JPS63223569A - Method and device for calibrating anemometer for measuring air current - Google Patents

Abstract

PURPOSE:To execute a measurement with high accuracy by providing horizontally in a straight line a Pitot tube and an anemometer to an axis provided on the tip of a detecting probe, and bringing this axis to a rotation or a reciprocating motion along a gas flow. CONSTITUTION:A Pitot tube 8 and a thermal type anemometer 9 of equal length are attached to one axis 10, and this axis 10 is brought to a rotation or a reciprocating motion at a low speed. When a detecting probe 1 is installed in a duct 7, each part connected to this probe 1 transfers an electrical signal received by a nose tube in a detecting probe 1, to an information converting part 4, in an information and motion transfer part 2, and also, transfers it to the detecting probe 1 from a motion control part 3. Also, in the motion control part 3, motion speed of the probe 1 inserted into the duct 7 is controlled arbitrarily, and in a data processing and indicating part 5, the periodical variation of pressure and the electrical signal, which follows up the rotation and the reciprocating motion of the Pitot tube 8 and the anemometer 9 is indicated, therefore, a gas flow velocity in the duct can be known, and by executing a data analysis, a true gas flow velocity can be indicated.

Description

Detailed Description of the Invention C. Industrial Application Field This invention relates to an anemometer used in measuring the flow rate of gas flowing in a flue or duct, or in measuring air flow in a general environment such as a working environment, The present invention relates to a method and device for calibrating a type anemometer.

[Conventional technology]

Conventionally, when measuring the flow rate of airflow, an L-shaped Pitot tube (Prandtl-type Pitot tube) shown in Fig. 4 has been used as a standard measuring device. while the static pressure C at the side wall of the nasal canal
The difference between the two, that is, the dynamic pressure, is measured using a water column meter (usually a tilted manometer), and the flow velocity is calculated. However, this pitot tube is used when the airflow velocity is small (for example, 5+a
/s or less), the water column height is about 1lI11 or less, and the dynamic pressure value can only be read in one digit.
This is disadvantageous in terms of measurement accuracy, and therefore it has been difficult to use anemometers with different principles, such as thermal type.

However, as is well known, these anemometers are based on the physical properties of gas,
In particular, it is affected by the density, that is, the gas composition, so it is necessary to calibrate it using a standard Pitot tube before use.In this case, if air is the measurement target, a test wind tunnel with air as a carrier gas is used. Calibration is relatively easy and there are no particular problems, but in the case of airflow other than air, such as combustion exhaust gas, it is necessary to adjust and send the relevant gas mixture into the test wind tunnel.
Its proofreading is not easy.

[Problem that the invention seeks to solve]

In other words, these anemometers require calibration using pitot tubes, and on the other hand, pitot tubes are unsuitable for low-velocity measurements. It would be possible to find a place where the flow velocity is increasing and then take measurements using an anemometer at a measurement position in a low-velocity region, but this is not practical, and therefore high-precision measurements in low-velocity areas are considered difficult. ing.

[Means for solving the problem] For this purpose, when performing comparative calibration using these anemometers in combination with a pitot tube, it is necessary to use this value, since the dynamic pressure (differential pressure) is extremely small in the low flow velocity region. Highly accurate measurements can be made by detecting changes in the indicated values of both while moving them along the flow direction to enlarge the flow. This invention focuses on this point, and the pitot tube and the detection probe of another anemometer are arranged side by side, and the tips of both probes are coaxially rotated parallel to the flow direction at an arbitrary number of rotations, or at an arbitrary speed. By reciprocating along the flow direction,
Detect changes in both indicated values (electrical signals or pressure signals) by moving relative to the flow once, then change the rotational speed or reciprocating speed as necessary and compare the detected values of both. This allows the degree of influence on the (thermal) anemometer to be determined based on the gas composition and other properties, and measurement and calibration can then be performed.

[Embodiments of the invention]

An embodiment of the device according to the present invention will be described with reference to the drawings. As shown in FIG. 1, the entire device consists of a detection probe 1
, information/movement transmission section 2, motion control section 3, information conversion section 4,
Data processing/instruction unit 5. It is composed of a recording section 6.

The detection probe 1 is formed as a probe installed in the duct 7, i.e. as an input of the equipment, as a separate unit which transmits the signal to be measured via a flexible cable to the external equipment, as shown in FIGS. As is clear from FIG. 3, a pitot tube 8 and a thermal anemometer 9 of equal length are attached to one shaft 10, and this shaft 10 rotates or reciprocates at a low speed.

Figures 2 (A) and (B) are plan views of the rotating type;
A front view is shown. As shown in the figure, a shaft 10 is provided at one end of the information/movement transmitting section 2 in series with a low-speed motor 11 provided inside, and a pitot tube 8 of equal length is provided at the tip of the shaft 10. Thermal anemometers 9 are provided to protrude outward from each other. As a result, as shown in FIG. 2(B), while the tip of the nasal tube a of the pitot tube 8 moves downward due to the axis lO rotating counterclockwise in the figure, it resists the flow of exhaust gas shown by the arrow. Turn around.

FIGS. 3(A), 3(B), and 3(C) are plan views of the reciprocating type.

A front view and an explanatory diagram of the reciprocating mechanism are shown. As shown in the figure, a guide arm 1 is connected to one end of the information/movement transmitting section 2 via a rotation mechanism 12.
3 is attached to the guide arm 13, and a shaft 10 projects outward from a slot 14 provided in the guide arm 13, and a pitot tube 8. A thermal anemometer 9 is attached. This shaft 10 is reciprocated by a suitable reciprocating mechanism, for example, as shown in FIG. It is supposed to be done. In the device shown in FIG. 3, the guide arm 13 at the tip of the probe inserted into the duct must be placed along the direction of the airflow indicated by the arrow.
After inserting this into the duct, the rotation mechanism 12 is operated by remote control to maintain the above state. In this way, the tip of the nasal tube a of the pitot tube 8 is moved by the reciprocating shaft 10 as shown in FIG.
), it faces the flow of exhaust gas while moving downward.

[Action/Effect]

With the above configuration, when the detection probe 1 is installed in the duct 7 as shown in FIG. The electrical signal received by the nasal tube of the body is transmitted to the information converting unit 4, and the movement is transmitted from the movement control unit 3 to the detection probe 1, and in the movement control unit 3,
The speed of movement of the probe 1 inserted into the duct 7 is controlled arbitrarily, and the information converter 4 converts and amplifies both pressures received through the nasal tube into electrical signals. 1, that is, the rotation or reciprocating motion of the pitot tube 8 and anemometer 9. Therefore, from the correspondence between the maximum value or singular value of the periodic change and the motion speed, The indicated value when the movement is zero,
That is, the gas flow velocity within the duct can be known, and by performing such data analysis, the true gas flow velocity can be indicated. Then, in the recording section 6, this instruction value can be recorded by an analog or digital method and can also be displayed numerically.

As described above, according to the present invention, although it has conventionally been considered effective when measuring air velocity, particularly at low flow velocity, when air is the measurement target, it is possible to measure the velocity of gas other than air. In some cases, such as thermal anemometers, which require calibration of measured values because gas composition etc. affect the indicated values, the calibration can be performed extremely easily on-site.
Moreover, it can be performed with high precision.

[Brief explanation of drawings]

1, 2, and 3 show an embodiment of the apparatus according to the present invention, FIG. 1 is an overall system diagram, FIGS. 2 and 3 show each side of the detection probe, and FIG. Figure (A) is a plan view of the rotary probe, Figure (B) is a front view, Figure 3 (A) (B)
) (C) shows a plan view, a front view, and an explanatory diagram of the reciprocating mechanism of the reciprocating probe, and FIG. 4 shows a front view of the pitot tube. DESCRIPTION OF SYMBOLS 1... Detection probe, 5... Data processing/instruction unit, 7... Duct, 8... Pitot tube, 9... Anemometer, 10... Shaft, 11... Motor, 12... Rotation mechanism, 13... Guide arm, 14... Slot, a... Nasal tube.

Claims (2)

[Claims] (1) A pitot tube and an anemometer are horizontally installed in a straight line on a shaft provided at the tip of a detection probe, and by rotating or reciprocating this shaft along the gas flow to be measured, the pitot tube and the wind speed are measured. The tip of the meter is moved to face the gas flow, and changes in the readings of the pitot tube and anemometer are detected, and the gas flow velocity is measured from the readings and the speed of movement.
Anemometer calibration method for airflow measurement. (2) A shaft that rotates or reciprocates is provided at the tip of the detection probe to be inserted into the gas flow, and a pitot tube and an anemometer are horizontally installed on this shaft in a straight line. Anemometer calibration device for airflow measurement, which is equipped with a mechanism to detect changes in each indicated value.