Self-cooling pump testing device

Abstract

The invention relates to the technical field of pump testing, in particular to a self-cooling pump testing device. The device comprises a tested pump and a high-level water tank connected with an inlet and an outlet of the tested pump, a self-suction connector is further connected between the outlet of the tested pump and the high-level water tank, the outlet of the tested pump is provided with a first necking pipe inserted into the inlet end of the self-suction connector, and the outlet end of the self-suction connector is provided with a second necking pipe communicated with the high-level water tank; the middle part of the self-suction joint is communicated with the low-position water tank through a water suction pipe. Through reasonable pipeline layout, on the basis that the operation cost of the pump test device is not increased too much, the pump test device has the advantages of a self-water-feeding function of high-position installation of the water supply tank and slow temperature rise of low-position installation of the water supply tank.

Description

Technical Field

[0001] The invention relates to the technical field of pump testing, in particular to a self-cooling pump testing device. Background Art

[0002] A pump test rig is a key piece of equipment used to test, verify, and evaluate pump performance. It primarily consists of a water supply tank and a circulation pipeline connecting the water supply tank to the pump under test. The water supply tank can be installed in either a high-position configuration, above the inlet of the pump under test, or a low-position configuration, below the inlet of the pump under test.

[0003] When the water supply tank is installed high, the water in the water supply tank can flow back into the test pump, eliminating the need for a pre-pump or other self-priming device to feed the pump. However, due to limited construction space and costs, the water supply tank is often small. This results in a rapid temperature rise of the test medium during large test pump tests, necessitating the addition of cooling and heat exchange equipment to reduce the temperature, increasing operating costs.

[0004] The low-position installation of the water supply tank, by excavating a pool to create a large water supply tank structure, can prevent rapid temperature rise in the water tank and significantly improve self-heating performance. However, since ordinary pumps do not have self-priming capabilities, a pre-submersible pump must be added to the pump's suction port to provide pre-priming for the pump under test. This means that two pumps must be operated simultaneously for each pump test, resulting in at least double the amount of unnecessary energy waste.

[0005] Obviously, the two existing water supply tank installation solutions cannot achieve both low cost and high heat dissipation effects, so they need to be solved urgently. Summary of the Invention

[0006] In order to avoid and overcome the technical problems existing in the prior art, the present invention provides a self-cooling pump test device. Through reasonable pipeline layout, the pump test device can take into account the self-feeding function of the high-position installation of the water supply tank and the slow heating advantage of the low-position installation of the water supply tank without increasing the operating cost of the pump test device too much.

[0007] To achieve the above object, the present invention provides the following technical solutions: A self-cooling pump test device includes a test pump and a high-level water tank connected to the inlet and outlet of the test pump, a self-priming joint is further connected between the outlet of the test pump and the high-level water tank, the outlet of the test pump is installed with a first necked pipe inserted into the inlet end of the self-priming joint, and the outlet end of the self-priming joint is provided with a second necked pipe connected to the high-level water tank; and a low-level water tank is also included, and the middle part of the self-priming joint is connected to the low-level water tank through a water suction pipe.

[0008] As a further solution of the present invention: the equivalent diameters of the first necked tube and the second necked tube are adjustable, wherein the equivalent diameter of the first necked tube is adjusted according to the following formula: ; Where, is the equivalent diameter of the first constricted tube, in mm; is the density of the test medium, in kg / m 3 ; The flow rate of the tested pump, in m 3 / s; is the outlet pressure of the tested pump, in Pa; is the atmospheric pressure of the liquid surface of the low-level water tank, in Pa; is the acceleration due to gravity, in m / s²; is the liquid level height of the low-level water tank, in m; is the flow rate of the suction pipe, in m 3 / s; is the diameter of the suction pipe, in m; is the length of the suction pipe, in m; is the friction coefficient of the fluid when it flows in the suction pipe, dimensionless; The equivalent diameter of the second necking tube is adjusted according to the following formula: ; Where, is the equivalent diameter of the second necking tube, in mm; c is the empirical coefficient, dimensionless; y It is the proportional coefficient between the set flow rate of the suction pipe and the flow rate of the test pump, dimensionless.

[0009] As a further solution of the present invention: an overflow pipe connected to the low-level water tank is installed on the upper part of the high-level water tank.

[0010] As a further solution of the present invention: the high-level water tank is connected to the inlet of the test pump through a water inlet pipe, and a first control valve is installed on the water inlet pipe.

[0011] As a further solution of the present invention: a first pressure sensor is installed on the water inlet pipe near the inlet of the test pump.

[0012] As a further solution of the present invention: the outlet of the tested pump is connected to the first constricted pipe through a drainage pipe, and a second control valve is installed on the drainage pipe.

[0013] As a further solution of the present invention: a second pressure sensor is installed on the drain pipe adjacent to the outlet of the tested pump.

[0014] As a further solution of the present invention: a flow meter is installed on the drainage pipe.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. This application retains the structural arrangement of the high-level water tank. At the same time, a low-level water tank is also provided. During the circulation of the test medium between the high-level water tank and the test pump, the self-priming joint provided at the outlet of the test pump generates suction, thereby automatically sucking the low-temperature test medium in the low-level water tank into the self-priming joint, and mixing the test medium in the low-level water tank with the test medium discharged from the outlet of the test pump, thereby reducing the temperature of the test medium finally sent to the high-level water tank. Therefore, during the test process, there is no need to operate the cooling mechanism additionally, and thus no additional energy consumption is generated during the test process.

[0016] 2. The equivalent diameters of the first and second constricted tubes are adjustable. Adjusting this equivalent diameter adjusts the suction flow rate of the suction pipe. By increasing or decreasing the suction flow rate of the suction pipe, the mixing ratio of the high-speed test medium discharged by the test pump through the first constricted tube into the self-priming joint and the low-speed test medium sucked into the suction pipe changes, thereby adjusting the cooling effect of the test medium discharged by the test pump into the self-priming joint.

[0017] In addition, the present application also provides an adjustment algorithm for the equivalent diameters of the first necked tube and the second necked tube, so as to accurately adjust the equivalent diameters of the first necked tube and the second necked tube according to the required mixing ratio of the mixed flow, so that the ratio between the high-speed test medium discharged into the self-priming joint by the first necked tube and the low-speed test medium sucked into the water suction pipe in the mixed flow reaches the expected ratio, thereby providing technical support for adjusting the temperature of the mixed flow. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of the present invention.

[0019] In the figure: 10, low-level water tank; 20, high-level water tank; 30, test pump; 40, water inlet pipe; 50, discharge pipe; 51, first necked pipe; 60, water suction pipe; 70, self-priming joint; 71, second necked pipe; 80, overflow pipe. DETAILED DESCRIPTION

[0020] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0021] For ease of understanding, the specific structure and working mode of the present invention are further described below with reference to the accompanying drawings: The specific structure of the present invention refers to Figure 1 As shown, its main structure includes a test pump 30 and a high-level water tank 20 connecting the inlet and outlet of the test pump 30. A self-priming joint 70 is also connected between the outlet of the test pump 30 and the high-level water tank 20. The outlet of the test pump 30 is installed with a first necked pipe 51 inserted into the inlet end of the self-priming joint 70, and the outlet end of the self-priming joint 70 is provided with a second necked pipe 71 connected to the high-level water tank 20. It also includes a low-level water tank 10, and the middle part of the self-priming joint 70 is connected to the low-level water tank 10 through a suction pipe 60. The present application retains the structural arrangement of the high-level water tank 20, and the test medium in the high-level water tank 20 is automatically supplied to the test pump 30 under the action of gravity, thereby eliminating the need to set a pre-pump to continuously supply the test medium to the test pump 30 during the test. In addition, the present application is also provided with a low-level water tank 10. During the circulation of the test medium between the high-level water tank 20 and the test pump 30, the self-priming joint 70 provided at the outlet of the test pump 30 generates suction, and then automatically sucks the low-temperature test medium in the low-level water tank 10 into the self-priming joint 70, and mixes the test medium in the low-level water tank 10 with the test medium discharged from the outlet of the test pump 30, thereby reducing the temperature of the test medium finally sent to the high-level water tank 20. Therefore, during the test process, there is no need to operate the cooling mechanism additionally, and thus no additional energy consumption is generated during the test process.

[0022] The self-priming principle of the self-priming joint 70 is as follows: since the inlet of the self-priming joint 70 is connected to the outlet of the test pump 30 through the first constricted tube 51, the passage area of ​​the test medium at the first constricted tube 51 is significantly smaller than the liquid passage area at the outlet of the test pump 30. Therefore, the flow rate of the test medium delivered to the first constricted tube 51 increases. Since pressure energy is converted into kinetic energy, according to the principle of conservation of energy, the pressure in the chamber of the self-priming joint 70 decreases. When the pressure in the chamber of the self-priming joint 70 drops below atmospheric pressure, the negative pressure exerted on the test medium in the low-level water tank 10 through the suction pipe 60 creates a negative suction force, thereby achieving the self-priming function of the test medium in the low-level water tank 10. A second necked pipe 71 is provided at the outlet end of the self-priming joint 70. The high-speed test medium discharged into the self-priming joint 70 by the first necked pipe 51 and the low-speed test medium sucked into the water suction pipe 60 will mix into a mixed flow in the inner cavity of the self-priming joint 70. The mixed flow still flows through the first necked pipe 51 at a certain flow rate, and then converts the pressure energy into kinetic energy. According to the principle of conservation of energy, the subsequent pressure will gradually decrease, keeping the pressure in the inner cavity of the self-priming joint 70 lower than the pressure in the water suction pipe 60.

[0023] On the basis of the above, if Figure 1 As shown, since the test medium in the low-level water tank 10 is mixed and then sent to the high-level water tank 20, the liquid level of the test medium in the high-level water tank 20 will gradually increase during the test. The present application installs an overflow pipe 80 connected to the low-level water tank 10 on the upper part of the high-level water tank 20. When the water level of the high-level water tank 20 increases and exceeds the overflow pipe 80, the test medium in the high-level water tank 20 can flow back to the low-level water tank 10 through the overflow pipe 80, and the large space of the low-level water tank 10 is used for heat dissipation.

[0024] In addition, if Figure 1 As shown, the high-level water tank 20 is connected to the inlet of the test pump 30 through the water inlet pipe 40, and a first control valve is installed on the water inlet pipe 40, which is used to connect and disconnect the inlet of the test pump 30 with the high-level water tank 20 so as to replace a new test pump 30 for testing; at the same time, it can also be used to control the flow rate sent from the high-level water tank 20 to the inlet of the test pump 30.

[0025] Furthermore, a first pressure sensor is installed on the water inlet pipe 40 adjacent to the inlet of the test pump 30 , for obtaining the pressure value at the inlet of the test pump 30 .

[0026] On the basis of the above, if Figure 1 As shown, the outlet of the test pump 30 is connected to the first necked pipe 51 through the drain pipe 50. A second control valve is installed on the drain pipe 50 to connect and disconnect the outlet of the test pump 30 with the high-level water tank 20 so as to replace a new test pump 30 for testing; at the same time, it can also be used to control the flow rate of the outlet of the test pump 30.

[0027] In addition, a second pressure sensor is installed on the drain pipe 50 adjacent to the outlet of the test pump 30 , and a flow meter is installed on the drain pipe 50 , for respectively obtaining the pressure and flow at the outlet of the test pump 30 .

[0028] Based on the above, the equivalent diameters of the first and second constricted tubes 51, 71 are adjustable. Adjusting these equivalent diameters allows for adjustment of the suction flow rate of the suction pipe 60. By increasing or decreasing the suction flow rate of the suction pipe 60, the ratio of the mixed flow of the high-speed test medium discharged by the test pump 30 through the first constricted tube 51 into the self-priming joint 70 and the low-speed test medium drawn into the suction pipe 60 is varied, thereby adjusting the cooling effect of the test medium discharged by the test pump 30 into the self-priming joint 70.

[0029] Specifically, the present application also provides an adjustment algorithm for the equivalent diameters of the first necked tube 51 and the second necked tube 71 to accurately adjust the equivalent diameters of the first necked tube 51 and the second necked tube 71 according to the required mixing ratio of the mixed flow, so that the ratio between the high-speed test medium discharged from the first necked tube 51 into the self-priming joint 70 and the low-speed test medium sucked into the water suction pipe 60 in the mixed flow reaches the expected ratio, thereby providing technical support for adjusting the temperature of the mixed flow.

[0030] Specifically, the equivalent diameter of the first constricted tube 51 is adjusted according to the following formula: ; Where, is the equivalent diameter of the first constricted tube 51, in mm; is the density of the test medium, in kg / m 3 ; The flow rate of the tested pump 30, in m 3 / s; is the outlet pressure of the tested pump 30, in Pa; is the atmospheric pressure of the liquid surface of the low-level water tank 10, in Pa; is the acceleration due to gravity, in m / s²; is the liquid level of the low-level water tank 10. Since the area and volume of the low-level water tank 10 in this application are much larger than those of the high-level water tank 20, the liquid level of the low-level water tank 10 is almost constant during the circulation of the medium. The unit is m; is the flow rate of the suction pipe 60, in m 3 / s; is the diameter of the suction pipe 60, in meters; is the length of the suction pipe 60, in m; is the friction coefficient of the fluid when it flows in the suction pipe 60, dimensionless; The equivalent diameter of the second necked tube (71) is adjusted according to the following formula: ; Where, is the equivalent diameter of the second constricted tube 71, in mm; c It is an empirical coefficient, dimensionless. It is introduced to consider the mixing loss and flow non-uniformity in actual design and is taken as 1-1.3; y It is the proportional coefficient between the set flow rate of the suction pipe 60 and the flow rate of the test pump 30, and is dimensionless.

[0031] 1. The derivation logic of the equivalent diameter adjustment formula of the first constricted tube 51 is as follows: (1) The cross-sectional equation for the suction pipe 60 is: According to the principle of conservation of energy, the Bernoulli equation for the upper end of the suction pipe 60 can be obtained: (1); Where, is the atmospheric pressure of the liquid surface of the low-level water tank 10, in Pa; The unit of pressure at the upper end of the suction pipe 60 is Pa; is the density of the test medium, in kg / m 3 ; is the acceleration due to gravity, in m / s², take 9.81; is the liquid level height of the low-level water tank 10, in m; is the length of the suction pipe 60, in m; is the diameter of the suction pipe 60, in m; is the flow velocity of the test medium in the suction pipe 60, in m / s; is the friction coefficient of the fluid when it flows in the suction pipe 60, dimensionless; (2); The flow rate of the suction pipe 60, in m 3 / s; We can get: (3); From equations (1) to (3), we can solve: (4); Since the flow design of the suction pipe 60 is generally turbulent flow, the friction coefficient of the turbulent fluid when flowing in the suction pipe 60 is for: (5); in, is the drag coefficient, dimensionless, ; is the Reynolds number, dimensionless, ; u is the viscosity of the test medium, in Pa·s.

[0032] (2) The cross-sectional equation for the first constricted tube 51 is: According to the principle of conservation of energy, the Bernoulli equation for the cross section of the first constricted tube 51 can be obtained as follows: (6); Where, The outlet pressure of the tested pump 30, in Pa; before the test begins, it can be obtained through theoretical calculation of the inherent characteristics of the pump to determine the initial value , The flow rate is Q The corresponding head is obtained through actual measurement after the test starts; is the flow rate at the outlet of the test pump 30, in m / s. In the actual design, the diameter of the outlet of the test pump 30 is much larger than the first constricted tube 51. Therefore, the flow rate at the outlet of the test pump 30 is The flow rate is much smaller than the flow rate at the outlet of the first constricted tube 51, and is ignored in the calculation of this application. ; is the flow velocity at the outlet of the first constricted pipe 51, in m / s.

[0033] Therefore, ignoring When , formula (6) can be organized as: (7); And then reorganize it into: (8); is the flow rate of the tested pump 30, in m 3 / s; is the equivalent diameter of the first constricted tube 51 , in mm.

[0034] Combining equations (6) to (8), we can obtain: (9); Substituting formula (4) into formula (9), the diameter adjustment formula of the first necked tube 51 in this application is obtained: ; 2. The derivative formula of the equivalent diameter of the second necked tube 71 is specifically: (1) Flow equation for the mixed liquid in the suction pipe 70 When the test medium is sucked into the chamber of the suction pipe 70, the test medium sent in by the first necked pipe 51 and the test medium sucked in by the water suction pipe 60 exchange momentum. According to the law of conservation of momentum, the equation can be obtained: (10); is the discharge flow rate of the second constricted pipe 71, in m 3 / s; The flow rate of the tested pump 30, in m 3 / s; The flow rate of the suction pipe 60, in m 3 / s; is the discharge flow rate of the second constricted pipe 71, in m / s; is the flow velocity of the test medium in the suction pipe 60, in m / s; According to the principle of conservation of mass: (11); According to the required and The ratio between: (12); y For the setting and The proportional coefficient between The liquid flow rate in the suction pipe 60 is very small, and its flow rate is ignored in this application, that is, ; but: (13); b) According to the law of conservation of mass: (14); In the formula is the area of ​​the second constricted tube 71, in mm 2 ; Substituting equations (8), (11) and (12) into equation (14), we obtain: (15); And because: (16); Combining equations (15) and (16), the equivalent diameter of the second necking tube 71 can be calculated as for: (17); In actual design, mixing loss and flow non-uniformity need to be considered, and empirical coefficients are introduced. c Take 1.3 to 1.0 to get the actual equivalent diameter of the second necking tube 71 required by this application. for: (18).

[0035] During practice, practice conditions are divided into three groups: The first group is when the test medium is water at 20℃, the density of the test medium is 1000kg / m 3 ; The atmospheric pressure of the liquid level of the low level water tank 10 is 101325Pa; acceleration due to gravity 9.81m / s²; the liquid level of the low-level water tank 10 3m; suction pipe 60mm diameter 0.2m; length of suction pipe 60 At this time, the viscosity of the test medium is 3.5m. u Take 0.001Pa·s, the resistance coefficient along the way According to the diameter of the suction pipe 60 and the flow rate of the test medium in the suction pipe 60 Calculated is 40000, and the resistance coefficient of the fluid flowing in the suction pipe 60 can be obtained. is 0.50, the outlet pressure of the tested pump 30 The pressure is 500000Pa, and the flow rate of the tested pump is set to 30 100m 3 / h, suction pipe flow rate 60 100m 3 / h.

[0036] From this, we can calculate is 34.62mm, is 69.24 mm, and the empirical coefficient c is 1.05, then It is 72.70mm.

[0037] According to the obtained equivalent diameter of the first constricted tube 51 The value and the equivalent diameter of the second constricted tube 71 The equivalent diameters of the first and second constricted tubes 51 and 71 are adjusted and the test device is started. After the operation stabilizes, the flow rate of the test pump 30 is measured to be 99.7m 3 / h, the flow rate of the suction pipe 60 is 99.5m 3 / h, and the expected flow rate fluctuation range is 0.5m 3 Obviously, through the adjustment algorithm of the equivalent diameter of the first constricted pipe 51 and the equivalent diameter of the second constricted pipe 71 provided in this application, the ratio between the high-speed test medium discharged from the first constricted pipe 51 into the self-priming joint 70 and the low-speed test medium sucked into the water suction pipe 60 in the mixed flow can reach the expected ratio, thereby providing technical support for adjusting the temperature of the mixed flow.

[0038] The second group is when the test medium is water at 20.1℃, the density of the test medium is 1000kg / m 3 ; The atmospheric pressure of the liquid level of the low level water tank 10 is 101325Pa; acceleration due to gravity 9.81m / s²; the liquid level of the low-level water tank 10 3m; suction pipe 60mm diameter 0.2m; length of suction pipe 60 At this time, the viscosity of the test medium is 3.5m. u Take 0.001Pa·s, the resistance coefficient along the way According to the diameter of the suction pipe 60 and the flow rate of the test medium in the suction pipe 60 The calculated value is 40038, which is the resistance coefficient of the fluid flowing in the suction pipe 60. is 0.50, the outlet pressure of the tested pump 30 is 500000Pa; the flow rate of the tested pump is 30 120m 3 / h; suction pipe 60 flow 120m 3 / h.

[0039] From this, we can calculate is 37.86mm, is 75.71mm, empirical coefficient c Take 1.05, then It is 79.5mm.

[0040] According to the obtained equivalent diameter of the first constricted tube 51 The value and the equivalent diameter of the second constricted tube 71 The equivalent diameters of the first and second constricted pipes 51 and 71 are adjusted and the test device is started. After the operation stabilizes, the flow rate of the test pump 30 is measured to be 119.6 m 3 / h, the flow rate of the suction pipe 60 is 119.4m 3 / h, and the expected flow rate fluctuation range is 0.5m 3 / h.

[0041] The third group is when the test medium is water at 20.2℃, the density of the test medium is 1000kg / m 3 ; The atmospheric pressure of the liquid level of the low level water tank 10 is 101325Pa; acceleration due to gravity 9.81m / s²; the liquid level of the low-level water tank 10 3m; suction pipe 60mm diameter 0.2m; length of suction pipe 60 At this time, the viscosity of the test medium is 3.5m. u Take 0.001Pa·s, the resistance coefficient along the way According to the diameter of the suction pipe 60 and the flow rate of the test medium in the suction pipe 60 The calculated value is 39888, which is the resistance coefficient of the fluid flowing in the suction pipe 60. is 0.50, the outlet pressure of the tested pump 30 is 500000Pa; the flow rate of the tested pump is 30 150m 3 / h; suction pipe 60 flow 150m 3 / h.

[0042] From this, we can calculate is 42.18mm, is 84.37mm, empirical coefficient c Take 1.05, then It is 88.59mm.

[0043] According to the obtained equivalent diameter of the first constricted tube 51 The value and the equivalent diameter of the second constricted tube 71 , adjust the equivalent diameters of the first constricted pipe 51 and the second constricted pipe 71, and start the test device. After the operation stabilizes, the measured flow rate of the test pump 30 is 149.8m 3 / h, the flow rate of the suction pipe 60 is 149.6m3 / h, and the expected flow rate fluctuation range is 0.5m 3 / h.

[0044] Obviously, through the adjustment algorithm of the equivalent diameter of the first necked tube 51 and the equivalent diameter of the second necked tube 71 provided in this application, the ratio between the high-speed test medium discharged into the self-priming joint 70 by the first necked tube 51 and the low-speed test medium sucked into the suction pipe 60 in the mixed flow can reach the expected ratio, thereby providing technical support for adjusting the temperature of the mixed flow.

[0045] Of course, it will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, but also encompasses the same or similar structures that can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and it is intended that all variations that fall within the meaning and range of equivalents of the claims be encompassed within the present invention. Any reference signs in the claims should not be construed as limiting the claim to which they relate.

[0046] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0047] The technology, shape, and structure not described in detail in the present invention are all well-known technologies.

Claims

1. A self-cooling pump test device, comprising a test pump (30) and a high-level water tank (20) connected to the inlet and outlet of the test pump (30), characterized in that: A self-priming joint (70) is further connected between the outlet of the test pump (30) and the high-level water tank (20), and a first necked pipe (51) inserted into the inlet end of the self-priming joint (70) is installed at the outlet of the test pump (30), and a second necked pipe (71) connected to the high-level water tank (20) is provided at the outlet end of the self-priming joint (70); and a low-level water tank (10) is further included, and the middle part of the self-priming joint (70) is connected to the low-level water tank (10) through a water suction pipe (60).

2. A self-cooling pump test device according to claim 1, characterized in that: The equivalent diameters of the first necked tube (51) and the second necked tube (71) are adjustable, wherein the equivalent diameter of the first necked tube (51) is adjusted according to the following formula: ； Where, is the equivalent diameter of the first necked tube (51), in mm; is the density of the test medium, in kg / m 3 ; The flow rate of the tested pump (30), in m 3 / s; is the outlet pressure of the tested pump (30), in Pa; is the atmospheric pressure at the liquid level of the low-level water tank (10), in Pa; is the acceleration due to gravity, in m / s²; is the liquid level height of the low-level water tank (10), in m; is the flow rate of the suction pipe (60), in m 3 / s; is the diameter of the suction pipe (60), in m; is the length of the suction pipe (60), in m; is the friction coefficient of the fluid when it flows in the suction pipe (60), dimensionless; The equivalent diameter of the second necked tube (71) is adjusted according to the following formula: ； Where, is the equivalent diameter of the second necked tube (71), in mm; c is the empirical coefficient, dimensionless; y It is the proportional coefficient between the set flow rate of the suction pipe (60) and the flow rate of the test pump (30), dimensionless.

3. A self-cooling pump test device according to claim 1 or 2, characterized in that: An overflow pipe (80) communicating with the low-level water tank (10) is installed on the upper portion of the high-level water tank (20).

4. A self-cooling pump test device according to claim 1 or 2, characterized in that: The high-level water tank (20) is connected to the inlet of the test pump (30) through a water inlet pipe (40), and a first control valve is installed on the water inlet pipe (40).

5. A self-cooling pump test device according to claim 4, characterized in that: A first pressure sensor is installed on the water inlet pipe (40) adjacent to the inlet of the tested pump (30).

6. A self-cooling pump test device according to claim 1 or 2, characterized in that: The outlet of the test pump (30) is connected to the first constricted tube (51) via a drainage pipe (50), and a second control valve is installed on the drainage pipe (50).

7. A self-cooling pump test device according to claim 6, characterized in that: A second pressure sensor is installed on the drainage pipe (50) adjacent to the outlet of the tested pump (30).

8. A self-cooling pump test device according to claim 6, characterized in that: A flow meter is installed on the drainage pipe (50).

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