Tapered inflow inlet structure for fluid flow test and test method thereof

Abstract

The invention relates to the technical field of fluid flow experiments, in particular to a tapered inflow inlet structure for a fluid flow test and a test method of the tapered inflow inlet structure. The structure comprises a flow stabilizing section and a telescopic folding type reverse arc section which is detachably installed at the rear end of the flow stabilizing section and can stretch or unfold in the longitudinal direction, the transverse direction and the vertical direction. The flow stabilizing section and the telescopic folding type reverse arc section are each of a pipe-shaped structure with the two opposite sides open. The cross section of the telescopic folding type reverse arc section is of a circular structure; the cross sectional area of the telescopic folding type reverse arc section is gradually reduced from the end close to the flow stabilizing section to the end away from the flow stabilizing section. And a plurality of parallel flow stabilizing plates are arranged in the flow stabilizing section. According to the tapered inflow inlet structure for the fluid flow test and the test method of the tapered inflow inlet structure, fluid flow can be smoothly transited, and the application range is wide.

Description

Technical Field

[0001] The invention relates to the technical field of fluid flow experiments, and in particular to a tapered inlet structure for fluid flow experiments and a test method thereof. Background Art

[0002] Since the flowing fluid is surrounded by solid boundaries, it is often called the internal problem of the flow. Pipes are often used to transport fluids and are also basic components of chemical equipment (such as shell and tube heat exchangers, tube-in-tube fixed bed reactors, etc.); in addition, the geometric shape of the pipe is simple, which is convenient for theoretical research, and the results obtained can also be used as a reference for understanding other flows. Pipe flow is the movement of fluid in a pipe. More than two thousand years ago, humans were able to use pipe systems to supply water on a large scale. Nowadays, pipes are more commonly used to transport various liquids, gases and complex mixtures. According to the flow state of the fluid in the pipe, pipe flow can be divided into laminar pipe flow and turbulent pipe flow. Studying pipe flow is very important both in practice and in theory, so pipe flow is also the key knowledge to learn in hydraulics. When learning, learners usually use the pressurized pipe fluid flow test in the fluid flow test (test is also called experiment) to achieve the purpose of understanding the flow principle and verifying the empirical formula. At the same time, for the water inlet of large or important projects, the rationality of the design should also be verified through experiments or numerical simulation analysis.

[0003] In fluid flow tests, the water inlet type of the inlet structure (referred to as the inlet type) has a great influence on the fluid flow pattern. There are many different inlet types. A good inlet type can reduce energy loss, shorten the length of the starting section, and save model production costs. At present, with the widespread application of high-precision measurement technology for experimental fluid forces and higher processing accuracy of experimental models, the influence of the inlet type on flow characteristics has become more prominent. Therefore, the inlet structure that can make the fluid flow transition smoothly has always been the focus of research.

[0004] The existing inlet structure is usually fixed in shape, and is composed of structures such as a water pipe and an anti-arc section. Because of its relatively fixed structure, it cannot be applied to experiments for different purposes, and therefore has the problem of low applicability. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a tapered inlet structure for fluid flow testing which can achieve a smooth transition of fluid flow and has wide applicability and a test method thereof.

[0006] In order to solve the above technical problems, the invention provides a tapered inlet structure for fluid flow testing, comprising a steady flow section and a telescopic folding anti-arc section detachably mounted at the rear end of the steady flow section and capable of being telescoped or unfolded longitudinally, transversely, and vertically;

[0007] The flow stabilizing section and the telescopic folding anti-arc section are both tubular structures with openings on opposite sides; the cross section of the telescopic folding anti-arc section is a circular structure; the cross-sectional area of ​​the telescopic folding anti-arc section gradually decreases from one end close to the flow stabilizing section to one end away from the flow stabilizing section;

[0008] A plurality of mutually parallel flow stabilizing plates are arranged in the flow stabilizing section.

[0009] As a further improvement of the present invention: the cross section of the flow stabilizing section is a circular structure.

[0010] Preferably, the flow stabilizing plate is a circular plate-shaped structure.

[0011] As a further improvement of the present invention: the flow stabilizing section is bolted to the telescopic and foldable anti-arc section.

[0012] Preferably, the opening of the flow stabilizing section on the front side is an inlet, a first flange is installed at the inlet, and a second flange is installed at the edge of the opening of the flow stabilizing section on the rear side; a third flange for bolting to the second flange is installed at the opening of the telescopic folding anti-arc section on the front side, and a fourth flange for bolting to the model section is installed at the opening of the telescopic folding anti-arc section on the rear side.

[0013] Preferably, the first flange, the second flange, the third flange and the fourth flange are respectively provided with a plurality of screw holes in an annular direction around their own central axes.

[0014] As a further improvement of the present invention: the shape and size of the flow stabilizing plate are matched with the flow stabilizing section.

[0015] As a further improvement of the present invention: the inner surface of the telescopic and foldable anti-arc section is provided with a flexible epoxy resin material coating.

[0016] As a further improvement of the present invention: the outer surface of the telescopic and foldable anti-arc segment is provided with a polyurethane coating.

[0017] The present invention further provides a test method for the tapered inlet structure for fluid flow test based on the tapered inlet structure for fluid flow test, comprising:

[0018] According to the test pressure range, the cross-sectional shape and size of the model section, a tapered inlet structure of appropriate size for fluid flow test is selected;

[0019] According to the flow direction, the steady flow section, the telescopic folding anti-arc section and the model section are connected in sequence from front to back, ensuring that the connecting section of the telescopic folding anti-arc section has the same shape, size and slope as the model section and the axis coincides;

[0020] The telescopic and foldable anti-arc section is adjusted according to different pressures.

[0021] The beneficial effects of the present invention are as follows: the tapered inlet structure for fluid flow testing and the testing method thereof provided by the present invention can make the fluid flow transition smoothly and have wide applicability.

[0022] The present invention comprises a flow stabilizing section and a telescopic folding anti-arc section which is detachably mounted at the rear end of the flow stabilizing section and can be telescoped or unfolded in the longitudinal, transverse and vertical directions. Therefore, the length of the telescopic folding anti-arc section can be adjusted according to different inlet pressures. While adjusting the length, the curvature of the telescopic folding anti-arc section and the convexity and concavity of the inner wall surface can also be reasonably adjusted synchronously to optimize the structural type of the inner wall and ensure that the resistance of the inner wall is minimized, thereby minimizing the inlet resistance and maximally eliminating the influence of the inlet local resistance on the fluid, thereby achieving a smooth transition of the fluid flow. The whole process is also very simple to operate, and the type and model (size) can be adjusted according to the test pressure range and the size of the model section. The application range is wide and the applicability is strong.

[0023] At the same time, the cross-section of the telescopic foldable anti-arc section of the present invention is a circular structure; the cross-sectional area of ​​the telescopic foldable anti-arc section gradually decreases from the end close to the steady flow section to the end away from the steady flow section. Through such a design, the bottom of the telescopic foldable anti-arc section naturally has the curved surface structure of the anti-arc section, and at the same time has the function of being able to telescope and fold. Therefore, it can not only play the function of the anti-arc section, but also play the adjustment function at the same time, thereby improving the applicability of the present invention, so that the present invention can be applied to pressurized pipelines and other fields involving fluid transportation, and other fields such as transportation, navigation, aviation, civil engineering and water conservancy, environmental ecology, etc., involving tests (experiments) research on pressurized fluid transportation. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the overall structure of the steady flow section in the present invention;

[0025] Figure 2 It is a schematic diagram of the overall structure of the telescopic and foldable anti-arc segment in the present invention;

[0026] Figure 3 It is a realistic drawing of the local details of the telescopic and foldable anti-arc segment in the present invention;

[0027] Figure 4 It is the relationship diagram between the vertical coordinate z and the horizontal coordinate d of the telescopic folding anti-arc segment;

[0028] The names of the components corresponding to the marks in the above drawings are: 1, flow stabilization section; 101, flow inlet; 102, first flange; 103, second flange;

[0029] 2. telescopic folding anti-arc section; 201. third flange; 202. fourth flange;

[0030] 3. Flow stabilizer; 4. Screw hole. DETAILED DESCRIPTION

[0031] The present invention will be further described in detail below through specific implementation modes in conjunction with the accompanying drawings.

[0032] In some cases, some operations related to the present invention are not shown or described in the specification. This is to avoid the core part of the present invention being overwhelmed by excessive description. For those skilled in the art, it is not necessary to describe these related operations in detail. They can fully understand the related operations based on the description in the specification and general technical knowledge in the field.

[0033] In addition, the features, operations or characteristics described in the specification can be combined in any appropriate manner to form various implementations. At the same time, the steps or actions in the method description can also be interchanged or adjusted in a manner that is obvious to those skilled in the art. Therefore, the various sequences in the specification and the drawings are only for the purpose of clearly describing a certain embodiment and are not meant to be a required sequence unless otherwise specified that a certain sequence must be followed.

[0034] The serial numbers assigned to the components in the present invention, such as "S1", are only used to distinguish the objects described and do not have any order or technical meaning. The "connection" and "coupling" mentioned in the present invention include direct and indirect connections (couplings) unless otherwise specified.

[0035] Definitions of relevant terms involved in this invention:

[0036] (1) Pressure flow: refers to the flow of liquid that is constrained and has no free surface (interface between liquid and gas). The most common pressure flow is full pipe flow (see pipe flow), that is, the flow of liquid filling the pipe. The flow of liquid that does not fill the pipe follows the law of pressureless flow.

[0037] (2) Initial section length: the distance from the inlet flow velocity approaching uniformity to the maximum flow velocity.

[0038] (3) Inlet type: also known as the water inlet type, or simply the inlet type, it can be divided into open type, shallow hole type, and deep hole type according to the water flow conditions. It can be divided into dam type, bank type (bank tower type, shaft type, bank slope type), and tower type according to the location of the water inlet and the water diversion pipe.

[0039] (4) Anti-arc section: A curved section that connects with the straight section of the overflow surface to make the downstream nose sill, guardrail or riverbed transitional. It can make the water flowing down from the top of the weir change direction smoothly and connect with the downstream water flow. Generally, it adopts the arc form. The radius of the arc curve (anti-arc radius) is related to the height of the overflow dam, the water head at the top of the weir and the energy dissipation method. It should not be too small. It is usually about 5 times the water depth on the anti-arc, or even 8 to 10 times. When the flow rate is high or when it is connected to the guardrail, the upper limit value should be used. However, if the anti-arc radius is too large, its length will increase, which will increase the amount of engineering work.

[0040] like Figure 1 , Figure 2 As shown, the present invention provides a tapered inlet structure for fluid flow testing, comprising a flow stabilizing section 1 and a telescopic folding anti-arc section 2 detachably mounted at the rear end of the flow stabilizing section 1 and capable of being telescoped or unfolded longitudinally, transversely, and vertically, wherein the telescopic folding anti-arc section 2 is used to be connected to a model section. The model section is a cavity having a size equivalent to the rear opening of the telescopic folding anti-arc section 2;

[0041] The flow stabilizing section 1 and the telescopic folding anti-arc section 2 are both tubular structures with openings on opposite sides; the cross-sections of the flow stabilizing section 1 and the telescopic folding anti-arc section 2 are circular structures; a plurality of mutually parallel flow stabilizing plates 3 are arranged in the flow stabilizing section 1, and a plurality of holes are opened on the flow stabilizing plates 3, which are porous plates and have the function of stabilizing the flow field. The flow stabilizing plates 3 are circular plate-shaped structures, and the shape and size of the flow stabilizing plates 3 match the flow stabilizing section 1, that is, the diameter of the flow stabilizing plates 3 is equivalent to the inner diameter of the flow stabilizing section. The cross-sectional area of ​​the telescopic folding anti-arc section 2 gradually decreases from the end close to the flow stabilizing section 1 to the end away from the flow stabilizing section 1; the surface of the telescopic folding anti-arc section 2 is a tortuous corrugated structure. The outer surface of the telescopic folding anti-arc section 2 is provided with a polyurethane coating, which has anti-seepage and drag reduction effects, and the inner surface of the telescopic folding anti-arc section 2 is provided with a flexible epoxy resin material coating, which has an anti-seepage effect;

[0042] The flow stabilizing section 1 is bolted to the telescopic folding anti-arc section 2. The opening of the flow stabilizing section 1 on the front side is an inlet 101, and a first flange 102 is installed at the inlet 101. A second flange 103 is installed at the edge of the opening of the flow stabilizing section 1 on the rear side; a third flange 201 for bolting to the second flange 103 is installed at the edge of the opening of the telescopic folding anti-arc section 2 on the front side, and a fourth flange 202 for bolting to the model section is installed at the edge of the opening of the telescopic folding anti-arc section 2 on the rear side. A plurality of screw holes 4 are respectively provided in an annular direction around their own central axis on the first flange 102, the second flange 103, the third flange 201 and the fourth flange 202. Bolt connection can be completed by the cooperation of bolts and screw holes 4, which is convenient for installation and disassembly.

[0043] The present invention further provides a test method for a tapered inlet structure for fluid flow test based on the tapered inlet structure for fluid flow test, comprising:

[0044] S1. Select a tapered inlet structure of appropriate size for fluid flow test according to the test pressure range, cross-sectional shape and size of the model section;

[0045] S2. Connect the steady flow section 1, the telescopic folding anti-arc section 2, and the model section from front to back in sequence according to the flow direction, ensuring that the connecting section of the telescopic folding anti-arc section 2 has the same shape, size, and slope as the model section, and the axes coincide with each other;

[0046] S3. According to the different pressures, the telescopic foldable anti-arc segment 2 is adjusted. While adjusting the length of the anti-arc segment, the curvature of the telescopic foldable anti-arc segment 2 can be reasonably adjusted to achieve a smooth transition of the fluid flow, and the inner wall surface concave-convexity can be adjusted synchronously to optimize the inner wall structure of the telescopic foldable anti-arc segment 2, minimize the inlet local resistance, and minimize the inlet loss during the test.

[0047] like Figure 3 , Figure 4 As shown, the relationship between the radius R (cm) and the length L (cm) of the telescopic foldable anti-arc section 2 can be expressed as:

[0048] L=AR 1 / 2 (1)

[0049] In the formula, coefficient A is a constant;

[0050] The relationship between the front pressure p of the inlet section and the radius R of the telescopic folding anti-arc section 2 can be expressed as:

[0051] R 2 =Ap (2)

[0052] In formula (2), coefficient A is a constant;

[0053] The relationship between the vertical coordinate z and the horizontal coordinate d can be expressed as:

[0054] z 2 =ad (3)

[0055] Where a is the distance from the parabola directrix to the focus;

[0056] Based on the relationship between the front end pressure p of the inlet section and the radius R of the telescopic folding anti-arc section 2, the value of the coefficient a under different pressure conditions and the inner wall convexity (x / y) of the telescopic folding anti-arc section 2 are shown in Table 1. The inner wall convexity (x / y) refers to the unevenness of the inner wall surface of the telescopic folding anti-arc section 2, that is, the degree to which the shape of the inner wall surface deviates from the plane.

[0057] Table 1 Coefficient values ​​under different pressure conditions

[0058]

[0059] According to the analysis in Table 1, the relationship coefficient between the front end pressure p of the inlet section and the radius R of the telescopic folding anti-arc section 2, and the relationship coefficient a between the radius R (cm) and the length L (cm) of the telescopic folding anti-arc section 2 have good regularity. Therefore, it can be determined that the radius R and the length L are the most critical geometric parameters for reducing resistance, as well as the inner wall convexity of the telescopic folding anti-arc section 2 that matches the radius R and the length L.

[0060] The model can be tested before use. The test method is as follows:

[0061] 1. Experimental equipment: Use an electronic digital differential pressure gauge to measure the head loss, and use a flow meter to measure the flow rate.

[0062] 2. Experimental methods:

[0063] (1) Be familiar with experimental equipment and record relevant experimental constants;

[0064] (2) Turn on the power supply and start the water pump to fill the constant pressure water tank until it is full and overflowing;

[0065] (3) Debug and check that the instrument is in normal condition;

[0066] (1) Open the flow regulating valve, loosen the exhaust valve, and exhaust the air in the experimental pipeline;

[0067] (2) Close the flow regulating valve again, tighten the exhaust valve, wait for a while, and observe whether the liquid levels of the pressure measuring tubes are level. If not, exhaust the air and eliminate the fault until the liquid levels of the pressure measuring tubes are level.

[0068] (IV) Experimental data measurement:

[0069] Adjust 3 to 4 groups of different flow rates (one of which is the maximum flow rate). After each adjustment, wait for the liquid level of each pressure measuring tube to stabilize, and then measure and record the data and flow rate. During the experiment, the liquid level of each pressure measuring tube must not exceed the measurement range.

[0070] (V) After the experiment is completed, turn off the power, clean the instrument and restore it to its original state. You may leave the instrument only after the experimental instructor has checked that everything is correct.

[0071] 3. Experimental steps:

[0072] S1. Insert the temperature probe of the digital thermometer into the temperature measuring tube on the water tank, connect the water pump, the electronic digital differential pressure meter and the electronic digital flow meter, turn on the power switch, open the valve, remove the air in the test pipe and close it again;

[0073] S2. Check whether the liquid level of the pressure measuring tube of the inverted air-water pressure differential gauge on the panel of the intelligent digital pressure differential instrument is within the measuring range and flush. If not, remove the air valve on the pressure differential gauge, fill the pressure measuring tube with water, slowly open the valve, and when the liquid level of the pressure measuring tube drops to the lowest, immediately tighten the air valve screw, close the valve again, and observe whether the liquid level of the pressure measuring tube is flush;

[0074] S3. Keep the valve closed and rotate the zeroing knobs of the intelligent digital differential pressure meter and the intelligent digital flow meter to zero the instruments.

[0075] S4. Experimental data measurement:

[0076] Turn the laminar-turbulent switch on the electronic digital differential pressure meter panel to turbulent flow. Adjust the valve to change different flow rates, including the maximum flow rate. After each experimental parameter stabilizes, use the electronic digital differential pressure meter and flow meter to measure the head difference, flow rate, and temperature;

[0077] S5. After the experiment is completed, turn off the power switches of the intelligent digital differential pressure meter and flow meter, cut off the power supply, take out the thermometer probe, and restore the experimental device.

[0078] 4. Data recording reference format:

[0079] Table 2

[0080] Measuring point number 1 2 3 4 5 6 7 diameter <![CDATA[D1]]> <![CDATA[D2]]> <![CDATA[D3]]> <![CDATA[D4]]> <![CDATA[D5]]> <![CDATA[D6]]> <![CDATA[D7]]> Section spacing

[0081] Table 3

[0082]

[0083] The above specific examples are used to illustrate the present invention, which is only used to help understand the present invention and is not intended to limit the present invention. For those skilled in the art, according to the idea of ​​the present invention, several simple deductions, modifications or substitutions can be made.

Claims

1. A tapered inlet structure for fluid flow testing, characterized in that: It comprises a flow stabilizing section (1) and a telescopic foldable anti-arc section (2) which is detachably mounted at the rear end of the flow stabilizing section (1) and can be telescoped or unfolded in the longitudinal, transverse and vertical directions; The flow stabilizing section (1) and the telescopic folding anti-arc section (2) are both tubular structures with openings on two opposite sides; the cross section of the telescopic folding anti-arc section (2) is a circular structure; the cross-sectional area of ​​the telescopic folding anti-arc section (2) gradually decreases from an end close to the flow stabilizing section (1) to an end away from the flow stabilizing section (1); A plurality of mutually parallel flow stabilizing plates (3) are arranged in the flow stabilizing section (1).

2. The tapered inlet structure for fluid flow testing according to claim 1, characterized in that: The cross section of the flow stabilizing section (1) is a circular structure.

3. The tapered inlet structure for fluid flow testing according to claim 2, characterized in that: The flow stabilizing plate (3) is in the form of a circular plate.

4. The tapered inlet structure for fluid flow testing according to claim 1, characterized in that: The flow stabilizing section (1) is bolted to the telescopic and foldable anti-arc section (2).

5. The tapered inlet structure for fluid flow testing according to claim 4, characterized in that: The opening of the flow stabilizing section (1) located at the front side is an inlet (101), a first flange (102) is installed at the inlet (101), and a second flange (103) is installed at the edge of the opening of the flow stabilizing section (1) located at the rear side; A third flange (201) for bolting to the second flange (103) is installed at the opening on the front side of the telescopic foldable anti-arc section (2), and a fourth flange (202) for bolting to the model section is installed at the opening on the rear side of the telescopic foldable anti-arc section (2).

6. The tapered inlet structure for fluid flow testing according to claim 5, characterized in that: The first flange (102), the second flange (103), the third flange (201) and the fourth flange (202) are respectively provided with a plurality of screw holes (4) in a circumferential direction around their own central axes.

7. The tapered inlet structure for fluid flow testing according to claim 1, characterized in that: The shape and size of the flow stabilizing plate (3) are matched with those of the flow stabilizing section (1).

8. The tapered inlet structure for fluid flow testing according to claim 1, characterized in that: The inner surface of the telescopic and foldable anti-arc section (2) is provided with a flexible epoxy resin material coating.

9. The tapered inlet structure for fluid flow testing according to claim 1, characterized in that: The outer surface of the telescopic and foldable anti-arc section (2) is provided with a polyurethane coating.

10. A test method for a tapered inlet structure for fluid flow test based on the tapered inlet structure for fluid flow test according to any one of claims 1 to 9, characterized in that: include: According to the test pressure range, the cross-sectional shape and size of the model section, a tapered inlet structure of appropriate size for fluid flow test is selected; According to the flow direction, the steady flow section (1), the telescopic folding anti-arc section (2), and the model section are sequentially connected from front to back, ensuring that the connecting section of the telescopic folding anti-arc section (2) is the same in shape, size and slope as the model section, and the axes coincide with each other; The telescopic foldable anti-arc section (2) is adjusted according to different pressures.

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