A fully transparent dredging draghead test device

Abstract

The present invention discloses a fully transparent dredging draghead test device, which includes a water pump, a water tank, a draghead structure and an observation system; the water pump is controlled by a variable frequency motor, and the water tank includes a structural framework, transparent baffles, non-transparent baffles and an operation platform; the draghead structure includes a model draghead, pressure measuring short pipes, velocity measuring windows, nozzle assemblies, lifting lugs, supporting components, outlets and suction ports; the observation system includes tracer deflectors, pressure sensors and velocimeters; by using the device of the present invention, not only can the complex coupled flow field around and inside the draghead be observed, but also the key conditions and performance parameters of the draghead can be measured, thus providing important data for optimizing the draghead structure and its construction technology.

Description

Technical Field

[0001] The invention discloses a fully transparent dredging draghead test device, belonging to the technical field of dredging. Background Art

[0002] Trailing suction hopper dredgers are highly efficient, flexible and have strong anti-wave and anti-wind capabilities, and have developed rapidly in the dredging industry. The draghead is a key device for the construction of trailing suction hopper dredgers. It is the first to come into contact with sediment during construction, so the performance of the draghead is crucial, especially the flow field conditions around and inside it, which directly determine the productivity of the whole ship. However, the dredging draghead has many components, and many structures are irregular but have a great impact on performance, resulting in an extremely complex and variable flow field around and inside the draghead; to assist cutting and prevent siltation, multiple rows of nozzles are generally installed at different positions on the draghead, and the jets ejected by the nozzles are coupled with the suction of the draghead itself, further exacerbating the complexity of the flow field; and the engineering draghead is made of metal, the working water depth is often large, and the surrounding water-sediment two-phase flow field is relatively turbid during construction, making it difficult to observe and measure. All these factors seriously restrict the research on the draghead. At present, the research on the draghead mainly focuses on the numerical simulation of the internal flow field of local components, but the accuracy of the simulation is still in the stage of qualitative analysis, lacking accurate and effective test data for verification. Moreover, due to the complexity of the dredging draghead and its flow field, it is very difficult to numerically simulate the flow field of the comprehensive performance of the draghead, and there is an urgent need for a corresponding dredging draghead test device to provide platform support. Summary of the Invention

[0003] In order to overcome the above deficiencies, the invention designs a fully transparent dredging draghead test device. By using this device, not only can the complex coupled flow field around and inside the draghead be observed, but also the key conditions and performance parameters of the draghead can be measured, thus providing important data for optimizing the structure of the draghead and its construction technology.

[0004] The technical solution of the invention is as follows:

[0005] A fully transparent dredging draghead test device includes a water pump, a water tank, a draghead structure and an observation system;

[0006] The water pump is controlled by a variable-frequency motor, and the flow rate of the water pump is adjusted by changing the motor frequency. Steel pipes are connected to both the inlet and outlet of the water pump, which are the inlet pipeline and the outlet pipeline respectively; an electromagnetic flowmeter is installed in the outlet pipeline to measure the pipeline flow rate in real time;

[0007] The water tank includes a structural frame, transparent baffles, non-transparent baffles and an operation platform; transparent baffles are arranged in the area for observation, non-transparent baffles are used in the non-observation area, a water injection port and a drainage port are arranged on one side of the water tank, the operation platform spans above the structural frame, can move according to the test needs, and is tightly fixed to the structural frame by bolts; a lifting bracket is installed at the middle position of one side edge inside the water tank of the operation platform;

[0008] The drag head structure includes a model drag head, a pressure measuring short pipe, a speed measuring window, a nozzle assembly, a lifting lug, a support component, an outlet and a suction port;

[0009] The model drag head is made of plexiglass to ensure that the observation area consists of flat plates and is transparent. The outlet of the model drag head is turned upward through a bent pipe, and a standard flange is installed at the outlet according to the pipe diameter.

[0010] Round holes are drilled at the positions where pressure needs to be measured. The outer side of the round hole is bonded with a pressure measuring short pipe through welding glue, and the inner side of the pressure measuring short pipe is tapped with a sealing thread; Square holes are opened at the positions where speed needs to be measured. The size of the square hole is slightly larger than the size of the speedometer probe. Threaded blind holes are opened around the square hole. The speed measuring window consists of two parts on the left and right. When combined, it is a convex platform structure with a cuboid upper part and a cylindrical lower part. A central hole is drilled, and the hole diameter matches the diameter of the protruding rod of the speedometer. Through holes are drilled around the speed measuring window and match the threaded blind holes around the square hole. The speed measuring window is fixed to the square hole through bolts. Its thickness and bottom slope are determined according to the size of the model drag head around the square hole to ensure that the internal surface shape of the model drag head remains unchanged after installation;

[0011] There are [X] lifting lugs, which are arranged on both sides above the front part of the model drag head;

[0012] The support component is welded by a suction pipeline and a support rod. A standard flange is installed at the lower end of the suction pipeline and is connected to the outlet flange of the model drag head; The support rod cooperates with the lifting bracket of the operation platform and can drive the model drag head to move vertically, thereby changing the distance between the suction port of the model drag head and the bottom plate; A lifting point is arranged above the support rod, and the lifting point is connected to the [X] lifting lugs respectively through steel wires to improve the uniformity of the force distribution of the model drag head and prevent the stress of the plexiglass from being too concentrated due to eccentricity;

[0013] A steel wire hose is used to connect the outlet pipeline of the water pump and the water injection port of the water tank, and also between the inlet pipeline of the water pump and the suction pipeline;

[0014] The observation system includes a tracer flow deflector, a pressure measuring sensor and a speedometer; The tracer flow deflector includes a bracket, a liquid reservoir, a valve and a diversion pipe. The lower part of the liquid reservoir is connected to the diversion pipe through a valve, and the whole is fixed on the water tank through a bracket; Several branch pipes are arranged below the diversion pipe to ensure that the tracer liquid can be diverted to the area to be observed; The pressure measuring sensor is connected to the model drag head through a pressure measuring short pipe; The speedometer can be arranged around or inside the model drag head as needed. When speed measurement is required inside, the probe of the speedometer extends into the model drag head through the small hole of the speed measuring window.

[0015] Preferably, the above nozzle assembly includes a pressure stabilizing pipe, a nozzle block, and a compression ring; the pressure stabilizing pipe is a round pipe with one end sealed and the other end having a standard flange. Multiple holes are drilled on the circumferential surface of the pressure stabilizing pipe according to the required number of nozzles, and each hole is arranged in the same column; the pressure stabilizing pipe passes through two mounting hole plates behind the suction port of the model drag head and is fixed on the model drag head. By rotating the pressure stabilizing pipe, the nozzle angle can be changed; holes are drilled on the nozzle block according to the required nozzle diameter and number, and the holes on the nozzle block are aligned with the holes on the circumferential surface of the pressure stabilizing pipe, and the two are fixed together by a compression ring; a steel pipe with a flange is assembled at the flange of the pressure stabilizing pipe, and a hose is connected to it to supply water to the nozzle assembly, thereby generating a jet flow at the nozzle.

[0016] Preferably, the diameter of the holes on the circumferential surface of the above pressure stabilizing pipe is times the required nozzle diameter.

[0017] Preferably, the drilled holes on the above nozzle block have a contraction section and a straight hole section. The diameter of the straight hole section is the required nozzle diameter, and the length is not less than times the nozzle diameter. The contraction section gradually changes from the diameter of the hole drilled on the pressure stabilizing pipe to the nozzle diameter, and the length is times the nozzle diameter.

[0018] Preferably, an energy dissipator is arranged below the outlet of the water injection port to reduce the turbulence of the water flow entering the water tank.

[0019] Preferably, the above transparent baffle and non-transparent baffle are sealed by rubber gaskets and glass glue.

[0020] Preferably, the upper processor of the above velocimeter can be fixed on the operation platform or a support can be built separately for fixation.

[0021] Preferably, the above test device further includes a particle image velocimeter or a laser velocimeter for non-interference velocity measurement.

[0022] Preferably, the width of the above water tank is greater than or equal to 3 times the width of the model drag head, and the length is greater than or equal to 8 times the length of the drag head.

[0023] The beneficial effects of the present invention are:

[0024] The present invention provides a fully transparent dredging drag head test device. Since the drag head and the observation area of the water tank are fully transparent, and with the aid of a tracer liquid, the flow conditions around and inside the drag head can be observed. Even with the help of high-speed photography, the local flow process can be recorded and captured, thereby helping researchers to provide a qualitative understanding of the drag suction mechanism and the advantages and disadvantages of the structure of the drag head. On this basis, using this device, key conditions such as the suction flow rate of the drag head, the distance between the suction port of the drag head and the bed surface, and the jet parameters can be accurately adjusted, and performance parameters such as the pressure and flow velocity in the key areas of the drag head can be accurately measured. Thus, the influence law of key conditions on performance parameters can be quantitatively analyzed, and data support can be provided for the numerical simulation analysis of the drag head, so as to achieve the purpose of optimizing the drag head structure and improving the drag suction efficiency. Brief Description of the Drawings

[0025] Figure 1 is a schematic diagram of the overall device of the present invention;

[0026] Figure 2 is a schematic diagram of the water tank of the present invention

[0027] Figure 3 is a schematic diagram of the structure of the rake head of the present invention;

[0028] Figure 4 is a schematic diagram of the speed measurement window of the present invention;

[0029] Figure 5 is a schematic diagram of the nozzle assembly of the present invention;

[0030] Figure 6 is a schematic diagram of the support member of the present invention

[0031] Figure 7 is a schematic diagram of the tracer flow deflector of the present invention. Detailed Description of the Invention

[0032] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and cannot be used to limit the protection scope of the present invention.

[0033] A fully transparent dredging rake head test device includes a water pump 1, a water tank 2, a rake head structure 3 and an observation system 4;

[0034] The water pump 1 is controlled by a variable frequency motor, and the flow rate of the water pump is adjusted by changing the motor frequency. Steel pipes are connected to both the inlet and outlet of the water pump, which are the inlet pipe 1-1 and the outlet pipe 1-2 respectively; an electromagnetic flowmeter 1-3 is installed in the outlet pipe 1-2 to measure the pipeline flow rate in real time;

[0035] The water tank 2 includes a structural frame 2-1, a transparent baffle 2-2, a non-transparent baffle 2-3 and an operation platform 2-4; the transparent baffle 2-2 is arranged in the area for observation, and the non-observation area uses the non-transparent baffle 2-3. A water injection port 2-5 and a drainage port 2-6 are arranged on one side of the water tank 2. The operation platform 2-4 spans above the structural frame 2-1, can move according to the test needs, and is fixedly pressed against the structural frame by bolts; a lifting bracket 2-4-1 is installed at the middle position of one side inside the water tank 2 of the operation platform 2-4;

[0036] The rake head structure 3 includes a model rake head 3-1, a pressure measuring short pipe 3-2, a speed measurement window 3-3, a nozzle assembly 3-4, a lifting lug 3-5, a support member 3-6, an outlet 3-7 and a suction port 3-8;

[0037] The model drag head 3-1 is made of plexiglass, ensuring that the observation area consists of flat plates and is transparent. The outlet of the model drag head 3-1 is turned upward through a bent pipe, and a standard flange is installed at the outlet according to the pipe diameter.

[0038] Round holes are drilled at the positions where pressure measurement is required. The outer side of the round holes is bonded with pressure measurement short pipes 3-2 through welding glue, and the inner side of the pressure measurement short pipes 3-2 is tapped with sealing threads. Square holes are opened at the positions where speed measurement is required. The size of the square holes is slightly larger than the size of the speedometer probe. Threaded blind holes are opened around the square holes. The speed measurement window 3-3 consists of two parts on the left and right. When combined, it is a convex structure with a cuboid on the upper part and a cylinder on the lower part. A central hole is drilled, and the hole diameter matches the diameter of the protruding rod of the speedometer. Through holes are drilled around the speed measurement window 3-3, which match the threaded blind holes around the square holes. The speed measurement window 3-3 is fixed on the square hole through bolts. Its thickness and bottom slope are determined according to the size of the model drag head 3-1 around the square hole to ensure that the internal surface shape of the model drag head 3-1 remains unchanged after installation.

[0039] There are 2 lifting lugs 3-5, which are arranged on both sides above the front part of the model drag head 3-1.

[0040] The support component 3-6 is welded by a suction pipe 3-6-1 and a support rod 3-6-2. A standard flange is installed at the lower end of the suction pipe 3-6-1, which is connected to the outlet flange of the model drag head 3-1. The support rod 3-6-2 cooperates with the lifting bracket 2-4-1 of the operation platform and can drive the model drag head to move vertically, thereby changing the distance between the suction port of the model drag head and the bottom plate. A lifting point 3-6-3 is arranged above the support rod 3-6-2, and the lifting point 3-6-3 is connected to the 2 lifting lugs 3-5 respectively through steel wires to improve the uniformity of the force distribution of the model drag head 3-1 and prevent the stress of the plexiglass from being too concentrated due to eccentricity.

[0041] A steel wire hose is used to connect between the outlet pipe 1-2 of the water pump 1 and the water injection port 2-5 of the water tank 2, and between the inlet pipe 1-1 of the water pump and the suction pipe 3-6-1.

[0042] The observation system 4 includes a tracer flow deflector 4-1, a pressure measurement sensor 4-2, and a speedometer 4-3. The tracer flow deflector 4-1 includes a bracket 4-1-1, a liquid reservoir 4-1-2, a valve 4-1-3, and a diversion pipe 4-1-4. The lower part of the liquid reservoir 4-1-2 is connected to the diversion pipe 4-1-4 through the valve 4-1-3, and the whole is fixed on the water tank 2 through the bracket 4-1-1. Several branch pipes are provided below the diversion pipe 4-1-4 to ensure that the tracer liquid can be diverted to the area to be observed. The pressure measurement sensor 4-2 is connected to the model drag head 3-1 through the pressure measurement short pipe 3-2. The speedometer 4-3 can be arranged around or inside the model drag head 3-1 as needed. When speed measurement is required inside, the probe of the speedometer 4-3 extends into the model drag head 3-1 through the small hole of the speed measurement window.

[0043] Preferably, the above nozzle assembly 3-4 includes a pressure stabilizing pipe 3-4-1, a nozzle block 3-4-2 and a compression ring 3-4-3; the pressure stabilizing pipe 3-4-1 is a circular pipe with one end sealed and the other end having a standard flange. Multiple holes are drilled on the circumferential surface of the pressure stabilizing pipe 3-4-1 according to the required number of nozzles, and the holes are arranged in the same column; the pressure stabilizing pipe 3-4-1 passes through two mounting hole plates behind the suction port 3-8 of the model drag head and is fixed on the model drag head 3-1. By rotating the pressure stabilizing pipe 3-4-1, the nozzle angle can be changed; holes are drilled on the nozzle block 3-4-2 according to the required nozzle diameter and number, and the holes on the nozzle block 3-4-2 are aligned with the holes on the circumferential surface of the pressure stabilizing pipe 3-4-1, and the two are fixed together by the compression ring 3-4-3; a steel pipe with a flange 3-4-4 is assembled at the flange of the pressure stabilizing pipe 3-4-1, and a hose is connected to it to supply water to the nozzle assembly, so as to generate a jet at the nozzle.

[0044] Preferably, the aperture of the holes on the circumferential surface of the above pressure stabilizing pipe 3-4-1 is 3 times the required nozzle diameter.

[0045] Preferably, the drilled holes on the above nozzle block 3-4-2 have a contraction section and a straight hole section. The diameter of the straight hole section is the required nozzle diameter, and the length is not less than 5 times the nozzle diameter. The contraction section gradually changes from the diameter of the hole drilled on the pressure stabilizing pipe 3-4-1 to the nozzle diameter, and the length is 1-3 times the nozzle diameter.

[0046] Preferably, an energy dissipator 2-7 is arranged below the outlet of the water injection port 2-5 to reduce the turbulence of the water flow entering the water tank.

[0047] Preferably, the above transparent baffle 2-2 and the non-transparent baffle 2-3 are sealed by rubber gaskets and glass glue.

[0048] Preferably, the upper processor of the above speedometer 4-3 can be fixed on the operation platform 2-4, or a bracket can be built separately for fixing.

[0049] Preferably, the above test device further includes a particle image velocimeter or a laser velocimeter for non-interference velocity measurement.

[0050] Preferably, the width of the above water tank is greater than or equal to 3 times the width of the model drag head, and the length is greater than or equal to 8 times the length of the drag head.

[0051] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and deformations can be made, and these improvements and deformations should also be regarded as the protection scope of the present invention.

Claims

1. A fully transparent dredging grab bucket test device, characterized in that It includes a water pump (1), a water tank (2), a rake head structure (3) and an observation system (4); The water pump (1) is controlled by a variable-frequency motor, and the flow rate of the water pump is adjusted by changing the motor frequency. Steel pipes are connected to both the inlet and outlet of the water pump, which are the inlet pipe (1-1) and the outlet pipe (1-2) respectively. An electromagnetic flowmeter (1-3) is installed in the outlet pipe (1-2) to measure the pipeline flow rate in real time; The water tank (2) includes a structural frame (2-1), a transparent baffle (2-2), an opaque baffle (2-3) and an operation platform (2-4). The transparent baffle (2-2) is arranged in the area for observation, and the opaque baffle (2-3) is used in the non-observation area. A water injection port (2-5) and a drain port (2-6) are arranged on one side of the water tank (2). The operation platform (2-4) spans above the structural frame (2-1), can move according to the test requirements, and is fixed tightly to the structural frame through bolts. A lifting bracket (2-4-1) is installed at the middle position of one side inside the water tank (2) of the operation platform (2-4); The rake head structure (3) includes a model rake head (3-1), a piezometric short tube (3-2), a velocity measurement window (3-3), a nozzle assembly (3-4), a lifting lug (3-5), a support member (3-6), an outlet (3-7) and a suction port (3-8); The model rake head (3-1) is made of plexiglass to ensure that the observation area is composed of flat plates and is transparent. The outlet of the model rake head (3-1) is turned upward through a bent pipe, and a standard flange is installed according to the pipe diameter at the outlet; Round holes are drilled at the positions where pressure measurement is required. The piezometric short tube (3-2) is bonded to the outside of the round hole through welding glue, and the inside of the piezometric short tube (3-2) is tapped with sealing threads. Square holes are opened at the positions where velocity measurement is required. The size of the square hole is slightly larger than the size of the velocity meter probe. Threaded blind holes are opened around the square hole. The velocity measurement window (3-3) consists of two parts on the left and right. When combined, it is a convex platform structure with a cuboid on the upper part and a cylinder on the lower part. A central hole is drilled, and the hole diameter matches the diameter of the protruding rod of the velocity meter. Through holes are drilled around the velocity measurement window (3-3), which match the threaded blind holes around the square hole. The velocity measurement window (3-3) is fixed to the square hole through bolts, and its thickness and bottom slope are determined according to the size of the model rake head (3-1) around the square hole to ensure that the internal surface shape of the model rake head (3-1) remains unchanged after installation; There are 2 lifting lugs (3-5), which are arranged on both sides above the front part of the model rake head (3-1); The support member (3-6) is welded by a suction pipe (3-6-1) and a support rod (3-6-2). A standard flange is installed at the lower end of the suction pipe (3-6-1), which is connected to the outlet flange of the model rake head (3-1). The support rod (3-6-2) cooperates with the lifting bracket (2-4-1) of the operation platform and can drive the model rake head to move vertically, thereby changing the distance between the suction port of the model rake head and the bottom plate. Above the support rod (3-6-2), a suspension point (3-6-3) is arranged. The suspension point (3-6-3) is respectively connected to two lifting lugs (3-5) through steel wire ropes, improving the uniformity of the force distribution of the model rake head (3-1) and preventing the stress of the plexiglass from being too concentrated due to eccentricity. A steel wire hose is used to connect between the outlet pipe (1-2) of the water pump (1) and the water injection port (2-5) of the water tank (2), and also between the inlet pipe (1-1) of the water pump and the suction pipe (3-6-1). The observation system (4) includes a tracer flow deflector (4-1), a pressure sensor (4-2), and a velocimeter (4-3). The tracer flow deflector (4-1) includes a bracket (4-1-1), a liquid reservoir (4-1-2), a valve (4-1-3), and a diversion pipe (4-1-4). The liquid reservoir (4-1-2) is connected to the diversion pipe (4-1-4) through the valve (4-1-3) below, and the whole is fixed on the water tank (2) through the bracket (4-1-1). Several branch pipes are provided below the diversion pipe (4-1-4) to ensure that the tracer liquid can be diverted to the area to be observed. The pressure sensor (4-2) is connected to the model rake head (3-1) through a pressure measuring short pipe (3-2). The velocimeter (4-3) can be arranged around or inside the model rake head (3-1) as needed. When measuring the speed inside, the probe of the velocimeter (4-3) extends into the model rake head (3-1) through the small hole of the speed measuring window.

2. The full-transparency dredging draghead test device according to claim 1, characterized in that The nozzle assembly (3-4) includes a pressure stabilizing pipe (3-4-1), a nozzle block (3-4-2), and a pressure ring (3-4-3). The pressure stabilizing pipe (3-4-1) is a circular pipe with one end sealed and the other end having a standard flange. According to the required number of nozzles, multiple holes are drilled on the circumferential surface of the pressure stabilizing pipe (3-4-1), and the holes are arranged in the same column. The pressure stabilizing pipe (3-4-1) passes through two mounting hole plates behind the suction port (3-8) of the model rake head and is fixed on the model rake head (3-1). By rotating the pressure stabilizing pipe (3-4-1), the nozzle angle can be changed. According to the required nozzle diameter and number, holes are drilled on the nozzle block (3-4-2). The holes on the nozzle block (3-4-2) are aligned with the holes on the circumferential surface of the pressure stabilizing pipe (3-4-1), and the two are fixed together through the pressure ring (3-4-3). A steel pipe with a flange (3-4-4) is assembled at the flange of the pressure stabilizing pipe (3-4-1), and a hose is connected to it to supply water to the nozzle assembly, thereby generating a jet flow at the nozzle.

3. A fully transparent dredging draghead test device according to claim 2, characterized in that The diameter of the holes on the circumferential surface of the pressure stabilizing pipe (3-4-1) is 3 times the required nozzle diameter.

4. The all-transparent dredging draghead test device according to claim 2, characterized in that The drilled holes on the nozzle block (3-4-2) have a constriction section and a straight hole section. The diameter of the straight hole section is the required nozzle diameter, and its length is not less than 5 times the nozzle diameter. The constriction section gradually changes from the diameter of the drilled hole on the pressure stabilizing pipe (3-4-1) to the nozzle diameter, and its length is 1-3 times the nozzle diameter.

5. The full-transparency dredging draghead test device according to claim 1, characterized in that An energy dissipator (2-7) is arranged below the outlet of the water injection port (2-5) to reduce the turbulence of the water flow entering the water tank.

6. The full-transparency dredging draghead test device according to claim 1, characterized in that The transparent baffle (2-2) and the non-transparent baffle (2-3) are sealed by rubber gaskets and glass glue.

7. The full-transparency dredging draghead test device according to claim 1, characterized in that The upper processor of the velocimeter (4-3) can be fixed on the operation platform (2-4), or a bracket can be built separately for fixation.

8. The all-transparent dredging draghead test device according to claim 1, characterized in that The test device also includes a particle image velocimeter or a laser velocimeter for non-intrusive velocity measurement.

9. The full-transparency dredging draghead test device according to claim 1, characterized in that The width of the water tank is greater than or equal to 3 times the width of the model drag head, and the length is greater than or equal to 8 times the length of the drag head.

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