JP5336640B1 - Thermal flow meter - Google Patents

Thermal flow meter Download PDF

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JP5336640B1
JP5336640B1 JP2012203765A JP2012203765A JP5336640B1 JP 5336640 B1 JP5336640 B1 JP 5336640B1 JP 2012203765 A JP2012203765 A JP 2012203765A JP 2012203765 A JP2012203765 A JP 2012203765A JP 5336640 B1 JP5336640 B1 JP 5336640B1
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flow
flow rate
temperature sensing
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pipe
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JP2014059191A (en
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祐二 高橋
光楠 金
玉▲カン▼ 段
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Tokyo Keiso Co Ltd
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Abstract

【課題】直管長が十分に確保できずに、管路内の流れ場が安定しないような設置個所においても、計測誤差の少ない流量値を得ることができる。
【解決手段】1個の発熱感温部M0がセンサユニットの内周面の中心部に位置する。また、センサユニットの管路13の中心部と管路13の壁面の間に等角度θで5個の第1の素子の発熱感温部M51〜55が配置されている。管路の中心部に配設した発熱感温部M0の測定値のマイナスの誤差と、管路13の中心部から0.7Rの円上に配設した複数の発熱感温部M51〜55の測定値の合計によるプラスとなる誤差を相殺させることで誤差の少ない測定値を得ることができる。
【選択図】図2
A flow rate value with a small measurement error can be obtained even in an installation location where a sufficient length of a straight pipe cannot be secured and a flow field in a pipeline is not stable.
One heat generation and temperature sensing part M0 is located at the center of the inner peripheral surface of the sensor unit. Further, between the central part of the pipe line 13 of the sensor unit and the wall surface of the pipe line 13, five heat generating temperature sensing parts M <b> 51 to 55 of the first element are arranged at an equal angle θ. A negative error in the measured value of the heat generation and temperature sensing unit M0 disposed at the center of the pipe line and a plurality of heat generation and temperature sensing parts M51 to 55 disposed on a circle of 0.7R from the center of the line 13 By canceling out the positive error due to the sum of the measurement values, it is possible to obtain a measurement value with a small error.
[Selection] Figure 2

Description

本発明は、複数の流速検知素子を流管路内に配置した熱式流量計に関するものである。   The present invention relates to a thermal flow meter in which a plurality of flow velocity detection elements are arranged in a flow line.

特許文献1には、図25に示すように流路管1内に4個の流速センサ2を配置した円筒形状のセンサユニット3を設置し、このセンサユニット3を通過する流体により持ち去られる熱量を測定して、流量を測定する熱式流量計が記載されている。このように複数の流速センサ2を用いることで、流速の平均値を算出し、正確な流量を求めることができる。   In Patent Document 1, as shown in FIG. 25, a cylindrical sensor unit 3 in which four flow rate sensors 2 are arranged in a flow pipe 1 is installed, and the amount of heat carried away by the fluid passing through the sensor unit 3 is measured. A thermal flow meter that measures and measures the flow rate is described. By using a plurality of flow velocity sensors 2 in this way, an average value of the flow velocity can be calculated and an accurate flow rate can be obtained.

特許文献2には、図26に示すように流路管1内の中央部に1個の流速センサ2を配設し、この流速センサ2によって得られた流路中央部の流速を流量演算部において流量に演算する熱式流量計が記載されている。   In Patent Document 2, as shown in FIG. 26, one flow rate sensor 2 is disposed at the center portion in the flow channel tube 1, and the flow rate at the center portion of the flow channel obtained by the flow rate sensor 2 is calculated as a flow rate calculation unit. Describes a thermal flow meter that calculates the flow rate.

特許文献3には、流路管1内の断面円形上に4個の流速センサ2を配置した熱式流量計が記載されている。複数の流速センサ2を配置することで、各流速センサ2の出力を相互に比較することにより、特性が劣化した流速センサ2を容易に特定することができる。   Patent Document 3 describes a thermal flow meter in which four flow velocity sensors 2 are arranged on a circular cross section in a flow channel tube 1. By arranging a plurality of flow rate sensors 2, by comparing the outputs of the respective flow rate sensors 2 with each other, it is possible to easily identify the flow rate sensor 2 having deteriorated characteristics.

特開平8−5426号公報JP-A-8-5426 特開平9−68448号公報Japanese Patent Laid-Open No. 9-68448 特開2007−192775号公報JP 2007-192775 A

安定して流速を計測するためには、流体の速度分布が安定した状態が必要であり、そのためには熱式流量計の設置個所の少なくとも上流に十分な直管長が不可欠である。しかし、設置環境によっては直管長が十分に確保できない場所に設置せざるを得ない場合がある。   In order to stably measure the flow velocity, a state in which the fluid velocity distribution is stable is necessary, and for that purpose, a sufficient straight pipe length is indispensable at least upstream of the installation location of the thermal flow meter. However, depending on the installation environment, it may be unavoidable to install in a place where the length of the straight pipe cannot be secured sufficiently.

このような環境では、流体の速度分布は管路内の中心軸から非対称となり、不均一な流れ場を形成するので、特許文献1〜3に記載された熱式流量計を設置したとしても、流れ場が乱れているため計測した流量値に大きな誤差が生じ、真値が得られないという問題がある。   In such an environment, the velocity distribution of the fluid becomes asymmetric from the central axis in the pipe and forms a non-uniform flow field. Therefore, even if the thermal flow meter described in Patent Documents 1 to 3 is installed, Since the flow field is disturbed, there is a problem that a large error occurs in the measured flow rate value and a true value cannot be obtained.

本発明の目的は、上述の課題を解決し、流体管路中の所定位置に複数個の流速検知素子を配置し、これらの出力を基に流量を求める熱式流量計を提供することにある。   An object of the present invention is to provide a thermal type flow meter that solves the above-described problems and that has a plurality of flow rate detection elements arranged at predetermined positions in a fluid pipe and obtains a flow rate based on these outputs. .

上記課題点を解決するための本発明に係る熱式流量計は、管路内において複数個の流速検知素子を有する熱式流量計であって、前記管路の断面上に、1個の流速検知素子を前記管路の中心部に配置し、他の複数個の流速検知素子を前記中心部と前記管路の管壁との間に等角度に配置し、これらの流速検知素子による測定値の平均を求めて測定値とすることを特徴とする。   A thermal flow meter according to the present invention for solving the above-mentioned problems is a thermal flow meter having a plurality of flow rate detection elements in a pipe, and one flow rate is provided on a cross section of the pipe. A detection element is arranged at the center of the pipe line, and a plurality of other flow velocity detection elements are arranged at an equal angle between the center part and the pipe wall of the pipe line. The average is obtained as a measured value.

本願発明の熱式流量計を用いることで、直管長が十分に確保できずに、管路内の流れ場が安定しないような設置個所においても、計測誤差の少ない流量値を得ることができる。   By using the thermal flow meter of the present invention, it is possible to obtain a flow rate value with a small measurement error even at an installation location where the straight pipe length cannot be sufficiently secured and the flow field in the pipe is not stable.

本実施例の熱式流量計の構成図である。It is a block diagram of the thermal type flow meter of a present Example. 中心部に1個、0.7Rの円上に5個の発熱感温部を配置した配置図である。It is the layout which has arrange | positioned one heat_generation | fever temperature sensing part on the circle of 0.7R at the center part. 流路管内の流体の速度分布の説明図である。It is explanatory drawing of the velocity distribution of the fluid in a flow-path pipe. 中心部に1個、0.7Rの円上に3個の発熱感温部を配置した配置図である。It is the layout which has arrange | positioned one heat_generation | fever temperature sensing part on the circle of 0.7R at the center part. 中心部に1個、0.7Rの円上に4個の発熱感温部を配置した配置図である。It is the layout which has arrange | positioned one heat generating temperature sensing part on the circle of 0.7R at the center part. 中心部に1個、0.7Rの円上に6個の発熱感温部を配置した配置図である。It is the layout which has arrange | positioned one heat_generation | fever temperature sensing part on the circle of 0.7R at the center part. 中心部に1個、0.7Rの円上に3個の発熱感温部を配置し、流量10%のときの直管長及び計測値と流速値との誤差を示すグラフ図である。FIG. 6 is a graph showing the straight pipe length and the error between the measured value and the flow velocity value when one exothermic temperature sensing portion is arranged in the center and three on the 0.7R circle and the flow rate is 10%. 中心部に1個、0.7Rの円上に4個の発熱感温部を配置し、流量10%のときの直管長及び計測値と流速値との誤差を示すグラフ図である。FIG. 5 is a graph showing a straight pipe length and an error between a measured value and a flow velocity value when one exothermic temperature sensing unit is arranged in a central part and four exothermic temperature sensing parts are arranged on a 0.7R circle and the flow rate is 10%. 中心部に1個、0.7Rの円上に5個の発熱感温部を配置し、流量10%のときの直管長及び計測値と流速値との誤差を示すグラフ図である。FIG. 5 is a graph showing the straight pipe length and the error between the measured value and the flow velocity value when one exothermic temperature sensing part is arranged at the center and five exothermic temperature sensing parts are arranged on a 0.7R circle and the flow rate is 10%. 中心部に1個、0.7Rの円上に6個の発熱感温部を配置し、流量10%のときの直管長及び計測値と流速値との誤差を示すグラフ図である。FIG. 5 is a graph showing the straight pipe length and the error between the measured value and the flow velocity value when one exothermic temperature sensing part is arranged on the center part and six exothermic temperature sensing parts are arranged on a 0.7R circle and the flow rate is 10%. 中心部に1個、0.7Rの円上に3個の発熱感温部を配置し、流量50%のときの直管長及び計測値と流速値との誤差を示すグラフ図である。FIG. 5 is a graph showing a straight pipe length and an error between a measured value and a flow velocity value when one exothermic temperature sensing portion is arranged in the center and three on a 0.7R circle and the flow rate is 50%. 中心部に1個、0.7Rの円上に4個の発熱感温部を配置し、流量50%のときの直管長及び計測値と流速値との誤差を示すグラフ図である。FIG. 5 is a graph showing the straight pipe length and the error between the measured value and the flow velocity value when one exothermic temperature sensing part is arranged on the center part and four exothermic temperature sensing parts are arranged on a 0.7R circle and the flow rate is 50%. 中心部に1個、0.7Rの円上に5個の発熱感温部を配置し、流量50%のときの直管長及び計測値と流速値との誤差を示すグラフ図である。FIG. 5 is a graph showing a straight pipe length and an error between a measured value and a flow velocity value when one exothermic temperature sensing portion is arranged in a center portion and five on a 0.7R circle and the flow rate is 50%. 中心部に1個、0.7Rの円上に6個の発熱感温部を配置し、流量50%のときの直管長及び計測値と流速値との誤差を示すグラフ図である。FIG. 6 is a graph showing the straight pipe length and the error between the measured value and the flow velocity value when one exothermic temperature sensing portion is arranged at the center and six exothermic temperature sensing portions are arranged on a 0.7R circle and the flow rate is 50%. 中心部に1個、0.7Rの円上に3個の発熱感温部を配置し、流量100%のときの直管長及び計測値と流速値との誤差を示すグラフ図である。FIG. 6 is a graph showing the straight pipe length and the error between the measured value and the flow velocity value when one exothermic temperature sensing portion is arranged in the center and three on a 0.7R circle and the flow rate is 100%. 中心部に1個、0.7Rの円上に4個の発熱感温部を配置し、流量100%のときの直管長及び計測値と流速値との誤差を示すグラフ図である。FIG. 6 is a graph showing the straight pipe length and the error between the measured value and the flow velocity value when one exothermic temperature sensing part is arranged on the center part and four exothermic temperature sensing parts are arranged on a 0.7R circle and the flow rate is 100%. 中心部に1個、0.7Rの円上に5個の発熱感温部を配置し、流量100%のときの直管長及び計測値と流速値との誤差を示すグラフ図である。FIG. 5 is a graph showing a straight pipe length and an error between a measured value and a flow velocity value when one exothermic temperature sensing portion is arranged in a central portion and five exothermic temperature sensing portions are arranged on a 0.7R circle and the flow rate is 100%. 中心部に1個、0.7Rの円上に6個の発熱感温部を配置し、流量100%のときの直管長及び計測値と流速値との誤差を示すグラフ図である。FIG. 6 is a graph showing the straight pipe length and the error between the measured value and the flow velocity value when one exothermic temperature sensing part is arranged on the center part and six exothermic temperature sensing parts are arranged on a 0.7R circle and the flow rate is 100%. 発熱感温部M0、Mnの誤差の平均値を流量10%で纏めたグラフ図である。It is the graph which put together the average value of the error of exothermic temperature sensing part M0 and Mn at a flow rate of 10%. 発熱感温部M0、Mnの誤差の平均値を流量50%で纏めたグラフ図である。It is the graph which put together the average value of the error of exothermic temperature sensing part M0 and Mn at a flow rate of 50%. 発熱感温部M0、Mnの誤差の平均値を流量100%で纏めたグラフ図である。It is the graph which put together the average value of the error of exothermic temperature sensing part M0 and Mn at a flow rate of 100%. 中心部に1個、0.3R、0.5R、0.7Rの円上に5個の発熱感温部を配置し、流量10%で纏めたグラフ図である。It is the graph which put together 5 exothermic temperature sensitive parts on the circle of 0.3R, 0.5R, and 0.7R at the center, and put it together by flow rate 10%. 中心部に1個、0.3R、0.5R、0.7Rの円上に5個の発熱感温部を配置し、流量50%で纏めたグラフ図である。It is the graph which put together 5 exothermic temperature sensing parts on the circle of 0.3R, 0.5R, and 0.7R at the center, and put it together by flow rate 50%. 中心部に1個、0.3R、0.5R、0.7Rの円上に5個の発熱感温部を配置し、流量100%で纏めたグラフ図である。FIG. 5 is a graph in which five heat-generating temperature sensing portions are arranged on a circle of 0.3R, 0.5R, and 0.7R at the center and are summarized at a flow rate of 100%. 従来例の流路管内に4個の流速センサを配置した構成図である。It is a block diagram which has arrange | positioned four flow velocity sensors in the flow-path pipe | tube of a prior art example. 従来例の流路管中心に1個の流速センサを配置した構成図である。It is the block diagram which has arrange | positioned one flow velocity sensor in the flow-path pipe center of a prior art example.

本発明を図1〜図24に図示の実施例に基づいて詳細に説明する。
図1は例えば実施例の気体流量測定用の熱式流量計の流体が流れる方向に沿った断面図である。流体は右から左の矢印方向に流れるようにされ、流路管11の途中に円筒状のセンサユニット12が挿入されており、センサユニット12の管路13の内径は、流路管11の内径と同径とされている。
The present invention will be described in detail based on the embodiment shown in FIGS.
FIG. 1 is a cross-sectional view along the direction in which a fluid flows, for example, in a thermal flow meter for gas flow measurement of an embodiment. The fluid flows in the direction of the arrow from right to left, and a cylindrical sensor unit 12 is inserted in the middle of the flow path tube 11. The inner diameter of the pipe line 13 of the sensor unit 12 is the inner diameter of the flow path pipe 11. And the same diameter.

センサユニット12は、気体の流れに対して上流側に加熱を行うと共に温度を計測する発熱感温部Mを先端に備えた第1の素子と、下流側に温度を計測する感温部mを先端に備えた第2の素子の一対から成る流速検知素子を複数組有している。第1の素子の発熱感温部M、第2の素子の感温部mは管路13の中心部に向けて突出するように挿入されている。第1、第2の素子の挿入個所は図1に示すように同じ深さとされ、上流側に第1の素子を設置するが、上流側に第2の素子を配置し、下流側に第1の素子を配置するようにしてもよい。この場合、上流側の素子による流れの影響を受けないようにするために挿入個所に段差等を設けてもよい。   The sensor unit 12 includes a first element having a heat generation temperature sensing part M at the tip for heating the gas flow upstream and measuring the temperature, and a temperature sensing part m for measuring the temperature downstream. A plurality of flow velocity detection elements each including a pair of second elements provided at the tip are provided. The exothermic temperature sensing part M of the first element and the temperature sensing part m of the second element are inserted so as to protrude toward the center of the conduit 13. The first and second elements are inserted at the same depth as shown in FIG. 1, and the first element is installed on the upstream side, but the second element is arranged on the upstream side and the first element on the downstream side. These elements may be arranged. In this case, a step or the like may be provided at the insertion location so as not to be affected by the flow of the upstream element.

個々の流速検知素子は上流側及び下流側に配設された一対の感温部m、発熱感温部Mによって検出される温度差を加熱により一定に保つために必要な電流を発熱感温部Mに流し、この電流量を基に流体の流速値を測定する。この測定値である流速値に管路13の断面積を乗じて流量を求めることができる。   Each flow rate detecting element is a pair of temperature sensing units m arranged on the upstream side and downstream side, and a current necessary for maintaining the temperature difference detected by the heating temperature sensing unit M constant by heating is a heating temperature sensing unit. The flow rate value of the fluid is measured based on this amount of current. The flow rate can be obtained by multiplying the measured flow velocity value by the cross-sectional area of the pipe 13.

図2は流体が流れる方向に対し直交する方向、つまり管路13の断面方向の発熱感温部Mから成る第1の素子の配置図であり、1個の発熱感温部M0がセンサユニット12の内周面の中心部に位置している。また、管路13の中心部と管路13の壁面の間に等角度θで5個の第1の素子の発熱感温部M51〜55が配置されている。本実施例においては、このような複数の流量検出素子により得られた測定値を組み合わせて精度の良い流量値を求めることができる。   FIG. 2 is a layout diagram of the first element composed of the heat generation and temperature sensing portion M in the direction orthogonal to the direction in which the fluid flows, that is, in the cross-sectional direction of the pipe line 13. It is located in the center of the inner peripheral surface of. Further, between the central part of the pipe line 13 and the wall surface of the pipe line 13, five heat generating temperature sensing parts M 51 to 55 of the first element are arranged at an equal angle θ. In the present embodiment, it is possible to obtain a highly accurate flow rate value by combining the measurement values obtained by such a plurality of flow rate detection elements.

図3は流路管11内の流体の速度分布の説明図である。線aはレイノルズ数が約3000とした乱流を示す速度分布であり、時間当りの流量が多い、つまり流路管11の流速が速いときの速度分布である。   FIG. 3 is an explanatory diagram of the velocity distribution of the fluid in the flow channel tube 11. Line a is a velocity distribution showing turbulent flow with a Reynolds number of about 3000, and is a velocity distribution when the flow rate per time is large, that is, when the flow velocity of the flow path tube 11 is high.

線bはレイノルズ数が約2000とした層流を示す速度分布であり、時間当りの流量が少ない、つまり流路管11の流速が遅いときの速度分布である。層流時には、流路管11の中心軸が最も流速が速く、流路管11の壁面に近付くにつれて流速が遅くなる。流路管11内に流れる時間当りの流速が速くなるに応じて、線bの層流の速度分布から線aの乱流の速度分布に変化する。   A line b is a velocity distribution showing a laminar flow with a Reynolds number of about 2000, and is a velocity distribution when the flow rate per time is small, that is, when the flow velocity of the flow path tube 11 is low. During laminar flow, the central axis of the channel tube 11 has the fastest flow rate, and the flow rate becomes slower as it approaches the wall surface of the channel tube 11. As the flow velocity per hour flowing in the flow channel pipe 11 increases, the velocity distribution of the laminar flow of the line b changes to the velocity distribution of the turbulent flow of the line a.

流路管11内では流体が一律に同じ流量で流れるのではなく、時間と共に変化する流量を測定している。そして、時間当りの流量の変化に対し、最も影響を受けない個所は、線aと線bの交点Pである。   In the channel tube 11, the fluid does not flow uniformly at the same flow rate, but the flow rate that changes with time is measured. Then, the point that is least affected by the change in the flow rate per time is the intersection P of the line a and the line b.

線aのような平均的な乱流の速度分布と線bのような平均的な層流の速度分布の交点Pは、流路管11の中心部から半径Rの約0.7倍の位置となることが分かっている。この0.7Rの円上に発熱感温部M51〜M55を配置し、これらの平均から流速を測定すると流路管11内が層流の流れ場から乱流の流れ場、乱流の流れ場から層流の流れ場へと変化していても、変化の影響の少ない測定値を算出することができる。   The intersection P between the average turbulent velocity distribution such as the line a and the average laminar velocity distribution such as the line b is a position about 0.7 times the radius R from the center of the flow channel 11. I know that When the heat generation and temperature sensing parts M51 to M55 are arranged on the circle of 0.7R and the flow velocity is measured from the average of these, the flow path 11 is changed from a laminar flow field to a turbulent flow field or a turbulent flow field. Even if the flow field changes from laminar to laminar flow field, it is possible to calculate a measurement value that is less affected by the change.

線cは直管長が十分に確保できない場所での推定される層流の速度分布であり、偏流となっている。管路が曲がりの直後の直管長の短い個所では、偏流が発生し易く、線bのような層流の中心対称となる速度分布が曲がりの方向等の影響により、線cのような中心から多少偏った速度分布の偏流となると推定される。この偏流により層流の速度分布の頂点がずれ、中心部の発熱感温部M0の測定値はマイナスの誤差が発生する。   Line c is an estimated laminar velocity distribution in a place where the length of the straight pipe cannot be sufficiently secured, and is uneven. In a portion where the straight pipe length is short immediately after the pipe is bent, a drift is likely to occur, and the velocity distribution that is symmetric with respect to the center of the laminar flow such as the line b is influenced from the center such as the line c due to the influence of the bending direction or the like. It is presumed that the drift of the velocity distribution is somewhat biased. Due to this drift, the top of the laminar flow velocity distribution shifts, and a negative error occurs in the measured value of the heat generation and temperature sensing part M0 at the center.

流路管11内の流体の速度分布が層流時において頂点がずれた場合に、通常の例えば中心部のみにセンサを配置した熱式流量計での測定値と実流速値の誤差は大きくなる。これに対し、流路管11内の流体の速度分布が乱流時においては、速度分布は中心が移動して非対称になったとしても、速度分布の変化は層流に比べ少ないので、流速計測における誤差は少ない。   When the velocity distribution of the fluid in the flow path pipe 11 is shifted at the time of laminar flow, the error between the measured value and the actual flow velocity value with a thermal flow meter in which a sensor is arranged only at the center, for example, becomes large. . On the other hand, when the velocity distribution of the fluid in the flow channel tube 11 is turbulent, the velocity distribution changes less than the laminar flow even if the center moves and becomes asymmetrical. There is little error in.

従って、流路管11内が速度分布が線cのような偏流、層流又は乱流の何れの流れ場であっても誤差の少ない測定値を得るために、本実施例では管路13の中心部に発熱感温部M0を配置し、この発熱感温部M0によって生ずるマイナスの誤差を補償するために、その周囲に複数の発熱感温部Mnを中心部から0.7Rの円上に等角度で配置する。   Therefore, in this embodiment, in order to obtain a measurement value with a small error regardless of whether the flow distribution in the flow pipe 11 is a drift flow, laminar flow or turbulent flow field as indicated by the line c, In order to compensate for a negative error caused by the heat generation and temperature sensing portion M0, a plurality of heat generation and temperature sensing portions Mn are arranged on a circle of 0.7R from the center. Arrange at equal angles.

この効果を実証するためにスーパーコンピュータによりRNGk−ε方程式による層流、乱流の物理モデルを採用したCFDシミュレータを用いてシミュレーションを行った。   In order to demonstrate this effect, simulation was performed using a CFD simulator employing a physical model of laminar flow and turbulent flow based on the RNGk-ε equation by a supercomputer.

即ち、中心部から0.7Rの円上に、等角度に管路13内に3〜6個の発熱感温部Mnを配置し、中心部に1個の発熱感温部M0を配置して、それぞれで得られた直管長に対するシミュレーション計測値と仮定の流速値との誤差を算出した。   That is, on the circle of 0.7R from the central part, 3 to 6 heat-generating temperature sensing parts Mn are arranged in the pipe 13 at an equal angle, and one heat-generating temperature sensing part M0 is arranged in the central part. The error between the simulation measurement value and the assumed flow velocity value for the straight pipe length obtained in each was calculated.

図4は、中心部に1個の発熱感温部M0及び0.7Rの円上に等角度に3個の発熱感温部M31〜M33を配置した配置図であり、図5は、中心部に1個の発熱感温部M0及び0.7Rの円上に等角度に4個の発熱感温部M41〜M44を配置した配置図であり、図6は、中心部に1個の発熱感温部M0及び0.7Rの円上に等角度に6個の発熱感温部M61〜M66を配置した配置図である。なお、図2が0.7Rの円上に等角度に5個の発熱感温部M51〜M55を配置した配置図である。   FIG. 4 is a layout diagram in which three exothermic temperature sensing parts M31 to M33 are arranged at equal angles on a circle of one exothermic temperature sensing part M0 and 0.7R in the central part, and FIG. FIG. 6 is a layout view in which four exothermic temperature sensing parts M41 to M44 are arranged at an equal angle on a circle of one exothermic temperature sensing part M0 and 0.7R, and FIG. It is the layout which has arrange | positioned the six heat_generation | fever temperature sensing parts M61-M66 on the circle of warm part M0 and 0.7R at equal angles. FIG. 2 is a layout diagram in which five exothermic temperature sensing parts M51 to M55 are arranged at an equal angle on a circle of 0.7R.

図7〜図10は、中心部の1個の発熱感温部M0及び中心部から0.7Rの円上に等角度に設置した3〜6個の発熱感温部Mnとした場合の直管長に対するシミュレーション計測値と仮定の流速値との誤差の割合を示すグラフ図であり、それぞれ流量が時間当りの最大流量に対して10%としたときのシミュレーション結果を示している。各グラフ図には、設置した発熱感温部M0、Mnのシミュレーション計測値の誤差及びこれらの誤差の平均値を示す曲線が記載されている。   7 to 10 show a straight pipe length in the case of one exothermic temperature sensing part M0 in the central part and 3-6 exothermic temperature sensing parts Mn installed at an equal angle on a circle 0.7R from the central part. Is a graph showing the ratio of error between the simulation measured value and the assumed flow velocity value, and shows the simulation result when the flow rate is 10% of the maximum flow rate per time. In each graph, a curve indicating an error in the simulation measurement values of the heat generation and temperature sensing portions M0 and Mn installed and an average value of these errors is described.

同様に、図11〜図14は、それぞれ中心部から0.7Rの円上の3個〜6個の発熱感温部Mnの配置であり、流量が時間当りの最大流量に対して50%としたときのシミュレーション結果を示すグラフ図である。   Similarly, FIG. 11 to FIG. 14 are arrangements of 3 to 6 exothermic temperature sensing parts Mn on a circle of 0.7 R from the center, respectively, and the flow rate is 50% with respect to the maximum flow rate per hour. It is a graph which shows the simulation result when doing.

図15〜図18は、中心部から0.7Rの円上の3個〜6個の発熱感温部Mnの配置であって、流量が時間当りの最大流量に対して100%としたときのシミュレーション結果を示すグラフ図である。   FIGS. 15 to 18 show the arrangement of 3 to 6 exothermic temperature sensing parts Mn on a circle of 0.7 R from the center, where the flow rate is 100% with respect to the maximum flow rate per hour. It is a graph which shows a simulation result.

図19〜図21は、発熱感温部M0、Mnの誤差の平均値のみを抽出し、流量が時間当りの最大流量に対して10%、50%、100%で纏めたグラフ図である。   19 to 21 are graphs in which only the average value of the errors of the heat-generating and temperature-sensitive parts M0 and Mn is extracted and the flow rates are summarized at 10%, 50%, and 100% with respect to the maximum flow rate per time.

これらのグラフ図において、直管長が40D(Dは管路13の直径)以上となると、誤差が生じないことは共通しており、本実施例においては直管長が40D以下の場合の誤差の処理に適用している。   In these graphs, it is common that no error occurs when the straight pipe length is 40D (D is the diameter of the pipe 13). In this embodiment, error processing is performed when the straight pipe length is 40D or less. Has been applied.

図7〜図21のグラフ図から、0.7Rの円上に等角度に設置した複数の発熱感温部Mnのシミュレーション結果の誤差は、個々のシミュレーション結果のシミュレーション計測値ではその設置位置により、プラス、マイナスの誤差が生じているものの、合計値については何れも時間当りの最大流量に対する割合に関係なく、プラスになることが分かる。   From the graphs of FIGS. 7 to 21, the error of the simulation results of the plurality of heat-sensitive parts Mn installed at the same angle on the circle of 0.7R depends on the installation position in the simulation measurement value of each simulation result. Although there are positive and negative errors, it can be seen that the total value is positive regardless of the ratio to the maximum flow rate per hour.

このことから、管路13の中心部に配設した発熱感温部M0のシミュレーション計測値のマイナスの誤差と、管路13の中心部から0.7Rの円上に配設した複数の発熱感温部Mnのシミュレーション計測値の合計ではプラスとなる誤差とを相殺させることで誤差の少ない計測値を得ることができる。   From this, a negative error in the simulation measurement value of the heat generation and temperature sensing unit M0 disposed in the central portion of the pipe 13 and a plurality of heat generation sensations disposed on a circle of 0.7R from the center of the pipe 13 are obtained. It is possible to obtain a measurement value with a small error by offsetting an error that is positive in the total of the simulation measurement values of the warm part Mn.

特に、図19〜図21のグラフ図から、図2に示した0.7Rの円上に等角度に5つの発熱感温部M51〜M55を配置したものが、最も誤差が少ない結果となった。   In particular, from the graphs of FIGS. 19 to 21, the one in which the five heat generation and temperature sensing portions M <b> 51 to M <b> 55 are arranged at the same angle on the 0.7 R circle shown in FIG. 2 has the smallest error. .

シミュレーション結果を検証するために、図2に示した配置の熱式流量計を作成し、直管長を5、10、15と変化させながら、流量を時間当りの最大流量に対して10%、50%、100%の実流量を流した状態にして測定したところ、検証実験結果と前述のシミュレーション結果はほぼ一致した。   In order to verify the simulation results, a thermal flow meter having the arrangement shown in FIG. 2 was created, and the flow rate was changed to 10%, 50% of the maximum flow rate per hour while changing the straight pipe length to 5, 10, and 15. When the measurement was performed with actual flow rates of 100% and 100% flowing, the results of the verification experiment and the simulation results described above almost coincided.

また、流れ場の変化の影響が最も小さいとされる交点Pは、流れ場が偏流、層流又は乱流の状況に応じて変化すると予想されるので、図2に示した発熱感温部M0、Mnの配置図において、0.7R以外にも、0.5R、0.3Rでも同様にシミュレーションを行った。図22〜図24は、0.3R、0.5R、0.7Rの配置で、それぞれ流量が時間当りの最大流量に対して10%、50%、100%で纏めたグラフ図である。   Further, the intersection P, which is considered to have the least influence of the change in the flow field, is expected to change depending on the situation of the drift, laminar flow, or turbulent flow, so the heat generation temperature sensing part M0 shown in FIG. In the arrangement diagram of Mn, simulation was performed in the same manner with 0.5R and 0.3R in addition to 0.7R. 22 to 24 are graphs in which the flow rates are summarized at 10%, 50%, and 100% with respect to the maximum flow rate per time in the arrangements of 0.3R, 0.5R, and 0.7R, respectively.

図22〜図24のグラフから管路13内の速度分布が線cのように変化したとしても、線a、線bの交点Pである0.7Rが最も信頼性が高くなることが分かる。   22 to 24, even if the velocity distribution in the pipeline 13 changes as shown by the line c, it can be seen that 0.7R that is the intersection point P of the lines a and b has the highest reliability.

このように、中心部の感温部mとその周囲に複数の発熱感温部Mを配置し、これらの測定値の平均を求め、特に図2に示した発熱感温部M0、Mnの配置とすることで、直管長が十分に確保できずに、管路内の流れ場が安定しないような設置個所においても、計測誤差の少ない流速値及び流量値を得ることができる。   In this way, the temperature sensing part m at the center and a plurality of heat sensing parts M are arranged around it, and the average of these measured values is obtained. In particular, the arrangement of the heat sensing parts M0 and Mn shown in FIG. As a result, it is possible to obtain a flow velocity value and a flow rate value with a small measurement error even at an installation location where the length of the straight pipe cannot be sufficiently secured and the flow field in the pipeline is not stable.

また、図4〜図6の発熱感温部M0、Mnの配置の構成であっても、発熱感温部M0又は発熱感温部Mnの測定値に係数を乗じて計算を行うことにより、図2の発熱感温部M0、Mnの配置の構成同様に誤差を小さくすることもできる。この係数は既知の実流量を流して較正を行う過程で決定することもできる。   4 to 6, even if the arrangement of the heat generation and temperature sensing portions M0 and Mn is arranged, the measured value of the heat generation temperature sensing portion M0 or the heat generation temperature sensing portion Mn is multiplied by a coefficient to perform calculation. The error can be reduced as in the configuration of the arrangement of the heat generation and temperature sensing parts M0 and Mn. This coefficient can also be determined in the process of calibration with a known actual flow rate.

更に、図4〜図6の発熱感温部M0、Mnの配置の構成において、中心部からの0.7Rを最適な半径長に調整することでも誤差を小さくすることができる。   Furthermore, in the configuration of the arrangement of the heat generation and temperature sensing portions M0 and Mn in FIGS. 4 to 6, the error can be reduced by adjusting 0.7R from the central portion to the optimum radius length.

11 流路管
12 センサユニット
13 管路
11 Channel pipe 12 Sensor unit 13 Pipe line

Claims (5)

管路内において複数個の流速検知素子を有する熱式流量計であって、前記管路の断面上に、1個の流速検知素子を前記管路の中心部に配置し、他の複数個の流速検知素子を前記中心部と前記管路の管壁との間に等角度に配置し、これらの流速検知素子による測定値の平均を求めて測定値とすることを特徴とする熱式流量計。   A thermal flow meter having a plurality of flow rate detection elements in a pipe, wherein one flow rate detection element is arranged at the center of the pipe on the cross section of the pipe, A thermal flow meter, wherein a flow rate detection element is disposed at an equal angle between the central portion and the pipe wall of the pipe, and an average of measurement values obtained by these flow rate detection elements is obtained as a measurement value. . 前記等角度に配置した流速検知素子は、前記管路の中心部から管路の半径の約0.7倍の円上の位置に配置したことを特徴とする請求項1に記載の熱式流量計。   2. The thermal flow rate according to claim 1, wherein the flow velocity detection elements arranged at the same angle are arranged at a position on a circle approximately 0.7 times the radius of the pipe line from the center of the pipe line. Total. 前記等角度に配置した流速検知素子の数は5としたことを特徴とする請求項1又は請求項2に記載の熱式流量計。   The thermal flow meter according to claim 1 or 2, wherein the number of flow velocity detecting elements arranged at the same angle is five. 前記中心部の流速検知素子又は前記複数の等角度に配置した流速検知素子の測定値に係数を乗ずることを特徴とする請求項1〜3の何れか1つの請求項に記載の熱式流量計。   The thermal flow meter according to any one of claims 1 to 3, wherein a coefficient is multiplied to a measured value of the flow rate detection element in the central portion or the plurality of flow rate detection elements arranged at the same angle. . 前記係数は既知の実流量を流して較正を行う過程で決定することを特徴とする請求項4の請求項に記載の熱式流量計。   5. The thermal type flow meter according to claim 4, wherein the coefficient is determined in a process of performing calibration by flowing a known actual flow rate.
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