Slit type dynamic and static water pressure gauge

Abstract

To provide a slit type dynamic and static water pressure gauge having a simple structure, capable of being manufactured at a low cost, and having high practicality capable of excellently measuring, for example, even a river, a water channel or the like in which sediment, refuse or the like flows.SOLUTION: This device is provided with a hollow cylindrical body 14 arranged in a fluid and provided with a slit 12 opposed to the direction of the flow of the fluid, and a measuring instrument housing part 16 internally communicating with the hollow cylindrical body 14 via a communication opening part 20 and forming a housing space 22 closed except the communication opening part 20. The hollow cylindrical body 14 is formed in a straight cylindrical shape, and the slit 12 is preferably provided long in parallel with the center axis.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a slit-type dynamic hydrostatic pressure gauge that can be used to measure the pressure and therefore the flow velocity of flowing water or fluid. [Background technology]

[0002] Due to the effects of global climate change in recent years, heavy rain and flood damage have occurred in various parts of the world. Flood prevention measures for rivers and other structures require monitoring of river flow rates, both during heavy rain and floods, and measuring the water level and flow velocity is necessary to measure the river flow rate. Conventional methods for measuring the flow velocity of water in rivers and other structures include, for example, the float method, in which workers measure the flow velocity of a river by throwing a float into the river during a flood and measuring the time it takes for the float to float a specified distance; the Doppler current meter method, in which sound waves are emitted into the water and reflected by underwater objects to measure the flow velocity using changes in the frequency of the sound waves; and the video image analysis method, in which the flow velocity of a river is measured by photographing the river with a video camera or the like and analyzing the video images.

[0003] Furthermore, as a flow meter for measuring the flow velocity of a flowing fluid, a Pitot tube is also known, which measures the flow velocity by using Bernoulli's theorem, taking the pressure difference between the total pressure generated in the flow of the fluid and the static pressure of the fluid as the dynamic pressure (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-118604 Summary of the Invention [Problem to be solved by the invention]

[0005] Measuring river flow velocity during floods requires simultaneous measurements at multiple points along the river, but conventional methods such as float methods, Doppler current meter methods, and video image analysis methods are expensive and make it difficult to conduct observations economically.

[0006] Furthermore, although conventional Pitot tubes are inexpensive and have a simple structure, when they are installed in rivers and other bodies of water, there is a risk that the narrow hole at the tip of the Pitot tube will become blocked by sediment or debris carried along with the water, making it impossible to make measurements, which makes them less practical as instruments for measuring river flow velocity.

[0007] The present invention has been made in view of the above-mentioned problems of the conventional art, and one object of the present invention is to provide a slit-type dynamic hydrostatic pressure gauge that has a simple structure, can be manufactured at low cost, and is highly practical so that it can be effectively used in, for example, rivers and waterways where earth and sand, garbage, etc. flow. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention provides: liquid placed inside liquid A slit is provided to face the direction of the flow. One The vehicle is provided with a hollow cylindrical body and an instrument storage section that is internally connected to the hollow cylindrical body through a communication opening and that forms a storage space that is closed except for the communication opening. The hollow cylindrical body is formed in a straight cylindrical shape to utilize the principle that a stagnation point occurs on the front side where the slit is provided, and the energy of the liquid flow is converted into the height of the liquid, and the hollow cylindrical body has a strength that does not break down against the energy of the flowing liquid, and the slit is provided long from one end side to the other end side of the hollow cylindrical body parallel to the central axis of the straight cylindrical hollow cylindrical body. The slit-type dynamic hydrostatic pressure gauge may be configured to include instruments and devices such as a pressure gauge and a water level gauge in the instrument storage section.

[0009] The hollow cylindrical body is cylindrical. formed This may also be considered to be the case.

[0010] Furthermore, at least one end of the hollow cylindrical body may be closed.

[0011] The hollow cylindrical body may be closed at both ends.

[0012] The instrument housing may also have a closed cylindrical body arranged to intersect with the hollow cylindrical body.

[0013] The instrument storage section may be provided so that the storage space can be opened and closed.

[0014] The hollow cylindrical body and the instrument housing may be connected in a substantially L-shape.

[0015] Furthermore, the present invention provides a method for manufacturing a dynamic hydrostatic pressure gauge by inserting the slit into the instrument housing of the dynamic hydrostatic pressure gauge. River water The hollow cylinder is oriented so as to face the flow of Rivers Install it inside, River flow velocity Measure River flow velocity It consists of measurement methods. [Effects of the Invention]

[0016] The slit-type dynamic static hydrometer of the present invention comprises a hollow cylindrical body disposed in a fluid and having a slit formed therein that faces the direction of the fluid flow, and an instrument housing that is connected to the hollow cylindrical body via a communication opening and forms a storage space that is closed except for the communication opening. This provides a simple method for estimating or measuring flow velocity from a physical phenomenon that utilizes stagnation points, and allows the hydrometer to be manufactured at low cost with a simple structure. Furthermore, the slit shape makes it possible to obtain the average flow velocity over the length of the slit, and even when the hydrometer is installed in, for example, a river or waterway, it is less likely to be clogged by sediment or debris carried along with the water, making it practical to measure flow velocity. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a perspective view of a slit-type dynamic hydrostatic pressure gauge according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a front view of the slit-type dynamic hydrostatic pressure gauge of FIG. 1. [Figure 3] FIG. 2 is a cross-sectional view taken along line AA of the slit-type dynamic hydrostatic pressure gauge of FIG. 1. [Figure 4]FIG. 2 is a schematic explanatory diagram of the principle of the slit-type dynamic hydrostatic pressure gauge of FIG. 1. [Figure 5] FIG. 2 is a perspective view of another embodiment of the slit-type dynamic hydrostatic pressure gauge of FIG. 1. [Figure 6] FIG. 2 is a side view of still another embodiment of the slit-type dynamic hydrostatic pressure gauge of FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0018] An embodiment of a slit-type dynamic hydrostatic meter according to the present invention will be described below with reference to the accompanying drawings. The slit-type dynamic hydrostatic meter according to the present invention is a fluid measuring device that is installed in a flow of water or other liquid (fluid) and can be used to measure the pressure in the liquid flow and, in turn, to measure the flow velocity of the fluid using the pressure.

[0019] Figures 1 to 4 show a first embodiment of a slit-type dynamic hydrostatic pressure gauge of the present invention. As shown in Figures 1, 2, and 3, a slit-type dynamic hydrostatic pressure gauge 10 according to this embodiment includes a hollow cylindrical body 14 having a slit 12 formed therein, and an instrument housing section 16 that is internally connected to the hollow cylindrical body 14.

[0020] The hollow cylinder 14 is a slitted cylinder or slit tube that connects the hollow interior and exterior of the hollow cylinder 14 via the slit 12. The hollow cylinder 14 is a means for measuring the dynamic static pressure (total pressure) of the flowing fluid while being placed in a fluid with the slit 12 facing the upstream side of the fluid so as to face the fluid flow, as will be described later, and allowing the fluid to flow into the cylinder through the slit. In this embodiment, the hollow cylinder 14 is formed from a hard material, for example, a synthetic resin such as plastic, or a metal, It has the strength to withstand the energy of flowing liquid,The hollow cylindrical body 14 is a long, straight cylindrical tube. Both ends of the hollow cylindrical body 14 are closed by closed end walls 18, 19, and the hollow cylindrical body 14 is connected to the outside only by a slit 12. The closed end wall 19 that closes the lower end of the hollow cylindrical body 14 in FIG. 1 also serves as part of a mounting base 26, which will be described later. Therefore, in this embodiment, when the hollow cylindrical body 14 is placed upright in the vertical direction, both the upper and lower ends are closed.

[0021] In this embodiment, the slit 12 of the hollow cylindrical body 14 is a narrow, linear gap along the central axis of the hollow cylindrical body 14, with a width sufficiently smaller than the diameter of the hollow cylindrical body 14. The slit 12 is formed in the peripheral wall of the hollow cylindrical body 14 parallel to the central axis of the hollow cylindrical body 14. The slit 12 is formed with a constant width over substantially the entire length of the hollow cylindrical body 14, from one end to the other. Therefore, the cross-sectional shape of the hollow cylindrical body 14 having the slit 12 is approximately C-shaped. Note that in FIG. 1 , the upper closed end wall 18 is positioned slightly below the end, leaving a small portion of the peripheral wall above the slit 12. By placing the hollow cylindrical body 14 having the slit 12 in a predetermined orientation in a fluid, the average flow velocity along the length of the slit 12 can be measured using a principle similar to that of a Pitot tube, which generates a pressure difference at the slit, as described below.

[0022] The shape of the hollow cylindrical body 14 is not limited to a cylindrical shape, but may be any other shape, such as a polygonal cylindrical shape, an elliptical cylindrical shape, or a semi-cylindrical shape.

[0023] The instrument storage section 16 is connected to the hollow cylindrical body 14 in an internally communicating state and serves as a storage means for storing instruments and devices such as pressure sensors and water level gauges. In this embodiment, the term "instruments" encompasses measuring instruments and devices such as pressure gauges and sensors for measuring fluid pressure. Therefore, the instrument storage section 16 may store sensors, measuring instruments and devices, control panels, and power sources such as batteries for sensing, measuring, or controlling various fluid conditions such as the fluid flow rate, water level, and temperature. As shown in FIGS. 1, 2, and 3, the instrument storage section 16 is internally connected to the hollow cylindrical body 14 via a communication opening 20, forming a closed storage space 22 with the exception of the communication opening 20. In other words, the fluid flowing into the hollow cylindrical body 14 through the slit 12 flows through the communication opening 20 to fill the closed storage space 22. This allows the dynamic and static pressures of the hollow cylindrical body 14 to be measured using a pressure gauge, a pressure-type water level gauge, or the like within the instrument housing 16. The instrument housing 16 is formed, for example, from the same material as the hollow cylindrical body 14, such as a synthetic resin such as plastic, or a hard material such as metal. As shown in FIGS. 1, 2, and 3, the instrument housing 16 is formed, for example, in a substantially cylindrical shape, with a communication opening 20 formed at one end and a closed other end, forming a closed cylindrical body. The cylindrical instrument housing 16 is connected such that its central axis intersects the central axis of the hollow cylindrical body 14 substantially perpendicularly. In this embodiment, one end of the instrument housing 16 is connected to the lower end of the hollow cylindrical body 14, and the hollow cylindrical body 14 and the instrument housing 16 are connected in a substantially L-shape. The shape and size of the instrument storage section 16 are not limited to the above shapes as long as they can store instruments and form a closed space, and may be box-shaped, polygonal cylindrical, semi-cylindrical, or any other shape.

[0024] In this embodiment, the closed end of the instrument housing 16 is provided with an opening / closing lid 24 that allows the instrument housing 16 to be opened and closed. The opening / closing lid 24 has, for example, a male thread integrally formed therewith that threads into a female thread formed inside the instrument housing 16, and is detachably attached. This allows instruments such as pressure gauges stored in the storage space 22 of the instrument housing 16 to be removed as needed to retrieve measurement data, replace batteries, perform maintenance, and so on. The opening / closing structure of the instrument housing 16 is not limited to the detachable structure described above, and may also be a sliding or revolving door type opening / closing structure. Furthermore, the connection between the instrument housing 16 and the hollow cylindrical body 14 may be detachable, allowing the instrument housing 16 to be opened and closed.

[0025] As shown in FIG. 1, a mounting base 26 that extends like a plate is integrally formed on the underside of the instrument storage section 16. The mounting base 26 is a mounting means for mounting the slit-type dynamic hydrostatic pressure gauge 10 at a desired position. The mounting base 26 is formed, for example, in a substantially rectangular shape in a plan view, and has mounting holes 28 that penetrate the plate surface at the four corners. For example, when installing the slit-type dynamic hydrostatic pressure gauge 10 in a river, waterway, or the like, bolts, anchors, or the like are inserted into the mounting holes 28 of the mounting base 26 to mount the slit-type dynamic hydrostatic pressure gauge 10 at a predetermined position. to The mounting means for the slit-type dynamic hydrostatic pressure gauge 10 is not limited to a structure such as a mounting base, and any structure may be used.

[0026] In this embodiment, as shown in FIG. 2 , the instrument housing 16 houses, for example, a pressure gauge 30 to form a water pressure gauge. The pressure gauge 30 is, for example, a well-known self-recording pressure gauge that is battery-powered and stores measured values ​​in memory. As described above, by placing the instrument housing 16 facing downward in the fluid, the pressure gauge 30 is installed, for example, on the bottom side of the water, and measures the pressure of the liquid on the bottom side. Note that the pressure gauge 30 may be of any type, such as a structure that can be supplied with power from an external source, a wired structure that transmits measurement data via an electric line, or a wireless structure that transmits measurement data wirelessly. The pressure gauge 30 may also be a pressure-type water level gauge that measures the water level from the pressure.

[0027] This makes it possible to realize a fluid pressure measurement method utilizing the configuration of the hollow cylindrical body 14 having the slit 12 by placing the hollow cylindrical body 14 in the fluid with the slit 12 facing the fluid flow while the pressure gauge 30 is housed in the instrument housing 16 of the slit-type dynamic static hydrometer 10, and measuring the fluid pressure using the pressure gauge in the instrument housing 16. Furthermore, it is preferable to provide a water level gauge that measures the fluid level or a pressure gauge that measures static pressure, and a water level gauge that measures the elevated water level inside the slit and hollow cylindrical body or a pressure gauge that measures dynamic static pressure (total pressure). The dynamic pressure of the fluid is measured by subtracting the static pressure from the dynamic static pressure, and if the dynamic pressure of the fluid can be measured, the flow velocity of the fluid can be calculated using Bernoulli's theorem.

[0028] Next, the principle and method of measuring flow velocity using a slit-type dynamic hydrostatic pressure gauge 10 will be described with reference to FIG. 4 . Note that the instrument housing is omitted in FIG. 4 to allow for explanation of water pressure and other factors. In this embodiment, the fluid is water, and installation in a river or the like will be described as an example. As shown in FIG. 4 , when measuring the flow velocity of water flowing at a water level H, for example, a hollow cylindrical body 14 is placed upright in the water flow, with the slit 12 facing upstream so as to face the fluid flow. The flowing water flows into the hollow cylindrical body 14 through the slit 12, but collides with the front side where the slit 12 is formed, and its velocity becomes zero. At this time, the flow velocity (speed) of the water is converted into pressure, raising the water level in the hollow cylindrical body 14 and at the slit 12 by h. The total pressure that hits the water level inside the slit 12 and the hollow cylindrical body 14 is the sum of static pressure and dynamic pressure, but since it is balanced with the static pressure inside the hollow cylindrical body 14, the following formula [Mathematical Formula 1] can be derived from the relationship between the static pressure of water at height H and the rise in water level h due to dynamic pressure caused by flow velocity v, where ρ is the water density, g is the gravitational acceleration, b is the slit width, h(z) is the height from the water bottom, and v(z) is the water flow velocity at height z from the water bottom.

[0029]

number

[0030] In the above formula [Math 1], the first term on the left side is the static pressure, the second term is the dynamic pressure, and the right side is the static pressure inside the hollow cylindrical body in a hollow cylindrical body with a slit placed in the flow of water at a water level H. The water flow velocity v can be calculated from the above formula [Math 1] based on the pressure at the slit-type dynamic hydrostatic pressure gauge 10, and is expressed by the following formula [Math 2].

[0031]

number

[0032] With the pressure gauge 30 housed in the instrument housing 16 of the slit-type dynamic and static hydrometer 10, the hollow cylindrical body 14 is placed in water as described above, and the dynamic and static pressures near the slits are measured using the pressure gauge 30. The static pressure of the water is then measured and subtracted from the dynamic and static pressures to determine the dynamic pressure, and the water flow velocity can be measured from this dynamic pressure. To verify the above formula [Equation 2], a propeller-type current meter was used at water level H to measure the flow velocity at six water depths: H (water surface), 4 / 5H (20% depth from the water surface), 3 / 5H (40% depth from the water surface), 2 / 5H (60% depth from the surface), 1 / 5H (80% depth from the water surface), and 0 (water depth H, i.e., the bottom).Compared with the flow velocity v in the above formula (Equation 2), it was experimentally confirmed that v was close to the average flow velocity of water in the slit and the interior of the hollow cylinder, i.e., at water level H+h.

[0033] In this way, the slit-type dynamic hydrostatic pressure gauge 10 can be used to measure the fluid pressure well, and in turn, the fluid velocity. As described above, the slit-type dynamic hydrostatic pressure gauge 10 is basically a simple device that is simply made by connecting a hollow cylindrical body with a slit and a closed cylindrical body. Na This structure allows for low-cost manufacturing. Furthermore, since the portion through which the fluid flows is formed with a slit, it is less likely to be clogged with sediment, debris, etc., and measurement functionality can be maintained. As a result, it can be practically used in terms of both functionality and economy, for example, to measure the flow rate of rivers during floods. Furthermore, it is possible to provide a water pressure gauge that can be widely used to measure the pressure and flow rate of various liquids, not just rivers.

[0034] 5 and 6 show other embodiments of the slit-type dynamic hydrostatic pressure gauge 10, with the same components as those in the above-described embodiments being assigned the same reference numerals. The embodiment in FIG. 5 has a configuration similar to that in FIG. 1, except that one end (top end) of the hollow cylindrical body 14 has an opening 32. Essentially, one end of the hollow cylindrical body 14 may be open and the other end closed, allowing for measurement of liquid pressure and flow velocity in a manner similar to that shown in FIG. 1, particularly under conditions of relatively slow flow velocity. In the embodiment in FIG. 5, since one end (top end) of the hollow cylindrical body 14 has an opening 32, the structure is slightly simpler than that shown in FIG. 1, making it easier to visually observe the water level inside the hollow cylindrical body from the outside. However, when the flow velocity of the flowing water increases beyond a certain level, the water level rise (h) increases at the stagnation point, causing the water level inside the hollow cylindrical body 14 to exceed the inflow rate at the front of the slit, making accurate measurement difficult. 1 to 3, the hollow cylindrical body 14 can measure fluid pressure relatively accurately even when the fluid is moving at a high speed or when the body is submerged in water, and the device can be widely used without being limited to specific locations or situations, improving its practicality. As a result, the device can accurately measure water pressure and water flow velocity even when the water level of a river changes, especially when the water level rises significantly during a flood.

[0035] 6, the instrument housing 16 may be connected to the hollow cylindrical body 14 in any manner, and may be connected to an intermediate position along the length of the hollow cylindrical body 14. Although the instrument housing 16 is connected to the hollow cylindrical body 14 substantially perpendicularly, it may be connected at any angle. That is, the hollow cylindrical body 14 and the instrument housing 16 may be connected in any other manner, such as a substantially T-shape or a substantially V-shape.

[0036] The slit-type dynamic hydrostatic pressure gauge of the present invention described above is not limited to the configuration of the above-described embodiment, and any modifications may be made without departing from the essence of the present invention as defined in the claims. [Explanation of symbols]

[0037] 10 Slit-type dynamic hydrostatic pressure gauge 12 Slit 14 Hollow cylindrical body 16 Instrument storage area 20 Communication opening 22 Storage space 30 Pressure Gauge

Claims

1. a hollow cylindrical body disposed in the fluid and having a slit formed therein that faces the direction of the fluid flow; and an instrument storage section that is internally connected to the hollow cylindrical body through a communication opening and forms a storage space that is closed except for the communication opening.

2. 2. The slit-type dynamic hydrostatic pressure gauge according to claim 1, wherein the hollow cylindrical body is formed in a straight cylindrical shape and has a long slit formed parallel to its central axis.

3. 3. A slit-type dynamic hydrostatic pressure gauge according to claim 2, wherein the hollow cylindrical body is formed in a cylindrical shape, and the slit is provided from one end side to the other end side of the hollow cylindrical body.

4. 3. A slit-type dynamic hydrostatic pressure gauge according to claim 2, wherein at least one end of the hollow cylindrical body is closed.

5. 3. A slit-type dynamic hydrostatic pressure gauge according to claim 2, wherein both ends of said hollow cylindrical body are closed.

6. 2. The slit-type dynamic hydrostatic pressure gauge according to claim 1, wherein the instrument housing portion has a closed cylindrical body disposed so as to intersect with the hollow cylindrical body.

7. 2. The slit-type dynamic hydrostatic pressure gauge according to claim 1, wherein the instrument storage section is provided so that the storage space can be opened and closed.

8. 2. A slit-type dynamic hydrostatic pressure gauge according to claim 1, wherein the hollow cylindrical body and the instrument housing are connected in a substantially L-shape.

9. A method for measuring fluid pressure, comprising: accommodating a pressure gauge in an instrument housing of a slit-type dynamic hydrostatic pressure gauge according to any one of claims 1 to 8; placing the hollow cylindrical body in a fluid with the slit facing the fluid flow; and measuring the pressure of the fluid.

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