A positive displacement pump gas-in-test performance testing system and method

Abstract

The application discloses a kind of volumetric pump gas-containing test performance test system and method, belong to pump performance test technical field, including oil tank body, oil tank body is separately provided with gas filling pipe group and test pipe group, forms two independent gas filling circuit and test circuit;Gas filling pipe group is provided with gas filling tee joint and gas mixing pump along the direction of medium flow, gas filling tee joint is communicated with air compressor by gas filling branch, in test state, gas mixing pump pressurized mixing gas-liquid two-phase medium, to prepare gas-liquid two-phase mixed medium containing uniform small gas bubble before sending medium back to oil tank body;Test pipe group is communicated and is provided with the pump to be measured, the test pipe group in the output end of the pump to be measured is provided with measuring pipe section, and gas content measuring instrument is communicated and arranged on the measuring pipe section.The application realizes the high uniformity and stability of small gas bubble net in gas-liquid two-phase medium in a wide range;Simultaneously eliminate the technical defects of multivariable interlaced interference caused by single linear series.

Description

Technical Field

[0001] This invention belongs to the field of pump performance testing technology, and in particular relates to a positive displacement pump gas-containing test performance testing system and method. Background Technology

[0002] In industrial systems such as hydraulics, lubrication, and petrochemical transportation, positive displacement pumps, including screw pumps and gear pumps, are widely used to transport various high-viscosity or low-viscosity media. In actual operating conditions, since the volume of the medium in the system is usually limited, when the pump's flow rate is too large relative to the tank volume, the circulation ratio of the medium within the entire system increases significantly. At this time, the residence time of the medium in the tank is too short, and gases (such as air) do not have enough time to naturally precipitate and escape from the medium, resulting in a significant increase in the gas content of the medium entering the pump suction end. When air or gas is mixed into the medium, under the continuous pressure increase of the positive displacement pump's closed profile, the bubbles undergo violent mechanical compression and collapse. This not only causes a severe decrease in the pump's flow rate and volumetric efficiency but also induces severe mechanical cavitation, leading to abnormal degradation problems such as increased pump vibration and aggravated mechanical noise. Therefore, in-depth research on the operating characteristics of positive displacement pumps under different gas content conditions, and high-precision simulation of various gas content conditions in the laboratory, is of extremely important engineering practical significance for the research and development of high-value pump sets and the optimization of anti-cavitation capabilities.

[0003] However, existing pump-based gas-liquid two-phase flow performance testing systems typically suffer from the following significant drawbacks when simulating operating conditions with different gas contents: First, the gas injection is uneven and the operating conditions are severely distorted. Current technologies typically involve directly injecting gas into the inlet pipe of the pump under test using a static mixer or aerator. Because media such as lubricating oil and hydraulic oil usually have high surface tension or viscosity, the injected gas easily forms large air pockets inside the pipe before entering the pump, failing to dissolve uniformly or form microbubbles in the medium. When this heterogeneous fluid with macroscopic air pockets directly impacts the pump, it can cause the pump's internal medium to be instantly sucked into the air or experience sudden, violent mechanical impacts. This fails to realistically and stably simulate the microbubble network formed when air cannot precipitate at high circulation rates in industrial settings, resulting in severely distorted test conditions.

[0004] Second, single-loop linear series connection leads to interference under multiple operating conditions. Existing testing systems often employ a single-loop closed-loop architecture, where gas-liquid mixing, flow measurement, temperature control, and the pump under test are all connected in series on a single closed main pipeline. In this structure, changes in the injection volume or flow rate to adjust the gas content directly interfere with the pressure flow field within the pipeline. Simultaneously, the frictional temperature rise introduced by the operation of high-power pump units cannot be independently and quickly mitigated, causing the viscosity and thermodynamic properties of the medium to continuously drift. This structure, characterized by intertwined and severe interference among multiple operating conditions, results in a lack of testing methods capable of achieving real-time, accurate, independent, and stepless adjustment and measurement of gas content over a wide range, and cannot guarantee a single variable in the testing environment. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a positive displacement pump gas-containing test performance testing system and method. It not only solves the technical pain point of traditional direct gas injection forming large gas pockets that are difficult to dissolve uniformly in the pipeline, causing serious distortion of the test conditions, but also achieves high uniformity and stability of the micro bubble network in the gas-liquid two-phase medium over a large range. At the same time, it eliminates the technical defects of multi-variable interference such as flow pressure and friction temperature rise caused by linear series connection of a single line.

[0006] The present invention is implemented as follows: on the one hand, a gas-containing test performance testing system for a positive displacement pump is provided, including an oil tank body, on which an air filling pipe group and a test pipe group are respectively arranged to form two independent air filling circuits and test circuits. The gas filling pipe assembly is equipped with a gas filling tee and a gas mixing pump along the medium flow direction. The gas filling tee is connected to the air compressor through a gas filling branch. In the test state, the gas mixing pump pressurizes and mixes the gas-liquid two-phase medium to pre-prepare a gas-liquid two-phase mixed medium containing uniform micro bubbles before sending the medium back to the oil tank. The test tube assembly is connected to a pump to be tested, and a measuring tube section is set in the test tube assembly located at the output end of the pump to be tested. A gas content measuring instrument is connected to the measuring tube section.

[0007] Furthermore, the oil tank body is also equipped with a cooling pipe assembly to form an independently operable cooling circuit. The cooling pipe assembly is equipped with an oil cooler and an outlet flow regulating valve in sequence along the medium flow direction.

[0008] Furthermore, a heater and a temperature sensor are provided at the lower end of the oil tank body, and the temperature sensor is located near the oil outlet of the oil tank body.

[0009] Furthermore, the mixing pump and the pump under test are respectively located on opposite sides of the fuel tank body; The lower end of the oil tank near the mixing pump is provided with an oil filling outlet and an oil filling return outlet. The oil filling outlet and the oil filling return outlet are respectively located on two opposite side walls of the oil tank. The oil filling outlet and the oil filling return outlet are connected by an oil filling pipe assembly. A test oil outlet is provided at the lower end of the oil tank near the side of the pump under test. The test oil outlet and the gas return oil outlet are located on two adjacent side walls of the oil tank. A test oil return oil outlet is provided at the upper end of the oil tank. The test oil outlet and the test oil return oil outlet are connected by a test pipe assembly.

[0010] Furthermore, the pump type structure of the gas mixing pump is the same as that of the pump under test, and the flow rate of the medium in the gas mixing pump is greater than 10% of the flow rate of the medium in the pump under test.

[0011] Furthermore, the inlet end and outlet end of the pump under test are respectively equipped with an inlet pressure sensor and an outlet pressure sensor; The inlet end of the pump under test is connected to the test tube assembly via an inlet flexible connector, and the outlet end of the pump under test is connected to the test tube assembly via an outlet flexible connector.

[0012] Furthermore, the length of the straight pipe section at the inlet end of the pump under test is greater than 12 times the diameter of the inlet pipe of the pump under test, and the length of the straight pipe section at the outlet end of the pump under test is greater than 4 times the diameter of the outlet pipe of the pump under test.

[0013] Furthermore, a medium flow regulating valve is installed on the gas filling pipe assembly located on the outlet side of the mixing pump; Along the gas flow direction, a gas pressure stabilizing tank, a gas flow regulating valve, and a filter are sequentially installed on the gas refueling branch. The test tube assembly shown is equipped with an inlet regulating valve and an outlet regulating valve, respectively, near the inlet and outlet ends.

[0014] Furthermore, a flow meter is installed on the test pipe assembly located at the outlet end of the outlet regulating valve, and the straight pipe section lengths at both the inlet and outlet ends of the flow meter are greater than 5 times the nominal diameter of the pipeline at that location.

[0015] On the other hand, a testing method using any of the above-described testing systems is provided, comprising the following steps: Temperature control stage: Start the oil cooler or heater to circulate and control the temperature of the medium in the oil tank until it reaches the set test target temperature; Gas-liquid medium mixing stage: Start the gas mixing pump and air compressor, and deliver the set flow rate of gas to the gas filling tee through the gas filling branch. After the gas and medium flow through the gas mixing pump and are pressurized and mixed, they return to the oil tank body and continue to circulate until the medium in the oil tank body is transformed into the target gas content medium with a uniformly distributed bubble network. Performance testing phase: Keep the gas filling circuit running continuously, start the pump under test, and adjust the gas supply of the gas filling branch and / or the medium flow rate of the gas filling circuit based on the data fed back by the gas content measuring instrument until the medium gas content on the suction side of the pump under test stably reaches the test requirement value. The inlet and outlet pressures of the pump under test are adjusted by the inlet / outlet regulating valves of the test circuit to meet the test requirements, and the performance test data of the pump under test are collected after the operating conditions stabilize.

[0016] The advantages and technical effects of this invention are as follows: By adopting the above-mentioned technical solution, the main oil tank body, the gas filling circuit, and the test circuit are connected in parallel, and a mixing pump is introduced into the gas filling pipe group. This not only solves the technical problem of traditional direct gas injection forming large air pockets that are difficult to dissolve uniformly in the pipeline, causing serious distortion of the test conditions, but also achieves high uniformity and stability of the microbubble network in the gas-liquid two-phase medium over a large range. At the same time, it eliminates the technical defects of multi-variable interference such as flow pressure and frictional temperature rise caused by linear series connection of a single line, and successfully prefabricates a homogeneous two-phase fluid with high simulation degree of the working conditions and precise controllable gas content over a large range at the front end (suction side) of the test circuit. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure provided in an embodiment of the present invention.

[0018] Figure 2 This is a schematic diagram of the fuel tank body and gas filling circuit structure provided in an embodiment of the present invention.

[0019] Figure 3 This is a schematic diagram of the oil tank body and cooling circuit structure provided in an embodiment of the present invention.

[0020] Figure 4 This is a schematic diagram of the tank body and test circuit structure provided in an embodiment of the present invention.

[0021] In the picture: 10. Main oil tank; 101. Oil tank body; 102. Oil tank cover; 103. Temperature sensor; 104. Heater; 105. Pneumatic butterfly valve; 106. Blind flange; 107. Level gauge; 20. Gas filling circuit; 201. Air compressor; 202. First gas shut-off valve; 203. Gas pressure stabilizing tank; 204. Gas flow regulating valve; 205. Filter; 206. Second gas shut-off valve; 207. Gas filling tee; 208. Mixing pump; 209. Medium flow regulating valve; 210. First shut-off valve at the oil tank outlet; 211. First shut-off valve at the oil tank inlet; 30. Cooling circuit; 301. Second shut-off valve at oil tank outlet; 302. Shut-off valve at oil cooler inlet; 303. Oil cooler; 304. Outlet flow regulating valve; 305. Second shut-off valve at oil tank inlet; 40. Test circuit; 401. Third shut-off valve at the oil tank outlet; 402. Inlet regulating valve; 403. Inlet flexible connecting pipe; 404. Inlet pressure sensor; 405. Pump under test; 406. Test bench; 407. Outlet pressure sensor; 408. Outlet flexible connecting pipe; 409. Measuring pipe section; 410. Rubber elbow; 411. Outlet regulating valve; 412. Flow meter. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0023] It should be noted that the terms "upper", "lower", "left", "right", "top", "bottom", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the present invention.

[0024] like Figures 1 to 4 As shown, this application provides a positive displacement pump gas-containing test performance testing system, including a main oil tank 10. The main oil tank 10 includes an oil tank body 101 and an oil tank cover 102. An air filling pipe group and a test pipe group are respectively provided on the oil tank body 101, forming two independent air filling circuits 20 and test circuits 40. The gas filling pipe assembly is provided with a gas filling tee 207 and a gas mixing pump 208 along the medium flow direction. The gas filling tee 207 is connected to the air compressor 201 through a gas filling branch. In the test state, the gas mixing pump 208 pressurizes and mixes the gas-liquid two-phase medium to pre-prepare a gas-liquid two-phase mixed medium containing uniform micro bubbles before sending the medium back to the oil tank 101. The test tube assembly is connected to a test pump 405, and a measuring tube section 409 is provided in the test tube assembly located at the output end of the test pump 405. A gas content measuring instrument is connected to the measuring tube section 409.

[0025] It should be noted that the fuel tank body 101 can be an open type with a volume of 12 cubic meters. The top of the fuel tank body 101 is bolted to the fuel tank cover plate 102. The upper interior of the fuel tank body 101 is provided with a grid structure to slow down the flow rate of oil entering through the return port and prevent the fluid from generating air bubbles.

[0026] The gas filling circuit 20 allows for stepless adjustment of the gas content (GVF volume fraction) of the test system medium from 1% to 15%. This ensures that as much of the medium in the tank 101 as possible participates in the circulation, and that the fluid returns from the bottom to prevent backflow from generating bubbles.

[0027] The pump under test is mounted on the test bench 406. The lower part of the measuring pipe section 409 near the pump is connected to the inlet of the gas content measuring instrument, and the upper part of the measuring pipe section 409 far from the pump is connected to the outlet of the gas content measuring instrument. The gas content measuring instrument has a measurement accuracy of ±0.1%, a measurement range of 0~100%, and a temperature range of 0~180℃, fully meeting the requirements for test accuracy, gas content, and temperature range. Connecting the gas content measuring instrument allows for accurate measurement of the gas content of the medium during the test process, with a large measurement range and high accuracy, effectively avoiding errors in the gas content value during the test. The pump under test 405 and the mixing pump 208 can be screw pumps, gear pumps, plunger pumps, or vane pumps, etc. In some embodiments, the mixing pump 208 and the test pump 405 are respectively located on opposite sides of the tank body 101. A gas filling outlet and a gas filling return outlet are provided at the lower end of the tank body 101 near the mixing pump 208. These two outlets are located on two opposite side walls of the tank body 101 and are connected by a gas filling pipe assembly. A first shut-off valve 210 for the tank outlet is provided on the gas filling outlet, and a first shut-off valve 211 for the tank inlet is provided on the gas filling return outlet. The gas filling outlet and return outlet, located on two opposite side walls of the tank body 101, create a fully flowing flow field for the medium at the bottom of the tank, eliminating dead zones, maintaining the stability of the medium flow, and reducing fluctuations in gas content.

[0028] A test oil outlet is provided at the lower end of the oil tank body 101 near the pump under test 405. The test oil outlet and the gas return oil outlet are located on two adjacent side walls of the oil tank body 101, respectively. A test oil return oil outlet is provided at the upper end of the oil tank body 101. The test oil return oil outlet and the gas outlet are located on the same side wall of the oil tank body 101, and are connected by a test pipe assembly. A third shut-off valve 401 is provided at the test oil outlet. The test oil outlet and the gas return oil outlet are located on two adjacent side walls of the oil tank body 101 and are at the far end of the same low layer, realizing the dynamic replenishment of the gas-containing medium in the test circuit and maintaining a stable gas content.

[0029] The test oil outlet and test oil return port are connected to the lower end and upper end of the oil tank body 101, respectively, to achieve low suction and high return. Since the return oil may contain a large volume of heterogeneous gas, the return oil comes from the upper part (high position) of the oil tank body 101.

[0030] The test oil return port and the gas outlet are located on the side wall of the same oil tank body 101, so that the heterogeneous gas bubbles in the return oil are processed within a shorter path, avoiding affecting the stability of the medium in the overall oil tank.

[0031] Each oil outlet of the oil tank body 101 is equipped with a pneumatic butterfly valve 105, and the oil return port at the top of the oil tank body 101 is equipped with a blind flange 106 when not in use.

[0032] As a preferred embodiment, based on the above structure, the oil tank body 101 is further equipped with a cooling pipe assembly, forming an independently operable cooling circuit 30. An oil cooler 303 and an outlet flow regulating valve 304 are sequentially arranged along the medium flow direction on the cooling pipe assembly. Specifically, a cooling oil outlet is provided at the lower end of the oil tank body 101, and a cooling oil return port is provided at the upper end of the oil tank body 101. The cooling oil outlet and cooling oil return port are located on two adjacent side walls of the oil tank body 101, with the cooling oil outlet located at the lower end and the cooling oil return port located at the upper end. The cooling oil outlet and cooling oil return port are connected by the cooling pipe assembly, enabling all the medium within the oil tank body 101 to participate in the cooling circulation and preventing some medium from remaining uncirculated. A second shut-off valve 301 is provided on the cooling oil outlet, and a second shut-off valve 305 is provided on the cooling oil return port. An inlet shut-off valve 302 for the oil cooler 303 is installed on the cooling pipe assembly located at the inlet end of the oil cooler 303.

[0033] The cooling circuit 30 has a maximum cooling power of 50 kW. The oil cooler 303 incorporates a circulating pump, a plate heat exchanger, and an air-cooled unit. The circulating pump transports the medium from the oil tank 101 to the plate heat exchanger, while the air-cooled unit cools the heat exchange medium. The cooled oil medium returns to the oil tank 101 after passing through the plate heat exchanger. The outlet flow regulating valve 304 allows for full-range flow regulation from 0% to 100%, adjusting the cooling rate.

[0034] As a preferred embodiment, based on the above structure, a heater 104 and a temperature sensor 103 are provided at the lower end of the oil tank body 101. The temperature sensor 103 is positioned near the oil outlet of the oil tank body 101. This proximity of the temperature sensor to the oil outlet allows for real-time and direct capture of the actual temperature of the medium about to enter the pipeline, avoiding control distortion caused by localized thermal stratification within the large-capacity oil tank. The temperature sensor 103 has a measurement range of 0~150℃. A level gauge 107 for monitoring the liquid level of the medium inside the oil tank body 101 is provided on the side wall of the oil tank body 101. In some embodiments, four heaters 104 and three temperature sensors 103 are provided. Each heater 104 has a heating power of 25kW and can reach a maximum temperature of 100℃, with a temperature rise rate of 2℃ / min at maximum oil volume.

[0035] The heater 104 and the oil cooler 303 operate independently compared to other circuits, and can accurately control the temperature of the test medium with a wide control range and high precision.

[0036] As a preferred option, the mixing pump 208 has the same pump structure as the test pump 405, and the flow rate of the medium in the mixing pump 208 is 10% greater than that in the test pump 405, meeting the test requirement of a maximum gas content of 15%. The mixing pump 208 uses the same type of pump set as the test pump 405, simulating the uniform microbubbles formed by the pressurization, compression, and collapse of air in the pump during actual use. This ensures that the gas content of the medium in the test circuit 40 is uniform and small, and is no longer affected by the pressurization and compression of the test pump 405.

[0037] As a preferred option, based on the above structure, the inlet end and outlet end of the pump under test 405 are respectively equipped with an inlet pressure sensor 404 and an outlet pressure sensor 407. The inlet of the pump under test 405 is connected to the test tubing assembly via an inlet flexible connector 403, and the outlet of the pump under test 405 is connected to the test tubing assembly via an outlet flexible connector 408. Furthermore, rubber elbows 410 are used at the bends in the test tubing assembly. The flexible connectors at both the inlet and outlet of the pump under test 405, along with the rubber elbows 410 at the bends, effectively isolate the vibration and noise of the pump assembly from the influence of valves, flow meters 412, and pipelines, ensuring the reliability of the test results.

[0038] As a preferred option, based on the above structure, the length of the straight pipe section at the inlet end of the pump under test 405 is greater than 12 times the diameter of the inlet pipe of the pump under test 405, and the length of the straight pipe section at the outlet end of the pump under test 405 is greater than 4 times the diameter of the outlet pipe of the pump under test 405. This reduces mutual interference between valves, pump sets, flow meters 412, pipelines, etc.

[0039] As a preferred option, based on the above structure, a medium flow regulating valve 209 is installed on the gas filling pipe assembly located on the outlet side of the gas mixing pump 208. The medium flow regulating valve 209 can realize full-range adjustment of the medium flow rate from 1% to 100% after gas filling.

[0040] Along the gas flow direction, a gas pressure stabilizing tank 203, a gas flow regulating valve 204, and a filter 205 are sequentially arranged on the gas refueling branch. A first gas shut-off valve 202 is installed at the outlet end of the air compressor 201, and a second gas shut-off valve 206 is installed at the outlet end of the filter 205. The gas pressure stabilizing pipe is a closed, vertical, pressure-resistant gas storage tank with a pressure resistance of 1.0 MPa and a volume of 200 L, improving the stability of the gas injection flow. The gas flow regulating valve 204 can adjust the medium flow rate from 1% to 100% after refueling, facilitating the adjustment of the gas content in the medium within the tank body 101. The filter 205 has a filtration accuracy of 20 μm.

[0041] The test tube assembly shown is equipped with an inlet regulating valve 402 and an outlet regulating valve 411 near the inlet and outlet ends, respectively. The inlet regulating valve 402 adjusts the inlet pressure of the pump under test 405, allowing it to be adjusted from positive pressure to the required negative pressure. The outlet regulating valve 411 adjusts the outlet pressure of the pump under test 405, allowing it to be adjusted from zero pressure to the required pressure.

[0042] As a preferred option, based on the above structure, a flow meter 412 is installed on the test pipe assembly located at the outlet end of the outlet regulating valve 411. The straight pipe sections at both the inlet and outlet ends of the flow meter 412 are longer than five times the nominal diameter of the pipeline at that location. This reduces mutual interference between the valve, pump assembly, flow meter 412, and pipeline.

[0043] On the other hand, a testing method using any of the above-described testing systems is provided, comprising the following steps: Temperature control stage: Start the oil cooler 303 or heater 104 to circulate and control the temperature of the medium in the oil tank 101 until it reaches the set test target temperature. Specifically: If the medium temperature is lower than the test requirement temperature, turn on the heater 104 until the temperature meets the requirement; if the medium temperature is higher than the test requirement temperature, fully open the second shut-off valve 301 at the oil tank outlet and the second shut-off valve 305 at the oil tank inlet of the cooling circuit 30, fully open the shut-off valve 302 at the inlet of the oil cooler 303 and the outlet flow regulating valve 304, and start the oil cooler 303 until the temperature meets the requirement.

[0044] Gas-liquid medium mixing stage: Start the gas mixing pump 208 and air compressor 201, and deliver the set flow rate of gas to the gas filling tee 207 through the gas filling branch. After the gas and medium flow through the gas mixing pump 208 and are pressurized and mixed, they return to the oil tank 101, and the cycle continues until the medium in the oil tank 101 is transformed into a medium with a uniformly distributed bubble network and the target gas content. Specifically: Fully open the first shut-off valve 210 at the oil tank outlet and the first shut-off valve 211 at the oil tank inlet in the gas filling circuit 20, fully open the medium flow regulating valve 209, and start the gas mixing pump 208; fully open the first gas shut-off valve 202, the gas flow regulating valve 204, and the second gas shut-off valve 206, and start the air compressor 201.

[0045] Performance testing phase: Keep the gas filling circuit 20 running continuously, start the pump under test 405, and adjust the gas supply of the gas filling branch and / or the medium flow rate of the gas filling circuit 20 based on the data fed back by the gas content measuring instrument until the medium gas content on the suction side of the pump under test 405 stably reaches the test requirement value. The inlet / outlet pressure of the pump under test 405 is adjusted by the inlet / outlet regulating valve 411 of the test circuit 40 to meet the test requirements, and the performance test data of the pump under test 405 is collected after the operating conditions are stable.

[0046] Specifically: Fully open the third shut-off valve 401 at the oil tank outlet, the inlet regulating valve 402, and the outlet regulating valve 411; start the pump under test 405 and adjust it to the test speed; read the data from the gas content measuring instrument; based on the data, adjust the gas flow regulating valve 204 and the medium flow regulating valve 209 until the gas content meets the test requirements; adjust the outlet regulating valve 411 until the data from the outlet pressure sensor 407 meets the test requirements; adjust the inlet regulating valve 402 until the data from the inlet pressure sensor 404 meets the test requirements; and record the test data.

[0047] When testing different gas contents, the operating steps of the performance testing phase need to be repeated. After the gas content data stabilizes, the next set of tests can be conducted.

[0048] After the test is completed, fully open the inlet regulating valve 402 and the outlet regulating valve 411, close the pump under test 405, close the third shut-off valve 401 at the oil tank outlet, the inlet regulating valve 402 and the outlet regulating valve 411, and turn off the air compressor 201; close the first gas shut-off valve 202, the gas flow regulating valve 204 and the second gas shut-off valve 206, and turn off the mixing pump 208; close the first shut-off valve 210 at the oil tank outlet, the first shut-off valve 211 at the oil tank inlet and the medium flow regulating valve 209.

[0049] Working principle: Taking a screw pump as an example, the oil circulation rate in the system is greater than 10 times / hour. During operation, a large amount of gas is mixed in the oil. The bubbles cannot be separated or broken down in time during circulation, and they remain in the oil and re-enter the screw pump. Since the screw pump is a closed screw profile, when the conveyed medium contains a large number of bubbles, the uniform microbubbles formed by the pressure, compression, and collapse of the screw part will generate significant vibration and noise due to the pressure causing the bubbles to burst and impact. Usually, air is injected directly into the inlet pipeline, but the bubbles are not easily dissolved uniformly in media such as lubricating oil and hydraulic oil. Uneven air injection will lead to uneven gas content in the pump medium, which cannot simulate actual operating conditions. In this application, the air injection circuit 20 uses a pump set of the same type as the pump under test 405, namely a screw pump, to simulate the uniform microbubbles formed by the pressure, compression, and collapse of the screw part of the air in the screw pump during actual use. This makes the gas content in the medium in the test circuit 40 uniform and small, and no longer affected by the pressure and compression of the screw part of the test pump. It affects the operational stability of the screw pump.

[0050] By adopting the above technical solution, the main oil tank 10, the gas filling circuit 20, and the test circuit 40 are connected in parallel, and a mixing pump 208 is introduced into the gas filling pipe group. This not only solves the technical problem of traditional direct gas injection forming large air pockets that are difficult to dissolve uniformly in the pipeline, causing serious distortion of the test conditions, but also achieves high uniformity and stability of the microbubble network in the gas-liquid two-phase medium over a large range. At the same time, it eliminates the technical defects of multi-variable interference such as flow pressure and frictional temperature rise caused by linear series connection of a single line, and successfully prefabricates a homogeneous two-phase fluid with high simulation degree of the working conditions and precise controllable gas content over a large range at the front end (suction side) of the test circuit 40.

[0051] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A positive displacement pump gas-containing test performance testing system, characterized in that, The tank includes a fuel tank body, on which a gas filling pipe assembly and a test pipe assembly are respectively provided, forming two independent gas filling circuits and a test circuit; The gas filling pipe assembly is equipped with a gas filling tee and a gas mixing pump along the medium flow direction. The gas filling tee is connected to the air compressor through a gas filling branch. In the test state, the gas mixing pump pressurizes and mixes the gas-liquid two-phase medium to pre-prepare a gas-liquid two-phase mixed medium containing uniform micro bubbles before sending the medium back to the oil tank. The test tube assembly is connected to a pump to be tested, and a measuring tube section is set in the test tube assembly located at the output end of the pump to be tested. A gas content measuring instrument is connected to the measuring tube section.

2. The positive displacement pump gas-containing test performance testing system according to claim 1, characterized in that, The oil tank is also equipped with a cooling pipe assembly to form an independently operable cooling circuit. The cooling pipe assembly is equipped with an oil cooler and an outlet flow regulating valve in sequence along the medium flow direction.

3. The positive displacement pump gas-containing test performance testing system according to claim 1 or 2, characterized in that, A heater and a temperature sensor are installed at the lower end of the oil tank body, and the temperature sensor is located near the oil outlet of the oil tank body.

4. The positive displacement pump gas-containing test performance testing system according to claim 1, characterized in that, The air mixing pump and the pump under test are respectively located on opposite sides of the fuel tank body; The lower end of the oil tank near the mixing pump is provided with an oil filling outlet and an oil filling return outlet. The oil filling outlet and the oil filling return outlet are respectively located on two opposite side walls of the oil tank. The oil filling outlet and the oil filling return outlet are connected by an oil filling pipe assembly. A test oil outlet is provided at the lower end of the oil tank near the side of the pump under test. The test oil outlet and the gas return oil outlet are located on two adjacent side walls of the oil tank. A test oil return oil outlet is provided at the upper end of the oil tank. The test oil outlet and the test oil return oil outlet are connected by a test pipe assembly.

5. The positive displacement pump gas-containing test performance testing system according to claim 1, characterized in that, The pump type structure of the gas mixing pump is the same as that of the pump under test, and the flow rate of the medium in the gas mixing pump is greater than 10% of the flow rate of the medium in the pump under test.

6. The positive displacement pump gas-containing test performance testing system according to claim 1, characterized in that, The pump under test is equipped with an inlet pressure sensor and an outlet pressure sensor at its inlet and outlet ends, respectively. The inlet end of the pump under test is connected to the test tube assembly via an inlet flexible connector, and the outlet end of the pump under test is connected to the test tube assembly via an outlet flexible connector.

7. The positive displacement pump gas-containing test performance testing system according to claim 1, characterized in that, The length of the straight pipe section at the inlet end of the pump under test is greater than 12 times the diameter of the inlet pipe of the pump under test, and the length of the straight pipe section at the outlet end of the pump under test is greater than 4 times the diameter of the outlet pipe of the pump under test.

8. The positive displacement pump gas-containing test performance testing system according to claim 1, characterized in that, A medium flow regulating valve is installed on the gas filling pipe assembly located on the outlet side of the mixing pump; Along the gas flow direction, a gas pressure stabilizing tank, a gas flow regulating valve, and a filter are sequentially installed on the gas refueling branch. The test tube assembly shown is equipped with an inlet regulating valve and an outlet regulating valve, respectively, near the inlet and outlet ends.

9. The positive displacement pump gas-containing test performance testing system according to claim 8, characterized in that, A flow meter is installed on the test pipe assembly located at the outlet end of the outlet regulating valve. The length of the straight pipe section at both the inlet and outlet ends of the flow meter is greater than 5 times the nominal diameter of the pipeline at that location.

10. A testing method employing the testing system described in any one of claims 1 to 9, characterized in that, Includes the following steps: Temperature control stage: Start the oil cooler or heater to circulate and control the temperature of the medium in the oil tank until it reaches the set test target temperature; Gas-liquid medium mixing stage: Start the gas mixing pump and air compressor, and deliver the set flow rate of gas to the gas filling tee through the gas filling branch. After the gas and medium flow through the gas mixing pump and are pressurized and mixed, they return to the oil tank body and continue to circulate until the medium in the oil tank body is transformed into the target gas content medium with a uniformly distributed bubble network. Performance testing phase: Keep the gas filling circuit running continuously, start the pump under test, and adjust the gas supply of the gas filling branch and / or the medium flow rate of the gas filling circuit based on the data fed back by the gas content measuring instrument until the medium gas content on the suction side of the pump under test stably reaches the test requirement value. The inlet and outlet pressures of the pump under test are adjusted by the inlet / outlet regulating valves of the test circuit to meet the test requirements, and the performance test data of the pump under test are collected after the operating conditions stabilize.

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