A portable flowmeter based on numerical simulation and pressure sensors

Abstract

The present invention provides a portable flow velocity meter based on numerical simulation and pressure sensors, which includes a flow velocity sensing device. The flow velocity sensing device includes a first cone as the upstream-facing part and a second cone as the downstream-facing part. The bottoms of the first cone and the second cone are buckled together, and they are of the same size and material. The flow velocity sensing device is obtained based on Fluent numerical simulation. The pressure output by the flow velocity sensing device is amplified and transmitted to the pressure sensing device through the pressure transmission device. The pressure sensing device is used to receive the pressure signal transmitted by the pressure transmission device and convert it into a resistance signal. The resistance measurement circuit converts the resistance signal of the pressure sensing device into a voltage signal and visually outputs it by the digital voltmeter. The flow velocity meter of the present invention can directly measure the instantaneous flow velocity, ensure high measurement accuracy, and has an adjustable lever coefficient, maximizing the range of the flow velocity meter. The flow velocity meter is small in size and light in weight, making it convenient to carry.

Description

Technical Field

[0001] The present invention relates to the technical field of flow velocity detection, and in particular to a portable flow velocity meter based on numerical simulation and pressure sensors. Background Art

[0002] Existing flow velocity meters and flow velocity measurement technologies are diverse, but most of them calculate and analyze a physical process after the fluid completes it to give the average flow velocity during the process. It is difficult to complete the measurement in the case where the fluid flow velocity changes frequently and the instantaneous requirement for flow velocity measurement is high.

[0003] Currently, the acoustic flow velocity instruments used in scientific research work are complex in components and operation and inconvenient to carry; the most common rotor flow velocity meters on the market are costly, which causes great limitations to the flow velocity measurement in daily life and inspection work.

[0004] The pressure sensor flow velocity meters in the prior art have low measurement accuracy, are difficult to measure low-speed water flows, and are difficult to accurately measure high-speed water flows. Summary of the Invention

[0005] The purpose of the present invention is to provide a portable flow velocity meter based on numerical simulation and pressure sensors, which can directly measure the instantaneous flow velocity, ensure high measurement accuracy, and has an adjustable lever coefficient to maximize the range of the flow velocity meter.

[0006] An embodiment of the present invention provides a portable flow velocity meter based on numerical simulation and pressure sensors, and the flow velocity meter includes:

[0007] A flow velocity sensing device, which includes a first cone as the upstream part and a second cone as the downstream part. The bottoms of the first cone and the second cone are buckled, and they are the same in size and material; the flow velocity sensing device is obtained based on Fluent numerical simulation;

[0008] A pressure transmission device, which amplifies and transmits the pressure output by the flow velocity sensing device to a pressure sensing device;

[0009] A pressure sensing device, which is used to receive the pressure signal transmitted by the pressure transmission device and convert it into a resistance signal;

[0010] A voltage output device, which is arranged on the bottom plate. The resistance measurement circuit converts the resistance signal of the pressure sensing device into a voltage signal and visually outputs it by the digital voltmeter.

[0011] Optionally, when the flow velocity sensing device is in water, the line connecting the vertices of the two cones is consistent with the water flow direction, and the upstream part receives the impact of the water flow.

[0012] Optionally, the pressure transmission device includes:

[0013] An underwater transfer rod, which is connected to the flow velocity sensing device;

[0014] An above-water transfer rod, one end of the above-water transfer rod is connected to the underwater transfer rod;

[0015] A shifting component, which is used for the conversion between high speed gear and low speed gear;

[0016] A pressing part, which includes a first rod connected to one end of the above-water transfer rod, and a second rod transversely configured to connect the first rod.

[0017] Optionally, the shifting component includes:

[0018] A bearing, which is arranged on the bottom plate;

[0019] A fixed pin, and a steel ball with one side hollowed out. The above-water transfer rod is inserted into the bearing through the perforation of the fixed pin and fixed by the steel ball.

[0020] Optionally, the pressure transfer device further includes:

[0021] A sensor protection part, which is configured at both ends of the second rod.

[0022] Optionally, the pressure transfer device is a thin-film pressure sensor.

[0023] Optionally, the voltage output device includes:

[0024] A resistance measuring circuit, a circuit box, a circuit switch, a digital voltmeter,

[0025] wherein, the circuit box is an airtight plastic square box, which contains most of the wires in the resistance measuring circuit, the circuit switch and the digital voltmeter are placed outside the circuit box, and the circuit box can slide up and down through the slideway on the bottom plate.

[0026] Optionally, the resistance measuring circuit includes:

[0027] A power supply, a fixed-value resistor, a thin-film pressure sensor, a voltmeter,

[0028] The fixed-value resistor is connected in parallel with the voltmeter and then connected in series with the thin-film pressure sensor, and the power supply includes a voltage boost conversion module.

[0029] Optionally, the current meter further includes:

[0030] A fixing component, which includes three rotatable triangular bodies arranged at equal distances on the bottom plate, and two of them act together to fix the circuit box and keep the thin-film pressure sensor in contact with the second rod.

[0031] Optionally, the current meter further includes:

[0032] A bubble ball, which is a transparent glass water ball containing small bubbles. When the flow velocity meter is properly positioned, the small bubbles are located at the top of the glass ball to adjust the proper orientation of the flow velocity meter.

[0033] A bracket that adjusts the bracket according to the indication of the bubble ball.

[0034] Advantageous effects

[0035] The present invention provides a portable flow velocity meter based on numerical simulation and pressure sensors, including a flow velocity sensing device, which includes a first cone as the upstream-facing part and a second cone as the downstream-facing part. The bottoms of the first cone and the second cone are buckled together and have the same size and material. The flow velocity sensing device is obtained based on Fluent numerical simulation. The pressure output by the flow velocity sensing device is amplified and transmitted to the pressure sensing device through the pressure transmission device. The pressure sensing device is used to receive the pressure signal transmitted by the pressure transmission device and convert it into a resistance signal. The resistance measurement circuit converts the resistance signal of the pressure sensing device into a voltage signal and visualizes and outputs it by the digital voltmeter. It can directly measure the instantaneous flow velocity, ensure high measurement accuracy, and the lever coefficient is adjustable, maximizing the range of the flow velocity meter. The flow velocity meter is small in size and light in weight, making it convenient to carry. Description of the drawings

[0036] In order to more clearly illustrate the technical solutions in one or more embodiments of this specification or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments recorded in this specification. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0037] Figure 1 It is a schematic structural diagram of the flow velocity sensing device in a portable flow velocity meter based on numerical simulation and pressure sensors according to an embodiment of the present invention;

[0038] Figure 2 It is a schematic structural diagram of the pressure transmission device in a portable flow velocity meter based on numerical simulation and pressure sensors according to an embodiment of the present invention;

[0039] Figure 3 It is a front view of the pressure transmission device in a portable flow velocity meter based on numerical simulation and pressure sensors according to an embodiment of the present invention;

[0040] Figure 4 It is a right view of the pressure transmission device in a portable flow velocity meter based on numerical simulation and pressure sensors according to an embodiment of the present invention;

[0041] Figure 5 Schematic three - dimensional structure diagram of a portable flow velocity meter based on numerical simulation and pressure sensors according to an embodiment of the present invention;

[0042] Figure 6 Left view and right view of a portable flow velocity meter based on numerical simulation and pressure sensors according to an embodiment of the present invention;

[0043] Figure 7 Resistance measurement circuit diagram of the voltage output device of a portable flow velocity meter based on numerical simulation and pressure sensors according to an embodiment of the present invention;

[0044] Figure 8 Schematic three - dimensional structure diagram of a portable flow velocity meter based on numerical simulation and pressure sensors according to an embodiment of the present invention.

[0045] In the figure: 1, flow velocity sensing device; 2, underwater transfer rod; 3, above - water transfer rod; 4, fixed needle; 5, steel ball; 8, bearing; 9, pressure - applying device; 91, first rod; 92, second rod; 10, sensor protection part; 12, circuit box; 13, circuit switch; 14, slideway; 15, circuit box fixing device; 16, bottom plate; 17, bubble ball; 18, digital voltmeter; 19, first bracket connection device; 20, second bracket connection device 2; 21, bracket. Detailed implementation manners

[0046] Next, the technical solutions of the present invention will be clearly and completely described in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. 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 protection scope of the present invention.

[0047] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counter - clockwise", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. 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 thus should not be construed as a limitation of the present invention.

[0048] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present invention, "a plurality of" means two or more unless otherwise specifically defined. In addition, the terms "mounted", "connected" and "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0049] The main principle of the present invention lies in three steps: converting flow velocity into pressure, converting pressure into electrical signal, and outputting the electrical signal. "Converting flow velocity into pressure" is based on numerical simulation technology, and the specific tool used is Fluent. The specific principle is to numerically simulate and solve the "motion equation of viscous fluid" (hereinafter referred to as "N-S equation"). Relying on an electronic computer and combining the concept of finite elements, the engineering model is meshed and divided into multiple small regions that can be solved by the computer. The required physical quantities are iteratively calculated and solved for each region, and then the physical quantities of the whole composed of the small regions are calculated to achieve the purpose of studying engineering problems and physical problems.

[0050] The tool for numerical simulation is Fluent, which solves this problem by virtue of its physical model, numerical method and pre- and post-processing functions. By simulating the magnitudes of the pressures exerted on the "inductive object" by the fluid at different flow velocities under a sufficient number of working conditions and fitting them into a functional relationship, the flow velocity-pressure relationship can be obtained. The material and shape of the "inductive object" need to be comprehensively selected through multiple simulation experiments and actual measurement experiments.

[0051] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments:

[0052] An embodiment of the present invention provides a portable flow velocity meter based on numerical simulation and pressure sensors. The flow velocity meter includes:

[0053] A flow velocity sensing device, which includes a first cone as the upstream-facing part and a second cone as the downstream-facing part. The bottoms of the first cone and the second cone are buckled together and are of the same size and material; the flow velocity sensing device is obtained based on Fluent numerical simulation; it should be noted that the flow velocity sensing device can be integrally formed;

[0054] A pressure transmission device, which amplifies and transmits the pressure output by the flow velocity sensing device to the pressure sensing device;

[0055] A pressure sensing device, the pressure sensing device is used to receive the pressure signal transmitted by the pressure transmission device and convert it into a resistance signal;

[0056] The voltage output device is arranged on the bottom plate. The resistance measuring circuit converts the resistance signal of the pressure sensing device into a voltage signal and outputs it visually through the digital voltmeter.

[0057] This embodiment proposes a portable flow meter based on numerical simulation and pressure sensor, including a flow sensing device, which includes a first cone as a flow-front part and a second cone as a backflow part, the first cone and the second cone are buckled at the bottom, and have the same size and material; the flow sensing device is obtained based on Fluent numerical simulation; the pressure output by the flow sensing device is amplified and transmitted to the pressure sensing device by the pressure transmission device; the pressure sensing device is used to receive the pressure signal transmitted by the pressure transmission device and convert it into a resistance signal; the resistance measuring circuit converts the resistance signal of the pressure sensing device into a voltage signal and is visually output by the digital voltmeter. The instantaneous flow velocity can be directly measured, and a high measurement accuracy is guaranteed. The lever coefficient is adjustable to maximize the range of the flow meter. The flow meter is small in size, light in weight, and easy to carry.

[0058] Specifically, the flow velocity sensing device is a device immersed in water, which senses the impact of the fluid and transmits the pressure given by the fluid to the next part. It should be noted that there are two flow states of the fluid: stratified flow and turbulent flow. When the laminar flow rushes towards an object, turbulent flow with a more complex calculation principle and larger error may be formed behind it.

[0059] Specifically, in one embodiment, Figure 1 As shown, the double-cone flow velocity sensing device consists of a left half facing the flow and a right half facing the flow. The two parts are exactly the same in shape and material, and are both cones with a bottom radius of r = 0.5mm and a height of h = 10mm. In water, the line connecting the vertices of the two cones is consistent with the direction of the water flow, and the facing part is impacted by the water flow. It should be noted that the above dimensions are only used as a preferred embodiment, and the specific dimensions are not limited;

[0060] In this embodiment, the water pressure on the conical double-cone flow velocity sensing device with a bottom radius r=0.5mm and a height h=10mm is recorded as F1, and the flow velocity of the fluid to be measured before contacting it is recorded as v. There is a functional relationship between F1 and v.

[0061] The double cone model is placed in a fluid. Since both sides of the cone are in contact with the fluid, the pressure on the double cone model is the difference between the pressures on both sides, that is:

[0062] p=p frontside -p backside

[0063] The two sides of the double cone are symmetrical and the hydrostatic pressure is zero.

[0064] The dynamic fluid pressure is mostly calculated by solving the momentum equation, i.e.:

[0065]

[0066] Where, $F$ is the external force on the fluid, $\rho$ is the fluid density, $Q$ is the fluid flow rate, $v_1$ and $v_2$ are the average fluid velocities at the initial and final states respectively, and $\beta_1$ and $\beta_2$ are the momentum correction coefficients;

[0067] The force-bearing surface is divided into multiple micro-elements. The momentum equation can be written in the form of the N-S equation, and the force on each micro-element is calculated by program simulation. Summing them up gives the pressure on each surface, and the difference between the forces on the two surfaces gives the dynamic fluid pressure on the double cone model.

[0068] Specifically, the specific process of analyzing the F1-v function relationship is as follows:

[0069] Using the Fluent analysis method, assuming the fluid is near-water fluid, with density $\rho = 1000 kg / m^3$, viscosity coefficient $\mu = 1.0087 cP$, and flow velocity $v (0.1 m / s \leq v \leq 10 m / s)$.

[0070] 1). Mesh generation: The computational domain is divided using standard unstructured tetrahedral meshes. The near-wall area is encrypted, the far-wall area is relatively sparse, and the area near the spindle is further encrypted. To ensure high accuracy, the total number of double cone mesh generations is 1,500,000.

[0071] 2) Set the numerical method: The entire computational domain is a rectangular area of 160 mm x 80 mm. The left side and the upper and lower sides of the flow field are set as velocity inlet boundaries (velocity-inlet), and the right side of the flow field is set as a pressure outlet boundary (pressure-outlet). The surface of the projectile is a non-slip wall surface. Since this computational model is for single-phase flow calculation, the single-phase model is used for calculation. In the turbulent state, the turbulent state of each boundary variable also needs to be set. The k-e turbulent model is used in the calculation, and the turbulent intensity and turbulent viscosity ratio need to be set. The turbulent intensity at the inlet and outlet is set to 0.5, and the turbulent viscosity ratio is set to 1. Adjust the relaxation factor in FLUENT to make the calculation results converge easily. To suit the calculation of large Reynolds number flows, the PRESTO method is used for pressure variable interpolation, the SIMPLIC method is selected for pressure-velocity coupling, and the first-order upwind scheme is used for the discretization of momentum, volume ratio, k, and e.

[0072] 3). Numerical simulation: The flow velocities of the external flow field are input as 0.1 m / s, 0.2 m / s, 0.3 m / s, ……, 10 m / s (a total of 100 groups). The total resistance received by the windward surface and the leeward surface of the double-cone model is calculated by the simulation experiment, and the experimental results are recorded and fitted to obtain the flow velocity-pressure relationship as follows:

[0073]

[0074] During numerical simulation, the N-S model provided by Fluent is used to directly simulate the laminar flow scenario, and the k-ε model is used to simulate the turbulent flow scenario, with the relevant parameters selected optimally. The double-cone model is placed in the fluid. Since both sides of the conical surface are in contact with the fluid, the pressure received by the double-cone model is the difference between the pressures on both sides. In this way, the pressure received by the double-cone model can be obtained under the given parameters and fluid flow velocity conditions.

[0075] Using Fluent for analysis under different working conditions, the flow velocity-pressure corresponding relationship is obtained, and the flow velocity-pressure function relationship is fitted. After analyzing and fitting the results under the above working conditions, the flow velocity-pressure relationship is as follows:

[0076]

[0077] It should be noted that in the above embodiments, the specification setting of the same double-cone model is a preferred embodiment with relatively high result accuracy in the current situation, and the specific parameter settings can also be adjusted according to actual needs.

[0078] When the flow velocity sensing device is in water, the line connecting the vertices of the two cones is consistent with the water flow direction, and the oncoming part receives the impact of the water flow.

[0079] Figures 2 - 4 The three-dimensional structure schematic diagram, the front view and the right view of the flow velocity sensing device of a portable flow velocity meter based on numerical simulation and pressure sensors provided by the embodiments of the present invention are shown. Figure 5 The three-dimensional structure schematic diagram of a portable flow velocity meter based on numerical simulation and pressure sensors provided by the embodiments of the present invention is shown. Figure 6 The left view and the right view of a portable flow velocity meter based on numerical simulation and pressure sensors provided by the embodiments of the present invention are shown. Specifically, as Figures 2 - 6 shown, the pressure transmission device includes:

[0080] An underwater transmission rod 2, which is connected to the flow velocity sensing device; the underwater transmission rod 2 is the part of the pressure transmission device that is allowed to be immersed in water. For example, it can be a rectangular plastic sheet. Connecting the double-cone flow velocity sensing device 1 below. Such a design minimizes the area facing the flow under the premise of ensuring that the underwater transmission rod 2 is not easily bent, reduces its interference with the fluid field, and its length also determines the maximum depth at which the flow velocity meter is allowed to measure the flow velocity.

[0081] An above-water transfer rod 3, one end of the above-water transfer rod 3 is connected to the underwater transfer rod 2; the above-water transfer rod is the part that is not allowed to be submerged in water in the pressure transfer device, for example, it can be a columnar plastic body, and is connected to the underwater transfer rod 2 below.

[0082] A shifting component, which is used for the conversion between high speed and low speed; for example, the shifting component includes:

[0083] A bearing 8, which is arranged on the bottom plate 16; a fixed pin 4, and a steel ball 5 with one side hollowed out. The above-water transfer rod 3 is inserted into the bearing 8 through the perforation of the fixed pin 4. The fixed pin 4 can rotate freely in the bearing and can be fixed by the steel ball 5. The fixed pin 4 serves as the lever fulcrum of the entire pressure transfer device. The ratio of the length of the power arm to the length of the resistance arm of the lever is the lever coefficient. When the low-speed gear conversion device operates, the lever coefficient is larger, and the flowmeter can measure the flow rate of low-speed fluids. When the high-speed gear conversion device operates, the lever coefficient is smaller, and the flowmeter can measure the flow rate of high-speed fluids. The bearing 8 is used to fix the entire pressure transfer device and minimize friction loss to assist the function of the fixed pin 4 as the lever fulcrum.

[0084] Specifically, in one embodiment, a pressing part 9, which includes a first rod 91 connected to one end of the above-water transfer rod, and a second rod 92 transversely configured to connect the first rod. The pressing part 9 is the endmost part of the pressure transfer device, and the pressure signal is amplified and transmitted here, and is transmitted to the pressure sensing device through it.

[0085] Specifically, in one embodiment, the pressure transfer device further includes:

[0086] A sensor protection part 10, which is configured at both ends of the second rod 92. The sensor protection part can be, for example, a cube plastic block, and one is welded at each of the left and right ends of the pressing part 9 to protect the sensor and avoid damage caused by excessive pressure when the pressing part 9 transmits pressure to the pressure sensing device.

[0087] Specifically, in one embodiment, the pressure transfer device is a thin-film pressure sensor. The selection conditions for the thin-film pressure sensor are high sensitivity, high accuracy, and large range.

[0088] Preferably, the model of the thin-film pressure sensor is RP-C7.6LT-LF2, and its measurement range is 2g - 1500g. Combined with the pressure transfer device, it can measure the flow rate of fluids in most situations. According to the specifications of the selected thin-film pressure sensor, the optimal specifications of the pressure transfer device can be determined.

[0089] Specifically, in one embodiment, the voltage output device includes:

[0090] Resistance measurement circuit, circuit box 12, circuit switch 13, digital voltmeter 18;

[0091] A voltage output device, namely a resistance measurement circuit supporting the pressure sensing device, converts the resistance signal of the thin-film pressure sensor into voltage and visually outputs it through a digital voltmeter. The circuit box can be, for example, an airtight plastic square box, which contains most of the wires in the resistance measurement circuit. The power supply has the thin-film pressure sensor 11 adhered to its left side; the circuit switch 13 and the digital voltmeter 18 are placed outside the circuit box 12 for easy control of the circuit and reading of the voltage value. The circuit box can slide up and down through the slideway 14 on the bottom plate 16. For example, the circuit box slideway can be composed of two rows of metal slideways, which are fitted with the circuit box 12 and allow the circuit box 12 to slide on it to ensure that when the low / high-speed gear shifting device operates, the thin-film pressure sensor 11 can always be in contact with the sensor protection part 10 and receive the pressure from the pressure transmission device.

[0092] Specifically, in one embodiment, as Figure 7 shown, the resistance measurement circuit includes:

[0093] A power supply, a fixed-value resistor R1, a thin-film pressure sensor R f , a voltmeter V,

[0094] The fixed-value resistor R1 is connected in parallel with the voltmeter V and then in series with the thin-film pressure sensor R f , and the power supply includes a voltage boost conversion module.

[0095] The beneficial effects of the present invention will be described below with a preferred embodiment;

[0096] In this embodiment, the thin-film pressure sensor R f has a model of RP-C7.6LT-LF2. The composition of the resistance measurement circuit is as follows: 2 18650 lithium batteries and a 12V voltage boost conversion module are used as the power supply to provide current. The current flows in sequence through the series-connected circuit switch (key), a 2000Ω fixed-value resistor, the thin-film pressure sensor and then back to the power supply. The digital voltmeter is connected in parallel with the 2000Ω fixed-value resistor to measure the voltage across its two ends.

[0097] Among them, 2 18650 lithium batteries and a 12V voltage boost conversion module constitute the power supply. The voltmeter is a digital voltmeter with relatively high precision. R1 is a 2000Ω fixed-value resistor, and R f is the thin-film pressure sensor.

[0098] Connect the circuit, measure the readings of the digital voltmeter under a given pressure through experiments, obtain 50 sets of corresponding values of pressure and voltage, and after fitting, the functional relationship between pressure and voltage is:

[0099]

[0100] The physical quantity of pressure is amplified and transmitted through a pressure transmission device. Therefore, the pressures in the flow rate-pressure function and the pressure-voltage function do not have the same meaning, and there is a relationship of the multiple of the lever coefficient between them.

[0101] Combining the flow rate-pressure function relationship measured by the mechanical device experiment, the specifications of the pressure transmission device, and the pressure-voltage function relationship, the direct relationship between the flow rate to be measured and the voltage is obtained:

[0102]

[0103] The flow rates in the low-speed gear and the high-speed gear are respectively:

[0104]

[0105]

[0106] In this embodiment, the lever coefficient λ in the high-speed gear is 1, and the lever coefficient λ in the low-speed gear is 59. The specific specifications of the current meter in this embodiment are:

[0107] A double-cone flow rate sensing device 1, with each cone having a radius of 5 mm and a height of 10 mm;

[0108] The underwater transfer rod 2 has a length of 125 mm, a width of 5 mm, and a thickness of 0.8 mm;

[0109] The above-water transfer rod 3 has a length of 167.5 mm and a bottom circle radius of 2.5 mm;

[0110] The distance from the connection point of the high-speed gear to the underwater transfer rod 3 to the lower end of 3 is 20 mm;

[0111] The distance from the connection point of the low-speed gear to the underwater transfer rod 3 to the upper end of 3 is 2.5 mm;

[0112] The length of the first rod 91 is 2.5 mm;

[0113] The length of the second rod 92 is 5 mm.

[0114] Specifically, in this embodiment, the current meter further includes:

[0115] A fixing assembly, which includes three rotatable circuit box fixing devices 15 arranged at equal distances on the bottom plate, and two of them act together to fix the circuit box 12 and keep the thin-film pressure sensor 11 in contact with the second rod 92.

[0116] Specifically, in this embodiment, as Figure 8 shown, the current meter further includes:

[0117] The bubble ball 17 is a transparent glass water ball containing small bubbles. When the flowmeter is properly positioned, the small bubbles are located at the top of the glass ball to adjust the proper orientation of the flowmeter.

[0118] The first support connection device 19 is a metal ball with a hollow top. The first support connection device 19 is used to connect the support 21.

[0119] Specifically, the support 21 includes a rod body and a second support connection device 20.

[0120] The second support connection device 20 is composed of two arc-shaped hollow metal balls and two metal rods in the form of hinges. The directions in which the two hinges allow rotation are perpendicular to each other to achieve the overall omnidirectional rotation. The arc-shaped hollow metal balls are connected to the rod body in the form of hinges, and the lower rod body can be inserted into the first support connection device 19.

[0121] In this embodiment, the support can be composed of four identical parts, which are respectively connected to the second support connection device 20. The second support connection device 20 is connected by two telescopic metal rods and an arc-shaped hollow glass ball in the form of a hinge. In general flow rate measurement situations, the second support connection device 20 and the support 21 are not needed. When the measurement process is long or the measurement water area is large and it is inconvenient to measure the flow rate by hand-held flowmeter, the second support connection device 20 and the support 21 are used.

[0122] In summary, the beneficial technical effects of the present invention are as follows:

[0123] 1. Easy to operate, carry and move:

[0124] This flowmeter is very easy to operate. It only needs to turn on the switch → immerse the double cone into the fluid to be measured → adjust the bubble ball → read and convert. It saves a lot of time for measuring the flow rate. When continuously measuring the flow rates at multiple locations or at multiple time points, it does not need to be zeroed and can be directly used. This flowmeter is small in size and light in weight, making it easy to carry.

[0125] 2. High sensitivity and high precision:

[0126] The selected RP-C7.6LT-LF2 thin film pressure sensor has high sensitivity and precision. Coupled with the amplification of pressure by the pressure transmission device, its sensitivity and precision are increased several times. In addition, the flow-receiving area of the double cone flow induction device and the underwater transmission rod is extremely small, greatly reducing the influence of the device itself on the fluid field and making the measurement accuracy higher.

[0127] 3. Large measurement range:

[0128] The designed pressure transmission device includes a lever that can control the conversion between low and high gears. Under the displayed specifications, the flow velocity range is 0.1243 m / s - 9.8497 m / s. In actual production and application, the specifications of the pressure transmission device can be readjusted according to actual requirements to change the flow velocity range.

[0129] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A portable flowmeter based on numerical simulation and pressure sensors, characterized in that, The portable flow velocity meter includes: A flow velocity sensing device, which includes a first cone as the upstream-facing part and a second cone as the downstream-facing part. The bottoms of the first cone and the second cone are buckled, and they are of the same size and material. The flow velocity sensing device is numerically simulated using Fluent fluid simulation software; When the flow velocity sensing device is in water, the line connecting the vertices of the two cones is aligned with the water flow direction, and the upstream-facing part receives the impact of the water flow; A pressure transmission device, which amplifies and transmits the pressure output by the flow velocity sensing device to the pressure sensing device; The pressure transmission device includes: An underwater transmission rod, which is connected to the flow velocity sensing device; An above-water transmission rod, one end of which is connected to the underwater transmission rod; A shifting component, which is used for the conversion between high speed and low speed; The shifting component includes: A bearing, which is arranged on the bottom plate; A fixed pin and a steel ball with one side hollowed out. The above-water transmission rod is inserted into the bearing through the perforation of the fixed pin and fixed by the steel ball; A pressure application part, which includes a first rod connected to one end of the above-water transmission rod and a second rod transversely configured to connect the first rod; A pressure sensing device, which is used to receive the pressure signal transmitted by the pressure transmission device and convert it into a resistance signal; The pressure transmission device further includes: A sensor protection part, which is configured at both ends of the second rod; The pressure transmission device is a thin-film pressure sensor; A voltage output device, which is arranged on the bottom plate. The voltage output device includes: a resistance measurement circuit, a circuit box, a circuit switch, and a digital voltmeter. The resistance measurement circuit converts the resistance signal of the pressure sensing device into a voltage signal and visually outputs it by the digital voltmeter; Among them, the circuit box is an airtight plastic square box, which contains the wires in the resistance measurement circuit. The thin-film pressure sensor is adhered to the left side of the circuit box. The circuit switch and the digital voltmeter are placed outside the circuit box. The circuit box can slide up and down through the slideway on the bottom plate, and the thin-film pressure sensor continuously keeps in contact with the sensor protection part.

2. The portable flow velocity meter according to claim 1, characterized in that, The resistance measurement circuit includes: A power supply, a fixed-value resistor, a thin-film pressure sensor, and a voltmeter, The fixed-value resistor and the voltmeter are connected in parallel and then connected in series with the thin-film pressure sensor. The power supply includes a voltage boost conversion module.

3. The portable flow velocity meter according to claim 1, wherein, The portable flow velocity meter further includes: A fixing component, which includes three rotatable triangular bodies arranged at equal distances on the bottom plate. Two of them work together to fix the circuit box and keep the thin-film pressure sensor in contact with the second rod.

4. The portable flowmeter according to claim 1, wherein, The portable flow velocity meter further includes: A bubble ball, which is a transparent glass water ball containing small bubbles. When the flow velocity meter is placed in the proper position, the small bubbles are located at the top of the glass ball to adjust the proper orientation of the flow velocity meter; A bracket, which adjusts the bracket according to the indication of the bubble ball.

5. A flow velocity measurement method based on numerical simulation and pressure sensor, which is used for the portable flow velocity meter according to any one of claims 1 to 4. The method specifically includes: The flow velocity when the water flow to be measured collides is obtained through the first cone and the second cone of the flow velocity sensing device, and the flow velocity is converted into pressure according to Formula 1 by using numerical simulation technology, and the pressure is transmitted to the pressure transmission device; wherein, v represents the flow velocity when the water flow to be measured collides, and F1 represents the magnitude of the pressure exerted by the fluid on the sensing object at different flow velocities; The pressure output by the flow velocity sensing device is amplified and transmitted to the pressure sensing device through the pressure transmission device; The pressure signal transmitted by the pressure transmission device is received by the pressure sensing device and converted into a resistance signal, and the resistance signal is sent to the voltage output device; The resistance signal transmitted by the pressure sensing device is converted into a voltage signal through the voltage output device, and the voltage signal is visually output through the digital voltmeter in the voltage output device.

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