KR20150043598A - Method for measuring physical value of fluid flow in pipe using ultrasonic waves and apparatus for the same - Google Patents

Abstract

Disclosed is a method for measuring a physical value of fluid flow in a pipe using a time difference (Δt) measured by a propagation time difference method, a first propagation speed of the ultrasonic wave in a fluid when the fluid stops, a refraction angle in the fluid of the ultrasonic wave generated in a pair of ultrasonic wave converters, and a transmission distance of the ultrasonic wave calculated by the refraction angle (θ_f) and a size of a pipe.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring a physical quantity of a fluid flowing in a pipe using an ultrasonic wave,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for measuring a physical quantity related to a flow of a fluid using ultrasonic waves, and more particularly, to a technique for measuring a flow rate, a flow velocity and a flow direction of a fluid in a pipe by installing an ultrasonic transducer outside the pipe.

Drought often occurs due to the unusual weather caused by global warming. As a result, water reserves are rapidly decreasing in the domestic reservoir and there is a possibility of water shortage. It is necessary to develop technologies that can systematically establish and analyze water-related information such as flow analysis when waterworks are temporarily converted to agricultural water due to natural disasters such as drought and to develop technologies that can be monitored in real time. Do.

There are many types of flowmeters, such as differential pressure type, area type, volumetric type, electronic, and ultrasonic flowmeter, depending on the principle of measurement, but the meter must measure the amount of fluid flowing in the pipe. If it is difficult to install a flow meter in a pipeline that temporarily supplies water to an agricultural waterway, it takes a lot of time and effort to monitor the amount of water discharged from the waterway. Therefore, it is necessary to develop a technique to measure the flow rate of the fluid in the pipe easily and quickly.

The ultrasonic flowmeter is a device that can measure the flow rate and the flow rate at the same time, and utilizes the Doppler principle of the ultrasonic wave generated according to the direction of the fluid flowing in the tube. There are two types of ultrasonic flowmeter: a wet ultrasonic flowmeter which is inserted into the pipe according to the installation method and transmits ultrasonic waves in the fluid, and a dry ultrasonic flowmeter in which the ultrasonic wave is transmitted through the outer wall of the pipe in contact with the outside of the pipe.

Since the ultrasonic wave is transmitted well in the fluid as compared with the wet type, the propagation path is relatively simple, and therefore, the accuracy and accuracy are high. On the other hand, in the case of facilities that can not be disassembled such as in the ground or power plant pipelines, there are many limitations to apply a wet ultrasonic flowmeter widely due to various factors in the process of dismantling, correcting and reinstalling the flowmeter.

The dry ultrasonic flowmeter is installed on the surface of the piping because the ultrasonic transducer is not located inside the piping, which makes it easy to maintain and repair the piping. In addition, according to the type of piping, the angle of refraction of the ultrasonic waves generated by the transducer can be adjusted to apply to various pipe sizes, and the cost can be saved compared to a wet type flow meter in which a flow meter is fixedly installed for all pipes. However, there are few devices for measuring the flow direction of the fluid in the piping. In order to distinguish the main piping from the branch piping when the piping branching from the main piping is intricately intertwined in the piping system of the actual piping, Is required.

Currently, most of the flowmeters use ultrasonic Doppler principle and flow rate and flow rate can be measured, but there are few devices capable of measuring flow direction. Numerous studies have been conducted on ultrasonic flowmeters at home and abroad, and most of them have been mainly studied to improve the accuracy of flowmeters. These studies have been applied to a wide range of fields from power plants, water supply and sewerage to medical use, but application and development of ultrasonic flowmeters for agricultural greenhouses and precision agriculture have hardly been applied. Especially, when there is a complicated structure of the waterworks pipe network, there is almost no way to measure the flow that can distinguish the main pipe from the branch pipe.

The present invention provides a method for measuring the flow direction, flow rate, and flow rate of fluid in a piping by using ultrasonic waves. In particular, the present invention is to provide an ultrasonic measuring apparatus with a simplified structure for measuring a flow rate without disassembling a pipe. It is also intended to provide a wedge for each pipe to deflect the ultrasonic wave so that it can be applied to various piping. Also, it is aimed to provide a method of compensating the error in consideration of the accuracy and precision of the predicted flow rate according to the number of ultrasonic wave reflections in the pipe. In general, based on the above methods, a method for simultaneously measuring the flow direction, flow rate, and flow rate of a fluid in a piping by using the propagation speed difference of an ultrasonic wave is provided. However, these problems are exemplary and do not limit the scope of the present invention.

According to an aspect of the present invention, there can be provided a method of measuring a physical quantity relating to the flow of fluid in a piping by using an electric wave time difference method using a pair of ultrasonic transducers provided apart from each other on the outside of the piping. This method, ① a time difference measured by the propagation time difference method (Δt), ② the fluid ultrasound first propagation speed of the in the fluid at the stop state (V _m), ③ in the ultrasonic transducer of the pair A refraction angle? _F of the generated ultrasonic wave in the fluid, and? A propagation distance W of the ultrasonic wave calculated by the refraction angle? _F and the size of the pipe; And estimating the flow velocity (V _F ') of the fluid to a value proportional to equation (1).

Equation ^{_{(1): (V m 2}} · Δt) / (W · sin (θ f))

Obtaining a number of reflections (n) of the ultrasonic wave in the fluid, which is calculated from the refraction angle? _F , the size of the pipe, and the distance S between the pair of ultrasonic transducers; And estimating the flow velocity (V _F ') to a value proportional to the equation (2).

Equation ^{_{(2): (V m 2}} · Δt) / (n · W · sin (θ f))

The method may further include estimating the flow rate Q of the fluid to a value proportional to the estimated flow velocity V _F 'multiplied by the square of the inner diameter of the pipe d ² .

The method further includes the step of correcting the estimated flow Q by multiplying the estimated flow Q by a correction coefficient k. Wherein the correction coefficient k is a value calculated through a measurement process using the above estimation method and the correction coefficient k is a value obtained by multiplying the flow rate value obtained from the flow rate value measured by the flow rate meter Divided by the estimated flow velocity (V _F ') (= Measured velocity / Calculated and a velocity proportional to the velocity .

At this time, the separation distance S between the pair of ultrasonic transducers can satisfy the formula (3).

(3): S = 2 (t? Tan? _E + d? Tan? _F )

only,

t is the thickness of the wall of the pipe,

&thetas; _E is the refraction angle of the ultrasonic wave at the wall of the pipe,

d is the inner diameter of the pipe,

and? _f is the refraction angle of the ultrasonic wave in the fluid.

At this time, a wedge is interposed between each of the pair of ultrasonic transducers and the pipe, and the wedge angle? Of the wedge is a value adjusted so that only the transverse wave component of the ultrasonic wave propagates in the fluid. have.

At this time, the wedge angle? Is not less than a critical angle? _LC with respect to a refractive denominational wave at the wall of the pipe, and is not greater than a critical angle? _SC with respect to a transverse wave at the wall of the pipe.

At this time, the time difference DELTA t may be measured using the zero crossing point defined in Korean Industrial Standard KS B ISO TR12765.

According to another aspect of the present invention, there is provided an apparatus for measuring a physical quantity relating to a flow of fluid in a piping by using an electric wave time difference method using a pair of ultrasonic transducers spaced apart from each other outside the piping . The apparatus includes a storage unit and a processing unit, wherein the processing unit is configured to perform: (1) a time difference? T measured by the propagation time difference method from the storage unit; (2) 1 propagation velocity (V _m), ③ refraction angle (θ _f) of the fluid of the ultrasonic waves, and ④ the refraction angle (θ _f) and the propagation of the ultrasonic wave is calculated by the size of the pipe occurs in the ultrasonic transducer of the pair Obtaining a distance W; And estimating the flow velocity (V _F ') of the fluid to a value proportional to the above equation (1).

The processing unit may further include a step of estimating the flow rate Q of the fluid by a value proportional to a value obtained by multiplying the estimated flow velocity V _F 'by the square of the diameter of the pipe (d ² ) .

At this time, the processing section may be further adapted to execute a step of correcting the estimated flow rate Q by multiplying the estimated flow rate Q by a correction coefficient k. At this time, the correction coefficient k may be a value calculated through a measurement process using the above-described estimation method. The correction coefficient k may be a value proportional to a value obtained by dividing the flow rate value obtained from the flow rate value measured from the flow meter by the estimated flow rate V _F 'estimated in the measurement process.

According to another aspect of the present invention, a method for measuring a physical quantity relating to the flow of fluid in a piping embedded in the ground using ultrasonic waves can be provided. The method includes measuring a flow rate of the fluid based on a propagation distance of the ultrasonic wave propagating in the fluid portion and an ultrasonic propagation velocity of the fluid when the fluid does not flow. At this time, the method may further include measuring the flow rate of the fluid based on the flow rate and the cross-sectional area of the pipe. At this time, the measuring step may include correcting the measured flow rate and the flow rate based on a correction coefficient having a predetermined value.

According to another aspect of the present invention, a system for measuring the flow rate, flow rate, and flow direction of fluid in a piping embedded in the ground using ultrasonic waves can be provided. The apparatus comprises: measuring the flow rate based on a propagation distance of ultrasonic waves propagated in the fluid portion and an ultrasonic propagation velocity of the fluid when the fluid is not flowing; Measuring the flow rate based on the flow rate and the cross-sectional area of the pipe; And a processing unit configured to perform the step of measuring the flow direction using the flow velocity and the propagation velocity of the ultrasonic waves.

In this case, the system may further include a wedge for allowing the ultrasonic wave to propagate into the pipe in consideration of the propagation speed of the ultrasonic wave.

At this time, the ultrasonic waves propagate in a longitudinal wave form on the wedge, propagate in a transverse wave form in the pipe, and propagate in a longitudinal wave form in the fluid.

At this time, the angle of the wedge should be a value equal to or greater than a critical angle with respect to the refractive longitudinal wave, and may be a value less than the critical angle with respect to the refractive transverse wave.

According to the present invention, it is possible to provide a technique capable of easily and simultaneously measuring the flow direction, flow rate, and flow rate of a fluid in a pipe without affecting the pipe. The effects of the present invention are not limited to those mentioned above, and other effects not mentioned can be clearly understood by those skilled in the art from the following description.

FIG. 1 is a view for explaining a change in transmission / reception roles of a pair of transmitting and receiving ultrasonic transducers.
Fig. 2 shows an installation example of various ultrasonic transducers.
FIGS. 3 and 4 are views for explaining the piezoelectric phenomenon and the reverse piezoelectric phenomenon, respectively.
5 is a view for explaining an incident angle and a refraction wave of an ultrasonic wave incident on a wedge and a refraction angle of a diffraction wave due to mode conversion.
6 shows a progress path of the ultrasonic wave generated in the ultrasonic transducer and a cross-sectional view of the pipe.
FIG. 7 is a diagram for explaining a method of obtaining a propagation time difference of an ultrasonic wave generated when an ultrasonic wave is transmitted and received in a pair of ultrasonic transducers.
FIG. 8 is a block diagram of an apparatus configured to simultaneously measure a flow direction, a flow rate, and a flow rate of a fluid flowing through a pipe according to an embodiment of the present invention.
9 is a view for explaining a fixing jig designed to fix a wedge in the embodiment of FIG.
FIG. 10 shows propagation paths of ultrasonic waves according to the number of times the ultrasonic waves propagated through the pipe are reflected.
11 shows the ultrasonic signal received when the number of times the ultrasonic waves are reflected in the pipe in the pipe is one.
FIG. 12 shows a second received ultrasound signal when the number of times the ultrasonic waves are reflected in the pipe in the pipe is one.
13 is an enlarged view of a portion A in Fig.
14 is a conceptual diagram of transmission and reception of an ultrasonic signal reflected twice in the pipe.
Fig. 15 is an actual signal of the ultrasonic wave received by the configuration of Fig.
FIGS. 16 and 17 are enlarged views of time differences in the 'b' portion and the 'c' portion of FIG. 15, respectively.
18 is a conceptual diagram of transmission and reception of ultrasonic signals reflected three times in a pipe.
Fig. 19 is an actual signal of the ultrasonic wave received by the configuration of Fig.
20, 21, and 22 are enlarged views of 'b', 'c', and 'd' in FIG. 19, respectively.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art to which the present invention pertains. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. Like reference numbers in the accompanying drawings may represent like elements.

The principle of the ultrasonic flowmeter utilizes the change of the ultrasonic signal reflected or transmitted inside the pipe by inclining the ultrasonic wave into the pipe through which the fluid flows. Such changes in the ultrasonic signal include frequency, phase, and propagation time, and most of them use a difference in propagation time.

When a vessel with a constant velocity v ₁ is moving on the surface of the water, the velocity of the fluid (v ₀ ) is added to the velocity of the fluid, v ₁ + v ₀ , In the opposite direction to the flow direction, the traveling speed is v ₁ -v ₀ . This principle can be applied to the progress of ultrasonic wave in flowing fluid, and it is called the propagation time difference method. In other words, comparing the time when the ultrasonic wave advances in the direction of the fluid in the direction of the fluid and the time in which the ultrasonic wave advances in the direction opposite to the fluid in the pipe having the known inner diameter, when the ultrasonic wave advances in the same direction as the fluid, It is delivered faster. Applying this principle can be used to measure the flow direction of the fluid. That is, as shown in Fig. 1, the transmission / reception function of the transmitting / receiving ultrasonic transducer is changed once. In FIGS. 1 (a) and 1 (b), reference numerals 11, 12 and 13 denote a pipe wall, a bean path, and a flow direction, respectively.

When the fluid flowing in an arbitrary direction is flowing in the pipe, the time until the ultrasound transducer B is received by the ultrasonic transducer A is t ₁ , the time when the transducer A is received when the transducer B is excited is t ₂ . In this case, <0, and the flow direction is _{A → B, t 1 -t 2} > t 1 -t 2 is a flow direction of the fluid A ← B 0, if t ₁ -t ₂ ≒ 0 fluid does not flow . That is, it is possible to measure the flow direction by using the difference of the ultrasonic arrival times, and to measure the velocity and the flow rate of the fluid.

In the case of a dry ultrasonic flowmeter, a plurality of ultrasonic transducers may be arranged as shown in FIG. 2 (b) in order to install an ultrasonic transducer in the shape as shown in FIG. 2 (a) or to increase accuracy and accuracy. 2 (a), reference numerals 11, 12, and 13 denote the pipe wall, beam path, and flow direction, respectively.

However, in one embodiment of the present invention, an ultrasonic transducer is installed on the outer wall of the exposed pipe so as to be attached to the same side as shown in FIG. 1 in order to measure the orientations quickly and easily in the field.

Hereinafter, an ultrasonic transducer that can be used in an embodiment of the present invention will be described.

The ultrasonic transducer for measuring the flow rate at the outer wall of the pipe must transmit the inside of the pipe by minimizing the loss of ultrasonic energy generated in the transducer when it comes into contact with the pipe surface. A piezoelectric element is mainly used as a key element of such an ultrasonic transducer.

The piezoelectric effect is a material which causes piezoelectric effect and inverse piezoelectric effect. The piezoelectric effect is a voltage which is proportional to the magnitude of force or deformation when a force or deformation is applied to a certain kind of material, And the reverse piezoelectric phenomenon means the opposite phenomenon as shown in Fig. A material having such properties is called a piezoelectric material, and a piezoelectric material is processed into a plate shape, and then electrodes are deposited on both surfaces thereof to produce a piezoelectric vibrator.

When a voltage is applied to the anode of the oscillator, the oscillator starts oscillation (resonance) of expansion and contraction corresponding to its thickness. Ultrasonic wave of longitudinal wave and transverse wave is generated according to the vibration direction, and when the vibrator is brought into contact with the test body, the ultrasonic wave is transmitted by the expansion and contraction of the vibrator to the contact surface of the body to transmit ultrasonic waves. On the other hand, when the ultrasonic wave is transmitted to the contact surface of the vibrator, a force is applied to the surface of the vibrator, and a voltage is generated in the piezoelectric vibrator in proportion to the force, so that the electric signal is generated. An ultrasonic transducer is a device that transmits and receives ultrasonic waves to and from a piezoelectric element and outputs them as electric signals.

Hereinafter, a wedge that can be used in an embodiment of the present invention will be described.

There are various modes of propagation in ultrasonic wave, and mode conversion occurs at the interface where these modes are mixed according to the test conditions and the medium is changed. In general, modes of ultrasonic waves that can be observed in a solid are longitudinal waves, shear waves, Rayleigh waves, and Lamb waves. The longitudinal wave is a wave whose direction of vibration corresponds to the traveling direction of the particle that transmits wave, and the transverse wave is a wave whose ultrasonic wave propagates perpendicularly to the flaw surface. Surface waves represent the mixed behavior of longitudinal vibration and transverse vibration in the vicinity of the surface of the trombone body, and the plate wave is composed of a combined vibration type that proceeds through the entire thickness of the material.

The square test method uses a wedge to introduce ultrasonic waves at an arbitrary angle and to introduce ultrasonic waves into the test object. At this time, the ultrasonic wave generated from the longitudinal ultrasonic transducer is transmitted from the wedge to the longitudinal wave, but in the test body, the transverse wave is generated due to the mode conversion due to the wedge. 5 shows the incident angle and the refraction wave of the ultrasonic wave incident on the wedge, and the refraction angle of the diffraction wave due to the mode conversion. Reference numerals 20, 21, 22, 23, 24, 25, 26, 27, 28, 29 and 30 shown in FIG. 5 respectively denote an ultrasonic transducer 20, an incident beam (longitudinal direction) 21, an incident angle 22, (Lateral direction) 25, a refraction angle (longitudinal direction) 26, a refraction angle (lateral direction) 27, a plastic wedge 28 ), A steel pipe (29), and an interface (30).

In one embodiment of the present invention, the angle of the wedge and the angle of the ultrasonic wave to be refracted are selected by a Snell's law as shown in Equation (1), so that a suitable wedge angle in which forward and reverse ultrasonic propagation time differences are well observed is selected.

 only,

= 입사각

= Incident angle

= 굴절각

= Refraction angle

= 매질 I에서의 초음파 속도

= Ultrasonic velocity in medium I

= 매질 II에서의 초음파 속도

= Ultrasonic velocity in medium II

와

는 각각 입사파의 입사각과 속도이며,

와

는 각각 대상체에서의 굴절파의 굴절각과 속도이다. here

Wow

Are the incident angles and velocities of the incident waves, respectively,

Wow

Are the refraction angles and velocities of refraction waves in the object, respectively.

는, 수학식 1에 의해, 모드 변환될 때 탐상체 내부에서 횡파만을 전달시키기 위해서 굴절 종파에 대한 임계각

이상으로, 또 굴절횡파에 대한 임계각

미만이 되도록 조정해야 한다. 즉, 쐐기 각도

는

의 조건으로 결정된다.
At this time, the material of the pipe is mostly steel, and the material of the wedge has the ultrasonic velocity and the acoustic impedance which satisfy the Snell's law when the ultrasonic wave passes through the pipe. As shown in Fig. 5, when the ultrasonic waves pass through the interface between the wedge and the fulcrum, a part of the longitudinal waves is converted into transverse waves and longitudinal waves. At this time, in one embodiment of the present invention,

Is expressed by Equation (1), and when the mode conversion is performed, the critical angle &lt; RTI ID = 0.0 &gt;

As described above, the critical angle

. That is,

The

.

Hereinafter, a method of measuring the progress time of ultrasonic waves in a fluid in a pipe according to an embodiment of the present invention will be described.

The flow rate can be derived using the geometric representation of the travel time and distance of the ultrasonic waves in the pipe. 6 shows a progress path of ultrasonic waves generated in the ultrasonic transducer and a cross-sectional view of the pipe 11. Fig. In this case, the ultrasonic waves generated from the transducer A are transmitted from the wedge 28 to the pipe thickness part, the fluid to the inside (bottom) surface of the pipe, and then reflected from the bottom surface to the opposite path, . At this time, the following relationship can be obtained.

[next]

The time taken for ultrasonic wave to propagate through the wedge

Time taken for ultrasonic wave propagation in pipe thickness

The time it takes for the ultrasonic wave to propagate through the fluid part

The total delivery time is given by Equation (2).

 only,

   E = propagation distance of the ultrasonic wave at the wedge

   P = propagation distance of ultrasonic wave from pipe wall

   W = propagation distance of ultrasonic wave in fluid

= 쐐기에서의 초음파 속도

= Ultrasonic velocity at the wedge

= 파이프 벽에서의 초음파 속도

= Ultrasonic velocity in pipe wall

= 유체에서의 초음파 속도

= Ultrasonic velocity in fluid

Also, when the fluid flows, the propagation time difference of the ultrasonic waves generated when the ultrasonic waves are transmitted and received by the transducers A and B according to the orientations can be obtained from the geometrical analysis of FIG.

는 유체 속도의 벡터이다. 도 6의 변환기 A에서 출발한 초음파는 배관(11) 내에서 왼쪽 방향으로 진행하는 유체에 영향을 받아 흐르지 않을 때보다 더 늦은 시간에 변환기 B에 도달하게 될 것이다. 도 6의 변환기 위치에서 발생된 초음파가 A에서 B까지 도달하는데 소요되는 시간은

이며, 유체가 흐르지 않을 때의 초음파 속도

에서, 유체가 왼쪽으로 흐르면

로 증가하며, 도 6과 같이 거리 S에 대한 초음파 도달 시간은 수학식 3과 같이 표현된다.
7, when the flow direction of the fluid is left,

Is the vector of the fluid velocity. The ultrasonic waves originating from the transducer A in Fig. 6 will reach the transducer B at a later time than when they are not influenced by the fluid traveling in the leftward direction in the pipe 11. The time required for the ultrasonic waves generated at the transducer position in Fig. 6 to reach from A to B is

, And the ultrasonic velocity when the fluid does not flow

, When the fluid flows to the left

As shown in FIG. 6, the ultrasound arrival time with respect to the distance S is expressed by Equation (3).

only.

가 되며, 이때의 초음파 도달 시간은 수학식 4와 같이 표현된다.
If the fluid flow direction and the ultrasonic wave propagation direction are the same,

And the ultrasound arrival time at this time is expressed by Equation (4).

only,

는 수학식 5와 같다.
Therefore,

Is expressed by Equation (5).

 only,

흐름이 없는 상태에서의 초음파 속도

Ultrasonic velocity in the absence of flow

유체에서의 초음파 전파거리

Ultrasonic propagation distance in fluid

6, the propagation time of the ultrasonic beam is increased by n times when the ultrasonic wave is reflected many times (n times) unlike the case of once reflecting at the bottom of the pipe, so the propagation time difference is expressed by Equation 6 .

Hereinafter, an optimum distance between a pair of ultrasonic transducers used in an embodiment of the present invention will be described.

로부터, 수학식 7과 같이 표현할 수 있다.
In Figure 6, the optimum distance of transducers A and B is

(7) &quot; (7) &quot;

 only,

   t = thickness of pipe wall

Hereinafter, a method of measuring the flow velocity inside a pipe according to an embodiment of the present invention will be described.

)은 수학식 8과 같이 표현된다.
In Equation (6), when the ultrasonic wave is reflected n times in the inside of the pipe and is transmitted,

) Is expressed by Equation (8).

 only,

n = number of ultrasonic reflections

If the cross-sectional area A of the pipe is multiplied by the equation (8), the flow rate Q when the ultrasonic wave is reflected n times in the pipe and is transmitted can be obtained as shown in Equation (9).

 only,

   n = number of ultrasonic reflections

d = inner diameter of pipe

Hereinafter, the ultrasound transducer, wedge, method of measuring ultrasonic wave propagation time in a fluid in a pipe, method of measuring an optimum distance between ultrasonic transducers, and method of measuring a flow velocity inside a pipe can be used in an embodiment of the present invention An example of actual experimental results will be described.

In order to simultaneously measure the flow direction, flow rate, and flow rate of the piping, an experimental apparatus as shown in FIG. 8 was constructed. Reference numerals 11, 13, 20, 28, 31, 32, 33, 34, 35 and 36 in FIG. 8 denote pipes 11, flow direction 13, ultrasonic transducer 20, wedge 28, oscilloscope 31, a receiver 32 for receiving ultrasonic waves received by the ultrasonic transducer, a pulser 33 for controlling the ultrasonic transducer to generate ultrasonic waves, a flow meter 34, a water tank 35, and a pump 36.

The main experimental devices were a pressure pump (WPMS-5500 series, HWARANG SYSTEM, Incheon, Korea), an oscilloscope (Waverunner 62XI, Lecroy, USA), a pulser and receiver (HIS-2, Krautkramer, Japan), a flow meter (Z4005, Nuritech, Korea ), And the error range of the flowmeter is 5%. The ultrasonic signals obtained from the oscilloscope were averaged 100 times. The conditions of the ultrasonic receiver were attenuation 40dB, pulser energy 2, damping 1, and 25,000 data were collected per second.

이며, 가압 펌프(WPMS-5500 series, HWARANG SYSTEM, Incheon, Korea)의 성능은 최대

이다.The ultrasound transducer was a broadband ultrasonic transducer (Panametrics Co. Ltd. USA) with a nominal frequency of 1 MHz and a wedge was made to fit the curvature of a single diameter tube. The measuring range of the flow meter (Z4005, Nuritech, Korea) is

, And the performance of the pressure pump (WPMS-5500 series, HWARANG SYSTEM, Incheon, Korea)

to be.

, plexiglass)를 적용하였다. 스넬의 법칙을 적용하기 위해 SUS304와 poly methacrylate 사이에서의 모드 변환을 고려한 초음파 속도는 강 내에서의 횡파 초음파 속도(3,200 m/s)와, 쐐기의 종파 초음파 속도(2,760 m/s)를 수학식 1에 적용하였다. The material of the pipe is SUS304, and the wedge is made of poly methacrylate (

, plexiglass) was applied. In order to apply Snell's law, the ultrasound velocity considering mode conversion between SUS304 and poly methacrylate was calculated from the transverse ultrasonic velocity (3,200 m / s) in the steel and the longitudinal ultrasonic velocity of the wedge (2,760 m / s) 1.

이상의 각도를 계산하였으며 굴절 횡파가 발생하도록 제2 임계각

미만의 각도를 계산하였다. 따라서 임계각

,

를 각각 수학식 1에 대입하면 아래와 같이 각 변환 모드에 맞는 쐐기의 각도를 계산할 수 있다.
The first critical angle &lt; RTI ID = 0.0 &gt;

And the second critical angle &lt; RTI ID = 0.0 &gt;

Were calculated. Therefore,

,

Into the equation (1), the angle of the wedge corresponding to each conversion mode can be calculated as follows.

   only,

= Refraction angle of sect

= 횡파의 굴절각

= Refraction angle of transverse wave

= 쐐기의 초음파 종파 속도

= Ultrasonic wave velocity of the wedge

= SUS304의 초음파 종파 속도

= Ultrasonic wave velocity of SUS304

= SUS304의 초음파 횡파 속도

= Ultrasonic transverse velocity of SUS304

는

의 범위로 계산되었으며, 가능한 느린 유속에서도 전파시간차를 잘 관찰할 수 있도록 제2 임계각

인

에 가까운

로 결정하였다. 이때,

쐐기에서 굴절되는 초음파 굴절각은 약

가 된다. 결국 초음파는 초음파 변환기→쐐기(종파)→배관(횡파)→유체(종파)→배관(횡파)→쐐기(종파)→초음파 변환기의 경로로 이동한다. 한편 배관에 접촉하여 적용할 수 있도록 쐐기를 고정시키기 위해 도 9와 같은 고정 지그를 설계하여 이용하였다. 도 9의 참조번호 28, 37은 각각 쐐기(28)와 고정 지그(37)를 나타낸다.Therefore, the angle of the wedge

The

. In order to observe the difference in propagation time as slowly as possible, the second critical angle

sign

Close to

Respectively. At this time,

The ultrasonic refraction angle, which is refracted from the wedge,

. Ultrasonic ultrasound moves to the path of ultrasonic transducer → wedge (longitudinal wave) → piping (transverse wave) → fluid (longitudinal wave) → pipeline (transverse wave) → wedge (longitudinal wave) → ultrasound transducer. The fixing jig shown in FIG. 9 was designed and used to fix the wedge so that it can be applied to the pipe. Reference numerals 28 and 37 in Fig. 9 denote a wedge 28 and a fixing jig 37, respectively.

Based on the theoretical method for measuring the flow direction, flow rate and flow rate described above, the difference between the flow rate obtained by the actual ultrasonic experiment and the flow rate obtained by the conventional flow meter is compared, and the reflection of the ultrasonic signal reflected in the pipe Experiments were performed to determine the appropriate number of ultrasonic reflections and the optimal distance between the ultrasonic transducers by increasing the number of times. The reason for the increase of the number of ultrasonic wave reflections is to compare the measurement accuracy of the flow rate and the flow velocity while increasing the ultrasonic wave propagation time difference caused by the flow rate change, and the explanation thereof is shown in FIG. 10 (a), 10 (b) and 10 (c) show cases where ultrasonic waves are reflected once, twice, and three times in the pipe, respectively.

를 산출하여 오차를 줄이도록 하였다. 이하, 반사 횟수가 1회, 2회, 3회인 경우의 실험 결과를 설명한다.
In Fig. 8, when the water contained in the water tank is continuously circulated in the counterclockwise direction by the pump, the flow rate can be adjusted through the valves at both ends of the pipe provided with the ultrasonic transducer. At this time, the flow rate was measured using a flow meter. In order to compare the flow rate with the flow rate, we changed the flow rate to three levels of 30, 45, and 60 L / m, respectively. Ultrasonic signals were received to analyze the effect of the distance of the ultrasonic transducer. In order to correct the difference between the flow rate value obtained through the ultrasound signal and the flow rate value measured by the flow meter,

To reduce the error. Experimental results in the case where the number of reflections is 1, 2, and 3 will be described below.

<When the number of reflections is one time>

의 유량 조건에서 초음파 전파시간차를 이용하여 유향을 결정할 수 있는 지를 고찰하였다. 도 11은 배관 내에서 도 10의 (a)와 같이 초음파가 배관 내에서 반사되는 횟수가 1번일 때 유량

조건에서 수신된 초음파 신호를 나타냈다. 도 11에서 보는 바와 같이, 2개의 초음파 신호가 수신되었는데 2개의 신호 중 'a' 신호는 배관의 표면을 따라 전파되는 신호이며 향후 분석에서 이러한 배관의 표현을 따라 전파하는 초음파 신호는 제외하였다.Assuming that two ultrasonic transducers are fixed and water flows in an arbitrary direction,

And the flow direction of ultrasonic waves was used to determine the flow direction. 11 is a graph showing the relationship between the flow rate of the ultrasonic waves in the pipe when the number of times of reflection of the ultrasonic waves in the pipe is 1,

The ultrasound signals received under the conditions are shown. As shown in FIG. 11, two ultrasonic signals were received. The 'a' signal among the two signals propagated along the surface of the piping, and ultrasonic signals propagating along the pipeline expression in the future analysis were excluded.

일 때의 수신된 신호에 대하여 도 11에서의 2번째 수신 신호, 즉, 'b' 신호를 확대하여 나타낸 결과는 도 12에서 보는 바와 같다. 도 12에서 수신된 신호의 파형의 차이를 구분하기 곤란하여 "A" 부분을 확대하여 나타낸 결과는 도 13과 같다.Flow rate

12, the results of enlarging the second received signal in FIG. 11, that is, the 'b' signal, are shown in FIG. It is difficult to distinguish the waveform difference of the received signal in FIG. 12, and the result of enlarging the "A"

는 한국산업표준(KS B ISO TR12765)의 '영점 교차점'을 사용하여 측정하였다. '영점 교차점'이란 처음 수신된 신호의 반주기가 지나고 난 후에 도착하는 신호이다(도 13 참조).Ultrasonic wave propagation time difference in fluid

Was measured using the 'zero crossing point' of the Korean Industrial Standard (KS B ISO TR12765). The zero crossing is a signal arriving after the half period of the first received signal passes (see FIG. 13).

로 설계된 쐐기에 의해 굴절되는 초음파 빔의 굴절각은 수학식 1에 의해,

,

로 계산된다(도 6 참조). 유량이

일 때 초음파 전파시간차

를 구하기 위해, 유량의 정의(Q=AV, Q=유량, A=단면적, V=유속)로부터, 아래와 같이 측정 유속

을 구하였다.
The specification of the pipe is SUS 304, the outer diameter is 25.4 mm, and the inner diameter is 25 mm. Angle of incidence

The refraction angle of the ultrasonic beam refracted by the wedge designed by the equation (1)

,

(See FIG. 6). Flow rate

Ultrasonic wave propagation time difference

(Q = AV, Q = flow rate, A = cross sectional area, V = flow rate) to obtain the measured flow rate

Respectively.

를 수학식 5에 대입하면 전파시간차

는 아래와 같이

로 계산된다.

Is substituted into Equation (5), the propagation time difference

Is as follows

.

   only,

일 때 계산되는 이론적인 전파시간차

와 유속을 검토하기 위하여 수학식 8에 대입하여 얻어지는 계산 유속(

)은 다음과 같다.
Flow rate

Theoretical propagation time difference

And equation (8) to examine the flow velocity Calculation flow rate (

)Is as follows.

)과 측정 유속(

)의 오차는 약 0.02m/s(2.04m/s-2.02m/s)로서 본 발명에서의 이론식인 수학식 8이 타당하다고 판단된다. Accordingly, the calculated flow rate (

) And the measured flow rate (

) Is about 0.02 m / s (2.04 m / s-2.02 m / s), so that the equation (8), which is a theoretical formula in the present invention, is valid.

는 약

이며, 수학식 8에 대입하면 초음파 신호 측정으로부터 얻어지는 계산 유속(

)은 약

으로 나타났다.
In Fig. 13, the propagation time difference measured from the ultrasonic signal

About

(8), the calculation flow rate obtained from the ultrasonic signal measurement

) Is about

Respectively.

과 배관 단면적으로부터 얻어지는 측정 유속(

)과 수학식 8에 의해 얻어진 계산 유속(

)과의 오차(

)는 약

로서, 이론적으로 계산된 전파시간차

와 유속은 타당한 것으로 판단된다. 도 13에서 "B" 부분의 전파시간차

는 약

이며, 계산 유속(

)은 수학식 8에 의해

이며, 수학식 9에 의해 계산되는 유량은

로서, 실제 유량

과의 오차는 약 7.5%로 나타났다.
Given flow conditions

And the measured flow rate obtained from the pipe cross-sectional area (

) And the calculated flow rate (

)

) Is about

Theoretically calculated propagation time difference

And the flow rate is judged to be reasonable. In Fig. 13, the propagation time difference of the portion "B"

About

, And the calculated flow rate (

) &Lt; RTI ID = 0.0 &gt;

, And the flow rate calculated by equation (9) is

, The actual flow rate

And the error was 7.5%.

일 경우 배관 내에서 초음파의 반사 횟수가 1번일 때 각각 계산되는 초음파의 전파시간차

, 측정 유속(

), 측정 유량(

)과 실험을 통해 얻어지는 전파시간차

, 계산 유속(

), 계산 유량(

)을 비교하여 나타내었다. 이때, 각각의 실험에 의해 얻어진 측정값은 5회 반복에 의한 평균값이다.
Table 1 below shows the flow rates

The propagation time difference of the ultrasonic wave calculated when the number of reflection times of the ultrasonic waves in the pipe is 1

, Measured flow rate (

), Measured flow rate (

) And the propagation time difference

, The calculated flow rate (

), Computed flow rate

). At this time, the measurement value obtained by each experiment is an average value by repeating 5 times.

No . of reflection Measured values Calculated values

Error of flow rate

Flow rate

Flow velocity

Time difference

Flow rate

Flow velocity

Time difference

One 60 2.04 41 66.3 2.25 46 10 45 1.53 31 48 1.6 33 3 30 1.02 21 33 1.1 23 10

를 수학식 10과 같이 정의하였다.
In order to reduce the flow measurement error shown in Table 1,

Is defined as Equation (10).

를 유속을 이용하여 결정한 이유는 유량을 나타내는 식

에서 유속이 주요 인자이기 때문이다.
Correction coefficient

Is determined by using the flow rate,

Because the flow rate is the main factor.

Table 2 shows the results obtained by correcting the flow rate and flow rate using Table 1 and Equation 10.

No . of reflection Measured values Calculated values k Corrected values

Error of flow rate

Error of velocity rate

flow
rate

velocity

flow rate

velocity

flow rate

velocity

One 60 2.04 66.3 2.25 0.91 59 2 1.7% 2.0% 45 1.53 48 1.6 45 1.5 10% 2.0% 30 1.02 33 1.1 31 1.1 3.3% 7.8%

를 이용하여 최종적으로 유량

은 수학식 11과 같이 표현 될 수 있다.
Correction coefficient

And finally the flow rate

Can be expressed by Equation (11).

<When the number of reflections is two times>

The concept of transmission and reception of the ultrasonic signal reflected twice in the pipe is shown in FIG. That is, by increasing the distance of the ultrasonic transducer, an ultrasonic reception signal as shown in FIG. 15 can be obtained. In this case, the signal 'a' in FIG. 15 is a signal transmitted along the pipe surface.

일 때 도 15에서 신호 'b'와 'c'에서의 초음파 전파시간차를 분석하였다. 도 16 및 도 17은 도 15의 'b'부분과 'c'부분에서의 시간차를 확대한 모습이다. 도 16에서 'b'부분의 전파시간차는 약 53ns로 나타났으며 이 신호는 도 13에서와 같이 1회 반사된 신호가 배관의 표면을 전파하여 수신용 초음파 변환기 (B)에 도달되는 것으로 판단된다. 한편 도 15의 신호 'c'의 경우 이론적인 전파시간차는 수학식 5에 의해 83ns로 계산되었으며, 도 17에서 측정된 초음파 전파시간차

는 약 96.4ns로 나타났다. 전체적으로 초음파 신호가 2회 반사되어 수신되는 신호가 1회 반사되어 수신되는 신호보다 감쇠가 상대적으로 크게 나타났다.The flow rate in the pipe

In Fig. 15, the time difference of ultrasonic wave propagation in signals 'b' and 'c' is analyzed. FIGS. 16 and 17 are enlarged views of time differences in the portions 'b' and 'c' of FIG. In Fig. 16, the propagation time difference at the portion 'b' is about 53 ns. This signal is judged to be transmitted to the receiving ultrasound transducer (B) by propagating the once reflected signal on the surface of the pipe as shown in Fig. 13 . On the other hand, in the case of the signal 'c' in FIG. 15, the theoretical propagation time difference is calculated as 83 ns by Equation 5, and the ultrasonic wave propagation time difference

Was about 96.4 ns. Overall, the attenuation is relatively larger than the received signal by reflecting the ultrasonic signal two times.

일 때 유속

은 초음파의 반사 횟수와 관계없이 항상 동일하기 때문에 이론적인 유속은

이다. 수학식 9에 도 17에서 측정된 전파시간차

인 96.4ns를 대입하여 다음과 같이 계산하면 유속

은

가 된다.
Flow rate

Flow rate

Is always the same irrespective of the number of reflections of ultrasonic waves, so the theoretical flow rate

to be. In Equation (9), the propagation time difference

And the following calculation is performed to calculate the flow rate

silver

.

However, n = 2

은

이며 이때,

에 대하여 오차는 약 18%로 나타났다.
On the other hand, the flow rate

silver

At this time,

The error was about 18%.

However, n = 2

일 때 배관 내 초음파의 반사 횟수가 2번일 때 각각 계산되는 초음파의 전파시간차

, 유속

, 유량

과 초음파 실험을 통해 얻어지는 전파시간차

, 유속

, 유량

을 비교하여 나타내었다. 각각의 유량 조건에서 실험에 의해 얻어진 측정값은 5회 반복에 의한 평균값으로 나타내었다.
Table 3 shows the flow rates

The propagation time difference of the ultrasonic waves calculated when the number of reflection times of the ultrasonic waves in the pipe is 2

, Flow rate

, Flow rate

And the propagation time difference obtained by the ultrasonic experiment

, Flow rate

, Flow rate

Respectively. The measured values obtained by the experiment at each flow rate condition are shown by the average value by repeating 5 times.

No . of reflection Measured values Calculated values

Error of flow rate

Flow rate

velocity

Time difference

Flow rate

velocity

Time difference

2 60 2.04 83 73 2.25 100 17 45 1.53 62 55 1.6 76 18 30 1.02 41 39 1.1 54 9

Table 4 shows the results of applying correction coefficients for correcting flow measurement errors using ultrasonic waves.

No . of reflection Measured values Calculated values k Corrected values

Error of flow rate

Error of velocity rate

flow
rate

velocity

flow rate

velocity

flow rate

velocity

2 60 2.04 73 2.25 0.8 58 2 2.0% 3.3% 45 1.53 55 1.6 44 1.5 2.0% 2.2% 30 1.02 39 1.1 31 1.1 7.8% 3.3%

<When the number of reflections is three times>

The concept of transmission and reception of the ultrasonic signal reflected three times in the pipe is as shown in FIG. That is, by increasing the distance of the ultrasonic transducer, an ultrasonic reception signal as shown in FIG. 19 can be obtained. Similarly, in FIG. 19, the signal 'a' is a signal transmitted along the pipe surface.

인 41ns보다 도달 시간이 더 소요되는 것으로 나타났다.In FIG. 19, the signal 'a' is a signal transmitted along the pipe surface, and the signal 'b' is the signal 'c' when the number of times of ultrasonic reflection is one in the pipe, Is a signal when the number of reflections is three. FIG. 20 is an enlarged view of the signal 'b' in FIG. 19. The difference in the propagation time of the signal 'b' is about 52 ns. In FIG. 18, since the ultrasonic wave is reflected once and transmitted along the surface of the pipe Transmission time calculated by one reflection

Which is more than 41 ns.

는 각각 100ns, 150ns로 나타났다. 이들 값들은 반사 횟수가 각각 2회 및 3회 일 때

의 유량 조건에서 계산되는 이론적인 전파시간차인 83ns 및 170ns와 유사한 값을 나타내었다.21 and 22 are enlarged views of the signals 'c' and 'd', respectively. At this time,

Are 100 ns and 150 ns, respectively. These values are obtained when the number of reflections is 2 and 3, respectively

Which is the theoretical propagation time difference calculated from the flow condition of 83ns and 170ns.

일 때 측정된 (c)의 전파시간차

인 150ns를 수학식 8에 대입하였을 때 측정 유속

은 다음과 같이

로 계산되었다.
Flow rate

The propagation time difference of (c)

Is substituted into equation (8), the measured flow rate

Is as follows

Respectively.

However, n = 3

은

이며, 이때

에 대하여 오차는 약 12%로 나타났다.
The flow rate measured by Equation 9 as follows

silver

Lt; / RTI &gt;

The error was about 12%.

However, n = 3

일 경우 배관 내의 초음파의 반사 횟수가 3회일 때 각각 계산되는 초음파의 전파시간차

, 유속

, 유량

과 얻어지는 전파시간차

, 유속

, 유량

을 비교하여 나타내었다. 각각의 유량계에서 실험에 의해 얻어진 측정값은 5회 반복에 의한 평균값을 나타내었다.
Table 5 shows the flow rates

The propagation time difference of the ultrasonic wave calculated when the number of reflection times of the ultrasonic waves in the pipe is 3,

, Flow rate

, Flow rate

And the obtained propagation time difference

, Flow rate

, Flow rate

Respectively. The measured value obtained by the experiment in each flow meter showed the average value by repeating 5 times.

No . of reflection Measured values Calculated values

Error of flow rate

Flow rate

velocity

Time difference

Flow rate

velocity

Time difference

3 60 2.04 170 55 1.9 150 9 45 1.53 120 43 1.4 120 6 30 1.02 83 29 One 81 3

On the other hand, the correction coefficient for setting the flow measurement error under the three reflection conditions of the ultrasonic wave was obtained and applied.

No . of reflection Measured values Calculated values k Corrected values

Error of flow rate

Error of velocity rate

flow
rate

velocity

flow rate

velocity

flow rate

velocity

3 60 2.04 55 1.9 1.05 58 2.0 3.3% 2% 45 1.53 43 1.4 45 1.5 0% 2% 30 1.02 29 1.0 31 1.05 3.3% 7.8%

While the present invention has been described in connection with what is presently considered to be practical and exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, . The contents of each claim in the claims may be combined with other claims without departing from the scope of the claims.

Therefore, it should be understood that the disclosed embodiments are to be considered in an illustrative rather than a restrictive sense, and that the true scope of the invention is indicated by the appended claims rather than by the foregoing description, and all differences within the scope of equivalents thereof, .

Claims (14)

A method for measuring a physical quantity relating to a flow of fluid in a piping by using an electric wave time difference method using a pair of ultrasonic transducers installed apart from each other on a pipe,
A time difference (t) measured by the propagation time difference method, a first propagation speed (V _m ) of ultrasonic waves in the fluid in a state where the fluid is stopped, Obtaining a propagation distance (W) of the ultrasonic wave calculated by the refraction angle ( _f ) and the refraction angle ( _F ) and the size of the pipe; And
Estimating the flow velocity (V _F ') of the fluid to a value proportional to equation (1)
/ RTI &gt;
A method for estimating a physical quantity relating to a flow of fluid in a pipe.
Equation ^{_{(1): (V m 2}} · t) / (W · sin (f)) The method according to claim 1,
Obtaining the number of reflections (n) of the ultrasonic wave in the fluid, which is calculated from the refraction angle ( _f ), the size of the pipe, and the distance (S) between the pair of ultrasonic transducers; And
Estimating the flow velocity V _F 'as a value proportional to equation (2)
/ RTI &gt;
A method for estimating a physical quantity relating to a flow of fluid in a pipe.
Equation ^{_{(2): (V m 2}} · t) / (n · W · sin (f)) The method according to claim 1, further comprising the step of estimating the flow rate (Q) of the fluid as a value proportional to the estimated flow velocity (V _F ') multiplied by the square of the inner diameter (d ² ) , A method for estimating a physical quantity relating to a flow of fluid in a pipe. The method of claim 3,
Further comprising the step of correcting the estimated flow rate (Q) by multiplying the estimated flow rate (Q) by a correction coefficient (k)
Wherein the correction coefficient k is a value calculated through a measurement process using the estimation method of claim 1,
The correction coefficient k is a value proportional to a value obtained by dividing the flow velocity value obtained from the flow rate value measured from the flow meter by the estimated flow velocity V _F 'estimated in the measurement process (= Measured velocity / Calculated velocity ) Is used.
A method for estimating a physical quantity relating to a flow of fluid in a pipe. The method according to claim 1, wherein the separation distance ( S ) between the pair of ultrasonic transducers satisfies equation (3).
Equation (3): S = 2 ( t tan _E + d tan _f )
Where t is the thickness of the wall of the pipe,
_E is the refraction angle of the ultrasonic wave at the wall of the pipe,
d is the inner diameter of the pipe,
_{and f} is the refraction angle of the ultrasonic wave in the fluid. The ultrasonic diagnostic apparatus according to claim 1, wherein a wedge is interposed between each of the pair of ultrasonic transducers and the pipe, and the wedge angle () of the wedge is a value adjusted so that only the transverse wave component of the ultrasonic wave propagates in the fluid Of the fluid in the pipe. 2. The apparatus according to claim 1, characterized in that the wedge angle (?) Is not less than a critical angle ( _LC ) with respect to a refractive longitudinal wave at the wall of the pipe and not greater than a critical angle ( _SC ) A method for estimating a physical quantity relating to a flow of a fluid. The method of claim 1, wherein the time difference (t) is measured using a zero crossing point defined in Korean Industrial Standard KS B ISO TR12765. There is provided an apparatus for measuring a physical quantity relating to a flow of fluid in a piping by using a propagation time difference method using a pair of ultrasonic transducers spaced apart from each other,
A storage unit and a processing unit,
Wherein,
From the storage unit the time difference (t) measured by the propagation time difference method, the first propagation speed (V _m) ultrasonic waves in the fluid in the state in which the fluid is stopped, the generated in the ultrasonic transducer of the pair of ultrasonic Obtaining a refraction angle ( _F ) in the fluid and a propagation distance (W) of the ultrasonic wave calculated by the refraction angle ( _f ) and the size of the pipe; And
Estimating the flow velocity (V _F ') of the fluid to a value proportional to equation (1)
Lt; / RTI &gt;
A device for measuring a physical quantity relating to the flow of fluid in a pipe.
Equation ^{_{(1): (V m 2}} · t) / (W · sin (f)) The method according to claim 9, wherein the processing unit estimates the flow rate Q of the fluid as a value proportional to the estimated flow velocity V _F 'multiplied by the square of the diameter of the pipe (d ² ) Wherein the flow of the fluid in the piping is further adapted to perform the flow of the fluid in the pipe. 11. The method of claim 10,
Wherein the processing unit is further adapted to perform a step of correcting the estimated flow rate Q by multiplying the estimated flow rate Q by a correction coefficient k,
Wherein the correction coefficient k is a value calculated through a measurement process using the estimation method of claim 1,
The correction coefficient k is a value proportional to a value (= Measured velocity / Calculated velocity ) obtained by dividing the flow velocity value obtained from the flow rate value measured from the flow meter by the estimated flow velocity V _F 'estimated in the measurement process And the flow rate of the fluid in the pipe is measured. A method for measuring a physical quantity related to a flow of fluid in a piping embedded in the ground using ultrasonic waves,
Measuring the flow rate of the fluid based on the propagation distance of the ultrasonic wave propagated in the fluid portion and the ultrasonic propagation velocity when the fluid does not flow.
Method of measuring physical quantity relating to fluid flow. 13. The method of claim 12, further comprising measuring a flow rate of the fluid based on the flow rate and the cross-sectional area of the pipe. The method according to claim 12 or 13,
Wherein the measuring step comprises calibrating the measured flow rate and flow rate based on a correction factor having a predetermined value,
Method of measuring physical quantity relating to fluid flow.

Images