A device for collecting estuarine plume velocity field profile based on a rotating platform

Abstract

The present invention discloses a device for collecting velocity field profiles of estuarine plumes based on a rotating platform, comprising a PIV collection module, an electrically controlled synchronous displacement platform module, a variable slope terrain module, a rotating platform base structure and a water supply module; the PIV collection module is used for plume visualization and velocity field profile collection; the electrically controlled synchronous displacement platform module is used to control the position of the collection profile; the variable slope terrain module can change the slope according to demand; the rotating platform structure is used to provide Coriolis force condition environmental fluid; the water supply module is provided with two identical sets of water supply modules on the rotating platform structure to facilitate the study of multiple estuarine plumes, and is used to supply estuarine freshwater plumes. The device of the present invention is based on PIV technology and combined with a rotating platform to obtain the quasi-three-dimensional structure of the velocity field of the multi-angle profile layer of the estuarine plume, and the experimental data acquisition has strong real-time performance and high precision, and the device has good applicability.

Description

Technical Field

[0001] The invention relates to the field of offshore power and experimental fluid mechanics, and in particular to a device for collecting estuary plume velocity field profiles based on a rotating platform. Background Art

[0002] The estuarine plume is a low-salinity mass generated by the influx of freshwater from active rivers into the coastal waters. The classic estuarine plume structure is mainly composed of two parts: the bulge and the coastal current near the shore wall, and is usually divided into four regions: the source area, the near field, the mid-field, and the far field. As an important link connecting the transport of terrestrial materials to the coastal waters, the estuarine plume has a profound impact on the accumulation of freshwater, sediment, nutrients and pollutants in offshore seawater, the ice period and the distribution of primary productivity in offshore waters. Therefore, it has attracted great attention and research interest from scholars at home and abroad in recent years. Previous studies have shown that the above phenomena are mainly determined by the dominant dynamic characteristics of different regions of the estuarine plume. The dynamic characteristics of the river plume mainly come from the horizontal advection of freshwater in the estuary, which defines the shape and characteristics of the plume. Therefore, obtaining the horizontal velocity field profile of the estuarine plume is crucial to understanding the different dominant dynamic mechanisms in different regions. However, the current related research at home and abroad still lacks the means to continuously collect the spatiotemporal characteristics of the plume velocity field profile, and thus cannot explore the evolution mechanism of the entire development process of the estuarine plume from generation to extinction. In addition, the velocity field profiles collected by previous researchers are limited to the horizontal plane, and no data along the shelf slope are obtained. Therefore, designing a device that can continuously collect the horizontal velocity field profile of the plume at different angles and planes will provide new insights into the current research status.

[0003] Particle image velocimetry (PIV) technology and electronically controlled synchronization technology of the displacement stage provide technical support for the present invention. PIV technology has been widely used in recent years as a high-precision fluid measurement technology: when a test fluid carrying PIV particles and having a refractive index matching that of the ambient fluid flows out from the source, the PIV particles evenly distributed in the test fluid move with the development of the test fluid. Under the irradiation of a horizontal laser beam, the two-dimensional motion trajectory of the PIV particles corresponding to the laser surface will be continuously collected, and then the time series of the two-dimensional velocity field of the test fluid will be obtained by post-processing with the MATLAB-based PIVLAB software. The electronically controlled synchronization technology of the displacement stage uses a local area network to remotely control the synchronous and automatic movement of multiple displacement stages loaded with lasers. After completing the PIV acquisition of a section, all displacement stages automatically move with the same amplitude to ensure that the beam emitted by the laser is still in the same plane, and finally realize the acquisition of the two-dimensional velocity field of multiple laser surfaces. The combination of these two technologies can obtain the quasi-three-dimensional structure of the test fluid.

[0004] In the present invention, taking into account the bottleneck of experimental research on estuarine plumes in recent years, a device for collecting estuarine plume velocity field profiles based on a rotating platform is proposed, which can be used to obtain the quasi-three-dimensional structure of the multi-angle profile layer velocity field of estuarine plumes in experimental fluid mechanics under complex terrain. Summary of the invention

[0005] The purpose of the present invention is to propose a device for collecting estuarine plume velocity field profiles based on a rotating platform in view of the limitations of the prior art, so as to solve the problem that the estuarine plume velocity field profiles currently collected are limited to the horizontal plane, and the velocity field profiles along the shelf slope are not obtained. The test device has a simple structure and is easy to operate. It can realize the multi-profile collection of the plume velocity field at horizontal and inclined angles, which improves the dynamic characteristics analysis of the plume by one dimension.

[0006] The object of the present invention is achieved through the following technical solutions: a device for collecting velocity field profiles of estuarine plumes based on a rotating platform, comprising a PIV acquisition module, an electrically controlled synchronous displacement stage module, a variable slope terrain, a rotating platform structure for providing a Coriolis force condition environmental fluid, and a water supply module for supplying estuarine freshwater plumes;

[0007] The rotating platform structure consists of six parts: a top frame, a river mouth, a bank wall, a water tank, a water tank base and a bottom base. The river mouth is excavated on the vertical surface of the bank wall. The bank wall is installed in the water tank. The water tank is fixedly connected to the water tank base. The top frame is installed on the water tank base. The water tank base and the bottom base are coaxially connected and remain relatively still during the operation of the rotating platform.

[0008] The electric-controlled synchronous translation stage module is composed of four parts: a laser bracket, an inclination knob, a vertical displacement bracket and a bottom bracket. The electric-controlled synchronous translation stage modules are distributed on both sides of the rotating platform structure, one on each side. The laser bracket and the vertical displacement bracket are movably connected through the inclination knob, and the vertical displacement bracket and the bottom bracket are fixedly connected; the bottom bracket is installed on the outside of the water tank base;

[0009] The PIV acquisition module consists of a PIV camera and a PIV laser. The PIV camera is fixedly connected to the top structure of the rotating platform structure. The PIV lasers are distributed on both sides of the rotating platform, 4 on one side, and are fixedly connected to the laser bracket.

[0010] The variable slope terrain module is close to the lower edge of the estuary and vertically adjacent to the shore wall, and remains relatively still during the operation of the rotating platform structure. The variable slope terrain module has a support structure of variable height at one end away from the estuary. When the structure contracts, the slope becomes steeper, and when the structure extends, the slope becomes gentler, so that the slope can be changed according to experimental requirements;

[0011] The water supply module consists of three parts: a drainage pipe, a water supply tank and a constant flow pump. One end of the drainage pipe is connected to the water supply tank, and the other end is connected to the estuary. The constant flow pump is powered to pump fresh water into the estuary. Two completely identical water supply modules are arranged on the rotating platform structure to facilitate the study of multiple estuary plumes.

[0012] Furthermore, the PIV camera adopts a CCD sensor; the PIV laser light source adopts a 450nm laser, which is expanded into a uniform sheet of light through a built-in lens of the laser to form a laser surface.

[0013] Furthermore, the side wall of the water tank is made of transparent organic glass and has a cylindrical shape to facilitate PIV laser transmission.

[0014] Furthermore, the PIV acquisition module, the electrically controlled synchronous displacement stage module, and the rotating platform structure are remotely controlled by a workstation via WiFi, and the variable slope terrain module and the water supply module can be manually set before the experiment begins.

[0015] Furthermore, the rotating platform structure runs at a set constant speed after the power is turned on. After reaching the tempered state, the workstation opens the estuary gate through WiFi remote control, and the water supply module is manually started to run. The estuary plume carrying PIV particles flows out at a constant flow rate. At this time, the PIV camera starts to collect PIV images under the irradiation of 8 PIV lasers. The field of view of the PIV camera and the laser surface coverage both cover the farthest development position of the plume.

[0016] Furthermore, after the PIV image acquisition of the surface is completed, the laser brackets on both sides of the rotating platform structure will synchronously move downward on the vertical displacement bracket according to the set displacement amount and then perform PIV image acquisition again. After repeating the process several times and reaching the set total displacement amount, the laser bracket stops moving downward. At this time, the entire acquisition process is completed, and the laser bracket can be remotely controlled by WiFi to reset along the vertical displacement bracket.

[0017] Furthermore, after the variable slope terrain is placed in the rotating platform structure, the laser bracket can be adjusted to an angle parallel to the slope corresponding to the set slope by adjusting the inclination knob in advance. The adjusted laser bracket will still move downward synchronously and evenly along the vertical displacement bracket for collection until it reaches the terrain slope or the set total displacement. When the entire collection process is completed, multiple two-dimensional velocity field oblique profiles corresponding to the slope angle from top to bottom will be obtained through post-processing.

[0018] The beneficial effects of the present invention are as follows:

[0019] 1. The device of the present invention has a simple design structure and good integrity; it has stable operation and strong reliability; the manufacturing cost and the test cost are low; the device is made of recyclable materials and is green and environmentally friendly; the test process is highly automated and the whole process is remotely controlled by a computer, and the test efficiency is high.

[0020] 2. The device of the present invention basically realizes the upgrade from two-dimensional to three-dimensional acquisition of estuarine plume structure. The multi-layer vertical PIV particle two-dimensional motion trajectory profile is acquired through the electronically controlled synchronous displacement stage module. The multi-layer horizontal velocity field profile obtained after post-processing can jointly characterize the three-dimensional structure of the estuarine plume. In addition, the acquisition range for the three-dimensional structure is wide, the stability is strong, and it is not affected by changing the estuarine plume flow conditions or multiple interacting estuarine plume conditions.

[0021] 3. The device of the present invention also realizes the control of the vertical multi-layer profile angle. By adjusting the inclination knob, the vertical multi-layer profile can be changed from horizontal to parallel to the slope surface of the slope terrain. Then, the three-dimensional velocity field structure parallel to the shelf slope surface that simulates the evolution process of the estuarine plume on the shelf can be obtained. This structure can provide an important basis for understanding the interaction between the plume and the shelf.

[0022] 4. The device of the present invention fully combines the particle image velocimetry (PIV) technology with the electronically controlled synchronous displacement technology and is adapted to a rotating platform to conduct refined estuarine plume experiments. It provides strong support for data visualization of complex working conditions of the rotating platform. The test data is acquired in real time with high accuracy and good applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the three-dimensional structure of the device of the present invention;

[0024] Figure 2 It is a top view schematic diagram of the operation of the device of the present invention;

[0025] Figure 3 It is a side view schematic diagram of the device of the present invention under different slope working conditions;

[0026] In the figure: 1. Top frame; 2. PIV camera; 3. Drainage pipe; 4. Estuary; 5. Bank wall; 6. Variable slope terrain; 7. Flume; 8. PIV laser; 9. Laser bracket; 10. Tilt knob; 11. Vertical displacement bracket; 12. Bottom bracket; 13. Water supply tank; 14. Flume base; 15. Constant flow pump; 16. Bottom base; 17. PIV camera field of view; 18. Laser surface coverage; 19. Plume; DETAILED DESCRIPTION

[0027] The specific implementation modes of the present invention are further described in detail below with reference to the accompanying drawings.

[0028] like Figure 1 As shown, the present invention provides a device for collecting velocity field profiles of estuarine plumes based on a rotating platform, comprising a PIV acquisition module, an electrically controlled synchronous displacement stage module, a variable slope terrain, a rotating platform structure for providing a Coriolis force condition environmental fluid, and a water supply module for supplying estuarine freshwater plumes;

[0029] The rotating platform infrastructure consists of six parts: a top frame 1, a river mouth 4, a bank wall 5, a water tank 7, a water tank base 14 and a bottom base 16. The river mouth 4 is excavated on the vertical surface of the bank wall 5. The bank wall 5 is installed in the water tank 7. The water tank 7 is fixedly connected to the water tank base 14. The top frame 1 is installed on the water tank base 14. The water tank base 14 and the bottom base 16 are coaxially connected and remain relatively still during the operation of the rotating platform. The side wall of the water tank 7 is made of transparent organic glass and is cylindrical in shape to facilitate PIV laser transmission.

[0030] The electric-controlled synchronous displacement stage module is composed of four parts: a laser bracket 9, an inclination knob 10, a vertical displacement bracket 11 and a bottom bracket 12. The module is also distributed on both sides of the rotating platform, one on each side, wherein the laser bracket 9 and the vertical displacement bracket 11 are movably connected through the inclination knob 10, and the vertical displacement bracket 11 and the bottom bracket 12 are fixedly connected; the bottom bracket 12 is installed on the outside of the water tank base 14;

[0031] The PIV acquisition module consists of two parts: a PIV camera 2 and a PIV laser 8. The PIV camera 2 is fixedly connected to the top structure 1 of the rotating platform. The PIV lasers 8 are distributed on both sides of the rotating platform, with 4 on one side, and are fixedly connected to the laser bracket 9. The PIV camera 2 uses a CCD sensor. The PIV laser 8 light source uses a 450nm laser, which is expanded into a uniform sheet of light through the built-in lens of the laser to form a laser surface.

[0032] The variable slope terrain module 6 is close to the lower edge of the estuary 4 and vertically adjacent to the shore wall 5, and remains relatively still during the operation of the rotating platform. The end away from the estuary 4 has a support structure with a variable height. When the structure contracts, the slope becomes steeper, and when the structure extends, the slope becomes gentler, so that the slope can be changed according to the experimental requirements;

[0033] The water supply module consists of three parts: a drainage pipe 3, a water supply tank 13 and a constant flow pump 15, wherein one end of the drainage pipe 3 is connected to the water supply tank 13, and the other end is connected to the estuary 4, and the constant flow pump 15 is powered to pump fresh water into the estuary 4. Two identical sets of water supply modules are arranged on the rotating platform to facilitate the study of multiple estuary plumes.

[0034] The PIV acquisition module, the electric-controlled synchronous displacement stage module, and the rotating platform infrastructure are remotely controlled by a workstation via WiFi, and the variable slope terrain module and the water supply module can be manually set before the experiment begins.

[0035] like Figure 2 As shown, the rotating platform structure runs at a set speed after the power is turned on. After reaching the tempered state, the estuary gate 4 is opened by WiFi remote control, and the water supply module is running at the same time. The estuary plume 19 carrying PIV particles flows out at a constant flow rate. At this time, the PIV camera 2 starts to collect PIV images under the irradiation of 8 PIV lasers 8. The PIV camera field of view range 17 and the laser surface coverage range 18 both cover the farthest development position of the plume 19. After the surface PIV image acquisition is completed, the laser brackets 9 on both sides of the rotating platform will synchronously move down on the vertical displacement bracket 11 according to the set displacement amount and then perform PIV image acquisition again. After repeating the process several times and reaching the set total displacement amount, the laser bracket 9 stops moving down. At this time, the entire acquisition process ends, and the laser bracket 9 can be reset along the vertical displacement bracket 11 by WiFi remote control.

[0036] like Figure 3 As shown, after the variable slope terrain 6 is placed on the rotating platform, the laser bracket 9 can be adjusted to an angle parallel to the slope corresponding to the set slope by adjusting the inclination knob 10 in advance. After the adjustment, the laser bracket 9 will still move down synchronously and evenly along the vertical displacement bracket 11 for collection until it reaches the terrain slope or the set total displacement. When the entire collection process is completed, multiple two-dimensional velocity field oblique sections corresponding to the slope angle from top to bottom will be obtained through post-processing. Figure 3 The device can be tested under the following two working conditions, specifically:

[0037] Case 1: Horizontal two-dimensional velocity field measurement test of estuary plume without slope terrain

[0038] After the rotating platform on the non-slope terrain runs long enough to allow the entire fluid to reach a tempered state, quickly open the estuary gate 4 and start the water supply module, while starting the PIV acquisition module and the electronically controlled synchronous displacement stage module. At this time, the laser bracket 9 is flush with the horizontal plane, and the horizontal two-dimensional velocity field measurement test of the estuary plume can be realized;

[0039] Case 2: Test of measuring the inclined two-dimensional velocity field of an estuarine plume with a slope terrain

[0040] After the rotating platform with the slope terrain has been running for a long enough time to allow the entire fluid to reach a tempered state, adjust the inclination knob 10 according to the slope required for the test, and adjust the laser bracket 9 to an angle parallel to the slope surface corresponding to the set slope. The slope can be set to a gentle slope ( Figure 3 left, inclination angle θ1) or steep slope ( Figure 3Right, inclination angle θ2), after adjustment, quickly open the estuary gate 4 and start the water supply module, and at the same time start the PIV acquisition module and the electronically controlled synchronous displacement stage module. At this time, the laser bracket 9 is parallel to the slope surface, and the inclined two-dimensional velocity field measurement test of the estuary plume can be realized;

[0041] During the above experiments, the evolution of the estuarine plume was recorded by the PIV acquisition module, and the two-dimensional motion trajectory profile of the PIV particles was collected in real time. After completion, the time series of the two-dimensional velocity field of the estuarine plume was obtained by post-processing with the MATLAB-based PIVLAB software.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A device for collecting estuarine plume velocity field profiles based on a rotating platform, characterized in that: It includes a PIV acquisition module, an electric-controlled synchronous displacement stage module, a variable slope terrain module, a rotating platform structure for providing Coriolis force conditioned environmental fluid, and a water supply module for supplying estuary freshwater plumes; The rotating platform structure is composed of six parts: a top frame (1), a river mouth (4), a bank wall (5), a water tank (7), a water tank base (14) and a bottom base (16), wherein the river mouth (4) is excavated on the vertical plane of the bank wall (5), and the bank wall (5) is installed in the water tank (7); the water tank (7) is fixedly connected to the water tank base (14), the top frame (1) is installed on the water tank base (14), and the water tank base (14) and the bottom base (16) are coaxially connected and remain relatively still during the operation of the rotating platform; The electrically controlled synchronous displacement stage module is composed of four parts: a laser bracket (9), an inclination knob (10), a vertical displacement bracket (11) and a bottom bracket (12). The electrically controlled synchronous displacement stage modules are distributed on both sides of the rotating platform structure, with one module on each side. The laser bracket (9) and the vertical displacement bracket (11) are movably connected via the inclination knob (10), and the vertical displacement bracket (11) and the bottom bracket (12) are fixedly connected. The bottom bracket (12) is mounted on the outside of the water tank base (14); The PIV acquisition module consists of a PIV camera (2) and a PIV laser (8), wherein the PIV camera (2) is fixedly connected to the top structure (1) of the rotating platform structure, and the PIV lasers (8) are distributed on both sides of the rotating platform, with four on one side, and are fixedly connected to the laser bracket (9); The variable slope terrain module (6) is closely attached to the lower edge of the estuary (4) and vertically adjacent to the shore wall (5), and remains relatively still during the operation of the rotating platform structure. The variable slope terrain module (6) has a support structure with a variable height at one end away from the estuary (4). When the structure contracts, the slope becomes steeper, and when the structure extends, the slope becomes gentler. After the variable slope terrain module (6) is placed in the rotating platform structure, the laser bracket (9) can be adjusted in advance to an angle parallel to the slope corresponding to the set slope by adjusting the inclination knob (10). After the adjustment, the laser bracket (9) will still move downward synchronously and evenly along the vertical displacement bracket (11) for collection until it reaches the terrain slope or the set total displacement. When the entire collection process is completed, a plurality of two-dimensional velocity field oblique profiles corresponding to the slope inclination angle from top to bottom will be obtained through post-processing, so that the slope can be changed according to experimental requirements. The water supply module is composed of three parts: a drainage pipe (3), a water supply tank (13) and a constant flow pump (15), wherein one end of the drainage pipe (3) is connected to the water supply tank (13) and the other end is connected to the estuary (4), and fresh water is pumped into the estuary (4) through the constant flow pump (15). Two identical sets of water supply modules are arranged on the rotating platform structure to facilitate the study of multiple estuary plumes.

2. The device for collecting estuarine plume velocity field profile based on a rotating platform according to claim 1, characterized in that: The PIV camera (2) adopts a CCD sensor; the PIV laser (8) light source adopts a 450nm laser, which is expanded into a uniform sheet of light through a built-in lens of the laser and forms a laser surface.

3. The device for collecting estuarine plume velocity field profile based on a rotating platform according to claim 1, characterized in that: The side wall of the water tank (7) is made of transparent organic glass and has a cylindrical shape to facilitate PIV laser transmission.

4. The device for collecting estuarine plume velocity field profile based on a rotating platform according to claim 1, characterized in that: The PIV acquisition module, the electric-controlled synchronous displacement stage module, and the rotating platform structure are remotely controlled by the workstation via WiFi, and the variable slope terrain module and the water supply module can be manually set before the experiment begins.

5. The device for collecting estuarine plume velocity field profile based on a rotating platform according to claim 4, characterized in that: The rotating platform structure runs at a constant speed set after the power is turned on. After reaching the tempered state, the workstation opens the estuary (4) gate through WiFi remote control, and the water supply module is manually started to run. The estuary plume (19) carrying PIV particles flows out at a constant flow rate. At this time, the PIV camera (2) starts to collect PIV images under the irradiation of 8 PIV lasers (8). The PIV camera field of view (17) and the laser surface coverage (18) both cover the farthest development position of the plume (19).

6. The device for collecting estuarine plume velocity field profile based on a rotating platform according to claim 5, characterized in that: After the PIV image acquisition of the surface layer is completed, the laser brackets (9) on both sides of the rotating platform structure will move downward synchronously on the vertical displacement bracket (11) according to the set displacement amount and then perform PIV image acquisition again. After repeating the process several times and reaching the set total displacement amount, the laser bracket (9) stops moving downward. At this time, the entire acquisition process is completed, and the laser bracket (9) can be remotely controlled by WiFi to reset along the vertical displacement bracket (11).

Images