JPH07260532A - Ultrasonic flowmeter - Google Patents
Ultrasonic flowmeterInfo
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- JPH07260532A JPH07260532A JP6053721A JP5372194A JPH07260532A JP H07260532 A JPH07260532 A JP H07260532A JP 6053721 A JP6053721 A JP 6053721A JP 5372194 A JP5372194 A JP 5372194A JP H07260532 A JPH07260532 A JP H07260532A
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- Prior art keywords
- flow
- flow velocity
- pipe
- ultrasonic
- correction coefficient
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Abstract
Description
【０００５】[0005]
【産業上の利用分野】本発明は、超音波流量計に関し、
より詳細には、反射方式の超音波流量計において、上流
側に湾曲管が配設され、流体の流れに偏流や旋回流が含
まれることによって生ずる誤差を補正し、正規の平均流
速にする器差補正装置を有する超音波流量計に関する。BACKGROUND OF THE INVENTION The present invention relates to an ultrasonic flowmeter,
More specifically, in the reflection type ultrasonic flowmeter, a curved pipe is arranged on the upstream side to correct an error caused by a drift or swirling flow in the fluid flow to obtain a normal average flow velocity. The present invention relates to an ultrasonic flowmeter having a difference correction device.
【０００６】[0006]
【従来の技術】周知のように、超音波流量計は、被測定
流体を媒体とし、該被測定流体内に超音波を発射したと
き、流れにより超音波が変調されることを利用した可動
部を持たない推測形の流量計である。超音波流量計は、
流れを遮えぎる要素がないので、圧力損失が小さく、大
口径であっても超音波の送受波器を有する簡単な構成で
あるため、安価な流量計を提供することができる。As is well known, an ultrasonic flowmeter uses a fluid to be measured as a medium, and when ultrasonic waves are emitted into the fluid to be measured, the ultrasonic waves are modulated by the flow of the movable portion. It is a speculative type flowmeter that does not have. Ultrasonic flowmeter
Since there is no element for blocking the flow, the pressure loss is small, and even with a large diameter, the ultrasonic wave transmitter / receiver has a simple structure, so that an inexpensive flow meter can be provided.
【０００７】超音波流量計には、超音波が流体流れの順
方向と逆方向に発射されたときの超音波の伝播時間差か
ら流速を求める伝播速度差法や、流体内を流体と共に流
れる粒子に超音波を発射したとき、粒子から反射される
反射波が流速に比例して周波数変化を生ずることを利用
して流速を求めるドップラー法とに大別されるが、微粒
子が含まれない流体に対しては、通常、伝播速度差法の
超音波流量計が用いられる。The ultrasonic flowmeter includes a propagation velocity difference method for obtaining a flow velocity from a propagation time difference of ultrasonic waves when the ultrasonic waves are emitted in the forward direction and the reverse direction of the fluid flow, and a method for measuring particles flowing in the fluid together with the fluid. When ultrasonic waves are emitted, it is roughly divided into a Doppler method that calculates the flow velocity by utilizing the fact that the reflected wave reflected from the particles changes frequency in proportion to the flow velocity. For this purpose, an ultrasonic flowmeter of the propagation velocity difference method is usually used.
【０００８】伝播速度差法による超音波流量計には、超
音波の送波器および受波器を流管に一対又は複数対配設
したものがあるが、一対の超音波送受波器を配設した基
本的な超音波流量計の超音波伝播の方式には、超音波が
流管の流れ軸を斜めに横切るように送受波する超音波送
受波器を対向する流管壁に配設された透過法と、流管壁
の流れ方向に所定距離離間して配設された超音波送受波
器間において、対向する管壁で反射されて送受波される
超音波の伝播速度差を求める反射法とがある。Some ultrasonic flowmeters based on the propagation velocity difference method have a plurality of ultrasonic wave transmitters and ultrasonic wave receivers arranged in a flow tube. The ultrasonic wave transmission method of the basic ultrasonic flowmeter installed is to install an ultrasonic wave transmitter / receiver that transmits and receives ultrasonic waves diagonally across the flow axis of the flow tube on the opposite wall of the flow tube. Between the transmission method and the ultrasonic wave transmitter / receiver arranged at a predetermined distance in the flow direction of the flow tube wall. There is a law.
【０００９】透過法による超音波流量計は、超音波が反
射により減衰することが少なく、高感度な受波信号を得
ることができる。しかし、流体の流れの中に流管軸に直
角方向の流れ成分があると、同じ方向の速度成分をもつ
超音波の伝播速度に影響を与え、これが流速測定の誤差
要因となり、流速測定精度が低下する。これに対し、反
射法による超音波流量計では、流管軸に直角方向の流れ
成分影響は打ち消されて超音波の伝播速度に影響を与え
ることが少ない。In the ultrasonic flowmeter by the transmission method, ultrasonic waves are less likely to be attenuated by reflection, and a highly sensitive received signal can be obtained. However, if there is a flow component in the direction perpendicular to the flow tube axis in the fluid flow, it will affect the propagation velocity of ultrasonic waves with velocity components in the same direction, which will cause an error in flow velocity measurement, and the accuracy of flow velocity measurement will decrease. descend. On the other hand, in the ultrasonic flowmeter based on the reflection method, the influence of the flow component in the direction perpendicular to the flow tube axis is canceled and the propagation velocity of the ultrasonic wave is rarely affected.
【００１０】通常、推測式の流量計においては、流管軸
に軸対称な流速をもつ正規流速分布の流れを得るため
に、流量計の上流側に所定の整流装置を配設して偏流や
旋回流を取り除いて偏流や旋回流による流速誤差を取り
除いている。超音波流量計においては、流体流れの順方
向と逆方向に送受波される超音波が、流れに対し傾射し
た直線上を伝播するときの順方向と逆方向の伝播時間差
が計測される。しかし、流管内の流速分布は、レイノル
ズ数（Ｒｅ数）により変化するので、計測された伝播時
間差は平均流速に比例したものではなく、正確な流速を
求めるためには伝播時間差に対し、流速分布による補正
を必要とする。Usually, in a speculative flowmeter, in order to obtain a flow having a normal flow velocity distribution having an axially symmetrical flow velocity with respect to the flow tube axis, a predetermined rectifying device is arranged on the upstream side of the flowmeter so as to cause a drift or The swirling flow is removed to eliminate flow velocity errors due to uneven flow and swirling flow. In the ultrasonic flowmeter, the difference in propagation time between the forward and backward directions when ultrasonic waves transmitted and received in the forward and reverse directions of the fluid flow propagate on a straight line inclined with respect to the flow. However, since the flow velocity distribution in the flow tube changes depending on the Reynolds number (Re number), the measured propagation time difference is not proportional to the average flow velocity. Need to be corrected.
【００１１】[0011]
【発明が解決しようとする課題】反射法によって超音波
伝播速度を求める超音波流量計は、偏流だけがある場合
のように、超音波が伝播する伝播面上で流管軸に直角な
同一方向の流れ成分のみがある場合は、超音波伝播速度
の影響を小さくすることができるが、流管の軸に直角な
方向に互いに反対の流れ、例えば、旋回流がある場合
は、流れ影響を取り除くことができない。このため、超
音波流量計の上流側に偏流や旋回流を取り除くための管
長の長い規格された直管か、あるいは高価な整流装置を
取り付ける必要がある。このため、長い直管や整流装置
を取り付けるスペースのない場所に超音波流量計を配設
する場合は、高精度で流量測定することが不可能であっ
た。The ultrasonic flowmeter for determining the ultrasonic wave propagation velocity by the reflection method has the same direction perpendicular to the flow tube axis on the propagation plane where the ultrasonic wave propagates, as in the case where there is only a drift. If there is only the flow component of the ultrasonic wave, the effect of the ultrasonic wave propagation velocity can be reduced, but if there are flows opposite to each other in the direction perpendicular to the axis of the flow tube, for example, if there is a swirl flow, the flow effect is removed I can't. For this reason, it is necessary to install a standard straight pipe having a long pipe length or an expensive rectifying device for removing a drift or a swirling flow on the upstream side of the ultrasonic flowmeter. Therefore, when the ultrasonic flowmeter is installed in a place where there is no space to install a long straight pipe or a rectifier, it is impossible to measure the flow rate with high accuracy.
【００１２】本発明は、上述の問題点に鑑みなされたも
ので、長い直管あるいは高価な整流装置を配設すること
なく、安価・高精度で流速又は流量を計測可能とする伝
播速度差方式の超音波流量計を提供することを目的とす
るものである。The present invention has been made in view of the above problems, and is a propagation velocity difference method capable of inexpensively and highly accurately measuring a flow velocity or a flow rate without disposing a long straight pipe or an expensive rectifying device. It is an object of the present invention to provide an ultrasonic flowmeter.
【００１３】[0013]
【課題を解決するための手段】本発明は、上記目的を達
成するために、（１）少くとも一つのベンドを有する上
流側の湾曲管に直管を接続した同一口径の流管と、前記
直管の管壁に流れ方向に所定間隔を隔てて配設された一
対の超音波送受波器と、該超音波送受波器の一方向から
発射され対向する流管壁に反射された超音波が他方側に
達する迄の流れの順方向と逆方向に伝播する伝播時間の
時間差に基づいて流体の流速または流量を求める超音波
流量計において、該超音波流量計により求められた流速
と、流管の口径と、流体の密度および粘度とに基づいて
レイノルズ数（Ｒｅ数）を演算するレイノルズ数演算手
段と、正規の流速分布で流れる流体の中を超音波が伝播
する伝播時間から求めた流速を平均流速に補正するため
のレイノルズ数補正係数を求める標準レイノルズ数特性
補正手段と、前記湾曲管のあるときの超音波の伝播時間
差から得られた流速を、湾曲管のない場合の流速に補正
するための流管形状補正係数を求める流管形状補正手段
と、前記超音波流量計により求められた流速に対し、演
算された前記Ｒｅ数における前記レイノルズ数補正係数
と流管形状補正係数とを乗算し、正規の流速または流量
を求める器差補正装置とからなること、更には、（２）
前記（１）において、前記流管の上流側の湾曲管を２重
ベンドとして前記超音波流量計により求められた未補正
の流速をＶ、演算されたＲｅ数をＲｅとし、ａ,ｂ,ｃ,
ｄを定数としたとき、レイノルズ数補正係数Ｋ1をIn order to achieve the above object, the present invention provides: (1) a flow pipe of the same diameter, in which a straight pipe is connected to an upstream curved pipe having at least one bend, and A pair of ultrasonic transducers arranged on the wall of the straight pipe at a predetermined interval in the flow direction, and ultrasonic waves emitted from one direction of the ultrasonic transducers and reflected by the opposing wall of the flow tube. In the ultrasonic flowmeter for determining the flow velocity or flow rate of the fluid based on the time difference of the propagation time of propagating in the forward direction and the reverse direction of the flow until reaching the other side, the flow velocity obtained by the ultrasonic flow meter and the flow rate Reynolds number calculating means for calculating the Reynolds number (Re number) based on the diameter of the pipe and the density and viscosity of the fluid, and the flow velocity obtained from the propagation time of the ultrasonic wave in the fluid flowing at the regular flow velocity distribution. Reynolds number correction to correct A standard Reynolds number characteristic correcting means for obtaining a coefficient and a flow tube shape correction coefficient for correcting the flow velocity obtained from the difference in propagation time of ultrasonic waves with the curved pipe to the flow velocity without the curved pipe. A vessel shape correction means and a device for obtaining a normal flow rate or flow rate by multiplying the flow rate obtained by the ultrasonic flowmeter by the Reynolds number correction coefficient and the flow tube shape correction coefficient at the calculated Re number. A difference correction device, and (2)
In the above (1), the uncorrected flow velocity obtained by the ultrasonic flowmeter is V with the curved pipe upstream of the flow pipe as a double bend, and the calculated Re number is Re, and a, b, c ,
When d is a constant, the Reynolds number correction coefficient K 1 is
【００１４】[0014]
【数３】 [Equation 3]
【００１５】配管形状補正係数Ｋ2を Ｋ2＝ｃ＋ｄlog（Ｒｅ） とし、補正された流速Ｖ0を Ｖ0＝Ｖ／(Ｋ1・Ｋ2) から求めること、更には、（３）２重ベンドを有する上
流側の湾曲管に直管が接続された口径の等しい流管と、
前記直管の管壁に、流れ方向に所定間隔を隔てて配設さ
れた一対の超音波送受波器と、該超音波送受波器の一方
向から発射され対向する流管壁に反射された超音波が、
他方側に達する迄の流れの順方向と逆方向に伝播する伝
播時間差に基づいて流体の流速または流量を求める超音
波流量計において、求められた未補正の流速をＶ、演算
されたレイノルズ数をＲｅとし、ｅ，ｆ，ｇを定数とし
たとき、補正係数Ｋは、The pipe shape correction coefficient K 2 is set to K 2 = c + dlog (Re), and the corrected flow velocity V 0 is obtained from V 0 = V / (K 1 · K 2 ). Further, (3) double A flow tube of equal diameter, in which a straight tube is connected to an upstream curved tube having a bend,
A pair of ultrasonic wave transmitters / receivers arranged at predetermined intervals in the flow direction on the tube wall of the straight pipe, and emitted from one direction of the ultrasonic wave transmitter / receiver and reflected by the opposing flow tube walls. Ultrasonic waves
In an ultrasonic flowmeter that finds the flow velocity or flow rate of a fluid based on the propagation time difference of propagating in the forward direction and the reverse direction until reaching the other side, V is the calculated uncorrected flow rate and V is the calculated Reynolds number. When Re and e, f, and g are constants, the correction coefficient K is
【００１６】[0016]
【数４】 [Equation 4]
【００１７】とし、補正された流速Ｖ0を Ｖ0＝Ｖ／Ｋ から求めることを特徴としたものである。The corrected flow velocity V 0 is obtained from V 0 = V / K.
【００１８】[0018]
【作用】伝播速度差方式の超音波流量計において、超音
波流量計を配設する直管の上流に、少くとも一つの湾曲
管を有する湾曲配管がある場合、配管形状が定まれば、
流体の流速分布はＲｅ数に応じて一定に変化することに
着目して、流体流のＲｅ数を演算し、演算により求めら
れたＲｅ数により、Ｒｅ数の関数として与えられる充分
長い直管長で計測したとき行われる周知の流速補正を超
音波流量信号に施し、更にＲｅ数により変化する流管形
状による補正を施すことにより、長い直管や整流装置な
しでも高精度に流速又は流量を計測する。In the ultrasonic velocity meter of the propagation velocity difference type, when there is a curved pipe having at least one curved pipe upstream of the straight pipe in which the ultrasonic flow meter is arranged, if the pipe shape is determined,
Paying attention to the fact that the flow velocity distribution of the fluid changes constantly according to the Re number, the Re number of the fluid flow is calculated, and with the Re number obtained by the calculation, with a sufficiently long straight pipe length given as a function of the Re number. The well-known flow velocity correction that is performed at the time of measurement is applied to the ultrasonic flow rate signal, and the flow velocity shape that changes according to the Re number is also applied to measure the flow velocity or flow rate with high accuracy even without a long straight pipe or a rectifying device. .
【００１９】[0019]
実施例１（請求項１に対応） 図１は、本発明による超音波流量計の一実施例を説明す
るためのブロック図であり、図中、１は直管、２は湾曲
管、３,４は超音波送受波器、５は流速検出装置、６は
器差補正装置、７は出力装置である。Embodiment 1 (corresponding to claim 1) FIG. 1 is a block diagram for explaining an embodiment of an ultrasonic flowmeter according to the present invention, in which 1 is a straight pipe, 2 is a curved pipe, 3, Reference numeral 4 is an ultrasonic wave transmitter / receiver, 5 is a flow velocity detection device, 6 is a device difference correction device, and 7 is an output device.
【００２０】図１において、口径がＤの直管で矢印Ｖ方
向に流体が流れる直管１の上流側には、少くとも一つの
ベンド（図においては２重ベンド）２ａを有する湾曲管
２が接続されている。直管１の管壁には、矢印Ｖで示す
流れ方向に所定間隔を隔てて一対の超音波送受波器３,
４が配設されており、直管１と超音波送受波器３,４と
により超音波流量計が構成される。超音波送受波器３,
４は、同一のもので、一方が超音波の送波器となったと
き、他方が受波器となり、超音波送受波器３,４は、矢
印の実線と点線で示すように、流体流れの順方向と逆方
向に向けて交互に送波と受波とを繰り返す。このとき、
送波された超音波は、超音波送受波器３,４の中間位置
と対向する位置の管壁１ａで反射される。In FIG. 1, a curved pipe 2 having at least one bend (double bend in the drawing) 2a is provided on the upstream side of the straight pipe 1 having a diameter D and in which a fluid flows in the direction of arrow V. It is connected. On the tube wall of the straight tube 1, a pair of ultrasonic wave transmitters / receivers 3 are provided at predetermined intervals in the flow direction indicated by arrow V.
4 is provided, and the straight pipe 1 and the ultrasonic wave transmitters / receivers 3, 4 constitute an ultrasonic flowmeter. Ultrasonic transducer 3,
4 are the same, when one becomes an ultrasonic wave transmitter, the other becomes a wave receiver, and the ultrasonic wave transmitters / receivers 3 and 4 are fluid flow as shown by the solid and dotted arrows. The wave transmission and the wave reception are alternately repeated in the forward direction and the reverse direction. At this time,
The transmitted ultrasonic wave is reflected by the tube wall 1a at a position facing the intermediate position between the ultrasonic wave transmitters / receivers 3 and 4.
【００２１】超音波の送受波器３,４から管壁１ａで反
射されて送受波された超音波信号は、流速検出装置５に
入力され、周知の超音波の伝播速度差法に基づいて流速
が検出される。このときの流速信号は、超音波送受波器
３と管壁１ａと超音波送受波器４とを結ぶ直線間の平均
流速信号であり、流管１内を所定の流速分布をもって流
れる流体の平均流速をあらわすものではない。The ultrasonic signal reflected from the ultrasonic wave transmitters / receivers 3, 4 by the tube wall 1a and transmitted / received is input to the flow velocity detecting device 5 and the flow velocity is detected based on the well-known ultrasonic velocity difference method. Is detected. The flow velocity signal at this time is an average flow velocity signal between straight lines connecting the ultrasonic wave transmitter / receiver 3, the pipe wall 1a and the ultrasonic wave transmitter / receiver 4, and the average of the fluid flowing in the flow pipe 1 with a predetermined flow velocity distribution. It does not represent the flow velocity.
【００２２】直管１内の流体流れの中には、湾曲管２に
より生じた流体の２次流に基づく旋回流および偏流が含
まれており、超音波の伝播路となる流体の流れの中に
は、Ｒｅ数に従って変化する直管１の軸方向の流れの他
に、Ｒｅ数により変化する上記の旋回流と偏流が含まれ
ている。The fluid flow in the straight pipe 1 includes a swirling flow and a non-uniform flow based on the secondary flow of the fluid generated by the bending pipe 2, and the fluid flow becomes the propagation path of ultrasonic waves. In addition to the axial flow of the straight pipe 1 that changes according to the Re number, the swirling flow and the drift flow that change according to the Re number are included.
【００２３】器差補正装置６は、流速検出装置５により
検出された偏流や旋回流を含む流速信号に対して補正を
施し、平均流速をあらわす流速信号を出力する装置であ
り、補正された流速信号は、出力装置７に入力される。
出力装置７では、目的とするアナログやディジタル等の
流量信号に変換されて出力される。器差補正装置６の例
を、図２に示す。The instrumental error correction device 6 is a device that corrects the flow velocity signal including the drift and swirl flow detected by the flow velocity detection device 5 and outputs a flow velocity signal that represents the average flow velocity. The signal is input to the output device 7.
The output device 7 converts and outputs the target analog or digital flow rate signal. An example of the instrumental difference correction device 6 is shown in FIG.
【００２４】図２は、本発明による超音波流量計に係る
器差補正装置の一実施例を説明するためのブロック図で
あり、図中、８はレイノルズ数演算回路、９は定数入力
部、１０は補正式メモリ、１１は補正係数演算回路、１
２は器差補正回路である。FIG. 2 is a block diagram for explaining one embodiment of the instrumental difference correction apparatus for an ultrasonic flowmeter according to the present invention. In the figure, 8 is a Reynolds number arithmetic circuit, 9 is a constant input section, 10 is a correction type memory, 11 is a correction coefficient calculation circuit, 1
Reference numeral 2 is an instrument difference correction circuit.
【００２５】レイノルズ数演算回路８は、流体が超音波
流量計を流れているときのＲｅ数を演算する回路であ
る。この場合、Ｒｅ数は、代表長さと流速との積を動粘
度で除して得られる無次元数で、代表長さを流管径Ｄ、
流速Ｖを流速検出装置５により検出された偏流や旋回流
を含む誤差のある流速としたもので、動粘度νは流体の
粘性率ηを密度ρで割って得られる。The Reynolds number calculation circuit 8 is a circuit for calculating the Re number when the fluid is flowing through the ultrasonic flowmeter. In this case, the Re number is a dimensionless number obtained by dividing the product of the representative length and the flow velocity by the kinematic viscosity, and the representative length is the flow tube diameter D,
The flow velocity V is defined as a flow velocity with an error including a drift and a swirl detected by the flow velocity detecting device 5, and the kinematic viscosity ν is obtained by dividing the viscosity η of the fluid by the density ρ.
【００２６】例えば、流体が性状が既知の気体であれ
ば、レイノルズ数演算回路８に入力される密度および粘
度信号は、流体の温度信号および圧力信号を入力するこ
とにより算出され、これより動粘度νが演算され、更
に、前記口径Ｄと流速Ｖとにより、Ｒｅ数が演算され
る。流体が性状既知の液体の場合は、温度信号により動
粘度νおよびＲｅ数が演算され、演算されたＲｅ数は補
正係数演算回路１１に入力される。For example, if the fluid is a gas of known properties, the density and viscosity signals input to the Reynolds number calculation circuit 8 are calculated by inputting the temperature signal and pressure signal of the fluid, and the kinematic viscosity is calculated from this. ν is calculated, and further, the Re number is calculated from the diameter D and the flow velocity V. When the fluid is a liquid whose properties are known, the kinematic viscosity ν and the Re number are calculated by the temperature signal, and the calculated Re number is input to the correction coefficient calculation circuit 11.
【００２７】一方、器差補正回路１２は、流速検出装置
５により検出された流速信号Ｖに対して、補正係数Ｋを
乗算して補正演算を施し、正確な平均流速Ｖ0を得るた
めの回路である。補正係数Ｋは、補正式メモリ回路１０
にメモリされた実験式に基づいて得られたもので、Ｒｅ
数の関数で与えられる補正係数演算回路１１により演算
される。演算式に入力されるＲｅ数は、レイノルズ数演
算回路８より演算されたＲｅ数である。なお、演算式の
定数は、定数入力部９から入力され、補正式と共に補正
式メモリ回路１０にメモリされる。次に、以上の構成か
らなる超音波流量計の器差特性について説明する。On the other hand, the instrumental error correction circuit 12 performs a correction calculation by multiplying the flow velocity signal V detected by the flow velocity detection device 5 by a correction coefficient K to obtain an accurate average flow velocity V 0. Is. The correction coefficient K is the correction-type memory circuit 10
It was obtained based on the empirical formula stored in
It is calculated by the correction coefficient calculation circuit 11 given as a function of the number. The Re number input to the arithmetic expression is the Re number calculated by the Reynolds number calculation circuit 8. The constant of the arithmetic expression is input from the constant input unit 9 and stored in the correction expression memory circuit 10 together with the correction expression. Next, the instrumental difference characteristics of the ultrasonic flowmeter having the above configuration will be described.
【００２８】図３は、反射式の超音波流量計の器差のレ
イノルズ数特性の一例を示すもので、横軸にＲｅ数（対
数）、縦軸に器差をとった実験値である。図３の器差特
性Ａは、流体が空気で、直管径と圧力をパラメータとし
て測定されたものである。超音波流量計の直管長が４０
Ｄであり、充分長い直管のため、旋回流や偏流が取り除
かれ、正規の乱流流速分布となっている。器差特性Ａ
は、Ｒｅ数が１０5を境として小Ｒｅ数域ではプラスに
漸増し、大Ｒｅ数域では僅かにマイナスとなり、略一定
の器差特性となっている。FIG. 3 shows an example of the Reynolds number characteristic of the instrumental error of the reflection type ultrasonic flowmeter, which is an experimental value with the Re number (logarithm) on the horizontal axis and the instrumental error on the vertical axis. The instrumental error characteristic A in FIG. 3 is measured using the fluid as air and the straight pipe diameter and pressure as parameters. Straight pipe length of ultrasonic flowmeter is 40
Since the straight pipe is D, the swirling flow and the uneven flow are removed, and the regular turbulent flow velocity distribution is obtained. Instrumental error characteristic A
Shows that the Re number gradually increases to a positive value in the small Re number region and becomes a slight negative value in the large Re number region at a boundary of 10 5 , and has a substantially constant instrumental error characteristic.
【００２９】図３の器差・Ｒｅ数特性曲線によると、上
流に充分長い直管長があり、流管内の流体の流速が正規
の分布を示している場合は、反射式の超音波流量計にお
いても透過式の場合と同様に器差補正が可能であること
を示している。器差特性Ａに対して、Prandtl による器
差特性Ｂおよび Rothfus ＆ Monradによる器差特性Ｃを
示したが、これらは、透過法によるものである。反射式
の器差特性Ａは、器差特性Ｂ,Ｃの中間に位置してい
る。According to the instrumental difference / Re number characteristic curve of FIG. 3, when there is a sufficiently long straight pipe length upstream and the flow velocity of the fluid in the flow pipe shows a normal distribution, in the reflection type ultrasonic flowmeter. Also shows that instrumental error correction is possible as in the case of the transmission type. The instrumental difference characteristic B is represented by Prandtl and the instrumental characteristic difference C by Rothfus & Monrad is shown with respect to the instrumental difference characteristic A, but these are due to the transmission method. The reflection-type instrumental error characteristic A is located between the instrumental error characteristics B and C.
【００３０】図４は、上流側に湾曲管があるときの図３
の器差・Ｒｅ数特性曲線を基準として得られた偏差・Ｒ
ｅ数特性曲線である。図４によると、湾曲管から超音波
流量計までの直管長が定まれば、偏差と対数Ｒｅ数との
関係は、直線であらわされるから、図３で得られた器差
補正結果に対し、上流側の湾曲管の形状により定まる器
差補正を施すことが可能であることを示す。FIG. 4 is a diagram of FIG. 3 when there is a curved pipe on the upstream side.
Deviation / R obtained from the instrumental error / Re number characteristic curve
It is an e-number characteristic curve. According to FIG. 4, if the straight pipe length from the bending pipe to the ultrasonic flowmeter is determined, the relationship between the deviation and the logarithmic Re number is expressed by a straight line. Therefore, with respect to the instrumental error correction result obtained in FIG. It is shown that it is possible to perform instrumental error correction determined by the shape of the upstream bending tube.
【００３１】すなわち、実施例１によると、上流側に少
くとも一つの湾曲管がある場合でも、配管形状が定めら
れると、流体の流速分布はＲｅ数の関数として一義的に
定められることを示しており、配管形状による器差補正
が可能である。この結果、従来のように、長い直管や整
流装置により整流して流体の流れを正規流速分布に直し
てから、超音波流量計により流速又は流量を計測する必
要がなくなり、配管スペースが小さい場合でも、長い直
管や整流装置の不要な安価な超音波流量計とすることが
できる。That is, according to the first embodiment, even when there is at least one curved pipe on the upstream side, when the pipe shape is determined, the flow velocity distribution of the fluid is uniquely determined as a function of Re number. Therefore, the instrumental error can be corrected by the pipe shape. As a result, it is not necessary to measure the flow velocity or flow rate with an ultrasonic flow meter after rectifying the fluid flow to a regular flow velocity distribution by rectifying it with a long straight pipe or a rectifying device as in the conventional case, and when the piping space is small However, it is possible to provide an inexpensive ultrasonic flowmeter that does not require a long straight pipe or a rectifying device.
【００３２】実施例２（請求項２に対応） 図３，図４に示すように、超音波流量計の上流側に２重
ベンドの湾曲管がある場合は、図３に示した上流直管長
が充分長く、正規の流速分布となったときに超音波流量
計流速信号を平均流速信号に補正を施こすための標準レ
イノルズ数特性補正係数Ｋ1と、更に標準レイノルズ数
補正係数Ｋ1により補正された流速信号に対し、上流側
に湾曲管がある場合の配管形状補正係数Ｋ2による補正
を施すことにより、正確な平均流速Ｖ0が得られること
を示す。すなわち、 Ｖ0＝Ｖ／(Ｋ1・Ｋ2) （１） で示される。Embodiment 2 (corresponding to claim 2) As shown in FIGS. 3 and 4, when there is a double bend curved pipe on the upstream side of the ultrasonic flow meter, the upstream straight pipe length shown in FIG. When the flow velocity signal is sufficiently long and the flow velocity distribution becomes regular, the standard Reynolds number characteristic correction coefficient K 1 for correcting the ultrasonic flow meter flow velocity signal to the average flow velocity signal and the standard Reynolds number correction coefficient K 1 are used for correction. It is shown that an accurate average flow velocity V 0 can be obtained by correcting the obtained flow velocity signal by the pipe shape correction coefficient K 2 when there is a curved pipe on the upstream side. That is, V 0 = V / (K 1 · K 2 ) (1)
【００３３】このとき、標準レイノルズ数補正係数Ｋ1
は、At this time, the standard Reynolds number correction coefficient K 1
Is
【００３４】[0034]
【数５】 [Equation 5]
【００３５】配管形状補正係数Ｋ2は、 Ｋ2＝ｃ＋ｄ ｌog（Ｒｅ） （３） ここで、ｃ,ｄは、湾曲管形状と、超音波流量計と湾曲
管との間の直管長により定められる定数である。The pipe shape correction coefficient K 2 is K 2 = c + d log (Re) (3) where c and d are determined by the curved pipe shape and the straight pipe length between the ultrasonic flowmeter and the curved pipe. Is a constant.
【００３６】（１）式の標準レイノルズ数補正係数Ｋ1
および配管形状補正係数Ｋ2の式は、予め補正式メモリ
１０に記憶されており、レイノルズ数演回路８により演
算して得られたＲｅ数が補正係数演算回路１１に入力さ
れ、（２）,（３）式に基づいて標準レイノルズ数補正
係数Ｋ1，配管形状補正係数Ｋ2が演算され、器差補正回
路１２により（１）式に基づいて補正後の平均流速Ｖ0
が演算される。Standard Reynolds number correction coefficient K 1 in equation (1)
And the equation of the pipe shape correction coefficient K 2 is stored in advance in the correction expression memory 10, and the Re number obtained by the operation by the Reynolds number operation circuit 8 is input to the correction coefficient operation circuit 11, (2), The standard Reynolds number correction coefficient K 1 and the pipe shape correction coefficient K 2 are calculated based on the equation (3), and the mean error velocity V 0 after correction is performed by the instrumental error correction circuit 12 based on the equation (1).
Is calculated.
【００３７】実施例２によれば、実施例１を具体化した
もので、実施例１と同様に長い直管や整流装置を必要と
せず、超音波流量計を精度低下させることなしに、簡単
な配管により小さいスペースにでも配設することができ
る。According to the second embodiment, like the first embodiment, a long straight pipe and a rectifying device are not required as in the first embodiment, and the ultrasonic flowmeter can be easily manufactured without degrading the accuracy. It can be installed in a small space in a simple pipe.
【００３８】実施例３（請求項３に対応） 実施例１,２において説明した器差レイノルズ数補正
は、まず、超音波信号を正規分布に対する補正を施し、
これに対し、配管形状の補正を施すものであるが、流体
の流れは配管形状が定まればＲｅ数の関数として一義的
に定められるという原則によると、予め配管形状により
定められる一つの補正係数をもって器差補正が可能とな
る。Example 3 (corresponding to claim 3) In the instrumental Reynolds number correction described in Examples 1 and 2, first, an ultrasonic signal is corrected to a normal distribution,
On the other hand, although the pipe shape is corrected, according to the principle that the fluid flow is uniquely determined as a function of the Re number if the pipe shape is determined, one correction coefficient determined in advance by the pipe shape is used. With this, instrumental error correction becomes possible.
【００３９】図５は、本発明による超音波流量計の他の
実施例を説明するための器差・Ｒｅ数特性を示すもの
で、横軸にＲｅ数（対数）、縦軸に器差をとってあり、
超音波流量計の上流に直管部１０Ｄ，２５Ｄを隔てて平
面２重エルボの接続された配管での器差・Ｒｅ数特性を
示す。FIG. 5 shows instrumental difference / Re number characteristics for explaining another embodiment of the ultrasonic flowmeter according to the present invention. The abscissa axis represents the Re number (logarithm) and the ordinate axis represents the instrumental difference. There is
The instrumental difference and Re number characteristics in a pipe in which a flat double elbow is connected upstream of an ultrasonic flowmeter with straight pipe portions 10D and 25D being separated are shown.
【００４０】図５に示した器差・Ｒｅ数特性曲線によれ
ば、上流直管部が２５Ｄの器差・Ｒｅ数特性曲線Ｆと、
上流直管部が１０Ｄの器差・Ｒｅ数特性曲線とは、平行
に離間した曲線であり、図３，図４に示した器差・Ｒｅ
数特性曲線を合成した形になっている。According to the instrumental difference / Re number characteristic curve shown in FIG. 5, the instrumental difference / Re number characteristic curve F in which the upstream straight pipe section is 25D,
The instrumental difference / Re number characteristic curve where the upstream straight pipe section is 10D is a curve separated in parallel, and the instrumental error / Re number characteristic curve shown in FIGS.
It has a shape that combines several characteristic curves.
【００４１】従って、超音波流速信号Ｖに対する補正係
数は一つでよく、補正係数をＫとすると、 Ｖ0＝Ｖ／Ｋ （４） により補正された平均流速Ｖ0が得られる。このときの
補正係数Ｋは、図５に示した曲線から得られた実験式Therefore, the correction coefficient for the ultrasonic flow velocity signal V may be one, and when the correction coefficient is K, the average flow velocity V 0 corrected by V 0 = V / K (4) can be obtained. The correction coefficient K at this time is an empirical formula obtained from the curve shown in FIG.
【００４２】[0042]
【数６】 [Equation 6]
【００４３】により与えられる。（５）式でのｅ,ｆ,ｇ
は、配管形状や湾曲管と超音波流量計との間の直管の長
さにより定められる定数である。Is given by E, f, g in equation (5)
Is a constant determined by the shape of the pipe and the length of the straight pipe between the curved pipe and the ultrasonic flowmeter.
【００４４】補正係数Ｋを定める実験式（５）は、補正
式メモリ１０に記憶され、レイノルズ数演算回路８によ
り演算して得られたＲｅ数を補正係数演算回路１１に入
力して、補正係数Ｋを演算し、器差補正回路１２により
（４）式に基づいて補正された平均流速Ｖ0が演算され
る。The empirical expression (5) for determining the correction coefficient K is stored in the correction expression memory 10 and the Re number obtained by the operation by the Reynolds number operation circuit 8 is input to the correction coefficient operation circuit 11 to obtain the correction coefficient. K is calculated, and the average velocity V 0 corrected by the instrumental error correction circuit 12 is calculated based on the equation (4).
【００４５】実施例３によれば、一つの補正係数Ｋを演
算して求めるだけであるから、実施例１,２と同様の効
果が得られるとともに、実施例１,２の場合に比べて、
より簡単に補正された平均流速を得ることができる。According to the third embodiment, since only one correction coefficient K is calculated and obtained, the same effect as in the first and second embodiments can be obtained, and in comparison with the first and second embodiments,
The corrected average flow velocity can be obtained more easily.
【００４６】[0046]
【発明の効果】以上の説明から明らかなように、本発明
によれば、以下の効果が得られる。請求項１,２に対応
する効果：超音波流量計の上流に湾曲管がある場合の超
音波流量計の器差は、充分長い直管長がある場合の正規
流速分布をもつ流れに対して行う器差・Ｒｅ数に基づ
く、予め実験等により求められて記憶された補正式によ
る補正結果に対して、予め実験により求められた湾曲配
管だけによる器差・Ｒｅ数特性に基づく補正を施すこと
により、従来の上流に長い直管や整流装置が配設された
場合と同様の精度の流速信号が得られるので、長い直管
や整流装置が不要となり、安価で省スペースの流量計測
が可能となる。請求項３に対応する効果：請求項１,２
に対応する効果に加え、補正係数が一つであるから、請
求項１,２に対し演算が更に容易となる。As is apparent from the above description, according to the present invention, the following effects can be obtained. Effects corresponding to claims 1 and 2: The instrumental difference of the ultrasonic flowmeter when the curved pipe is provided upstream of the ultrasonic flowmeter is performed for the flow having the normal flow velocity distribution when the straight pipe length is sufficiently long. By performing the correction based on the instrumental difference / Re number characteristic only by the curved pipe previously obtained by the experiment, with respect to the correction result based on the instrumental error / Re number, which is previously obtained by the experiment and stored and is stored. Since a flow velocity signal with the same accuracy as in the case where a long straight pipe or a rectifying device is installed in the conventional upstream can be obtained, a long straight pipe or a rectifying device is not required, and an inexpensive and space-saving flow rate measurement is possible. . Effect corresponding to claim 3: Claims 1 and 2
In addition to the effect corresponding to the above, since there is only one correction coefficient, the calculation becomes easier with respect to claims 1 and 2.
【図１】 本発明による超音波流量計の一実施例を説明
するためのブロック図である。FIG. 1 is a block diagram for explaining an embodiment of an ultrasonic flowmeter according to the present invention.
【図２】 本発明による超音波流量計に係る器差補正装
置の一実施例を説明するためのブロック図である。FIG. 2 is a block diagram for explaining an embodiment of an instrumental difference correction device for an ultrasonic flowmeter according to the present invention.
【図３】 反射式の超音波流量計の器差のレイノルズ数
特性の一例を示す図である。FIG. 3 is a diagram showing an example of Reynolds number characteristics of instrumental difference of a reflection type ultrasonic flowmeter.
【図４】 上流側に湾曲管があるときの図３の器差・Ｒ
ｅ数特性曲線を基準として得られた偏差・Ｒｅ数特性曲
線である。[Fig. 4] Instrumental difference / R of Fig. 3 when there is a curved pipe on the upstream side
9 is a deviation / Re number characteristic curve obtained based on the e number characteristic curve.
【図５】 本発明による超音波流量計の他の実施例を説
明するための器差・Ｒｅ数特性を示す図である。FIG. 5 is a diagram showing instrumental difference / Re number characteristics for explaining another embodiment of the ultrasonic flowmeter according to the present invention.
１…直管、２…湾曲管、３,４…超音波送受波器、５…
流速検出装置、６…器差補正装置、７…出力装置、８…
レイノルズ数演算回路、９…定数入力部、１０…補正式
メモリ、１１…補正係数演算回路、１２…器差補正回
路。1 ... Straight tube, 2 ... Curved tube, 3, 4 ... Ultrasonic wave transmitter / receiver, 5 ...
Flow velocity detection device, 6 ... Instrumental error correction device, 7 ... Output device, 8 ...
Reynolds number calculation circuit, 9 ... Constant input section, 10 ... Correction formula memory, 11 ... Correction coefficient calculation circuit, 12 ... Instrument difference correction circuit.
Claims (3)
湾曲管に直管を接続した同一口径の流管と、前記直管の
管壁に流れ方向に所定間隔を隔てて配設された一対の超
音波送受波器と、該超音波送受波器の一方向から発射さ
れ対向する流管壁に反射された超音波が他方側に達する
迄の流れの順方向と逆方向に伝播する伝播時間の時間差
に基づいて流体の流速または流量を求める超音波流量計
において、該超音波流量計により求められた流速と、流
管の口径と、流体の密度および粘度とに基づいてレイノ
ルズ数（Ｒｅ数）を演算するレイノルズ数演算手段と、
正規の流速分布で流れる流体の中を超音波が伝播する伝
播時間から求めた流速を平均流速に補正するためのレイ
ノルズ数補正係数を求める標準レイノルズ数特性補正手
段と、前記湾曲管のあるときの超音波の伝播時間差から
得られた流速を、湾曲管のない場合の流速に補正するた
めの流管形状補正係数を求める流管形状補正手段と、前
記超音波流量計により求められた流速に対し、演算され
た前記Ｒｅ数における前記レイノルズ数補正係数と流管
形状補正係数とを乗算し、正規の流速または流量を求め
る器差補正装置とからなることを特徴とする超音波流量
計。1. A flow pipe of the same diameter, in which a straight pipe is connected to an upstream curved pipe having at least one bend, and a pair of pipe pipes which are arranged on the pipe wall of the straight pipe at a predetermined interval in the flow direction. Of the ultrasonic wave transmitter / receiver and the propagation time of the ultrasonic wave emitted from one direction of the ultrasonic wave transmitter / receiver that propagates in the forward direction and the reverse direction of the flow until the ultrasonic wave reflected by the opposite flow tube wall reaches the other side In an ultrasonic flowmeter that determines the flow velocity or flow rate of a fluid based on the time difference of, the Reynolds number (Re number) based on the flow velocity obtained by the ultrasonic flowmeter, the diameter of the flow tube, and the density and viscosity of the fluid. ) To calculate the Reynolds number,
A standard Reynolds number characteristic correction means for obtaining a Reynolds number correction coefficient for correcting the flow velocity obtained from the propagation time of ultrasonic waves propagating in a fluid flowing in a regular flow velocity distribution to an average flow velocity; The flow velocity obtained from the difference in the propagation time of ultrasonic waves, the flow pipe shape correction means for obtaining the flow pipe shape correction coefficient for correcting the flow velocity in the case where there is no curved pipe, and the flow velocity obtained by the ultrasonic flowmeter. An ultrasonic flow meter, comprising: an instrumental difference correction device that multiplies the Reynolds number correction coefficient and the flow tube shape correction coefficient for the calculated Re number to obtain a normal flow velocity or flow rate.
として前記超音波流量計により求められた未補正の流速
をＶ、演算されたＲｅ数をＲｅとし、ａ,ｂ,ｃ,ｄを定
数としたとき、レイノルズ数補正係数Ｋ1を 【０００１】 【数１】 【０００２】配管形状補正係数Ｋ2を Ｋ2＝ｃ＋ｄlog（Ｒｅ） とし、補正された流速Ｖ0を Ｖ0＝Ｖ／(Ｋ1・Ｋ２） から求めることを特徴とする請求項１記載の超音波流量
計。2. An uncorrected flow velocity obtained by the ultrasonic flowmeter is V, and a calculated Re number is Re, where a, b, c, a When d is a constant, the Reynolds number correction coefficient K 1 is given by The pipe shape correction coefficient K 2 is K 2 = c + dlog (Re), and the corrected flow velocity V 0 is obtained from V 0 = V / (K 1 · K 2 ). Ultrasonic flow meter.
管が接続された口径の等しい流管と、前記直管の管壁
に、流れ方向に所定間隔を隔てて配設された一対の超音
波送受波器と、該超音波送受波器の一方向から発射され
対向する流管壁に反射された超音波が、他方側に達する
迄の流れの順方向と逆方向に伝播する伝播時間差に基づ
いて流体の流速または流量を求める超音波流量計におい
て、求められた未補正の流速をＶ、演算されたレイノル
ズ数をＲｅとし、ｅ，ｆ，ｇを定数としたとき、補正係
数Ｋは、 【０００３】 【数２】 【０００４】とし、補正された流速Ｖ０を Ｖ0＝Ｖ／Ｋ から求めることを特徴とする超音波流量計。3. A flow pipe having a straight pipe connected to a curved pipe on the upstream side having a double bend and having an equal diameter, and a pair of pipe pipes arranged on the pipe wall of the straight pipe at a predetermined interval in the flow direction. Of the ultrasonic wave transmitter / receiver and the ultrasonic wave emitted from one direction of the ultrasonic wave transmitter / receiver and reflected by the opposing flow tube wall propagates in the forward direction and the reverse direction of the flow until reaching the other side. In an ultrasonic flowmeter that determines the flow velocity or flow rate of a fluid based on a time difference, when the obtained uncorrected flow velocity is V, the calculated Reynolds number is Re, and e, f, and g are constants, a correction coefficient K Is the following: An ultrasonic flow meter characterized in that the corrected flow velocity V 0 is obtained from V 0 = V / K.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP06053721A JP3103264B2 (en) | 1994-03-24 | 1994-03-24 | Ultrasonic flow meter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP06053721A JP3103264B2 (en) | 1994-03-24 | 1994-03-24 | Ultrasonic flow meter |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH07260532A true JPH07260532A (en) | 1995-10-13 |
| JP3103264B2 JP3103264B2 (en) | 2000-10-30 |
Family
ID=12950701
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP06053721A Expired - Fee Related JP3103264B2 (en) | 1994-03-24 | 1994-03-24 | Ultrasonic flow meter |
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| Country | Link |
|---|---|
| JP (1) | JP3103264B2 (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007051913A (en) * | 2005-08-17 | 2007-03-01 | Tokyo Keiso Co Ltd | Correction method for ultrasonic flowmeter |
| JP2008216034A (en) * | 2007-03-05 | 2008-09-18 | Takasago Thermal Eng Co Ltd | Method and tool for measuring flow rate |
| CN102809740A (en) * | 2012-07-17 | 2012-12-05 | 暨南大学 | Error correction device and error correction method for installation of electric energy meter |
| KR20160029656A (en) | 2014-09-05 | 2016-03-15 | 아즈빌주식회사 | Ultrasonic flowmeter and method for measuring flow rate |
| EP4273512A1 (en) * | 2022-05-04 | 2023-11-08 | Levitronix GmbH | Ultrasonic measuring system and measuring tube for such a system |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP6454600B2 (en) * | 2015-05-14 | 2019-01-16 | 株式会社キーエンス | Ultrasonic flow switch |
-
1994
- 1994-03-24 JP JP06053721A patent/JP3103264B2/en not_active Expired - Fee Related
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007051913A (en) * | 2005-08-17 | 2007-03-01 | Tokyo Keiso Co Ltd | Correction method for ultrasonic flowmeter |
| JP2008216034A (en) * | 2007-03-05 | 2008-09-18 | Takasago Thermal Eng Co Ltd | Method and tool for measuring flow rate |
| CN102809740A (en) * | 2012-07-17 | 2012-12-05 | 暨南大学 | Error correction device and error correction method for installation of electric energy meter |
| KR20160029656A (en) | 2014-09-05 | 2016-03-15 | 아즈빌주식회사 | Ultrasonic flowmeter and method for measuring flow rate |
| US9816847B2 (en) | 2014-09-05 | 2017-11-14 | Azbil Corporation | Ultrasonic flowmeter and method for measuring flow |
| EP4273512A1 (en) * | 2022-05-04 | 2023-11-08 | Levitronix GmbH | Ultrasonic measuring system and measuring tube for such a system |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3103264B2 (en) | 2000-10-30 |
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