KR100189166B1 - New liquid quantity measurement apparatus and measurement method - Google Patents

Abstract

The present invention relates to a novel flow rate measuring device and a measuring method. More specifically, the present invention provides a flow measuring device and a flow measuring method capable of freely varying the mounting position and the measuring position, and capable of measuring the flow rate inside the pipe in which the fluid flows without changing the shape of the pipe and the flow of the fluid. It is about. The flow rate measuring apparatus of the present invention uses the signal generator 10 for generating white noise of a predetermined frequency band, the power amplifier 9 for amplifying the white noise, and the power amplifier 9 and the signal obtained from the electric power amplifier 9. An excitation part composed of an excitation device (5) for excitation; A signal composed of an accelerometer (1, 2, 3) for collecting vibration signals and an amplifier (6) for amplifying the acceleration signal obtained from the accelerometer (1, 2, 3) attached to the surface of the tube (4) at equal intervals. Collecting unit; And a signal processor comprising a multi-channel frequency analyzer 7 and a computer 8 for converting the acceleration signal collected by the signal collector into a flow rate. In addition, the flow rate measuring method of the present invention includes the step of obtaining the cross spectrum of each signal using the multi-channel frequency analyzer 7 of the flow rate measuring device described above, and obtaining the flow rate inside the tube from the cross spectrum.

Description

New flow measuring device and measuring method

1 is a schematic block diagram of a flow measurement device according to an embodiment of the present invention

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2 is a schematic view showing the geometrical shape of the tube illustrated to explain the flow measurement method of the present invention.

* Explanation of symbols for main parts of the drawings

1,2,3 Magnetometer 4: Pipe

5: exciter 6: amplifier

7 multichannel frequency analyzer 8 computer

9: power amplifier 10: signal generator

The present invention relates to a novel measuring device and a measuring method. More specifically, the present invention relates to a measuring device and a flow measuring method capable of freely varying the mounting position and the measuring position and capable of measuring the flow rate inside the tube through which the fluid flows without changing the shape of the tube and the flow of the fluid. It is about.

Tubes are used for supplying or discharging fluids to various fields such as production facilities of various chemical plants and fluid supply paths such as water supply pipes. Known as

Various types of flow rate measuring devices have been developed and used for measuring the flow rate of the fluid.

The conventional flow rate measuring device can be roughly divided into two types, one of which is manufactured in a form in which the cross-sectional area and shape of the pipe is modified, and the pipe is mounted as a part to measure the flow rate. Not only disrupts the flow of fluid flowing inside the tube inside the tube. There was a problem that the mounting position of the flow rate measuring device cannot be arbitrarily changed.

Another type of flow measuring device is a device using ultrasonic waves or electromagnetic waves. The conventional device described above has the advantage that it does not disturb the flow of the fluid. Since a hole for deforming or mounting an ultrasonic wave and an electromagnetic wave sensor must be formed on the surface of the pipe, the flow rate measuring device once mounted has a problem that the mounting position and the measuring position cannot be arbitrarily changed.

After all, the invention has been devised in view of the above-described problems of the prior art, and the main object of the present invention is that the mounting position and the measurement position can be freely changed, and the fluid flows without changing the shape of the pipe and the flow of the fluid. It is to provide a flow rate measuring device capable of measuring the flow rate inside the pipe.

Another object of the present invention is to change the mounting position and the measurement position freely using the fluency measuring device of the present invention described above, and to change the flow rate inside the tube through which the fluid flows without changing the shape of the tube and the flow of the fluid. It is to provide a measuring method that can be measured easily.

Flow rate measuring apparatus of the present invention for achieving the above object of the present invention is a signal generator for generating white noise of a predetermined frequency band (random signal generator) and a power amplifier for amplifying the electric white noise ( an excitation unit configured to excite a tube through a signal obtained from a power amplifier and an electric wave amplifier; A signal collector comprising three accelerometers attached to the surface of the tube at equal intervals for collecting vibration signals and an amplifier for amplifying the acceleration signals obtained from the electrical accelerometers; And a signal register composed of a multichannel FFT analyzer and a computer for converting the acceleration signals collected by the signal collector.

In addition, the superior measurement method of the present invention comprises the steps of generating a white noise of a certain frequency band through a signal generator and amplifying through a power amplifier having a tube by the exciter; Amplifying an acceleration signal obtained from three accelerometers equidistantly attached to the surface of the tube by an amplifier and obtaining a cross spectrum of each signal using a multichannel frequency analyzer; And calculating a flow rate inside the tube according to the following equation from the cross spectrum obtained from the electricity;

In the above, U represents the flow rate of the flowing fluid of the tube; a, p; F, p; s and t represent the inner diameter of the tube, the density of the fluid, the density of the tube and the thickness of the tube, respectively; c; s represents the free wave speed in the tube; Δx represents a change in length in the x-axis direction of the tube; C ₁₂ and C ₂₃ represent the real part of the cross-spectrum S ₁₂ and S ₂₃ , wherein the subscripts 1, 2 and 3 represent the respective accelerometers; And imaginary parts of the Q ₁₂ and Q ₂₃ cross spectra S ₁₂ and S ₂₃ .

The flow rate measuring apparatus of the present invention having the above-described configuration calculates the wavenubmer of waves propagating through the tube from signals obtained by three accelerometers mounted on the surface of the tube, and converts it into a flow rate in the tube.

In the above-described flow rate measuring apparatus of the present invention, if a home appliance is used with a pipe-type exciter in which a fluid flows, a tradition occurs in the tube, and the electric wave of the tube can be expressed as the sum of wave propagation, so the wave number of the wave is dependent on the velocity of the internal fluid. Will change accordingly. Therefore, it is possible to predict the relationship between the fluid velocity inside the pipe and the wave change amount, and to measure the velocity and flow rate of the fluid by an algorithm that calculates the wave change amount from the measured vibration signal.

In the flow rate measuring apparatus of the present invention, the vibration signal can be measured by attaching an accelerometer to the surface of the tube. Since the excitation operation of the tube is performed on the surface of the tube, the flow rate measuring apparatus of the present invention can measure the flow of fluid inside the tube. In addition to measuring flow without disturbing flow, the measuring position and mounting position can be freely changed.

Hereinafter, a flow rate measuring method using a flow rate measuring device and an electric flow rate measuring device according to a preferred embodiment of the present invention will be described in more detail with reference to the accompanying drawings.

1 is a schematic block diagram of a flow rate measuring apparatus according to an embodiment of the present invention. As shown, the flow rate measuring apparatus of the present invention includes a large excitation part, a signal collecting part, and a signal processing part.

In this case, the electrical excitation unit is connected to the signal generator 10 for generating white noise of a predetermined frequency band, the power amplifier 9 for amplifying the white noise, and the signal obtained from the electrical power amplifier 9. 4) and an exciter 5 for home appliances.

In addition, the electrical signal collector is attached to the surface of the tube 4 at equal intervals, and the acceleration signals obtained from the three accelerometers 1, 2 and 3 for collecting the vibration signals and the accelerometers 1, 2 and 3 described above. It consists of an amplifier (6) for amplifying.

In addition, the electrical signal processor is composed of a signal processor consisting of a multi-channel frequency analyzer 7 and a computer 8 for converting the acceleration signal collected by the electrical signal collector into a flow rate.

In the flow rate measuring apparatus of the present invention, the white noise of a predetermined frequency band generated from the signal generator 10 is amplified by the power amplifier 9, and the pipe (excited by the exciter 5) from the signal obtained from the power amplifier 9 is used for the pipe ( 4) This is done. When the tube 4 is excited, vibration signals are collected by three accelerometers 1, 2, and 3 attached at equal intervals to the surface of the tube 4, and amplified by the amplifier 6, and multi-channel frequency analyzer The cross spectra S ₁₂ and S ₂₃ of each signal according to (7) are obtained.

In this case, the aforementioned cross spectrum may be obtained by measuring a time signal using an analog-to-digital converter instead of a multi-channel frequency analyzer and performing Fourier transformation.

In FIG. 1, when arbitrary boundary conditions 11 and 12 are set at both ends of a certain position of the tube 4, the cross spectra S _{12 and} S ₂₃ measured at the surface of the tube 4 are determined _. The wave number propagation of the wave propagating through the tube 4 and the signal (Δk = (k ^-- k ⁺ ) / 2, where k ^- denotes the wave number of the wave propagating in the negative direction of the χ axis shown in FIG. Where k ⁺ represents the wave number of the wave propagating in the positive direction of the χ axis) is expressed in the following equation (1) in the low frequency region (see SA Seybert, J. Acoust. Soc. Am., 83: 2233-2239 (1988):

Where

Δχ represents the change in length in the χ-axis direction of the tube:

C ₁₂ and C ₂₃ represent the real part of the cross spectra S ₁₂ and S ₂₃ ; And imaginary parts of Q ₁₂ and Q ₂₃ and cross spectra S ₁₂ and S ₂₃ .

In addition, the relationship between the wavelet change amount Δk and the flow rate inside the pipe is expressed by the following equation (2):

In the above formula,

U represents the flow rate of the fluid flowing inside the tube; a, ρf, ρs and t represent the inner diameter of the tube, the density of the fluid, the density of the tube and the thickness of the tube, respectively, as shown in the tube geometry shown in FIG. 2; And cs represents the free sound velocity in the tube.

Therefore, the relationship between the cross spectrum measured from said Formula (1) and Formula (2) and the flow volume inside a pipe | tube can be represented by following formula (3);

Where

U, a, ρf, ρs, t, cs, Δχ, C _12, C _23, Q ₁₂ and Q ₂₃ are as defined above.

Therefore, in the flow measuring apparatus of the present invention, the white noise of a predetermined frequency band is generated through the signal generator 10 and amplified by the power amplifier 9 to excite the tube 4 by the exciter 5. Next, the acceleration signals obtained from the three accelerometers 1, 2, 3 attached at equal intervals on the surface of the tube 4 are amplified by the amplifier 6 and the multi-channel frequency analyzer 7 is used to By calculating the cross spectrum and calculating the flow rate by the computer 8 according to the above formula (3), the flow rate inside the tube can be measured.

In the present invention described above, the flow rate measuring device using the accelerometer sensor has been described, but the flow rate measurement may be performed by the same algorithm for obtaining the wave number using another type of sensor other than the accelerometer sensor, and the acceleration described in the present invention. The method of measuring the wave change of the pipe through the measurement can be used for purposes other than the flow measurement.

As described in detail above, the flow rate measuring device of the present invention can freely vary the mounting position and the measuring position, and can measure the flow rate inside the pipe in which the fluid flows without changing the shape of the pipe and the fluid. According to the flow rate measuring method of the present invention, the flow rate inside the pipe through which the fluid flows can be easily measured.

Claims (2)

An excitation unit comprising a signal generator 10 for generating white noise of a predetermined frequency band and a power amplifier 9 for amplifying the white noise; A signal collecting unit comprising an amplifier 6 for amplifying the excitation signal from the electric excitation unit; And a flow rate measuring device comprising a multi-channel frequency analyzer 7 and a computer 8 for converting the signal collected by the signal collection unit into a flow rate, wherein the electric excitation unit is amplified by the power amplifier 9. An exciting signal is input to excite the tube (4) comprises an exciter (5), and the electrical signal collecting portion is generated on the surface of the tube (4) due to the operation of the electrical excitation on the surface of the tube (4) And an accelerometer (1, 2, 3) for measuring the generated vibration wave. (i) Generate the white noise of a certain frequency band through the signal generator 10, amplify the white noise transmitted through the power amplifier 9, and operate the exciter 5 with the amplified signal to operate the pipe 4; Letting having; (ii) measuring the vibration wave generated in the electrical phase and generated on the surface of the tube 4 with accelerometers 1, 2 and 3 at equal intervals on the surface of the tube 4, and measuring the measured acceleration signal with an amplifier ( Amplifying by 6); And (iii) inputting the amplified acceleration signal obtained in the electrical step into the multi-channel frequency analyzer 7 to obtain a cross spectrum, and from the cross spectrum obtained therefrom, obtaining a flow rate inside the tube 4 according to the following equation. Flow measurement method comprising: Wherein U represents the flow rate of the fluid flowing inside the tube, and a, ρf, ρs and t represent the inner diameter of the tube, the density of the fluid, the density of the tube and the thickness of the tube, respectively; Cs represents the free sound velocity in the tube; Δχ represents a change in length in the χ axis direction of the tube; C ₁₂ and C ₂ , wherein the subscripts 1,2 and 3 each represent an accelerometer, represent the real part of the cross spectrum; And Q ₁₂ and Q ₂₃ represent an imaginary part of the cross spectrum.