Visual measurement system and measurement method for flow field of impact water entry of landslide block

Abstract

The invention relates to a flow field visualization measurement system and a measurement method for impact entry of a landslide block into water. The flow field visualization measurement system comprises a water tank, a slope arranged in the water tank, a landslide block body arranged on the slope, and PIV equipment used for observing the distribution of an inflow flow field impacted by the landslide block body. The water tank is filled with experimental fluid; the landslide block body is formed by stacking transparent solid particles with the same refractive index as the experimental fluid; the PIV equipment comprises a laser light source and a camera; wherein the laser light source illuminates an impact water-entering area of the landslide block rushing into the experimental fluid, and the camera directly faces the impact water-entering area and is used for acquiring an image. Compared with the prior art, the flow field distribution in the collapse block and the flow field distribution under the action of the block body and water flow when the landslide block body impacts into water can be accurately observed, so that more accurate data support is provided for understanding and predicting the flow field dynamic state when the landslide block body impacts into water.

Description

Technical Field

[0001] This invention belongs to the field of flow field observation technology, and in particular relates to a flow field visualization measurement system and method for landslide block impact into water. Background Technology

[0002] Observing the flow field of landslide blocks impacting water is a complex fluid dynamics problem involving multiple fields such as sediment, hydrodynamics, and solid mechanics. Commonly used techniques for observing and analyzing the flow field of landslide blocks impacting water include high-speed imaging, ordinary particle image velocimetry (PIV), and pressure sensor and accelerometer measurements.

[0003] High-speed camera technology is a tool capable of capturing rapid motion processes. It has been used in experiments observing the flow field of landslide blocks impacting water to record the dynamic process of landslide blocks entering the water. Through high-speed cameras, the interaction between the landslide block and the water can be observed in detail, including the impact of the block, the splashing of water, and the formation of swells. This technology can provide continuous image sequences, helping researchers analyze the complex dynamic behavior during landslides. While high-speed camera technology can capture rapid motion processes, its effectiveness can be affected by extreme environments, such as poor lighting conditions or limited field of view. Furthermore, high-speed camera technology may struggle to capture all the details of the flow field, especially in complex and variable flow conditions. Additionally, the impact of landslide solids into the water can obstruct the high-speed camera's view, preventing the recording of the internal liquid flow within the landslide block. This obstruction not only affects the comprehensive understanding of the internal dynamic behavior of the flow field but also limits the application of high-speed camera technology in observing complex flow fields.

[0004] Particle image velocimetry (PIV) is a non-contact fluid dynamics measurement method. It involves scattering tracer particles in a flow field and illuminating a cross-sectional area of ​​the flow field with a laser to record particle images. By analyzing these images, the displacement of the particles in the flow field can be obtained, thereby determining the velocity distribution of the flow field. PIV technology enables transient, multi-point measurements of the velocity field in a flow field, which is of great value for analyzing the flow field changes caused by landslide debris impacting water. PIV technology overcomes the limitations of traditional single-point measurements, allowing simultaneous, non-contact measurement of two-dimensional or three-dimensional velocity distributions on a single cross-section of the flow field, achieving interference-free measurement, and the PIV method boasts high measurement accuracy.

[0005] For example, CN120160791A discloses a test method and apparatus for the initiation of bedload particles. This method achieves synchronous acquisition of instantaneous flow velocity and particle displacement by embedding a pressure sensor, a laser-PIV velocimetry system, and a high-speed camera array in a wave flume. The sediment particles in this test method are a mixture of hollow glass spheres and quartz sand. A pressure sensor is embedded in the surface of the hollow glass sphere, with the sensor wiring hidden inside the sphere and led out through the flume wall to a data acquisition instrument. However, PIV technology works best in pure fluid without solid particle interference. When solid boundaries or fluid-structure interaction exist in the flow field, the measurement effect of PIV is severely affected. Furthermore, the aforementioned sediment particles are a mixture of hollow glass spheres and quartz sand, which can block light, leading to discontinuities in the measurement area and incomplete data. Therefore, the above test method still cannot achieve effective flow field observation of landslide debris impacting into water.

[0006] Therefore, a new method for observing the internal flow field when landslide blocks impact water is still needed. Summary of the Invention

[0007] The purpose of this invention is to overcome at least one of the defects in the existing technology, such as light obstruction and difficulty in observing the flow field distribution of landslide block impact into water, and to provide a visualization measurement system and method for the flow field of landslide block impact into water.

[0008] The objective of this invention can be achieved through the following technical solutions:

[0009] The present invention first provides a visualization measurement system for the flow field of landslide block impacting water, including a water tank, a slope set in the water tank, a landslide block set on the slope, and a PIV device for observing the flow field distribution of the landslide block impacting water.

[0010] The water tank contains experimental fluid; the landslide block is composed of transparent solid particles with the same refractive index as the experimental fluid.

[0011] The PIV device includes a laser light source and a camera; wherein, the laser light source illuminates the impact water area where the landslide block is thrown into the experimental fluid, and the camera is positioned directly in front of the impact water area to acquire images.

[0012] Furthermore, the slope of the ramp is 30-45°.

[0013] Furthermore, the slope surface is made of glass.

[0014] Furthermore, the landslide blocks are piled up in a cuboid shape.

[0015] Furthermore, the transparent solid particles of the landslide block are spherical borosilicate glass beads.

[0016] Furthermore, the borosilicate glass beads are spherical with a diameter of 8-15 mm.

[0017] Furthermore, the experimental fluid is prepared by mixing ethanol and benzyl alcohol in a volume ratio of (3-5):(5-7), with the preferred volume ratio being 4:6.

[0018] Furthermore, the camera is a high-speed camera used to capture the flow field distribution in the internal region of the landslide block when it impacts the water.

[0019] Furthermore, the PIV device also includes a computer with a control system, and the laser light source and camera are both connected to the computer.

[0020] This invention also provides a measurement method using a flow field visualization measurement system for landslide block impact into water, the measurement method comprising the following steps:

[0021] S1: Use transparent solid particles to accumulate on the slope to form landslide blocks, and deploy laser light sources and cameras;

[0022] S2: Control the landslide blocks to slide down the slope and impact the water;

[0023] S3: The flow field distribution inside the landslide block and the landslide block is captured by a camera when the landslide block enters the water.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The flow field visualization measurement system for landslide block impact water of the present invention combines refractive index matching technology with particle image velocity measurement to solve the shortcomings of PIV technology in studying fluid-solid interaction in landslide block impact water scenario, and can effectively measure the flow field inside the landslide block.

[0026] (2) This invention uses a transparent solid material with the same refractive index as the fluid to simulate landslide blocks, thereby reducing the reflection and refraction of light at different medium interfaces, thus improving the transmission efficiency and imaging quality of the optical system. It achieves the goal of solids not blocking or refracting light, and improves the discontinuity of the measurement area and the incompleteness of the data.

[0027] (3) The present invention uses landslide blocks and experimental fluids with refractive index matching, which can reduce the reflection and refraction of light on the surface of solid models, reduce noise and artifacts in PIV images, and help improve the accuracy and reliability of flow field measurement, especially in complex fluid-structure interaction environments.

[0028] (4) The flow field visualization measurement method of the present invention allows PIV technology to penetrate the simulated landslide block and capture the particle image behind it, thereby accurately measuring the flow velocity in the near wall region, overcoming the limitations of traditional PIV technology in fluid-structure interaction scenarios.

[0029] (5) The flow field visualization measurement method of the present invention has important practical significance for understanding the impact of landslide blocks on water, assessing landslide hazards and formulating corresponding protective measures. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the flow field visualization measurement system of the present invention.

[0031] Figure 2 This is a schematic diagram illustrating the refractive index matching between the landslide block and the experimental fluid according to the present invention.

[0032] Explanation of markings in the diagram:

[0033] 1-Water tank, 2-Slope, 3-Landslide block, 4-Experimental fluid, 5-Laser light source, 6-Camera, 7-Computer. Detailed Implementation

[0034] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0035] Unless otherwise specified, the reagents, methods, instruments, and equipment used in this invention are conventional in the art. Unless otherwise specified, the reagents and materials used in the following examples are all commercially available.

[0036] In this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention; the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance; furthermore, unless otherwise explicitly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly, for example, they can be fixed connections, detachable connections, or integral connections; they can be mechanical connections or electrical connections; they can be direct connections or indirect connections through an intermediate medium; they can be internal connections between two elements. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0037] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0038] The core objective of this invention is to address the shortcomings of existing PIV (Potential Injection Volume) technology in studying fluid-solid interactions, particularly in scenarios involving landslide impacts into water. While PIV technology is widely used in fluid mechanics, providing non-contact velocity measurements across the entire flow field, it faces several challenges in complex flow fields involving fluid-structure interaction, especially when considering moving solid boundaries created by landslide impacts. PIV technology performs well in pure fluids, but in fluid-structure interaction experiments, especially when solid boundaries are present, it struggles to accurately measure velocities near the walls. This is because solid boundaries obstruct light, making it difficult for PIV technology to capture particle images behind the solid boundaries, leading to discontinuities and incomplete data in velocity measurements. In studies of landslide impacts, the presence of landslides significantly affects the distribution and structure of the flow field. Existing PIV technology cannot effectively penetrate landslides to measure the velocity distribution within them, limiting a deeper understanding of the interaction mechanism between landslide impacts and the flow field.

[0039] This invention aims to overcome the limitations of PIV technology in fluid-structure interaction scenarios through innovative measurement methods, particularly addressing the challenge of measuring the internal flow field of landslide blocks during impact with water. This new method allows for precise observation of the flow field distribution within the landslide block and its interaction with water flow during impact, thus providing more accurate data support for understanding and predicting the dynamic flow field during landslide impact.

[0040] Based on the above objectives, the first aspect of the present invention provides a flow field visualization measurement system for landslide block impact into water. This flow field visualization measurement system includes a water tank 1, a slope 2 disposed within the water tank 1, a landslide block 3 disposed on the slope 2, and a PIV device for observing the flow field distribution of the landslide block 3 impacting into water. The water tank 1 contains an experimental fluid 4; the landslide block 3 is composed of a buildup of transparent solid particles with the same refractive index as the experimental fluid 4. The PIV device includes a laser light source 5 and a camera 6; wherein the laser light source 5 illuminates the impact area of ​​the landslide block 3 impacting into the experimental fluid 4, and the camera 6 is positioned directly over the impact area and used to acquire images.

[0041] In some specific embodiments, the slope of the ramp 2 is 30-45°.

[0042] In some specific embodiments, the slope surface of the slope 2 is made of glass.

[0043] In some specific embodiments, the landslide blocks 3 are piled up in a cuboid shape.

[0044] In some specific embodiments, the transparent solid particles of the landslide block 3 are spherical borosilicate glass beads.

[0045] In some specific embodiments, the borosilicate glass beads are spherical with a diameter of 8-15 mm.

[0046] In some specific embodiments, the experimental fluid 4 is prepared by mixing ethanol and benzyl alcohol in a volume ratio of (3-5):(5-7).

[0047] In some specific embodiments, the camera 6 is a high-speed camera used to capture the flow field distribution in the internal region of the landslide block 3 when it impacts the water.

[0048] In some specific embodiments, the PIV device further includes a computer 7 with a control system, and the laser light source 5 and the camera 6 are both connected to the computer 7.

[0049] A second aspect of the present invention provides a measurement method using the above-described flow field visualization measurement system, the measurement method comprising the following steps:

[0050] S1: Use transparent solid particles to accumulate on slope 2 to form landslide blocks 3, and set up laser light sources 5 and cameras 6;

[0051] S2: Control the landslide block 3 to slide down the slope 2 and impact the water;

[0052] S3: The flow field distribution inside the landslide block 3 when it enters the water is captured by camera 6.

[0053] Each of the above embodiments can be implemented individually, or in any combination of two or more. The following detailed description of specific examples will further illustrate these embodiments.

[0054] Example 1:

[0055] This embodiment provides a visualization measurement system for the flow field of landslide blocks impacting water. For example... Figure 1 As shown, the flow field visualization measurement system includes a water tank 1, a slope 2 located in the water tank 1, a landslide block 3 located on the slope 2, and a PIV device for observing the flow field distribution of the impact of the landslide block 3 into the water.

[0056] In this embodiment, the slope of ramp 2 is 30°, and the slope surface of ramp 2 is made of glass.

[0057] In this embodiment, the landslide block 3 is piled up in a cuboid shape. The transparent solid particles of the landslide block 3 are spherical borosilicate glass beads with a diameter of 8-15 mm.

[0058] In this embodiment, the water tank 1 contains experimental fluid 4, which is prepared by mixing ethanol and benzyl alcohol in a volume ratio of 4:6. The landslide block 3 is composed of transparent solid particles with the same refractive index as the experimental fluid 4.

[0059] The PIV device in this embodiment includes a laser light source 5, a camera 6, and a computer 7 with a control system. Both the laser light source 5 and the camera 6 are connected to the computer 7. In this embodiment, the laser light source 5 illuminates the impact area of ​​the landslide block 3 entering the experimental fluid 4, and the camera 6 is positioned directly in front of the impact area to acquire images. The camera 6 in this embodiment is a high-speed camera used to capture the flow field distribution within the collapsed area of ​​the landslide block 3 during impact with the water.

[0060] Example 2:

[0061] This embodiment provides a flow field visualization measurement system and method for landslide block impact into water. The key point is to use a transparent solid material with the same refractive index as the experimental fluid to simulate the landslide block. This solves the problem of the landslide block blocking and refracting light in the landslide block impact into water experiment, enabling PIV technology to accurately measure the flow field when the landslide block enters the water and inside the landslide block.

[0062] The specific technical solution of this embodiment is as follows:

[0063] (1) Constructing a landslide block model and preparing the experimental fluid. The landslide block was constructed from transparent solid granular material stacked into a cuboid shape and placed on a glass slope with a 45° incline. For example... Figure 2 As shown, the transparent solid particulate material is made of spherical borosilicate glass beads, whose refractive index is the same as that of the experimental liquid. The experimental fluid is prepared by mixing 40% ethanol and 60% benzyl alcohol by volume.

[0064] By fabricating a transparent solid material with the same refractive index as the experimental fluid to simulate landslide blocks, the goal of ensuring that the solid does not block or refract light is achieved. This significantly reduces light loss in PIV measurements caused by solid particles or collapsed blocks, reduces light reflection and refraction on the solid model surface, and reduces noise and artifacts in PIV images. Consequently, PIV technology can effectively measure the flow field inside landslide blocks, allowing it to penetrate the simulated landslide block and capture particle images behind it, thus accurately measuring the flow velocity in the near-wall region. This overcomes the limitations of traditional PIV technology in fluid-structure interaction scenarios.

[0065] (2) Deploy PIV equipment. Ensure that the area illuminated by the focused laser is located in the area where the landslide block impacts the water.

[0066] (3) Simulate the impact of landslide blocks into water. Release landslide blocks on the slope and let them rush into the experimental fluid.

[0067] (4) Camera shooting. The camera is placed in the impact water area of ​​the landslide block. The light from the laser source can pass through the landslide block without refraction, so that the camera can capture the flow field distribution behind the block or inside the collapsed block.

[0068] (5) Data processing and analysis.

[0069] Data processing and analysis are performed using PivLab software. The specific steps are as follows:

[0070] ① Data preparation and import

[0071] Import the image sequence, input the image resolution, and set the time interval.

[0072] ②Image preprocessing

[0073] Remove static background, enhance tracer particle contrast, crop ROI, and correct optical distortion.

[0074] ③ PIV analysis parameter settings

[0075] Set the initial / final query window and overlap rate, enable iterative refinement, and apply standard deviation and median filtering.

[0076] ④ Result verification and post-processing

[0077] Visualize the vector field, overlay the landslide block outline, extract the velocity profile, and calculate vorticity and shear stress.

[0078] ⑤ Data export and archiving

[0079] Export velocity field data (.mat / .csv), generate a video with vector overlay, and record experimental parameters and metadata.

[0080] This invention effectively solves the problems of solid obstruction and refracted light by applying refractive index matching and PIV (Pivot-Induced Variation) techniques, overcoming the limitations of PIV technology in fluid-structure interaction scenarios. This invention can successfully acquire the flow field when landslide blocks impact water. By comparing PIV image sequences and CFD numerical models, it verifies that this invention can accurately represent the flow field distribution in the vicinity, further confirming the effectiveness of the flow field visualization measurement system and method. This has significant practical implications for understanding the impact of landslide blocks impacting water, assessing landslide hazards, and developing corresponding protective measures.

[0081] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A visualization measurement system for the flow field of landslide blocks impacting water, characterized in that, It includes a water tank (1), a slope (2) in the water tank (1), a landslide block (3) on the slope (2), and a PIV device for observing the impact flow field distribution of the landslide block (3); The water tank (1) is filled with experimental fluid (4); the landslide block (3) is composed of transparent solid particles with the same refractive index as the experimental fluid (4); The PIV device includes a laser light source (5) and a camera (6); wherein the laser light source (5) illuminates the impact area of ​​the landslide block (3) into the experimental fluid (4), and the camera (6) is positioned in front of the impact area and is used to acquire images.

2. The flow field visualization measurement system for landslide block impact into water according to claim 1, characterized in that, The slope of the slope (2) is 30-45°.

3. The flow field visualization measurement system for landslide block impact into water according to claim 1, characterized in that, The slope surface of the slope (2) is made of glass.

4. The flow field visualization measurement system for landslide block impact into water according to claim 1, characterized in that, The landslide blocks (3) are piled up in a cuboid shape.

5. The flow field visualization measurement system for landslide block impact into water according to claim 1, characterized in that, The transparent solid particles of the landslide block (3) are spherical borosilicate glass beads.

6. The flow field visualization measurement system for landslide block impact into water according to claim 4, characterized in that, The borosilicate glass beads are spherical with a diameter of 8-15 mm.

7. The flow field visualization measurement system for landslide block impact into water according to claim 1, characterized in that, The experimental fluid (4) was prepared by mixing ethanol and benzyl alcohol in a volume ratio of (3-5):(5-7).

8. The flow field visualization measurement system for landslide block impact into water according to claim 1, characterized in that, The camera (6) is a high-speed camera used to capture the flow field distribution in the internal region of the landslide block (3) when it impacts the water.

9. A visualization measurement system for the flow field of landslide block impact into water according to claim 1, characterized in that, The PIV device also includes a computer (7) with a control system, and the laser light source (5) and the camera (6) are both connected to the computer (7).

10. A measurement method using the flow field visualization measurement system for landslide block impact into water as described in any one of claims 1-9, characterized in that, Includes the following steps: S1: Use transparent solid particles to build up landslide blocks (3) on the slope (2), and set up laser light source (5) and camera (6); S2: Control the landslide block (3) to slide down the slope (2) and impact the water; S3: The flow field distribution inside the landslide block (3) when it enters the water is collected by camera (6).

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