JP3615371B2 - Airflow measuring device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an air volume measuring device that measures an air volume flowing in a pipeline.
[0002]
[Prior art]
An air flow measuring device in which a rectifier is provided on the upstream side of the casing and a fluid pressure detector such as a Pitot tube is provided on the downstream side is known (see Japanese Utility Model Laid-Open No. 60-80316).
[0003]
[Problems to be solved by the invention]
In this known air volume measuring device, since the static pressure measuring hole of the fluid pressure detector is opened perpendicular to the fluid flow direction, measurement with a stable flow without vortex is required. Therefore, in order to avoid the influence of the vortex generated from the rectifier located in the upstream region, it is necessary to provide a sufficient straight pipe portion between the rectifier and the fluid pressure detector.
In general, the static pressure measurement hole of the fluid pressure detector is opened to face in a direction perpendicular to the fluid flow for the purpose of detecting the true static pressure in the flow path. When the differential pressure detector is provided immediately after the rectifier, it is greatly affected by the eddy current generated immediately after the rectifier. Therefore, there is a problem that the measurement accuracy of the detected pressure is deteriorated.
[0004]
From the above, in the Japanese Industrial Standard JIS B 8330 blower test and inspection method, the distance between the rectifier and the fluid pressure detector is set so as not to be affected by the vortex flow after the rectifier. Taking larger than the tube diameter is performed. This is a problem with an air flow measuring device having a built-in rectifier, in which the length in the fluid flow direction becomes longer, the device must be enlarged, and the installation space for the device increases.
Furthermore, the position where the air volume in the pipe is measured is not always limited to a straight pipe, but rather, it must be measured in a narrow place immediately after a bent pipe or a branch pipe. For this purpose, there is a problem that the air flow measuring device itself is required to be shortened in the flow direction size and to be able to measure even in a place where the straight pipe size upstream of the device is short.
[0005]
In view of the above problems, the present invention reduces the size of the apparatus in particular by shortening the dimension in the fluid flow direction, relaxes restrictions on installation in a pipe line, and is a novel type that supports a wide range of applications. It aims at providing a flow measuring device.
[0006]
[Means for Solving the Problems]
The flow rate measuring device of the present invention is an air flow measuring device in which a rectifier is provided on the upstream side in a casing and a fluid pressure detector is provided on the downstream side, wherein the fluid pressure detector is flat so as to follow the fluid flow direction. Rutotomoni such a substantially rectangular shape hollow body, one side wall positioned either before or after the flow direction of the fluid in the arcuate cross-section, bored a plurality of pressure measurement hole on one side wall to the arcuate cross-section It consists of a total pressure measurement sensing element and static pressure measurement sensing body in which said the total pressure measurement sensing element and static pressure measurement sensing member is formed the same shape, the same dimensions, Yes and connecting them back to back, the total pressure The total pressure measurement hole of the measurement detector is directed toward the upstream side of the fluid flow, and the static pressure measurement hole of the static pressure measurement detector is positioned toward the downstream side of the fluid flow.
[0007]
The flow rate measuring device of the present invention is an air volume measuring device in which a rectifier is provided on the upstream side in the casing and a fluid pressure detector is provided on the downstream side, and the fluid pressure detector is arranged along the fluid flow direction. In addition to a flat, generally rectangular hollow body, one side wall located either before or after the fluid flow direction is formed in a circular arc shape, and a plurality of pressure measurement holes are formed in the single side wall. It consists of a total pressure measurement detector and a static pressure measurement detector, and the total pressure measurement detector and the static pressure detection detector are formed in the same shape and dimensions, and they are spaced apart from each other back to back. With the total pressure measurement hole of the total pressure measurement detector facing the upstream side of the fluid flow and the static pressure measurement hole of the static pressure measurement detector facing the downstream side of the fluid flow. It is characterized by being.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described based on examples shown in the drawings.
1 and 2 show an embodiment in which the casing has a square shape. In the figure, reference numeral 10 denotes a casing, and a rectifier 11 is attached to the upstream side thereof. The structure of the rectifier 11 may be a conventionally known honeycomb structure or a mesh structure, or may be an approximate honeycomb structure in which corrugated corrugated plates are alternately laminated between flat plates. In any case, it is desirable that this rectifier is made of stainless steel so that it can withstand various environments from the viewpoint of enhancing durability.
[0009]
In the figure, 1 and 1 are fluid pressure detectors, and a plurality of them are arranged and fixed in parallel on the downstream side of the rectifier 11.
As shown in FIGS. 4 and 5, the fluid pressure detector is configured by connecting fluid pressure detectors 1a and 1b having the same shape and the same size back to back. The fluid pressure detectors 1a and 1b are flat, substantially rectangular hollow hexahedrons, and the flat upper wall 2 and lower wall 3 and the left and right blocking walls 4 and 4 with the hollow hexahedron placed horizontally It is formed by front and rear walls 5 and 5 that are located either before or after in the flow direction. A pressure outlet 6 is provided in one of the left and right blocking walls 4, 4, and a plurality of pressure measurement holes 7 are formed in one of the front and rear walls 5, 5.
Then, the pressure outlets 6 and 6 are positioned in the same direction, and are connected back to back so that the pressure measurement holes 7 and 7 are in opposite directions. Thus, the one located on the upstream side of the flow is the total pressure measurement detector serving as the total pressure measurement hole, and the one located on the downstream side is the static pressure measurement detector serving as the static pressure measurement hole.
In the illustrated embodiment, the one side wall 5 in which the pressure measurement hole 7 is bored has an arcuate cross section, but it may not necessarily be arcuate but may be a flat plate positioned perpendicular to the flow. Further, the fluid pressure detector may be formed into a pipe shape without being flattened.
[0010]
In the fluid pressure detector 1 described above, since the static pressure measurement hole is located at the most downstream end, the apparent static pressure is lower than the true static pressure due to the vortex generated by the fluid pressure detector itself. The apparent dynamic pressure, which is a differential pressure from the applied static pressure, becomes larger than the true dynamic pressure. In particular, in a low wind speed region where the dynamic pressure is small, the pressure reading error rate can be estimated to be smaller than that of a device that detects the true dynamic pressure. In addition, measuring the static pressure in the vortex created by the fluid pressure detector itself makes it less susceptible to vortices generated from the rectifier and can be expected to improve measurement accuracy.
Moreover, since the fluid pressure detector 1 has a flat hollow body, the fluid pressure detector itself has an effect of adjusting the flow of the fluid, which is effective.
[0011]
In the embodiment shown in FIG. 3, the left and right blocking walls 4 and 4 are configured to be fitted into the left and right open portions of the fluid pressure detector, for example, cap-shaped castings, etc., and use seal materials and adhesives as much as possible. The welding process is reduced and the work process is saved.
Each pressure outlet 6 protrudes outward from the casing 10, and the left and right blocking walls 4 are fixed to the casing by screws.
The pressure outlets 6 of the plurality of fluid pressure detection devices are communicated by a single communication pipe 12, and the average total pressure or the average static pressure is taken out by the average pressure outlet 18.
Further, as shown in FIG. 3, the communication pipe 12 is attached by covering the cover body 13 and attaching the left and right blocking walls 4 with screws 14 integrally with the cover body 13.
Furthermore, it is good also as a structure which makes a communicating tube the thing of a rubber tube shape, and inserts the pressure outlet 6 airtightly in the communicating hole formed in the tube.
[0012]
FIG. 6 shows an embodiment of a round device according to the present invention. Similar to the square type, the rectifier 11 is arranged on the upstream side, and the fluid pressure detector 1 is arranged on the downstream side.
As shown in FIGS. 6-8, the fluid pressure detector 1 attached to a round shape is combined in a cross shape.
In the illustrated embodiment, four fluid pressure detectors are radially connected to a sensor socket 15 made of a hollow body with the socket as a center. The total pressure measurement detectors and the static pressure measurement detectors communicate with each other through the hollow portion 16 of the sensor socket 15 so as to average the total pressure and the static pressure. The pressure take-out pipes so that the total pressure outlet 6 and the static pressure outlet 6 of the four total pressure measuring detectors or one of the four static pressure measuring detectors penetrate the inside of the respective measuring detectors. 17 is connected, its inner end is opened in the sensor socket 15, and the average total pressure or average static pressure of the four fluid pressure detectors is taken out from the average pressure outlet 18.
[0013]
Although not shown in the drawing, a plurality of fluid pressure detectors radially connected around the sensor socket are provided in a plurality of stages on different cross sections orthogonal to the fluid flow direction, and the plurality of fluid pressure detectors are connected to each other. It can also be arranged at a position that does not overlap the upstream side and the downstream side in the flow direction.
[0014]
FIG. 9 and FIG. 10 show the device of the present invention in which the space 8 is arranged slightly between the total pressure measurement detector 1a and the static pressure measurement detector 1b.
In the fluid pressure detector 1 arranged with the space portion 8 disposed, the directivity with respect to the flow direction can be lowered, and the yaw characteristic at the angle of attack can be enhanced. From this, coupled with the effect of the rectifier located upstream, it was possible to make the device less susceptible to errors in the detected pressure even under extreme drift conditions and unsteady flow fields where the flow direction is not stable. .
The results obtained from the experiment are displayed as a table, which is shown in FIG. In this experiment, a known device (referred to as device A) that has already been put into practical use, the device (referred to as device B) shown in FIGS. 1 and 6 in which fluid pressure detectors 1a and 1b are connected back to back, FIG. This is a comparison with the apparatus shown in FIG. 10 (referred to as “C apparatus”). According to this, good results were obtained at an angle of attack of 0 to 18 degrees.
Examples used in this experiment are as follows.
3 is a fluid pressure detector having a thickness of 10 mm, a width of 30 mm, and a length of 200 mm, in which one side wall provided with pressure measurement holes 7 and 7 has an arc shape, and the embodiment shown in FIG. A device having the same dimensions as the above-mentioned device B, and a device in which the fluid pressure detectors are arranged through a space of 2 mm was placed in a 200 mm × 300 mm duct and tested at a wind speed of 11 m / sec. .
[0015]
In the device of the present invention, the fluid pressure detector is constituted by a hollow body shaped so as to follow the fluid flow direction, and the static pressure measurement hole of the static pressure measurement detector is positioned toward the downstream side. The pressure is detected in the vortex induced by the vessel itself. This makes it less susceptible to vortex flow after the rectifier, thus reducing the dimension between the fluid pressure detector and the rectifier. That is, as shown in FIG. 2, the relationship between the dimension L between the rectifier and the fluid pressure detector and the tube diameter D of the casing can be set to L <D, which is shorter than JIS regulations.
[0016]
FIG. 12 shows the result of the functionality test performed by the embodiment shown in FIG. 6 of the air flow measuring device of the present invention. In this functional test, a 412 mm diameter round device was used, and the present invention device with a rectifier having a honeycomb structure and a device without a rectifier were installed downstream of the fan, and the wind speed was 23 m / s and 2.5 m / s. Tested. As a result, due to the presence of the rectifier, the error rate with respect to the true wind speed was extremely small, and highly accurate measurement results were obtained.
Furthermore, in the fluid pressure detector, if the total pressure measuring detector and the static pressure measuring detector are structured with the same shape and the same dimensions and are arranged back to back, their production and processing are easy.
Also, if the material of the differential pressure detector is aluminum, resin, etc., extrusion processing is possible, so a fluid pressure detector in which the total pressure measurement detector and the static pressure measurement detector are integrated can be formed. did it.
[0017]
【The invention's effect】
As described above, in the device of the present invention, the static pressure measurement hole of the static pressure measurement detector is arranged toward the downstream side of the fluid flow, so that it is less susceptible to the influence of the fluid flow vortex generated from the rectifier. The measurement error rate can be reduced in combination with the rectification effect of the rectifier.
As a result, there is no need to provide a sufficient straight pipe portion between the rectifier and the fluid pressure detector, and the measurement apparatus can be made compact.
Therefore, it is possible to attach the device immediately after the fan or elbow in the pipe line, and it is possible to alleviate restrictions on the installation of the apparatus in the pipe line, and to obtain a great practical effect that it can be used for a wide range of applications.
[Brief description of the drawings]
FIG. 1 is a partially cutaway perspective view of an embodiment of the square-type device of the present invention. FIG. 2 is a partially cutaway side view of the same. FIG. 3 is a partially cutaway side view of an embodiment of a fluid pressure detector. 4] Partially cutaway perspective view showing the basic structure of the fluid pressure sensing body [FIG. 5] Cross-sectional view of the basic structure same as above [FIG. 6] Partially cutaway perspective view showing an embodiment of the present invention of a round shape [FIG. Fig. 8 is a partially cutaway side view of the main part of the fluid pressure detector provided in the mold. Fig. 8 is a partially cutaway front view of the main part of the same. Partial cutaway perspective view. FIG. 10 is a partially cutaway perspective view of the same circular embodiment. FIG. 11 is a table obtained by experiment to compare yaw characteristics of angles of attack.
12 is a graph showing the results of a functional test performed on a device with and without a rectifier according to the embodiment shown in FIG.
FIG. 13 is an explanatory diagram showing a fluid flow direction and a relative angle θ of the pressure detector.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Fluid pressure detector 1a Fluid pressure detector 1b Fluid pressure detector 2 Upper wall 3 Lower wall 4 Left and right obstruction wall 5 Front and rear wall 6 Pressure outlet 7 Pressure measurement hole 8 Space part 10 Casing 11 Rectifier 12 Communication pipe 13 Cover body 14 Screw 15 Sensor socket 16 Hollow part 17 Pressure extraction pipe 18 Average pressure outlet

Claims (2)

An air volume measuring device provided with a rectifier on the upstream side in a casing and a fluid pressure detector on the downstream side, wherein the fluid pressure detector is a flat, substantially rectangular hollow body that follows the fluid flow direction. Tona Rutotomoni, one side wall positioned either before or after the flow direction of the fluid in the arcuate cross-section, the total pressure measurement sensing element and bored a plurality of pressure measurement hole on one side wall to the arcuate cross-section It consists of a static pressure measurement detector, and the total pressure measurement detector and the static pressure measurement detector are formed in the same shape and the same dimensions, and are connected back to back. An air volume measuring device, wherein the hole is positioned toward the upstream side of the fluid flow, and the static pressure measuring hole of the static pressure measurement detector is positioned toward the downstream side of the fluid flow. An air volume measuring device provided with a rectifier on the upstream side in a casing and a fluid pressure detector on the downstream side, wherein the fluid pressure detector is a flat, substantially rectangular hollow body that follows the fluid flow direction. Tona Rutotomoni, one side wall positioned either before or after the flow direction of the fluid in the arcuate cross-section, the total pressure measurement sensing element and bored a plurality of pressure measurement hole on one side wall to the arcuate cross-section It consists of a static pressure measurement detector, the total pressure measurement detector and the static pressure measurement detector are formed in the same shape and the same dimensions, and they are arranged back to back with a slight space, Air flow measurement, characterized in that the total pressure measurement hole of the total pressure measurement detector is directed toward the upstream side of the fluid flow, and the static pressure measurement hole of the static pressure measurement detector is positioned toward the downstream side of the fluid flow apparatus.

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