Water jet propulsion test bench for internal flow field test, instantaneous thrust test and hydraulic performance test and use method

Abstract

The invention discloses a water jet propulsion test bench used for internal flow field testing, instantaneous thrust testing and hydraulic performance testing and a using method of the water jet propulsion test bench, and belongs to the technical field of water conservancy projects and ship engineering. Comprising a pressure water inlet tank, a closed water tank and a pressure water outlet tank which are communicated through a conveying pipeline, and a water spraying propulsion pump device is arranged above the closed water tank; a pipeline centrifugal pump and a circulating pipeline are arranged in the lower frame, one end of the circulating pipeline is communicated with the pressure water outlet tank, the other end of the circulating pipeline is connected to the water inlet end of the pipeline centrifugal pump, and the water outlet end of the pipeline centrifugal pump is communicated with the pressure water inlet tank through a connecting bent pipe. Through the device, adjustment of multiple working conditions such as different water depth draft ratio working conditions, different rotating speed working conditions, different ship speed working conditions and cavitation working conditions of the water jet propulsion device, accurate observation of an internal flow field and instantaneous thrust experiment of a pump device are realized, repeated construction of a test device is avoided, the test cost is reduced, and the test precision is improved.

Description

Technical Field

[0001] The invention relates to the technical field of water conservancy engineering and ship engineering, and in particular to a water jet propulsion test bench for internal flow field testing, instantaneous thrust testing and hydraulic performance testing and a use method thereof. Background Art

[0002] The water jet propulsion device is a new type of propulsion device suitable for high-performance ships. This type of pump device uses the recoil effect of high-speed water flow ejected from the nozzle to drive the hull forward. Compared with the propeller propulsion device, the water jet propulsion pump device has low underwater noise and good concealment during operation. At the same time, this type of pump device has high propulsion efficiency and good anti-cavitation performance. Therefore, this type of pump device has excellent application prospects, which also makes the relevant research on the multi-condition hydraulic characteristics and thrust characteristics of the water jet propulsion pump device have important academic significance and engineering application value.

[0003] At present, the model test method is often used to study the various performances of water jet propulsion pump devices. The existing water jet propulsion pump device experimental device has the following characteristics: a water jet propulsion pump device with a hull is arranged in an open water pool, and the working conditions of different water depths and draft ratios are adjusted by changing the height of the test bench bottom plate. At the same time, the thrust generated by the pump device is measured by means of the slide rails above the hull and the pressure sensor. However, since the test bench has a fixed bottom plate, each time the water depth and draft ratio working conditions are changed, the test bench floor needs to be disassembled, processed and reinstalled. The process is cumbersome, resulting in a long test time; at the same time, due to the open water pool, it is impossible to change the internal pressure of the pump device, and it is impossible to conduct cavitation research. There are complex environmental interferences in the open water intake pool, which makes the tracer particles in the particle image velocimetry (PIV) experiment susceptible to environmental influences, which makes it difficult to accurately capture the flow characteristics of the water body. In addition, although the existing test bench can carry out thrust tests, it is impossible to accurately analyze the correspondence between the nozzle jet and the internal flow field and the thrust, which is difficult to match the current research needs of water jet propulsion devices. Therefore, it is necessary to optimize and upgrade the existing test bench.

[0004] At present, there are experimental devices and test methods related to water jet propulsion. The authorized invention patent CN104215426B proposes to suspend the power unit of the water jet propulsion internal flow field and external characteristic measurement device inside the hull model, collect the axial force, torque and speed data of the pump device through the data acquisition unit, and realize the observation and measurement of the internal flow field of the water jet propulsion through the propeller shell made of transparent organic glass; the authorized invention patent CN107702886B proposes a water jet propulsion ship model inlet flow test method based on PIV measurement; the authorized invention patent CN104332091B proposes a simple experimental device for pump water jet propulsion, which can be used to study the thrust performance of pump water jet propulsion under different free surface characteristics, various water flow speeds (ship speeds) and different ship loads (submerged depths). Although the above technologies all involve the modification of the test model of the water jet propulsion pump device, the functions realized are single, and multiple tests require repeated construction of the test device, which is cumbersome to operate and has high testing costs. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects in the prior art and provide a water jet propulsion test bench and a method of use for internal flow field testing, instantaneous thrust testing and hydraulic performance testing, so as to achieve the adjustment of different water depth draft ratio working conditions and cavitation working conditions of the water jet propulsion device, accurate observation of the internal flow field and instantaneous thrust experiment of the pump device, avoid repeated construction of the test device, reduce the test cost and improve the test accuracy.

[0006] The object of the present invention is achieved as follows: a water jet propulsion test bench for internal flow field testing, instantaneous thrust testing and hydraulic performance testing, comprising an upper frame and a lower frame arranged below the upper frame, the upper frame is provided with a test assembly, the test assembly comprises a pressure water inlet tank, a closed water tank and a pressure water outlet tank, the pressure water inlet tank, the closed water tank and the pressure water outlet tank are connected in sequence through a conveying pipeline, and a water jet propulsion pump device is provided above the closed water tank; a pipeline centrifugal pump and a circulation pipeline are provided in the lower frame, one end of the circulation pipeline is connected to the pressure water outlet tank through a connecting elbow, and the other end is connected to the water inlet end of the pipeline centrifugal pump, and the water outlet end of the pipeline centrifugal pump is connected to the pressure water inlet tank through a connecting elbow.

[0007] When the present invention is working, each device of the test bench is installed in place, and it is checked and ensured that the connections between the devices are tight and the sealing is good. Then, different working conditions are simulated according to the test requirements, and the cavitation conditions of the pump device and the working conditions of different water depths and draft ratios are studied. The water inlet, the inside of the flow channel and the flow state of the nozzle of the water jet propulsion pump device are tested. At the same time, the device can realize instantaneous thrust testing and pump device performance experiments.

[0008] Furthermore, the water jet propulsion pump device is fixedly connected to the upper frame through a steel plate, a sliding block is provided at the bottom of the steel plate, and the sliding block is slidably connected to the guide rail at the top of the upper frame; a motor is provided on the steel plate, and the output shaft end of the motor is drivingly connected to a rotating shaft, and a torque meter is provided on the rotating shaft, and the rotating shaft extends into the water jet propulsion pump body and is connected to an impeller, and the impeller is provided with guide vanes, and a sleeve is provided at the nozzle of the water jet propulsion pump body, and a thrust sensor is circumferentially provided between the nozzle and the sleeve, and the nozzle is connected to the pressure water outlet tank through a high-transparency and high-strength acrylic pipe, and the sleeve is made of high-transparency and high-strength acrylic material.

[0009] Furthermore, the inlet end of the water inlet pipe of the water jet propulsion pump body extends into the closed water tank, and the inlet end face of the water inlet is connected to the moving plane of the rolling connection plate mechanism. The rolling connection plate mechanism includes a limit plate connected to the upper frame, and a sliding groove is provided in the limit plate. The upper surface of the moving plane is in close contact with the upper inner wall of the sliding groove, and a plurality of sliding wheels in close contact with the bottom wall of the sliding groove are provided around the lower surface of the moving plane, and the moving plane is driven to move horizontally inside the limit plate by the sliding wheels.

[0010] Furthermore, an annular pressure measuring tube is respectively arranged at the outlet of the water jet propulsion pump body and the front side of the inlet end of the water inlet pipe of the water jet propulsion pump body in the closed water tank, and the annular pressure measuring tube is connected to the differential pressure transmitter through a line.

[0011] Furthermore, a rectifying grid is provided inside the pressure water inlet tank, and a vent valve 1 is provided on the top of the pressure water inlet tank.

[0012] Furthermore, a butterfly valve is provided at the junction of the connecting elbow below the pressure water outlet tank and the circulation pipeline, and a second vent valve is provided above the pressure water outlet tank; an electromagnetic flowmeter is also provided on the circulation pipeline.

[0013] Furthermore, a bottom plate is provided in the closed water tank, and the height of the bottom plate in the closed water tank can be changed by adjusting bolts.

[0014] Furthermore, the pressure water inlet tank, the closed water tank, the pressure water outlet tank, and the circulation pipeline are all made of highly transparent and high-strength acrylic material.

[0015] The method for using the water jet propulsion test bench of the present invention comprises:

[0016] Install each device in place, and check to ensure that the connections between the devices are tight and well sealed;

[0017] When conducting cavitation experiments, close vent valve 1 and vent valve 2, connect vent valve 1 to a vacuum pump, and run the water jet propulsion pump device under negative pressure. Change the working conditions, and use a high-speed camera to observe the underwater suction vortex area of ​​the pump body water inlet, the internal area of ​​the pump device, and the nozzle jet under different working conditions, and observe and explore the cavitation situation and cavitation evolution law of the pump device blades under cavitation conditions; release fluorescent particles in a closed water tank, and use a PIV device to carefully track the three-dimensional flow state of the flow field and vortex inside the pump device flow channel, the water inlet area, and the wake area;

[0018] The height of the bottom plate in the closed water tank is adjusted by adjusting the bolts to simulate the operation of the pump device under different water depth and draft ratio conditions;

[0019] When conducting the thrust test of the pump device, first adjust the position of the water jet propulsion pump device to ensure that the nozzle flange and the sleeve are in just contact, and obtain the friction data of the test bench through multiple friction tests and balance it; turn on the pump device, wait for the pump device to run stably, collect instantaneous thrust data through the thrust sensor and analyze it, and study the instantaneous thrust characteristics of the pump device;

[0020] When the pump device is running, the annular pressure measuring tubes at the inlet and outlet of the pump device are connected to the differential pressure transmitter to collect the head data, monitor the impeller torque of the pump device through the torque meter, and calculate the operating efficiency of the pump device based on the inlet and outlet pressure difference of the pump device.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] First, by adjusting the test bench to control multiple parameters such as the inlet and outlet water tank pressures, pipeline centrifugal pump flow, motor speed, closed water tank water depth, and bottom plate height, different working conditions can be simulated to study the cavitation conditions of the pump device, different ship speed conditions, different speeds, and different water depths and draft ratios. The water inlet, flow channel, and nozzle flow state of the waterjet propulsion pump device are tested. At the same time, the device can realize instantaneous thrust testing and pump device performance experiments.

[0023] Second, the pressure water inlet tank, closed water tank, pressure water outlet tank, circulation pipeline, and pump device water inlet pipe of this device are all made of highly transparent and high-strength acrylic material, ensuring that the flow field changes in the water tank can be clearly captured. At the same time, the pressure water tank is equipped with a water valve to achieve full closure, so that the pump device cavitation experiment can be carried out.

[0024] Third, the pressure water inlet tank, closed water tank and pressure water outlet tank of the device form a circulation loop through the pipeline centrifugal pump and the circulation pipeline, which fully utilizes water resources and saves test costs.

[0025] Fourth, the water inlet of the pump device is tightly connected to the rolling connecting plate mechanism, which helps to achieve horizontal movement of the pump device while ensuring the airtightness requirements of the closed water tank. Compared with the flexible sealing means used in the prior art, it has a longer service life and less friction loss. It can also effectively avoid test errors and inconvenience in replacement caused by aging of the flexible seal.

[0026] Fifth, this device adopts a sleeve placement thrust pulsation collection method. An ingenious sleeve structure is set at the water outlet of the pump device and the thrust sensor is placed inside in advance. During the test, it can effectively avoid external factors from interfering with the thrust sensor and improve the accuracy of thrust pulsation measurement. This method can also extend the service life of the thrust sensor.

[0027] Sixth, the overall structure of the device is easy to build, with high measurement accuracy and strong operability. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the overall structure of the water jet propulsion test bench of the present invention.

[0029] Figure 2 for Figure 1 Schematic diagram of the structure enlarged at point A in the middle.

[0030] Figure 3 for Figure 1 Schematic diagram of the enlarged structure at point B.

[0031] Figure 4 It is a structural schematic diagram of realizing sliding sealing with a rolling connection plate mechanism at the water inlet of the pump device in the present invention.

[0032] Among them, 1 pipeline centrifugal pump, 2 electromagnetic flowmeter, 3 butterfly valve, 4 lower frame, 5 pressure water inlet tank, 6 rectifier grid, 7 vent valve one, 8 closed water tank, 9 pressure water outlet tank, 10 vent valve two, 11 nozzle, 12 guide vane, 13 impeller, 14 water inlet pipe, 15 shaft, 16 torque meter, 17 motor, 18 steel plate, 19 guide rail, 20 sliding block, 21 upper frame, 22 rolling connection plate mechanism, 23 thrust sensor, 24 sleeve, 25 annular pressure measuring tube, 26 bottom plate, 27 adjusting bolt, 28 moving plane, 29 sliding wheel, 30 limit plate, 31 circulation pipeline, 32 connecting elbow. DETAILED DESCRIPTION

[0033] like Figures 1 to 4A water jet propulsion test bench for internal flow field testing, instantaneous thrust testing and hydraulic performance testing shown in the figure comprises an upper frame 21 and a lower frame 4 arranged below the upper frame 21, the upper frame 21 is provided with a test assembly, the test assembly comprises a pressure water inlet tank 5, a closed water tank 5 and a pressure water outlet tank 9, the pressure water inlet tank 5, the closed water tank 8 and the pressure water outlet tank 9 are connected in sequence through a conveying pipeline, and a water jet propulsion pump device is provided above the closed water tank 8; a pipeline centrifugal pump 1 and a circulation pipeline 31 are provided in the lower frame 4, one end of the circulation pipeline 31 is connected to the pressure water outlet tank 9 through a connecting elbow 32, and the other end is connected to the water inlet end of the pipeline centrifugal pump 1, and the water outlet end of the pipeline centrifugal pump 1 is connected to the pressure water inlet tank 5 through a connecting elbow 32; the connecting elbow 32 is a right-angle PVC elbow.

[0034] The water jet propulsion pump device is fixedly connected to the upper frame 21 through a steel plate 18, a sliding block 20 is provided at the bottom of the steel plate 18, and the sliding block 20 is slidably connected to the guide rail 19 at the top of the upper frame 21; a motor 17 is provided on the steel plate 18, and a rotating shaft 15 is transmission-connected to the output shaft end of the motor 17, and a torque meter 16 is provided on the rotating shaft 15. The rotating shaft 15 extends into the pump body of the water jet propulsion pump and is connected to an impeller 13, and a guide vane 12 is provided on the impeller 13. A sleeve 24 is provided at the nozzle 11 of the pump body of the water jet propulsion pump, and the sleeve 24 performs a movable seal on the nozzle 11, and also ensures the horizontal movement of the water jet propulsion pump device The sleeve 24 made of highly transparent and high-strength acrylic material is also convenient for real-time monitoring of the flow state of the nozzle 11 of the pump device; a thrust sensor 23 is circumferentially arranged between the nozzle 11 and the sleeve 24, which is convenient for collecting thrust data during the operation of the pump device and studying the instantaneous thrust characteristics of the pump device; the nozzle 11 is connected to the pressure water outlet tank 9 through a highly transparent and high-strength acrylic pipe; a water jet propulsion pump device is installed above the steel plate 18, and the bottom of the steel plate 18 moves along the guide rail 19 on the top of the upper frame 21 through the sliding block 20, so as to realize the horizontal movement of the water jet propulsion pump device, which is convenient for testing the pump device under different working conditions.

[0035] The inlet end of the water inlet pipe 14 of the water jet propulsion pump body extends into the closed water tank 8, and the inlet end surface of the water inlet is connected to the moving plane 28 of the rolling connection plate mechanism 22. The rolling connection plate mechanism 22 includes a limit plate 30 connected to the upper frame 21, and a sliding groove is provided in the limit plate 30. The upper surface of the moving plane 28 is in close contact with the upper inner wall of the sliding groove. The lower surface of the moving plane 28 is provided with a plurality of sliding wheels 29 in close contact with the bottom wall of the sliding groove. The sliding wheels 29 drive the moving plane 28 to move horizontally inside the limit plate 30. When the water jet propulsion pump device is running, the moving plane 28 connected to the water inlet pipe 14 moves horizontally, and the upper surface of the moving plane 28 is in close contact with the upper inner wall of the sliding groove inside the limit plate 30, and the plurality of sliding wheels 29 on the lower surface of the moving plane 28 are in close contact with the bottom wall of the sliding groove, so as to ensure that the water inlet pipe 14 can move horizontally synchronously with the moving plane 28, ensure the overall consistency of the movement of the water jet propulsion pump device, and at the same time ensure the sealing requirements of the closed water tank 8. Compared with the flexible sealing means used in the prior art, it has a longer service life and less friction loss.

[0036] An annular pressure measuring tube 25 is respectively arranged at the outlet of the water jet propulsion pump body and the front side of the inlet end of the water inlet pipe 14 of the water jet propulsion pump body in the closed water tank 8. The annular pressure measuring tube 25 is connected to the differential pressure transmitter through a line to facilitate the collection of head data. The torque of the impeller 13 and the inlet and outlet pressure difference are monitored by the torque meter 16 to calculate the operating efficiency of the water jet propulsion pump.

[0037] A rectifying grid 6 is provided inside the pressure water inlet tank 5, and a vent valve 7 is provided on the top of the pressure water inlet tank 5; the rectifying grid 6 is used to smooth the inlet water flow, eliminate the water flow backflow area inside the pressure water inlet tank 5, and reduce the influence of water body fluctuation on the experiment; a butterfly valve 3 is provided at the junction of the connecting elbow 32 below the pressure water outlet tank 9 and the circulation pipeline 31, and a vent valve 10 is provided above the pressure water outlet tank 9; an electromagnetic flowmeter 2 is also provided on the circulation pipeline 31; the pressure water inlet tank 5, the closed water tank 8, the pressure water outlet tank 9, and the circulation pipeline 31 are all made of highly transparent and high-strength acrylic material; the pressure water inlet tank 5, the closed water tank 8, and the pressure water outlet tank 9 can be connected to the air pump through the vent valve to adjust the internal pressure of the water jet propulsion pump device, so as to realize the cavitation experiment of the water jet propulsion pump device; the butterfly valve 3 and the electromagnetic flowmeter 2 are used to adjust and monitor the water outlet flow of the pressure water outlet tank 9 to the circulation pipeline 32, so as to facilitate timely adjustment.

[0038] A bottom plate 26 is provided in the closed water tank 8, and the height of the bottom plate 26 in the closed water tank 8 can be changed by adjusting the bolts 27, so as to simulate the operation of the pump device under different water depths and draft ratios. The bottom plate 26 is made of a transparent acrylic plate, which is lighter than a metal plate, has a low cost, is not easy to rust under water for a long time, and is convenient for observing the internal condition of the closed water tank 8 without interference.

[0039] The method for using the water jet propulsion test bench of the present invention comprises:

[0040] Install each device in place, and check to ensure that the connections between the devices are tight and well sealed;

[0041] When conducting a cavitation experiment, first turn on the motor to allow the pump device to operate normally at a given speed, and after the pump device is running stably, record the flow and lift data on the electromagnetic flowmeter 2 and the annular pressure measuring tube 25, and calculate the pump device operating efficiency η at this time according to the pump device efficiency calculation formula (Formula 1); then close the vent valve 1 7 and the vent valve 2 10, connect the vent valve 1 7 to the vacuum pump, use the vacuum pump to evacuate the inside of the pump device to allow the water jet propulsion pump device to operate under negative pressure, and at the same time monitor the lift data of the annular pressure measuring tube 25 in real time and calculate the pump device efficiency η. When the efficiency of the pump device decreases, 1%, it is considered that cavitation occurs at this time; after cavitation occurs, the underwater suction vortex area of ​​the pump body water inlet, the internal area of ​​the pump device and the nozzle jet are observed using a high-speed camera to observe and explore the cavitation situation of the pump device blades and the cavitation evolution law under cavitation conditions; fluorescent particles are also released in a closed water tank, and the PIV device is used to carefully track the three-dimensional flow state of the flow channel inside the pump device, the water inlet area, and the flow field and vortex in the wake area; thereafter, the vacuum pump can be used again to adjust the internal pressure of the pump device, and the high-speed camera and PIV device can be used to test and analyze the characteristics of different cavitation occurrence stages in the pump.

[0042] The height of the bottom plate 26 in the closed water tank 8 is adjusted by adjusting the bolts 27 to simulate the operation of the pump device under different water depth and draft ratio conditions;

[0043] When conducting a thrust test on a pump device, first adjust the position of the water jet propulsion pump device to ensure that the flange of the nozzle 11 is in contact with the thrust sensor 23 provided at the sleeve 24, and obtain the friction data of the test bench through multiple friction tests and balance it; start the pump device, wait for the pump device to run stably, collect instantaneous thrust data through the thrust sensor 23 and analyze it to study the instantaneous thrust characteristics of the pump device; this device can also realize the collection of instantaneous thrust pulsation data in the cavitation state and under different water depth and draft ratio conditions according to the above-mentioned operating steps.

[0044] When the pump device is running, the annular pressure measuring tubes 25 at the inlet and outlet of the pump device are connected to the differential pressure transmitter to collect the head data, and the impeller torque of the pump device is monitored by the torque meter 16. The operating efficiency η of the pump device is calculated in combination with the inlet and outlet pressure difference of the pump device.

[0045] The formula for calculating the pump unit efficiency is:

[0046]

[0047] Where: ρ is the liquid density, Kg / m 3; g is the acceleration due to gravity, m / s 2 ; Q is the flow rate, m 3 / s; H is head, m; N a is the shaft power, W.

[0048] The propulsion pump performance obtained by simulating different working conditions by adjusting some parameters is shown in Tables 1 to 4, where 1 atm represents a standard atmospheric pressure (101.3 Kpa), K r It represents the average value of thrust pulsation data of water jet propulsion pump device within 3 minutes under design conditions, Q d represents the design flow rate of the water jet propulsion pump device, R d Indicates the design speed of the water jet propulsion pump device, T r It indicates the water depth to draft ratio under fully flooded conditions.

[0049] Table 1 Performance characteristics of water jet propulsion pumps under different cavitation conditions

[0050] Working conditions Inlet tank pressure Water tank pressure Waterjet pump performance No cavitation conditions 1 atm 1atm <![CDATA[K r ]]> Cavitation inception 0.93atm 0.93atm <![CDATA[0.82K r ]]> Cavitation occurs 0.87atm 0.87atm <![CDATA[0.61K r ]]>

[0051] Table 2 Performance characteristics of water jet pumps under different flow conditions

[0052] Working conditions description flow Waterjet pump performance Design flow conditions <![CDATA[Q d ]]> <![CDATA[K r ]]> Small flow conditions <![CDATA[0.6Q d ]]> <![CDATA[0.68K r ]]> Large flow conditions <![CDATA[1.4Q d ]]> <![CDATA[1.01K r ]]>

[0053] Table 3 Performance characteristics of water jet pumps at different speeds

[0054] Working conditions Motor speed Waterjet pump performance Design speed condition <![CDATA[R d ]]> <![CDATA[K r ]]> Low speed condition <![CDATA[0.6R d ]]> <![CDATA[0.72K r ]]> High speed conditions <![CDATA[1.4R d ]]> <![CDATA[1.45K r ]]>

[0055] Table 4 Performance characteristics of water jet pumps at different water depths and draft ratios

[0056] Working conditions Water depth to water ratio Waterjet pump performance Total flooding condition <![CDATA[T r ]]> <![CDATA[K r ]]> Semi-submerged condition <![CDATA[1.04T r ]]> <![CDATA[0.91K r ]]> No flooding conditions <![CDATA[1.08T r ]]> <![CDATA[0.53K r ]]>

[0057] When the present invention is working, each device of the test bench is installed in place, and it is checked and ensured that the connections between the devices are tight and the sealing is good. Then, different working conditions are simulated according to the test requirements, and the cavitation conditions of the pump device and the working conditions of different water depths and draft ratios are studied. The water inlet, the inside of the flow channel and the flow state of the nozzle of the water jet propulsion pump device are tested. At the same time, the device can realize instantaneous thrust testing and pump device performance experiments. The overall structure of the device is easy to build, the measurement accuracy is high, and the operability is strong.

[0058] The present invention is not limited to the above-mentioned embodiments. On the basis of the technical solution disclosed in the present invention, technicians in this field can make some substitutions and deformations to some technical features therein according to the disclosed technical content without creative labor, and these substitutions and deformations are all within the protection scope of the present invention.

Claims

1. A water jet propulsion test bench for internal flow field testing, instantaneous thrust testing and hydraulic performance testing, comprising an upper frame and a lower frame arranged below the upper frame, characterized in that: The upper frame is provided with a test assembly, which includes a pressure water inlet tank, a closed water tank and a pressure water outlet tank. The pressure water inlet tank, the closed water tank and the pressure water outlet tank are connected in sequence through a delivery pipeline, and a water jet propulsion pump device is provided above the closed water tank; a pipeline centrifugal pump and a circulation pipeline are provided in the lower frame, one end of the circulation pipeline is connected to the pressure water outlet tank through a connecting elbow, and the other end is connected to the water inlet end of the pipeline centrifugal pump, and the water outlet end of the pipeline centrifugal pump is connected to the pressure water inlet tank through a connecting elbow.

2. A water jet propulsion test bench for internal flow field testing, instantaneous thrust testing and hydraulic performance testing according to claim 1, characterized in that: The water jet propulsion pump device is fixedly connected to the upper frame through a steel plate, a sliding block is provided at the bottom of the steel plate, and the sliding block is slidably connected to the guide rail at the top of the upper frame; a motor is provided on the steel plate, and the output shaft end of the motor is drivingly connected to a rotating shaft, and a torque meter is provided on the rotating shaft, and the rotating shaft extends into the water jet propulsion pump body and is connected to an impeller, and the impeller is provided with guide vanes, and a sleeve is provided at the nozzle of the water jet propulsion pump body, and a thrust sensor is circumferentially provided between the nozzle and the sleeve, and the nozzle is connected to the pressure water outlet tank through a high-transparency and high-strength acrylic pipe, and the sleeve is made of high-transparency and high-strength acrylic material.

3. A water jet propulsion test bench for internal flow field testing, instantaneous thrust testing and hydraulic performance testing according to claim 2, characterized in that: The inlet end of the water inlet pipe of the water jet propulsion pump body extends into the closed water tank, and the inlet end face of the water inlet is connected to the moving plane of the rolling connection plate mechanism. The rolling connection plate mechanism includes a limit plate connected to the upper frame, and a sliding groove is provided in the limit plate. The upper surface of the moving plane is in close contact with the upper inner wall of the sliding groove, and a plurality of sliding wheels in close contact with the bottom wall of the sliding groove are provided around the lower surface of the moving plane, and the moving plane is driven to move horizontally inside the limit plate by the sliding wheels.

4. A water jet propulsion test bench for internal flow field testing, instantaneous thrust testing and hydraulic performance testing according to claim 3, characterized in that: An annular pressure measuring tube is respectively arranged at the outlet of the water jet propulsion pump body and the front side of the inlet end of the water inlet pipe of the water jet propulsion pump body in the closed water tank, and the annular pressure measuring tube is connected to the differential pressure transmitter through a line.

5. A water jet propulsion test bench for internal flow field testing, instantaneous thrust testing and hydraulic performance testing according to claim 1, characterized in that: A rectifying grid is arranged inside the pressure water inlet tank, and a vent valve 1 is arranged on the top of the pressure water inlet tank.

6. A water jet propulsion test bench for internal flow field testing, instantaneous thrust testing and hydraulic performance testing according to claim 1, characterized in that: A butterfly valve is provided at the junction of the connecting elbow below the pressure water outlet tank and the circulation pipeline, and a second vent valve is provided above the pressure water outlet tank; an electromagnetic flow meter is also provided on the circulation pipeline.

7. A water jet propulsion test bench for internal flow field testing, instantaneous thrust testing and hydraulic performance testing according to claim 1, characterized in that: A bottom plate is arranged in the closed water tank, and the height of the bottom plate in the closed water tank can be changed by adjusting bolts.

8. A water jet propulsion test bench for internal flow field testing, instantaneous thrust testing and hydraulic performance testing according to any one of claims 1 to 7, characterized in that: The pressure water inlet tank, the closed water tank, the pressure water outlet tank and the circulation pipeline are all made of highly transparent and high-strength acrylic material.

9. A method for using a water jet propulsion test bench for internal flow field testing, instantaneous thrust testing and hydraulic performance testing according to any one of claims 1 to 7, characterized in that: The steps include: Install each device in place, and check to ensure that the connections between the devices are tight and well sealed; When conducting cavitation experiments, close vent valve 1 and vent valve 2, connect vent valve 1 to the vacuum pump, and make the water jet propulsion pump device operate under negative pressure. Change the pressure conditions to reduce the efficiency of the pump device by 1%, and it can be considered that the pump device has entered the cavitation condition. At this time, use a high-speed camera to observe the underwater suction vortex area of ​​the pump body water inlet, the internal area of ​​the pump device, and the nozzle jet under different working conditions, and observe and explore the cavitation situation and cavitation evolution law of the pump device blades under cavitation conditions; release fluorescent particles in a closed water tank, and use the PIV device to carefully track the three-dimensional flow state of the flow field and vortex inside the flow channel of the pump device, the water inlet area, and the wake area; use the vacuum valve again to adjust the pressure in the pump to conduct relevant experiments on the pump device at different cavitation stages; The height of the bottom plate in the closed water tank is adjusted by adjusting the bolts to simulate the operation of the pump device under different water depth and draft ratio conditions; When conducting the thrust test of the pump device, first adjust the position of the water jet propulsion pump device to ensure that the nozzle flange and the sleeve are in just contact, and obtain the friction data of the test bench through multiple friction tests and balance it; turn on the pump device, wait for the pump device to run stably, collect instantaneous thrust data through the thrust sensor and analyze it, and study the instantaneous thrust characteristics of the pump device; When the pump device is running, the annular pressure measuring tubes at the inlet and outlet of the pump device are connected to the differential pressure transmitter to collect the head data, monitor the impeller torque of the pump device through the torque meter, and calculate the operating efficiency of the pump device based on the inlet and outlet pressure difference of the pump device.

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