual leakage recorded in advance is recorded. 2. The method according to claim 1, wherein a frequency component of an electric signal for driving the vibration exciter is adjusted so as to approximate a waveform.