A system applicable to flow visualization and velocity measurement in a closed flow channel

Abstract

The present invention relates to a system applicable to flow visualization and velocity measurement in a closed flow channel, which includes a flow visualization device and a velocity measurement device. The velocity measurement device includes a plexiglass sealing device, a Pitot tube, a handheld micro manometer, and a rubber pipe; the flow visualization device includes a rubber plug, a syringe, a dye tank, a nozzle bottle, a capillary tube, a rubber tube, a steel elbow, and a sealing device. Compared with the existing closed flow channel detection technology, this system can measure the velocity distribution at the throat of the pump pipe in the closed flow channel, improving the accuracy and convenience of flow visualization in the intake basin.

Description

Technical Field

[0001] The present invention relates to a system applicable to flow visualization and velocity measurement in a closed flow channel. Background Art

[0002] When designing and manufacturing a pumping station, it is usually necessary to build a physical model to simulate the hydraulic conditions of the prototype pumping station. When conducting physical model tests on a closed flow channel, flow visualization and velocity measurement in the closed flow channel are usually difficult. For pipe velocity measurement in a closed flow channel, particle image velocimetry or a laser Doppler velocimeter is generally used for measurement. However, these two velocity measurement methods require expensive equipment and harsh operating conditions. An acoustic Doppler velocimeter can only measure the average velocity in the pipe and cannot measure the velocity distribution across the pipe cross-section, and is not suitable for flow visualization in a closed flow channel and velocity measurement in the pipe within a closed flow channel. Summary of the Invention

[0003] The object of the present invention is to design an observation system that can simply, quickly, and efficiently perform flow visualization and velocity distribution measurement in a closed flow channel in order to overcome the problems such as expensive equipment required for flow visualization in a closed flow channel and measurement of the pipe velocity distribution within a closed flow channel at the current stage, and harsh operating conditions.

[0004] To achieve the above object, the technical solution adopted by the present invention is: A system applicable to flow visualization and velocity measurement in a closed flow channel, including a flow visualization device and a velocity measurement device. The velocity measurement device includes a handheld manometer, a pitot tube, and an acrylic sealing device located outside the pump pipe. The acrylic sealing device includes a wall transition adaptation section, a sealing rubber ring, and a fixed cover plate. One end of the pitot tube is located at the throat of the pump pipe, and the other end is connected to the handheld manometer. To ensure measurement accuracy, after inserting the pitot tube (17), a sealing rubber ring (19) can be installed on the long strip-shaped opening (18) on the inner wall of the pump pipe to reduce the influence of the opening on the internal flow of the pipe and enhance the measurement accuracy. The acrylic sealing device (16) is adhesively bonded to the opening at the sealing section of the long strip-shaped opening (18) with special acrylic glue. A hole is drilled in the sealing rubber ring (19) with a diameter smaller than the diameter of the pitot tube. The sealing rubber ring (19) is tightly pressed against the acrylic block of the wall transition adaptation section through the fixed cover plate (20) to form a sealing effect. The handheld manometer is separately provided for collecting pressure signals. The pitot tube transmits the pressure signals generated by its static pressure hole and total pressure hole to the handheld manometer, and the flow velocity v2 at the static pressure hole at the throat of the pump pipe where the pitot tube is located is calculated through formula (2);

[0005]

[0006] In the formula: p1 is the pressure measured by the total pressure hole; p2 is the pressure measured by the static pressure hole; v2 is the flow velocity at the static pressure hole; ρ is the fluid density.

[0007] In the above solution, the plexiglass sealing device includes a wall surface transition adaptation section, a sealing rubber ring, and a fixed cover plate. The plexiglass sealing device is bonded to the opening of the sealing section with special plexiglass glue. An opening is made on the sealing rubber ring, and the aperture is slightly smaller than the diameter of the pitot tube. The sealing rubber ring is tightly pressed against the plexiglass block in the transition section through the fixed cover plate to form a sealing effect.

[0008] In the above solution, the flow visualization device includes a dye and a flow visualization observation area. The dye is sent into the display observation area through a dye delivery device.

[0009] In the above solution, the scheme for the dye to enter the display observation area is as follows: The dye is stored in a pointed bottle. By squeezing the pointed bottle to generate high pressure, the dye in the pointed bottle is pressed into the capillary tube, and then the position of the capillary tube is moved to display the flow conditions in different areas.

[0010] In the above solution, the scheme for the dye to enter the display observation area is as follows: Determine the area to be observed in the closed flow channel. After drilling a hole on the outer surface of the closed flow channel, block it with a rubber plug. The syringe is inserted into the flow channel through the rubber plug, and the dye is injected into the closed flow channel to observe the flow conditions.

[0011] In the above solution, the scheme for the dye to enter the display observation area is as follows: Drill a hole at the steel structure part in the upstream of the closed flow channel and extend a steel elbow into the flow channel. Special through screws, nuts, and O-rings are used between the steel pipe and the pipe wall for fixing and sealing. A rubber tube is connected between the dye tank and the steel elbow. The dye in the dye tank enters the upstream of the flow channel due to gravity and then enters the display area.

[0012] The beneficial effects of the present invention are as follows: (1) The plexiglass sealing device of the present invention can effectively enable the pitot tube to enter the pipeline in the closed flow channel to measure the flow velocity distribution; (2) The surface transition adaptation section in the plexiglass sealing section is manufactured through the outer surface of the observation area, so the plexiglass sealing device has relatively low requirements for the surface of the measurement area; (3) The sealing device of the closed flow channel section of the present invention can effectively send the dye to the upstream of the flow visualization area, and the through screw section provided can effectively fix the steel elbow and rotate the flow direction of the dye to expand the flow visualization area; (4) In the velocity measurement distribution system of the present invention, a polycarbonate tube is used for connection between the handheld micro-manometer and the pitot tube to reduce the error caused by the pipeline; (5) The through screw adopts a stepped design, the aperture of the head is slightly larger than that of the O-ring, and the aperture of the rod part is smaller than that of the O-ring and larger than that of the steel elbow, avoiding the sealing failure caused by the detachment of the O-ring. Description of the Drawings

[0013] Figure 1 It is a schematic structural diagram of the flow visualization and velocity measurement system of the present invention.

[0014] Figure 2 Observation schematic diagram of the forebay of a model pump station with an open reservoir upstream.

[0015] Figure 3 Schematic diagram of the structure of a pointed bottle.

[0016] Figure 4 Observation schematic diagram of the flow pattern in the forebay of the intake basin of a model pump station with a closed culvert upstream.

[0017] Figure 5 Schematic diagram of the sealing structure at the steel elbow.

[0018] Figure 6 Schematic diagram of the bottom surface of the intake basin at the suction inlet and the pigment injection points.

[0019] Figure 7 Schematic diagram of the seal at the pigment injection points around the suction inlet.

[0020] Figure 8 Schematic diagram of the structure of the plexiglass sealing device.

[0021] Figure 9 Schematic diagram of the device for measuring the velocity distribution at the throat of the pump pipe. Detailed implementation manners

[0022] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and illustrated herein can be arranged and designed in various different configurations.

[0023] Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed present invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention. It should be noted that similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0024] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the invention product is customarily placed during use. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention. In addition, the terms "first", "second", etc. are only used for distinguishing descriptions and cannot be construed as indicating or implying relative importance.

[0025] As Figure 1 shown, a system applicable to flow visualization and velocity measurement in a closed channel in this embodiment is divided into two types of closed channels. One is that the upstream of the forebay of the model pumping station is an open reservoir, and the other is that the upstream of the forebay of the model pumping station is a closed culvert. The flow visualization methods in the two channels are only different in the forebay area, specifically including a flow visualization device 1 and a velocity measurement device 2.

[0026] As Figure 2 shown, when observing the flow pattern of the intake sump of the model pumping station with an open reservoir upstream of the forebay, fill the pointed bottle 3 with dye, squeeze the body of the pointed bottle 3, and the pigment enters the upstream of the intake sump of the pumping station through the capillary 4 from the outlet of the pointed bottle 3. Move the outlet of the capillary 4 to allow the dye to enter the forebay of the model pumping station evenly, so as to display the flow pattern of the forebay of the model pumping station.

[0027] As Figure 3 shown, the pointed bottle 3 is composed of a soft bottle body 3-1, a hose 3-2 in the bottle, a through-hole bottle cap 3-3, and a pointed elbow 3-4 extending out of the bottle mouth. The bottle cap 3-3 connects the hose 3-2 in the bottle and the pointed elbow 3-4 extending out of the bottle mouth. The soft bottle body 3-1 is suitable for squeezing to generate a pressure difference to push the dye in the bottle out. The pointed elbow 3-4 is connected to the capillary 4 and sealed with raw tape.

[0028] As Figure 4 shown, when observing the flow pattern of the intake sump of the model pumping station with a closed culvert upstream of the forebay, when performing flow visualization, open the valve 6 below the dye tank 5 to allow the dye to enter the rubber tube and enter the upstream of the forebay of the model pumping station through the steel elbow 7, so as to display the flow pattern of the forebay of the model pumping station.

[0029] As Figure 5 shown, the steel elbow 7 passes through the through-hole screw 8 and enters the closed culvert. The O-ring 8-1 inside the through-hole screw 8 is squeezed with the steel elbow 7 and the inner wall of the through-hole screw 8 to form a seal. The through-hole screw 8 plays a role in fixing the steel elbow 7, and after loosening the through-hole screw 8, the direction of the steel elbow 7 can be adjusted to allow the dye to fill the upstream of the forebay of the model pumping station.

[0030] As Figure 6As shown in the figure, before observing the wall-attached vortex around the suction inlet of the model pump station, it is necessary to appropriately transform the inside of the closed flow passage. The four injection points of the closed flow passage are generally the rear wall vortex observation injection point 9 at the junction of the axis of the pump port in the water flow direction and the rear wall, the left side wall vortex observation injection point 10 and the right side wall vortex observation injection point 11 where the center line of the pump port perpendicular to the water flow direction intersects the two side walls, and the bottom vortex observation injection point 12 at the bottom directly below the pump port.

[0031] As Figure 7 shown in the figure, when observing the vortex, the measuring points around the pump suction inlet are selected according to the standard "ANSI HI 9.8-2012". The measuring point borehole is a through hole that is relatively thin and allows the syringe needle 13 to pass through. The diameter of the through hole is slightly smaller than the diameter of the rubber plug 14 to facilitate the rubber plug to play a sealing role. The through hole is blocked with the rubber plug 14 and glue to enhance the strength of the rubber plug 14. The pigment is injected into the closed flow passage by the syringe 15 from the rubber plug 14. The sealing structure of the dye injection hole around the pump suction inlet is that the diameter of the injection hole is generally 10 mm, and the diameter of the rod part of the rubber plug is 10.5 mm to 11 mm. After drilling, the injection point is sealed with the rubber plug and glue.

[0032] As Figure 8 and Figure 9 shown in the figure, when measuring the velocity distribution at the throat of the pump pipe of the model pump station, before installing the plexiglass sealing device 16, first process the pipe wall, the outer shell of the model pump, and the wall surface of the flow passage to ensure that the pitot tube 17 can penetrate into the throat of the model pump pipe. To ensure the measurement accuracy, a rubber ring 19 can be installed on the long strip-shaped opening 18 on the inner wall of the pump pipe after inserting the pitot tube 17 to reduce the influence of the opening on the internal flow of the pipeline and enhance the measurement accuracy. The plexiglass sealing device 16 is bonded at the opening of the sealing section with special plexiglass glue. A hole is drilled in the sealing rubber ring 19, and the diameter of the hole is slightly smaller than the diameter of the pitot tube. The sealing rubber ring 19 is tightly pressed against the plexiglass block in the transition section through the fixed cover plate 20 to form a sealing effect. When measuring the velocity distribution at the throat of the pump pipe of the model pump station, the pitot tube 17 extends into the interior of the model pump pipe. The pitot tube 17 is placed in the pump pipe so that the tube axis is consistent with the direction of the air flow, and the leading edge of the tube faces the oncoming flow. The static pressure port 17-1 and the dynamic pressure port 17-2 of the pitot tube 17 are respectively connected to the hand-held micro-pressure gauge sensor 22 through the polycarbonate tube 21, and the pressure is transmitted to the hand-held micro-pressure gauge sensor 22. The hand-held micro-pressure gauge sensor 22 obtains the dynamic pressure through the difference between the total pressure and the static pressure, and then through the Bernoulli equation

[0033]

[0034] In the formula

[0035] p1 is the pressure measured by the total pressure hole;

[0036] p2 is the pressure measured by the static pressure hole;

[0037] v1 is the flow velocity at the total pressure orifice;

[0038] v2 is the flow velocity at the static pressure orifice;

[0039] h1 is the elevation at the total pressure orifice;

[0040] h2 is the elevation at the static pressure orifice;

[0041] ρ is the fluid density;

[0042] g is the acceleration due to gravity;

[0043] Ignoring the height difference between the static pressure orifice and the total pressure orifice, the flow velocity v1 at the total pressure orifice is zero. Simplifying the equation gives:

[0044]

[0045] (p1 - p2) is the pressure difference measured by the sensor of the handheld differential pressure gauge. The velocity of the measured point is obtained through the above formula. By adjusting the extended part of the Pitot tube, the velocity distribution on a straight line at the throat is obtained. After stopping the machine, by adjusting the flange, the measurement direction of the Pitot tube is changed, and then the velocity distributions of different centerlines of the cross-section of the throat of the model pump pipe are measured, so as to obtain the velocity distribution of the entire throat interface.

[0046] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be within the protection scope of the present invention.

Claims

1. A system applicable to flow visualization and velocity measurement in a closed flow channel, comprising a flow visualization device and a velocity measurement device, characterized in that, The speed measurement device includes a handheld manometer, a Pitot tube, and an acrylic glass sealing device located outside the pump pipe. The acrylic glass sealing device includes a wall surface transition adaptation section, a sealing rubber ring, and a fixed cover plate. One end of the Pitot tube is located at the throat of the pump pipe, and the other end is connected to the handheld manometer. To ensure the measurement accuracy, after installing the Pitot tube (17), a sealing rubber ring (19) is installed on the long strip-shaped opening (18) on the inner wall of the pump pipe to reduce the influence of the opening on the internal flow of the pipe and enhance the measurement accuracy. The acrylic glass sealing device (16) is bonded to the opening of the sealing section of the long strip-shaped opening (18) with special acrylic glass glue. A hole is drilled in the sealing rubber ring (19) with a diameter smaller than the diameter of the Pitot tube. The sealing rubber ring (19) is tightly pressed against the acrylic glass block of the wall surface transition adaptation section through the fixed cover plate (20) to form a sealing effect. The handheld manometer is set separately and is used to collect pressure signals. The Pitot tube transmits the pressure signals generated by its static pressure hole and total pressure hole to the handheld manometer, and the flow velocity v2 at the static pressure hole at the throat of the pump pipe where the Pitot tube is located is calculated through formula (2); Where: p1 is the pressure measured by the total pressure hole; p2 is the pressure measured by the static pressure hole; v2 is the flow velocity at the static pressure hole; ρ is the fluid density.

2. The system for flow visualization and velocity measurement applicable to a closed flow channel according to claim 1, wherein The flow display device includes a dye and a flow display observation area, and the dye is sent into the display observation area through a dye delivery device.

3. The system for flow visualization and velocity measurement applicable to a closed flow channel according to claim 2, wherein The scheme for the dye to enter the display observation area is as follows: The dye is stored in a pointed bottle, and the dye in the pointed bottle is pressed into the capillary by generating high pressure through squeezing the pointed bottle, and then the flow conditions in different areas are displayed by moving the position of the capillary.

4. A system for flow visualization and velocity measurement in a closed flow channel according to claim 2, wherein, The scheme for the dye to enter the display observation area is as follows: Determine the area to be observed in the closed flow channel. After drilling a hole on the outer surface of the closed flow channel, block it with a rubber plug. The syringe is inserted into the flow channel through the rubber plug, and the dye is injected into the closed flow channel to observe the flow conditions.

5. A system for flow visualization and velocity measurement in a closed channel according to claim 2, wherein, The scheme for the dye to enter the display observation area is as follows: Drill a hole in the steel structure at the upstream part of the closed flow channel and insert a steel elbow into the flow channel. Special through screws, nuts, and O-rings are used to fix and seal between the steel pipe and the pipe wall. A rubber tube is connected between the dye tank and the steel elbow. The dye in the dye tank enters the upstream of the flow channel due to the action of gravity and then enters the display area.

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