Pump station forebay vortex experiment system and method for measuring suction rate of suction vortex

Abstract

The invention discloses a pump station forebay vortex experiment system and a method for measuring the air suction rate of an air suction vortex in the field of water conservancy projects. The system comprises a forebay device; the water level adjusting device is used for adjusting the water level at the water inlet of the forebay device; the rectifying device is used for guiding water flow to be deflected to the horizontal direction and eliminating water surface fluctuation; the vortex display and shooting auxiliary device is used for releasing a dyeing tracer agent to the water body in the forebay device and acquiring an image at the water outlet of the forebay device; the gas collecting device comprises three gas collecting pipes, bubble collecting mechanisms are arranged at the bottoms of the gas collecting pipes, exhaust valves are arranged at the tops of the gas collecting pipes, and volume scale marks and volume scale values are arranged on the pipe walls; the pump and pipeline device is used for communicating the forebay device, the gas collecting device and the water level adjusting device to form a circulation loop; and the information acquisition device is used for acquiring and recording the pressure intensity of the gas in the gas collection device and the liquid flow in the pipeline device at different acquisition times. The water level of the forebay can be stably adjusted, the air suction rate can be accurately measured, and underwater vortexes can be reliably observed.

Description

Technical Field

[0001] The invention belongs to the technical field of water conservancy projects, and in particular relates to a vortex experimental system for a pump station forebay and a method for measuring an air suction rate of an air suction vortex. Background Art

[0002] The forebay is one of the important hydraulic structures in the pump station project, which affects the safe operation of the entire pump station project. Due to the changes in the water level and flow rate of the pump station and the unreasonable design of the forebay, vortices in the forebay are often difficult to avoid, and these vortices will seriously affect the stable operation of the pump station. The vortices in the forebay include two categories: surface vortices and underwater vortices, which are the focus of attention and research by scientific research and engineering and technical personnel. The existing forebay experimental system is imperfect, mainly reflected in: (1) During the experiment, the water level is difficult to stabilize; (2) When the surface vortex sucks air to form an intake vortex, it is difficult to accurately capture and measure the rate of inhaled gas; (3) The underwater vortex is difficult to observe. Summary of the invention

[0003] The purpose of the present invention is to provide a vortex experimental system for a pump station forebay and a method for measuring the air suction rate of an air suction vortex, which can stably adjust the water level of the forebay, accurately measure the air suction rate and reliably observe the underwater vortex.

[0004] In order to achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a vortex experimental system for a forebay of a pump station, comprising: a forebay device; a water level regulating device, used to regulate the water level height at the water inlet of the forebay device; a rectifying device, used to guide the water flow to turn to the horizontal direction and eliminate water surface fluctuations; a vortex display and shooting auxiliary device, used to release dye tracers into the water body in the forebay device and obtain an image at the water outlet of the forebay device; an air collecting device, comprising an air collecting pipe 1, an air collecting pipe 2 and an air collecting pipe 3, wherein the bottoms of the air collecting pipes 1, 2 and 3 are all provided with bubble collection mechanisms, the tops are all provided with exhaust valves, and the tube walls are all provided with volume scale lines and volume scale values ​​from bottom to top; a pump and pipeline device, used to connect the forebay device, the air collecting device and the water level regulating device to form a circulation loop; an information acquisition device, used to acquire and record the pressure of the gas in the air collecting device and the liquid flow in the pump and pipeline device at different acquisition times.

[0005] Compared with the prior art, the beneficial effects of the present invention are as follows: the height of the water level in the forebay device can be quickly and stably adjusted through the water level regulating device, thereby avoiding water waste caused by overflow due to excessively high water level in the forebay, and also avoiding the phenomenon of inaccurate observation data due to excessively low water level in the forebay; the rectifying device is used to ensure that the water inlet of the forebay device and its flow channel have a good water flow state, so that the overall system can operate stably and efficiently; the vortex display and shooting auxiliary device is used to simulate the motion trajectory of the surface vortex and the underwater vortex and the acquired image with the motion trajectory of the dye tracer, which is convenient for the experimenter to observe intuitively on the one hand, and to monitor the surface vortex and the underwater vortex in real time on the other hand; the gas collecting device and the information acquisition device are used to provide an accurate data basis for calculating the rate of inhaled gas; the pump and pipeline device can realize the recycling of experimental water, save energy and protect the environment, and reduce experimental costs.

[0006] As a further improvement of the technical solution of the present invention, the front pool device includes an inlet pool bottom, a front pool slope, an outlet pool bottom, a front side plate, a rear side plate, a left side plate, a right side plate and a top plate, the inlet pool bottom is provided with an inlet hole, the front side plate is provided with a water replenishment port, the outlet pool bottom is provided with a drain valve, and the rear side plate is provided with an outlet hole. The device has a compact structure and reduces the space occupied by the experiment.

[0007] As a further improvement of the technical solution of the present invention, the bottom of the water outlet pool, the left side plate and the right side plate are all made of acrylic material. The fore pool device made of acrylic not only facilitates personnel to directly observe the real-time state of the water level and the vortex, but also has non-fragile and good impact resistance, ensuring the safety of the experimenters.

[0008] As a further improvement of the technical solution of the present invention, the water level regulating device includes a water tank, a submersible pump is arranged in the water tank, and the output end of the submersible pump is connected to the water inlet of the fore pool device through a hose. The submersible pump is small in size and light in weight, so it is easy to transport and install, saving land and experimental costs.

[0009] As a further improvement of the technical solution of the present invention, the rectifying device comprises a rectifying plate 1, a rectifying grid and a rectifying plate 2 which are arranged in sequence, the rectifying grid and the bottom of the water inlet pool are arranged perpendicular to each other, the rectifying plate 1 is rotatably connected to the front side plate through a telescopic rod, the rectifying plate 2 is connected to the top plate through a fixing rod, and a rotatable fixing clamp is arranged on the fixing rod for fixing the rectifying plate 2 and adjusting the angle of the rectifying plate 2 relative to the top plate. The rectifying plate 1 can guide the water flow to bend to the horizontal direction to reduce the water surface fluctuation, and the rectifying plate 2 can eliminate the water surface fluctuation behind the rectifying grid.

[0010] As a further improvement of the technical solution of the present invention, the vortex display and shooting auxiliary device includes an instrument box arranged at the water outlet of the fore pool device, wherein a camera and a paint injector are arranged in the instrument box, wherein the output end of the paint injector is connected to the fore pool device, and the input end is connected to the paint delivery pipe, and the input end of the paint delivery pipe passes through and extends out of the instrument box. By installing the camera and the paint injector at the water outlet of the fore pool device, the underwater vortex and the suction vortex morphology can be obtained in time, which is convenient for subsequent analysis.

[0011] As a further improvement of the technical solution of the present invention, the bubble collection mechanism includes a fixed plate, a lifting plate, two mirror-distributed traction plates and two symmetrically distributed slide plates. The upper sides of the two traction plates are slidably connected to the fixed plate, and the lower sides are respectively hinged to the two sides of the lifting plate. A fixed round rod is provided at the center of the upper side of the lifting plate, and a baffle is provided on the lower side of the lifting plate. The upper sides of the two slide plates are respectively slidably connected to the corresponding traction plates, and the lower sides are rotatably connected to the fixed round rod; four springs symmetrically distributed in a rectangular shape are provided between the lifting plate and the fixed plate. The flow area in the pipeline device is adjusted by adjusting the height of the lifting plate, so that the bubbles in the water body can enter the gas collecting pipe to the greatest extent, thereby ensuring the accuracy of the experimental data.

[0012] As a further improvement of the technical solution of the present invention, the fixed plate is provided with two slide rails distributed at intervals, the upper side of the traction plate is provided with two pulleys distributed at intervals, the two pulleys are respectively connected to the corresponding slide rails in a rolling manner, the ends of the fixed round rods are provided with bolts, a slide groove is provided at the center of the traction plate, a slider is provided at the top of the traction plate, and the slider is connected to the slide groove in a sliding manner, so that personnel can quickly adjust the lifting plate.

[0013] As a further improvement of the technical solution of the present invention, the cross-sectional area of ​​the gas collecting pipe 2 is 1.5-2 times the cross-sectional area of ​​the gas collecting pipe 1 and the gas collecting pipe 3. The bubbles in the water body are mainly collected by the gas collecting pipe 2, but some bubbles move upstream under the action of buoyancy. At this time, the gas collecting pipe 1 set on the upstream side collects these bubbles, while the other part of the bubbles moves rapidly to the downstream with the water flow and is not collected by the gas collecting pipe 2 in time. At this time, the gas collecting pipe 3 set on the downstream side collects these bubbles, which can increase the amount of bubbles collected.

[0014] As a further improvement of the technical solution of the present invention, the information collection device includes a pressure sensor arranged on the gas collecting device and an electromagnetic flowmeter arranged on the pump and pipeline device, the pressure sensor is electrically connected to the collection box, and the collection box is electrically connected to the computer.

[0015] As a further improvement of the technical solution of the present invention, the pump and pipeline device includes a circulation pipeline, a butterfly valve and an auxiliary pump, the butterfly valve and the auxiliary pump are arranged on the circulation pipeline at intervals, the input end of the circulation pipeline is connected to the water outlet of the forebay device, and the output end is connected to the water inlet of the forebay device. The liquid flow in the circulation pipeline is adjusted by the butterfly valve to ensure stable operation of the system.

[0016] The present invention also provides a method for measuring the suction rate of the suction vortex in the vortex experimental system of the pump station forebay, comprising the following steps:

[0017] Step 1: To measure the amount of air inhaled, use the definition of the air inhalation rate:

[0018]

[0019] Where: β is the air absorption rate; Q a is the air flow rate, m 3 / s;Q w is the liquid flow rate, m 3 / s;

[0020] Step 2: Calculate Q by the accumulated gas mass in a single gas collecting pipe per unit time a According to the ideal gas state equation, the mass calculation formula of the collected gas in the gas collection device over a period of time is derived:

[0021]

[0022] Where: p0 is the gas pressure at the initial moment; V0 is the gas volume in the gas collecting pipe at the initial moment. The height of the gas column is obtained by observing the scale on the gas collecting pipe, and then multiplied by the cross-sectional area A of the gas collecting pipe; A is the cross-sectional area of ​​the gas collecting pipe; ρ w is the density of water; Δp is the change in gas pressure within a certain period of time; M is the molar mass of air; R is the gas constant; T is the gas temperature;

[0023] Step 3: Measure the three gas collecting pipes respectively to obtain the total mass ∑Δm of the collected gas over a period of time. The gas flow rate is finally calculated by the following formula:

[0024]

[0025] Where: a,0 is the density of air at room temperature and one atmosphere of pressure. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the three-dimensional structure of the system of the present invention.

[0027] Figure 2 It is a side view of the system of the present invention.

[0028] Figure 3 A top view of the system of the present invention.

[0029] Figure 4 It is a schematic diagram of the three-dimensional structure of the bubble collection mechanism of the present invention.

[0030] Among them, 1 front pool device, 101 water inlet pool bottom, 102 front pool slope, 103 water outlet pool bottom, 104 front side plate, 105 rear side plate, 106 left side plate, 107 right side plate, 108 top plate, 109 drain valve, 2 water level regulating device, 201 water tank, 202 submersible pump, 203 hose, 3 rectifier device, 301 rectifier plate 1, 302 rectifier grid, 303 rectifier plate 2, 304 fixing rod, 5 vortex display and shooting auxiliary device, 501 instrument box, 502 paint injector, 503 paint delivery pipe, 6 Gas collecting device, 601 gas collecting pipe one, 602 gas collecting pipe two, 603 gas collecting pipe three, 604 exhaust valve, 605 fixed plate, 606 lifting plate, 607 traction plate, 608 slide plate, 609 fixed round rod, 610 baffle, 611 spring, 612 slide rail, 613 pulley, 614 slide groove, 615 bolt, 7 pump and pipeline device, 701 circulation pipeline, 702 butterfly valve, 703 auxiliary pump, 8 information collection device, 801 pressure sensor, 802 electromagnetic flowmeter, 803 collection box, 804 computer. DETAILED DESCRIPTION

[0031] like Figure 1-3 As shown, the pump station forebay vortex experimental system includes: a forebay device 1; a water level regulating device 2, used to adjust the water level at the water inlet of the forebay device 1; a rectifying device 3, used to guide the water flow to bend to the horizontal direction and eliminate the water surface fluctuation; a vortex display and shooting auxiliary device 5, used to release the dye tracer into the water body in the forebay device 1 and obtain the image at the water outlet of the forebay device 1; an air collecting device 6, including an air collecting pipe 1 601, an air collecting pipe 2 602 and an air collecting pipe 3 603, and the air collecting pipe 1 601, the air collecting pipe 2 602 and the air collecting pipe 3 603 are connected to the forebay device 1. 3 are all provided with a bubble collecting mechanism at the bottom, and an exhaust valve 604 is provided at the top. Volume scale lines and volume scale values ​​are provided on the tube wall from bottom to top. The cross-sectional area of ​​the gas collecting pipe 2 602 is preferably 1.75 times the cross-sectional area of ​​the gas collecting pipe 1 601 and the gas collecting pipe 3 603; the pump and pipeline device 7 is used to connect the forebay device 1, the gas collecting device 6 and the water level regulating device 2 to form a circulation loop; the information collection device 8 is used to obtain and record the pressure of the gas in the gas collecting device 6 and the liquid flow in the pump and pipeline device 7 at different collection times.

[0032] In this embodiment, the front pool device 1 includes an inlet pool bottom 101, a front pool slope 102, an outlet pool bottom 103, a front side plate 104, a rear side plate 105, a left side plate 106, a right side plate 107 and a top plate 108. The inlet pool bottom 101 is provided with a water inlet hole, the front side plate 104 is provided with a water replenishment port, the outlet pool bottom 103 is provided with a drain valve 109, and the rear side plate 105 is provided with a water outlet hole. Preferably, the outlet pool bottom 103, the left side plate 106 and the right side plate 107 are all made of acrylic material; the water level regulating device 2 includes A water tank 201 is provided with a submersible pump 202, and the output end of the submersible pump 202 is connected to the water supply port through a hose 203; the rectifying device 3 includes a rectifying plate 1 301, a rectifying grid 302 and a rectifying plate 2 303 arranged in sequence along the water flow direction, the rectifying grid 302 and the water inlet pool bottom 101 are arranged perpendicular to each other, the rectifying plate 1 301 is rotatably connected to the front side plate 104 through a telescopic rod, the rectifying plate 2 303 is connected to the top plate 108 through a fixing rod 304, and a rotatable fixing clamp is provided on the fixing rod 304 for fixing the rectifying plate The vortex display and shooting auxiliary device 5 includes an instrument box 501 arranged at the lower side of the water outlet of the front pool device 1, and a camera and a paint injector 502 are arranged in the instrument box 501. The output end of the paint injector 502 is connected to the front pool device 1, and the input end is connected to the paint delivery pipe 503. The input end of the paint delivery pipe 503 passes through and extends out of the instrument box 501; the pump and pipeline device 7 includes a circulation pipeline 701, a butterfly valve 702 and an auxiliary pump 703, the butterfly valve 702 and Auxiliary pumps 703 are arranged at intervals on the circulation pipe 701. The auxiliary pumps 703 are preferably pipeline centrifugal pumps. The input end of the circulation pipe 701 is connected to the water outlet of the front pool device 1, and the output end is connected to the water inlet of the front pool device 1; the information collection device 8 includes three pressure sensors 801 arranged on the top of the gas collecting pipe 1 601, the gas collecting pipe 2 602 and the gas collecting pipe 3 603, and an electromagnetic flowmeter 802 arranged on the circulation pipe 701, the pressure sensor 801 is electrically connected to the collection box 803, and the collection box 803 is electrically connected to the computer 804.

[0033] Below through Figure 4The bubble collecting mechanism is described in detail, including a fixed plate 605, a lifting plate 606, two traction plates 607 distributed in a mirror image, and two slide plates 608 distributed symmetrically with each other; the upper sides of the two traction plates 607 are slidably connected to the fixed plate 605, and the lower sides are hinged to the two sides of the lifting plate 606 through hinges; a fixed round rod 609 is connected to the center of the upper side of the lifting plate 606 through screws, and a baffle 610 is arranged on the lower side of the lifting plate 606; the upper sides of the two slide plates 608 are slidably connected to the corresponding traction plates 607, and the lower sides are hinged to the fixed plate 605 through hinges. The fixed round rod 609 is rotatably connected; four springs 611 symmetrically distributed in a rectangular shape are arranged between the lifting plate 606 and the fixed plate 605; specifically, two spaced-apart slide rails 612 are arranged on the fixed plate 605, and two spaced-apart pulleys 613 are arranged on the upper side of the traction plate 607, and the two pulleys 613 are respectively rollingly connected with the corresponding slide rails 612; a slide groove 614 is opened at the center of the traction plate 607, and a slider is arranged on the top of the traction plate 607, and the slider is slidably connected to the slide groove 614; a bolt 615 is arranged at the end of the fixed round rod 609.

[0034] Since the bubbles are balanced under the condition of low flow rate in the circulation pipe 701, they cannot float up into the gas collecting pipe. In order to increase the flow rate and make them float, a bubble collecting mechanism is used. When the flow rate is low, the lifting plate 606 is adjusted to be lowered to reduce the flow area in the pipe, accelerate the local flow rate in the pipe directly below the gas collecting pipe, and make the bubbles float up into the gas collecting pipe. When the flow rate is high, the lifting plate 606 is adjusted to be close to the fixed plate 605, and the pipe is restored to its original diameter. The two traction plates 607 can realize the rise and fall of the lifting plate 606 by tightening and loosening the slide plate 608, the fixed round rod 609 and the bolt 615. The springs 611 set on the four corners of the lifting plate 606 make it still balanced under the scouring of water flow. The baffle 610 set on the downstream side of the lifting plate 606 can intercept the bubbles flowing downstream, so that as many bubbles as possible can be collected by the gas collecting pipe.

[0035] The present invention also provides a method for measuring the suction rate of the suction vortex in the vortex experimental system of the pump station forebay, comprising the following steps:

[0036] Step 1: To measure the amount of air inhaled, use the definition of the air inhalation rate:

[0037]

[0038] Where: β is the air absorption rate; Q a is the air flow rate, m 3 / s;Q w is the liquid flow rate, m 3 / s, measured by electromagnetic flowmeter;

[0039] Step 2: Calculate Q by the accumulated gas mass in a single gas collecting pipe per unit timea According to the ideal gas state equation, the mass calculation formula of the collected gas in the gas collection device over a period of time is derived:

[0040]

[0041] Where: p0 is the gas pressure at the initial moment; V0 is the gas volume in the gas collecting pipe at the initial moment. The height of the gas column is obtained by observing the scale on the gas collecting pipe, and then multiplied by the cross-sectional area A of the gas collecting pipe; A is the cross-sectional area of ​​the gas collecting pipe; ρ w is the density of water, and you can query the density of water at the corresponding temperature and atmospheric pressure; Δp is the change in gas pressure within a certain period of time; M is the molar mass of air; R is the gas constant; T is the gas temperature;

[0042] Step 3: Measure the three gas collecting pipes respectively to obtain the total mass ∑Δm of the collected gas over a period of time. The gas flow rate is finally calculated by the following formula:

[0043]

[0044] Where: a,0 is the density of air at room temperature and one atmosphere of pressure.

[0045] The present invention is not limited to the above-mentioned embodiments. On the basis of the technical solution disclosed in the present invention, technicians in this field can make some substitutions and deformations to some technical features therein according to the disclosed technical content without creative labor, and these substitutions and deformations are all within the protection scope of the present invention.

Claims

1. Pump station forebay vortex experimental system, characterized by: include: Forebay device; A water level regulating device, used for regulating the water level at the water inlet of the forebay device; A straightening device is used to guide the water flow to the horizontal direction and eliminate the fluctuation of the water surface; A vortex display and photography auxiliary device, used for releasing dye tracers into the water in the forebay device and obtaining an image at the water outlet of the forebay device; The gas collecting device comprises a gas collecting pipe 1, a gas collecting pipe 2 and a gas collecting pipe 3, wherein the gas collecting pipe 1, the gas collecting pipe 2 and the gas collecting pipe 3 are all provided with a bubble collecting mechanism at the bottom, an exhaust valve at the top, and volume scale lines and volume scale values ​​are all provided on the pipe walls from bottom to top; A pump and pipeline device, used to connect the forebay device, the air collecting device and the water level regulating device to form a circulation loop; The information collection device is used to obtain and record the gas pressure in the gas collection device and the liquid flow in the pump and pipeline device at different collection times.

2. The pump station forebay vortex experimental system according to claim 1, characterized in that: The front pool device includes an inlet pool bottom, a front pool slope, an outlet pool bottom, a front side plate, a rear side plate, a left side plate, a right side plate and a top plate. The inlet pool bottom is provided with an inlet hole, the front side plate is provided with a water replenishment port, the outlet pool bottom is provided with a drain valve, and the rear side plate is provided with an outlet hole.

3. The pump station forebay vortex experimental system according to claim 1, characterized in that: The water level regulating device comprises a water tank, a submersible pump is arranged in the water tank, and the output end of the submersible pump is connected with the water inlet of the front pool device through a hose.

4. The pump station forebay vortex experimental system according to claim 2, characterized in that: The rectifying device comprises a rectifying plate 1, a rectifying grid and a rectifying plate 2 which are arranged in sequence. The rectifying grid and the bottom of the water inlet pool are arranged perpendicular to each other. The rectifying plate 1 is rotatably connected to the front side plate through a telescopic rod. The rectifying plate 2 is connected to the top plate through a fixing rod. A rotatable fixing clamp is arranged on the fixing rod for fixing the rectifying plate 2 and adjusting the angle of the rectifying plate 2 relative to the top plate.

5. The pump station forebay vortex experimental system according to claim 1, characterized in that: The vortex display and shooting auxiliary device includes an instrument box arranged at the water outlet of the front pool device, and a camera and a paint injector are arranged in the instrument box. The output end of the paint injector is connected to the front pool device, and the input end is connected to the paint delivery pipe. The input end of the paint delivery pipe passes through and extends out of the instrument box.

6. The pump station forebay vortex experimental system according to claim 1, characterized in that: The bubble collection mechanism includes a fixed plate, a lifting plate, two traction plates distributed in a mirror image and two slide plates distributed symmetrically to each other. The upper sides of the two traction plates are slidably connected to the fixed plate, and the lower sides are respectively hinged to the two sides of the lifting plate. A fixed round rod is arranged at the center of the upper side of the lifting plate, and a baffle is arranged on the lower side of the lifting plate. The upper sides of the two slide plates are respectively slidably connected to the corresponding traction plates, and the lower sides are both rotatably connected to the fixed round rod; four springs distributed symmetrically in a rectangular shape are arranged between the lifting plate and the fixed plate.

7. The pump station forebay vortex experimental system according to claim 1, characterized in that: The cross-sectional area of ​​the gas collecting pipe 2 is 1.5-2 times of the cross-sectional area of ​​the gas collecting pipe 1 and the gas collecting pipe 3.

8. The pump station forebay vortex experimental system according to claim 1, characterized in that: The information collection device includes a pressure sensor arranged on the gas collection device and an electromagnetic flowmeter arranged on the pump and pipeline device. The pressure sensor is electrically connected to a collection box, and the collection box is electrically connected to a computer.

9. The pump station forebay vortex experimental system according to claim 1, characterized in that: The pump and pipeline device includes a circulation pipeline, a butterfly valve and an auxiliary pump. The butterfly valve and the auxiliary pump are arranged on the circulation pipeline at intervals. The input end of the circulation pipeline is connected to the water outlet of the fore pool device, and the output end is connected to the water inlet of the fore pool device.

10. The method for measuring the suction rate of the suction vortex in the vortex experimental system of the pump station forebay according to any one of claims 1 to 9, characterized in that: The following steps are involved: Step 1: To measure the amount of air inhaled, use the definition of the air inhalation rate: Where: β is the air absorption rate; Q a is the air flow rate, m 3 / s;Q w is the liquid flow rate, m 3 / s; Step 2: Calculate Q by the accumulated gas mass in a single gas collecting pipe per unit time a According to the ideal gas state equation, the mass calculation formula of the collected gas in the gas collection device over a period of time is derived: Where: p0 is the gas pressure at the initial moment; V0 is the gas volume in the gas collecting pipe at the initial moment. The height of the gas column is obtained by observing the scale on the gas collecting pipe, and then multiplied by the cross-sectional area A of the gas collecting pipe; A is the cross-sectional area of ​​the gas collecting pipe; ρ w is the density of water; Δp is the change in gas pressure within a certain period of time; M is the molar mass of air; R is the gas constant; T is the gas temperature; Step 3: Measure the three gas collecting pipes respectively to obtain the total mass ∑Δm of the collected gas over a period of time. The gas flow rate is finally calculated by the following formula: Where: a,0 is the density of air at room temperature and one atmosphere of pressure.

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