Hydrodynamic simulation test system and method for scouring protection of human-shaped submerged dike offshore wind power pile foundation under reciprocating flow

Abstract

The invention discloses a hydrodynamic simulation test system and method for scouring protection of a human-shaped submerged dike offshore wind power pile foundation under reciprocating flow, and the method comprises the steps: collecting environment and reciprocating flow data, and building a numerical model of the influence of the reciprocating flow on the pile foundation through the hydrodynamics; numerical simulation is carried out through the numerical model, the human-shaped submerged embankment and an offshore wind power pile foundation model, experimental verification is carried out, the numerical model is optimized, and the optimal angle, length and width of the human-shaped submerged embankment and the optimal distance between the human-shaped submerged embankment and the pile foundation are adopted in an optimized mode, so that scouring of the pile foundation is effectively reduced, and the durability and the protection effect of the human-shaped submerged embankment are improved; the method comprises the following steps: establishing a numerical model of the influence of a reciprocating flow on a pile foundation based on data in S1 and by adopting a fluid dynamics principle in S2, and establishing a physical model of an offshore wind power pile foundation and a human-shaped submerged dike in S3 at the same time; a numerical model and a physical model under a reciprocating flow condition are provided.

Description

Technical Field

[0001] The invention relates to the field of fluid dynamics tests, and in particular to a fluid dynamics simulation test system and method for scour protection of offshore wind power pile foundations under reciprocating flow. Background Art

[0002] Reciprocating flow refers to a tidal current in which the rising and falling tides are opposite or substantially opposite due to the influence of topography. In the field of marine science and technology, it is regarded as a periodic flow in which the tidal ellipse degenerates into a straight line;

[0003] Fluid dynamics is a discipline that studies the laws of fluid motion and its interaction with boundaries. In the design and application of human-shaped submerged dikes, the principles of fluid dynamics play a vital role. By applying the principles of fluid dynamics, the force, deformation characteristics and stability of human-shaped submerged dikes under the action of reciprocating flow can be analyzed;

[0004] In the marine environment, the presence of pile foundations will change the original flow pattern of the water around them, resulting in local scouring around the pile foundations. This scouring phenomenon will affect the bearing capacity of the pile foundations and the safety of offshore wind turbines. Therefore, effective scouring protection measures are needed to protect offshore wind turbine pile foundations. The human-shaped submerged dike can change the dynamic characteristics of the surrounding water flow through its special shape and structure, thereby reducing the scouring effect on the pile foundation;

[0005] In practical applications, the fluid dynamics model needs to accurately reflect the complex marine environmental conditions. The human-shaped submerged dike needs to be set up near the pile foundation to protect the pile foundation. It is necessary to conduct multiple tests on the protective effect of the human-shaped submerged dike on the pile foundation.

[0006] Therefore, it is necessary to improve the existing method for testing scour protection of offshore wind power pile foundations of submarine energy dissipation nets based on fluid dynamics numerical simulation for reciprocating flow in order to solve the above problems. Summary of the invention

[0007] The present invention overcomes the shortcomings of the prior art and provides a fluid dynamics simulation test system and method for scour protection of offshore wind power pile foundations under reciprocating flow.

[0008] To achieve the above object, the technical solution adopted by the present invention is: a fluid dynamics simulation test system and method for scour protection of offshore wind power pile foundations under reciprocating flow, comprising: S1, collecting environmental data of the pile foundation and reciprocating flow data of the area in which it is located;

[0009] S2. Based on the data of S1, a numerical model of the effect of reciprocating flow on pile foundation is established by using the principles of fluid dynamics;

[0010] S3. Construct the physical model of offshore wind power pile foundation and human-shaped submerged dike;

[0011] S4, conduct a water tank experiment based on the data of S1 and the physical model of S3;

[0012] S5. Perform numerical simulations with the numerical model and the offshore wind turbine pile foundation model to simulate the scouring process of the offshore wind turbine pile foundation and the human-shaped submerged dike under the action of reciprocating flow;

[0013] S6. Compare the numerical simulation and flume test data to optimize the numerical simulation model.

[0014] In a preferred embodiment of the present invention, in step S1, the environmental data includes: seabed slope, seabed topography characteristics and sediment characteristic data in the sea area.

[0015] In a preferred embodiment of the present invention, in step S1, the reciprocating flow data includes flow velocity and flow direction data.

[0016] In a preferred embodiment of the present invention, the specific steps for collecting reciprocating flow data are: using an acoustic Doppler current meter and a current meter placed at a measuring point for measurement, and after processing the collected data, making a flow velocity and direction diagram to intuitively display the reciprocating flow situation.

[0017] In a preferred embodiment of the present invention, in step S2, the specific steps are:

[0018] S21. Select the continuity equation and momentum equation as the core equations in this step, which describe the conservation of mass and momentum of the fluid respectively;

[0019] Specifically, the continuity equation:

[0020]

[0021] Where ρ is the fluid density and u is the fluid velocity vector;

[0022] Momentum equation:

[0023]

[0024] Where n is the pressure, g is the gravitational acceleration vector, μ is the dynamic viscosity, represents the vector Laplace operator, F is the interaction force between the fluid and the pile foundation;

[0025] S22, using the turbulence model equation:

[0026] Use the turbulence kinetic energy equation and the turbulence dissipation rate equation;

[0027] Turbulent kinetic energy equation:

[0028] Turbulence dissipation rate equation:

[0029] Where k is the turbulent kinetic energy, ∈ is the turbulent dissipation rate, μ t is the turbulent viscosity, p k is the term for turbulent kinetic energy generation, C 1∈ and C 2∈ is an empirical constant, σ ∈ and σ k is the Prandtl number;

[0030] S23, inputting the reciprocating flow data collected in S1 into the model as the boundary condition of the model;

[0031] The seafloor topography in the model is constructed using the seafloor slope and seafloor geomorphic feature data collected in S1. This usually involves importing elevation data into the software and generating a three-dimensional terrain model. The seafloor slope and elevation data are extracted from S1. The terrain construction formula is: Among them, Δz is the elevation difference between adjacent points, and Δx is the horizontal distance between adjacent points;

[0032] The sediment characteristic data (particle size distribution, density, settling velocity) collected in S1 are input into the model to simulate the transport and deposition process of sediment under the action of reciprocating flow; Sediment characteristic input: Where v is the dynamic viscosity of water, ρ w is the density of water and g is the gravitational acceleration vector.

[0033] In a preferred embodiment of the present invention, the actual single pile foundation diameter is 3-6m, and a scaled model pile foundation is arranged in the water tank. The size and spacing of the scaled model pile foundation are scaled by 1:10-15 according to actual conditions, and the scaled model pile foundation diameter is 30-40cm.

[0034] In a preferred embodiment of the present invention, in step S3, the angle of the human-shaped submerged dike is 10°-20°, the length is 1-3 times the diameter of the pile foundation, the distance between the human-shaped submerged dike and the pile foundation is 1-4 times the diameter of the pile foundation, and the width is 1-2 times the diameter of the pile foundation. The material of the dike is usually a permeable material composed of porous concrete and crushed stone, or an impermeable material composed of concrete and reinforced concrete; the human-shaped submerged dike composed of permeable materials allows water to flow through, which is conducive to siltation and water quality improvement; the human-shaped submerged dike composed of impermeable materials is mainly used to change the direction of water flow and dissipate the energy of reciprocating flow.

[0035] In a preferred embodiment of the present invention, in step S4, the water tank experiment is:

[0036] Build the experimental environment: The specifications of the water tank are as follows: the water tank size is 20m long, 4m wide, and 2m high;

[0037] Prepare acoustic Doppler current meters, pressure sensors, displacement sensors, and materials for simulating sediment internally; use multi-beam bathymetric system data to build a corresponding seafloor terrain model in the water tank to ensure that the slope and landform characteristics meet actual conditions;

[0038] Fine sand with simulated particle size distribution of 0.01-0.1 mm, accounting for 40%-60% of the total sediment, is evenly laid on the bottom of the water tank. The high proportion of fine sand can simulate the suspension and transportation characteristics of sediment;

[0039] Medium sand of 0.1-1 mm accounts for 25% to 35% of the total sediment. The particle size of medium sand is larger, the sedimentation speed is faster, and the scouring effect on the submerged dike is more significant;

[0040] Coarse sand larger than 1 mm accounts for 15% to 25% of the total sediment. Coarse sand has the largest particle size, the fastest sedimentation rate, and the greatest impact on the local scouring of the submerged dike.

[0041] And the sediment density range is set at 2.55g / cm 3 Up to 2.65g / cm 3 ,This density range reflects the specific gravity of different types of sediment, which is crucial for simulating the movement and deposition behavior of sediment in water flow;

[0042] The measurement equipment was installed in the experiment, and flow meters, pressure sensors and displacement sensors were installed in the flume to ensure that the effect of the reciprocating flow on the submerged dike could be monitored in real time;

[0043] By starting a bidirectional pump to simulate reciprocating water flow, the set water flow conditions are generated to ensure that the flow rate and direction of the water flow are stably converted according to a fixed cycle;

[0044] The test water level was set at 0.05m-0.2m. This range takes into account extreme conditions such as extreme tide levels and storm surge water increase and decrease, covering mild to severe sea conditions to ensure that the submerged dike design can cope with different reciprocating flow conditions;

[0045] The period range of the reciprocating flow is set at 1.5s-3s, reflecting the periodic changes of the reciprocating flow, which is crucial for simulating the impact effect of the reciprocating flow on the submerged dike;

[0046] The flow velocity range is set at 0.16m / s-0.48m / s. This range simulates tidal currents of different intensities, which is very important for evaluating the stability and scour protection effect of the submerged dike under different flow velocity conditions.

[0047] In a preferred embodiment of the present invention, in step s4, the steps of executing the water tank experiment are:

[0048] S41, start the bidirectional pump, gradually increase the flow rate to the set value, and ensure the water flow is stable;

[0049] S42. Use ADV or other current meters to measure velocity profiles at different locations in the flume, including before, after, and on both sides of the submerged dike; record time series of velocity data to capture dynamic changes in reciprocating flow and velocity;

[0050] S43. Pressure sensors and displacement sensors installed on the submerged dike and pile foundation record the changes in water pressure and the displacement of the submerged dike and pile foundation to evaluate their stability;

[0051] S44. Use a depth sounder to regularly measure the scour depth before and after the submerged dike, and evaluate the changes in the scour extent by measuring the size of the scour pit.

[0052] In a preferred embodiment of the present invention, in step S6,

[0053] S61. Arrange the data of flume experiment and numerical simulation to ensure the consistency of time series, spatial position and measurement parameters

[0054] Use interpolation or fitting methods to align experimental and simulated data in time and space

[0055]

[0056] Among them, (x1, y1) and (x2, y2) are two known plane points, and (x, y) is the plane coordinate of the required value point;

[0057] S62. Use statistical methods to assess the significance of differences;

[0058] t-test:

[0059]

[0060] in, is the mean S of the two groups of samples pcoled is the combined standard deviation, n1 and n2 are the sample sizes;

[0061] S63, numerical simulation model optimization;

[0062]

[0063] Among them, ρ is density, u is velocity vector, p is pressure, g is gravitational acceleration, and μ is dynamic viscosity;

[0064] Also considering the turbulence effect, the corresponding optimization is:

[0065]

[0066] where k is the turbulent kinetic energy, ∈ is the turbulent dissipation rate, μ i is the turbulent viscosity, P kis the turbulence generation term, C 1∈ , C 2∈ , σ k , σ ∈ is the model constant;

[0067] S64. Use error analysis methods to evaluate the differences between simulation results and experimental data

[0068]

[0069] Among them, y i is the experimental data, is the simulated data, and n is the number of data points.

[0070] The present invention solves the defects existing in the background technology and has the following beneficial effects:

[0071] (1) The present invention collects environmental and reciprocating flow data, uses fluid dynamics to establish a numerical model of the impact of reciprocating flow on pile foundations, performs numerical simulations on the numerical model, a human-shaped submerged dike, and an offshore wind turbine pile foundation model, and performs experimental verification to optimize the numerical model and optimize the angle, length, width, and spacing between the human-shaped submerged dike and the pile foundation to effectively reduce the scouring of the pile foundation and improve the durability and protective effect of the human-shaped submerged dike.

[0072] (2) The present invention establishes a numerical model of the influence of reciprocating flow on pile foundations based on the data of S1 and the principles of fluid dynamics in S2, and simultaneously establishes a physical model of offshore wind turbine pile foundations and human-shaped submerged dikes in S3; a numerical model and a physical model under reciprocating flow conditions are provided; compared with the prior art, the degree of influence on the pile foundation under the condition of reciprocating flow is more obvious, and after experimental verification, the structure of the human-shaped submerged dike can be adjusted synchronously to reduce the scouring of the pile foundation.

[0073] (3) The present invention sets a numerical model of a human-shaped submerged dike in S3 and verifies it through a water tank experiment, thereby further optimizing the angle, length, width, distance between the human-shaped submerged dike and the pile foundation, and materials to achieve the best protection effect for the pile foundation.

[0074] (4) The present invention combines the S2 numerical model with the S4 experimental verification, and has a numerical basis and actual experimental support, which can not only verify the accuracy of the numerical model, but also optimize the human-shaped submerged dike structure to achieve the best protection effect for the pile foundation. BRIEF DESCRIPTION OF THE DRAWINGS

[0075] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art are briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative work.

[0076] Figure 1 is a flow chart of a preferred embodiment of the present invention.

[0077] Figure 2 It is a schematic diagram of the pile foundation and the human-shaped submerged dike of the present invention. DETAILED DESCRIPTION

[0078] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0079] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0080] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the scope of protection of the present application. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the invention, unless otherwise specified, "multiple" means two or more.

[0081] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood by specific circumstances.

[0082] like Figure 1 As shown, a fluid dynamics simulation test system and method for scour protection of offshore wind power pile foundation under reciprocating flow of human-shaped submerged dikes includes:

[0083] S1. Collect environmental data of pile foundation and reciprocating flow data of the area;

[0084] S2. Based on the data of S1, a numerical model of the effect of reciprocating flow on pile foundation is established by using the principles of fluid dynamics;

[0085] S3. Construct the physical model of offshore wind power pile foundation and human-shaped submerged dike;

[0086] S4, conduct a water tank experiment based on the data of S1 and the physical model of S3;

[0087] S5. Perform numerical simulations with the numerical model and the offshore wind turbine pile foundation model to simulate the scouring process of the offshore wind turbine pile foundation and the human-shaped submerged dike under the action of reciprocating flow;

[0088] S6. Compare the numerical simulation and flume test data to optimize the numerical simulation model;

[0089] Further, in step S1, the environmental data includes: seabed slope, seabed geomorphic features, and sediment characteristic data in the sea area;

[0090] Specifically, the specific operation of collecting data on seabed slope and seabed geomorphic features is to use a multi-beam bathymetric system to scan the seabed at the sampling point, obtain the elevation data of the seabed topography, and then calculate the seabed slope. At the same time, through post-processing of multi-beam data, the seabed geomorphic features can be extracted.

[0091] Sampling point selection: latitude 32°28'23"N, longitude 121°54'32"E, water depth 20m;

[0092] Sediment characteristic data include particle size distribution, density, and settling velocity data. The specific collection steps are as follows: using a grab sampler to collect sediment samples and sending them to the laboratory for detailed physical and chemical analysis (analysis of particle size distribution, density, and settling velocity);

[0093] In the distribution of sediment particle size, particles between 0.01-0.1 mm account for 50%, particles between 0.1-1 mm account for 30%, and particles larger than 1 mm account for 20%;

[0094] The density of sediment is 2.60-2.70g / cm 3 between;

[0095] The sediment settling velocity is between 0.015-0.087.5 cm / s;

[0096] In step S1, the reciprocating flow data includes data such as flow velocity and flow direction; the specific steps of collecting the reciprocating flow data are: using an acoustic Doppler current meter (ADCP) and a current meter placed at a measuring point for measurement, and after processing the collected data, making a flow velocity and flow direction diagram to intuitively display the reciprocating flow situation.

[0097] Furthermore, in step S2, the specific steps are:

[0098] The continuity equation and momentum equation are selected as the core equations in this step, which describe the conservation of mass and momentum of the fluid respectively;

[0099] Specifically, the continuity equation:

[0100]

[0101] Where ρ is the fluid density and u is the fluid velocity vector;

[0102] Momentum equation:

[0103]

[0104] Where n is the pressure, g is the gravitational acceleration vector, μ is the dynamic viscosity, represents the vector Laplace operator, and F is the interaction force between the fluid and the pile foundation.

[0105] Turbulence model equations:

[0106] Use the turbulence kinetic energy equation and the turbulence dissipation rate equation;

[0107] Turbulent kinetic energy equation:

[0108] Turbulence dissipation rate equation:

[0109]

[0110] Where k is the turbulent kinetic energy, ∈ is the turbulent dissipation rate, μ t is the turbulent viscosity, p k is the term for turbulent kinetic energy generation, C 1∈ and C 2∈is an empirical constant, σ ∈ and σ k is the Prandtl number.

[0111] Furthermore, the reciprocating flow data (flow velocity and flow direction) collected in S1 are input into the model as the boundary conditions of the model;

[0112] The seafloor topography in the model is constructed using the seafloor slope and seafloor geomorphic feature data collected in S1. This usually involves importing elevation data into the software and generating a 3D terrain model; extracting seafloor slope (α) and elevation (z) data from S1, and the terrain construction formula is: Among them, Δz is the elevation difference between adjacent points, and Δx is the horizontal distance between adjacent points.

[0113] The sediment characteristic data (particle size distribution, density, settling velocity) collected in S1 are input into the model to simulate the transport and deposition process of sediment under the action of reciprocating flow; Sediment characteristic input: Where v is the dynamic viscosity of water, ρ w is the density of water and g is the gravitational acceleration vector.

[0114] In step S3, specifically:

[0115] 87.5cm87.5cmThe actual single pile foundation diameter is 3-6m. The scaled model pile foundation is arranged in the water tank. The size and spacing of the scaled model pile foundation are scaled by 1:10-15 according to the actual situation. The scaled model pile foundation diameter is 30-40cm;

[0116] The double human-shaped submerged dike design uses the inclination angle and width of the human-shaped submerged dike, and uses the shape and angle of the human-shaped submerged dike to change the flow direction and speed of the water flow, reduce the direct impact of the water flow on the pile foundation, effectively disperse the reciprocating flow energy, and reduce the direct impact on the pile foundation. This design can reduce the risk of local scour and protect the stability of the pile foundation; the dike top elevation is calculated based on the reciprocating flow climb to ensure that it can still effectively protect the pile foundation under extreme weather conditions.

[0117] The material of the submerged dike is usually concrete or stone to ensure its durability and stability in the marine environment;

[0118] like Figure 2 As shown, the detailed structure of the double human-shaped submerged dike is designed, including that the angle of the human-shaped submerged dike is 10°-20°, the length is 1-3 times the diameter of the pile foundation, the distance between the human-shaped submerged dike and the pile foundation is 1-4 times the diameter of the pile foundation, and the width is 1-2 times the diameter of the pile foundation. Such a design is helpful to disperse the water flow and reduce the direct scouring of the pile foundation;

[0119] The angle of the human-shaped submerged dike is 10°-20°, which can provide a good water flow dispersion effect and reduce the impact of the reciprocating flow on the front of the submerged dike. This design is based on the principles of fluid dynamics, especially the optimization of the energy dispersion efficiency of the reciprocating flow and water flow;

[0120] The length of the human-shaped submerged dike is 1-3 times the diameter of the pile foundation. This length setting can ensure sufficient water flow dispersion area, so that the reciprocating flow and water flow have enough distance and time to disperse their energy before reaching the pile foundation, reducing the direct impact on the pile foundation;

[0121] The width of the human-shaped submerged dike is 1-2 times the diameter of the pile foundation: the width setting ensures that there is enough space for the water flow to disperse on both sides of the submerged dike, avoiding erosion of the submerged dike and pile foundation due to concentrated water flow

[0122] The distance between the human-shaped submerged dike and the pile foundation is 1-4 times the diameter of the pile foundation: this distance can ensure that the submerged dike can effectively change the flow field and reduce the scouring of the pile foundation. At the same time, this distance also takes into account the feasibility of construction and the convenience of maintenance;

[0123] The materials of human-shaped submerged dikes are usually permeable materials such as porous concrete and crushed stone, or impermeable materials such as concrete and reinforced concrete; human-shaped submerged dikes made of permeable materials allow water to flow through, which helps to improve silt deposition and water quality; human-shaped submerged dikes made of impermeable materials are mainly used to change the direction of water flow and dissipate the energy of reciprocating flow.

[0124] In step S4, the water tank experiment is:

[0125] Build the experimental environment: The specifications of the water tank are as follows: the water tank size is 20m long, 4m wide, and 2m high;

[0126] Prepare acoustic Doppler velocimeters (ADVs), pressure sensors, displacement sensors, and materials for simulating sediments in-house; use multi-beam bathymetric system data to build a corresponding seafloor terrain model in the flume to ensure that the slope and geomorphic features meet actual conditions;

[0127] Fine sand with simulated particle size distribution of 0.01-0.1 mm, accounting for 40%-60% of the total sediment, is evenly laid on the bottom of the water tank. The high proportion of fine sand can simulate the suspension and transportation characteristics of sediment;

[0128] Medium sand of 0.1-1 mm accounts for 25% to 35% of the total sediment. The particle size of medium sand is larger, the sedimentation speed is faster, and the scouring effect on the submerged dike is more significant;

[0129] Coarse sand larger than 1 mm accounts for 15% to 25% of the total sediment. Coarse sand has the largest particle size, the fastest sedimentation rate, and the greatest impact on the local scouring of the submerged dike.

[0130] And the sediment density range is set at 2.55g / cm 3 Up to 2.65g / cm 3 ,This density range reflects the specific gravity of different types of sediment and is crucial for simulating the movement and deposition behavior of sediment in water flow.

[0131] The measurement equipment was installed in the experiment, by installing a flow meter, pressure sensor and displacement sensor in the flume to ensure the real-time monitoring of the effect of water flow and reciprocating flow on the submerged dike;

[0132] Start a bidirectional pump to simulate reciprocating water flow, ensure that the flow rate and flow direction conversion cycle are stable, and adjust the water flow rate to meet the test conditions;

[0133] The test water level was set at 0.05m-0.2m. This range takes into account extreme conditions such as extreme tide levels and storm surge water increase and decrease, covering mild to severe sea conditions to ensure that the submerged dike design can cope with different reciprocating flow conditions;

[0134] The period range of the reciprocating flow is set at 1.5s-3s, reflecting the periodic changes of the reciprocating flow, which is crucial for simulating the impact effect of the reciprocating flow on the submerged dike;

[0135] The flow velocity range is set at 0.16m / s-0.48m / s. This range simulates tidal currents of different intensities, which is very important for evaluating the stability and scour protection effect of the submerged dike under different flow velocity conditions.

[0136] The real-time collected data on flow rate, pressure, displacement, and scour depth and range around the submerged dike will be used to analyze the performance of the submerged dike and evaluate its protective effect against pile foundation scour; observe the effects of water flow and reciprocating flow on the submerged dike and pile foundation, and record scour and sedimentation phenomena. These observations will provide intuitive evidence for verifying numerical models and improving submerged dike design; analyze the collected data to evaluate the performance of the submerged dike, such as water flow dispersion effect, scour reduction effect, etc. These analysis results will directly guide the optimization of submerged dike design.

[0137] In step s4, the execution steps of the water tank experiment are:

[0138] S41, start the bidirectional pump, gradually increase the flow rate to the set value, and ensure the water flow is stable;

[0139] S42. Use ADV or other current meters to measure velocity profiles at different locations in the flume, including before, after, and on both sides of the submerged dike; record time series of velocity data to capture the dynamic changes in reciprocating flow and flow velocity.

[0140] S43. Pressure sensors and displacement sensors installed on the submerged dike and pile foundation record the changes in water pressure and the displacement of the submerged dike and pile foundation to evaluate their stability;

[0141] S44. Use a depth sounder to regularly measure the scour depth before and after the submerged dike, and evaluate the changes in the scour extent by measuring the size of the scour pit.

[0142] Example 1

[0143] A water tank experiment, comprising:

[0144] A physical model of a water tank with dimensions of 20m long, 4m wide and 2m high was constructed. Fine sand with simulated particle size distribution of 0.01-0.1mm was evenly laid on the bottom of the water tank, accounting for 50% of the total sediment; medium sand of 0.1-1mm accounted for 30% of the total sediment; and coarse sand larger than 1mm accounted for 20% of the total sediment.

[0145] The actual single pile foundation diameter is 3.5m, so the scaled model pile foundation diameter is 35cm;

[0146] The reciprocating flow data simulated by the bidirectional pump is as follows: the water level is set at 0.35m, the switching period of the reciprocating flow is set at 2s, and the flow rate is set at 0.25m / s.

[0147] The angle of the human-shaped submerged dike is 15°.

[0148] The length of the human-shaped submerged dike is twice the diameter of the pile foundation, i.e. 70 cm;

[0149] The width of the human-shaped submerged dike is 1.5 times the diameter of the pile foundation, i.e. 52.5 cm;

[0150] The distance between the human-shaped submerged dike and the pile foundation is 2.5 times the diameter of the pile foundation, i.e. 87.5 cm; it is arranged around the pile foundation of the scaled model;

[0151] The human-shaped submerged dike is made of permeable materials consisting of porous concrete and crushed stone;

[0152] Example 2

[0153] A water tank experiment, the same as that of Example 1 will not be repeated, the difference between this embodiment and Example 1 is that;

[0154] The angle of the human-shaped submerged dike is 10°;

[0155] Example 3

[0156] A water tank experiment, the same as that of Example 1 will not be repeated, the difference between this embodiment and Example 1 is that;

[0157] The angle of the human-shaped submerged dike is 20°;

[0158] Example 4

[0159] A water tank experiment, the same as that of Example 1 will not be repeated, the difference between this embodiment and Example 1 is that;

[0160] The length of the human-shaped submerged dike is 1.2 times the diameter of the pile foundation, i.e. 42 cm;

[0161] Example 5

[0162] A water tank experiment, the same as that of Example 1 will not be repeated, the difference between this embodiment and Example 1 is that;

[0163] The length of the human-shaped submerged dike is three times the diameter of the pile foundation, i.e. 105 cm;

[0164] Example 6

[0165] A water tank experiment, the same as that of Example 1 will not be repeated, the difference between this embodiment and Example 1 is that;

[0166] The width of the human-shaped submerged dike is 1 times the diameter of the pile foundation, i.e. 35 cm;

[0167] Example 7

[0168] A water tank experiment, the same as that of Example 1 will not be repeated, the difference between this embodiment and Example 1 is that;

[0169] The width of the human-shaped submerged dike is twice the diameter of the pile foundation, i.e. 70 cm;

[0170] Example 8

[0171] A water tank experiment, the same as that of Example 1 will not be repeated, the difference between this embodiment and Example 1 is that;

[0172] The distance between the human-shaped submerged dike and the pile foundation is 1 times the diameter of the pile foundation, that is, 35 cm;

[0173] Example 9

[0174] A water tank experiment, the same as that of Example 1 will not be repeated, the difference between this embodiment and Example 1 is that;

[0175] The distance between the human-shaped submerged dike and the pile foundation is twice the diameter of the pile foundation, that is, 70 cm;

[0176] Example 10

[0177] A water tank experiment, the same as that of Example 1 will not be repeated, the difference between this embodiment and Example 1 is that;

[0178] The distance between the human-shaped submerged dike and the pile foundation is 3 times the diameter of the pile foundation, i.e. 105 cm;

[0179] Embodiment 11

[0180] A water tank experiment, the same as that of Example 1 will not be repeated, the difference between this embodiment and Example 1 is that;

[0181] The distance between the human-shaped submerged dike and the pile foundation is 4 times the diameter of the pile foundation, that is, 140 cm;

[0182] Example 12

[0183] A water tank experiment, the same as that of Example 1 will not be repeated, the difference between this embodiment and Example 1 is that;

[0184] No human-shaped submerged dike is set up near the pile foundation of the scale model.

[0185] Example 13

[0186] A water tank experiment, the same as that of Example 1 will not be repeated, the difference between this embodiment and Example 1 is that;

[0187] The human-shaped submerged dike is made of permeable materials consisting of porous concrete and crushed stone;

[0188] Experimental Example 1

[0189] This experiment selected Example 1, Example 4-7, and Example 12 to detect the wave height in front and the wave height in the rear of the scaled model human-shaped submerged dike and the energy dissipation efficiency, as well as the parameters such as the front flow velocity and the rear flow velocity and the flow velocity reduction rate after 24 hours; the experimental data are shown in Table 1;

[0190]

[0191]

[0192] According to the data in Table 1, it can be obtained that the wave height reduction rate and flow velocity reduction rate of the human-shaped submerged dike with a length of 2 times the diameter of the pile foundation, i.e. 70 cm, and a width of 1.5 times the diameter of the pile foundation, i.e. 52.5 cm, are the highest, indicating that the human-shaped submerged dike of this length and width has the best protection effect on reciprocating flow; it indicates that when the reciprocating flow encounters the submerged dike, the water molecules in the reciprocating flow collide with the surface of the submerged dike, and the largest part of the kinetic energy is converted into heat energy or other forms of energy (such as eddy energy). As a result, the speed of the water molecules in the front of the reciprocating flow is greatly slowed down, and the wave height is reduced the most; and when the water flows through the submerged dike, the flow path is subject to the greatest restriction, and the flow velocity is therefore slowed down the most through the Bernoulli equation in fluid mechanics, and the resistance between water molecules is effectively and greatly increased.

[0193] According to Table 1, the length of the human-shaped submerged dike is twice the diameter of the pile foundation, that is, 70 cm; and the width of the human-shaped submerged dike is 1.5 times the diameter of the pile foundation, that is, 52.5 cm. This greatly reduces the scouring of the reciprocating flow and is the best in dealing with scouring.

[0194] Experimental Example 2

[0195] This experiment selected Example 1, Example 2-3, and Example 12 to detect the wave height in front and the wave height in the rear of the scaled model human-shaped submerged dike and the energy dissipation efficiency, as well as the parameters such as the front flow velocity and the rear flow velocity and the flow velocity reduction rate after 24 hours; the experimental data are shown in Table 2;

[0196]

[0197] According to the data in Table 2, it can be obtained that the wave height reduction rate and flow velocity reduction rate of the human-shaped submerged dike with a human-shaped submerged dike angle of 15° are the highest, indicating that the human-shaped submerged dike at this angle has the best protection effect on reciprocating flow; the reason is that: at the angle of this embodiment 1, after the reciprocating flow hits the submerged dike, more eddies and turbulence are generated. The water molecules in these eddies and turbulence are in a highly disordered state, and their kinetic energy is quickly converted into internal energy and dissipated. The submerged dike angle of embodiment 1 improves the energy dissipation efficiency by more effectively promoting the generation of eddies and turbulence; at the same time, at this angle, more friction and collision between water molecules are increased, which more effectively increases the fluid dynamics resistance, thereby achieving a higher flow velocity reduction effect.

[0198] Experimental Example 3

[0199] This experiment selected Example 1, Example 8-11, and Example 12 to detect the wave height in front and the wave height in the rear of the scaled model human-shaped submerged dike and the energy dissipation efficiency, as well as the parameters such as the front flow velocity and the rear flow velocity and the flow velocity reduction rate after 24 hours; the experimental data are shown in Table 3;

[0200]

[0201] According to the data in Table 3, the human-shaped submerged dike with a spacing between the human-shaped submerged dike and the pile foundation of 2.5 times the diameter of the pile foundation, that is, 87.5 cm, has the highest wave height reduction rate and flow velocity reduction rate, indicating that the human-shaped submerged dike at this angle has the best protection effect on reciprocating flow; the reason is that in the human-shaped submerged dike under Example 1, the spacing between the human-shaped submerged dike and the pile foundation is 2.5 times the diameter of the pile foundation. At this spacing, the space between the submerged dike and the pile foundation may form an optimized energy dissipation area, which allows water molecules to have more sufficient space to convert kinetic energy and potential energy after being obstructed by the submerged dike, thereby more effectively dissipating the reciprocating flow energy. At this spacing, the van der Waals force between water molecules is more fully utilized; when the spacing is 2.5 times the diameter of the pile foundation, the design of the submerged dike effectively suppresses the generation of excessive turbulence, while retaining sufficient eddies to dissipate the reciprocating flow energy; ultimately resulting in the highest flow velocity reduction rate and wave height reduction rate, and better anti-scouring.

[0202] Experimental Example 4

[0203] This experiment selected Example 1, Example 13, and Example 12 to detect the wave height in front and the wave height in the rear of the scaled model human-shaped submerged dike and the energy dissipation efficiency, as well as the front flow velocity and the rear flow velocity and the flow velocity reduction rate and other parameters after 24 hours; the experimental data are shown in Table 4;

[0204] Experimental Group Example 1 Example 13 Example 12 Front wave height (cm) 14.0 15.5 16.0 Rear wave height (cm) 4.5 8.0 9.5 Wave height reduction rate (%) 67.9 48.4 40.6 Front flow velocity (m / s) 0.60 0.68 0.72 Rear flow velocity (m / s) 0.20 0.35 0.42 Flow rate reduction rate (%) 66.7 48.5 41.7 Energy dissipation efficiency (%) 85.0 70.0 65.0

[0205] According to the data in Table 4, the wave height reduction rate and flow velocity reduction rate of the human-shaped submerged dike composed of porous concrete and crushed stone permeable materials are the highest, indicating that the human-shaped submerged dike at this angle has the best protection effect against reciprocating flow;

[0206] In step S6,

[0207] S61. Arrange the data of flume experiment and numerical simulation to ensure the consistency of time series, spatial position and measurement parameters

[0208] Use interpolation or fitting methods to align experimental and simulated data in time and space

[0209]

[0210] Among them, (x1, y1) and (x2, y2) are two known plane points, and (x, y) is the plane coordinate of the required value point;

[0211] S62. Use statistical methods to assess the significance of differences;

[0212] t-test:

[0213]

[0214] in, is the mean S of the two groups of samples pcoled is the combined standard deviation, and n1 and n2 are the sample sizes.

[0215] S63, numerical simulation model optimization;

[0216]

[0217] Among them, ρ is density, u is velocity vector, p is pressure, g is gravitational acceleration, and μ is dynamic viscosity.

[0218] Also considering the turbulence effect, the corresponding optimization is:

[0219]

[0220] where k is the turbulent kinetic energy, ∈ is the turbulent dissipation rate, μ i is the turbulent viscosity, P k is the turbulence generation term, C 1∈ , C2∈ , σ k , σ ∈ is the model constant.

[0221] S64. Use error analysis methods to evaluate the differences between simulation results and experimental data

[0222]

[0223] Among them, y i is the experimental data, is the simulated data, and n is the number of data points.

[0224] The above is based on the ideal embodiment of the present invention. Through the above description, relevant personnel can make various changes and modifications without departing from the technical concept of the present invention. The technical scope of the present invention is not limited to the content in the specification, and the technical scope must be determined according to the scope of the claims.

Claims

1. A fluid dynamics simulation test method for scour protection of offshore wind turbine pile foundations under reciprocating flow, characterized in that: include: S1. Collect environmental data of pile foundation and reciprocating flow data of the area; S2. Based on the data of S1, a numerical model of the effect of reciprocating flow on pile foundation is established by using the principles of fluid dynamics; S3. Construct the physical model of offshore wind power pile foundation and human-shaped submerged dike; S4, conduct a water tank experiment based on the data of S1 and the physical model of S3; S5. Perform numerical simulations with the numerical model and the offshore wind turbine pile foundation model to simulate the scouring process of the offshore wind turbine pile foundation and the human-shaped submerged dike under the action of reciprocating flow; S6. Compare the numerical simulation and flume test data to optimize the numerical simulation model.

2. According to claim 1, a fluid dynamics simulation test method for scour protection of offshore wind turbine pile foundations under reciprocating flow, characterized in that: In step S1, the environmental data includes: seabed slope, seabed topography characteristics and sediment characteristic data in the sea area.

3. The fluid dynamics simulation test method for scour protection of offshore wind power pile foundations under reciprocating flow according to claim 1 is characterized by: In step S1 , the reciprocating flow data includes flow velocity and flow direction data.

4. The fluid dynamics simulation test method for scour protection of offshore wind turbine pile foundations under reciprocating flow according to claim 1 is characterized by: The specific steps for collecting reciprocating flow data are: using acoustic Doppler current meters and current meters placed at measurement points for measurement, and after processing the collected data, making a flow velocity and direction diagram to intuitively display the reciprocating flow situation.

5. The fluid dynamics simulation test method for scour protection of offshore wind power pile foundations under reciprocating flow according to claim 1 is characterized by: In step S2, the specific steps are: S21. Select the continuity equation and momentum equation as the core equations in this step, which describe the conservation of mass and momentum of the fluid respectively; Specifically, the continuity equation: Where ρ is the fluid density and u is the fluid velocity vector; Momentum equation: Where n is the pressure, g is the gravitational acceleration vector, μ is the dynamic viscosity, represents the vector Laplace operator, F is the interaction force between the fluid and the pile foundation; S22, using the turbulence model equation: Use the turbulence kinetic energy equation and the turbulence dissipation rate equation; Turbulent kinetic energy equation: Turbulence dissipation rate equation: Where k is the turbulent kinetic energy, ∈ is the turbulent dissipation rate, μ t is the turbulent viscosity, p k is the term for turbulent kinetic energy generation, C 1∈ and C 2∈ is an empirical constant, σ ∈ and σ k is the Prandtl number; S23, inputting the reciprocating flow data collected in S1 into the model as the boundary condition of the model; The seafloor topography in the model is constructed using the seafloor slope and seafloor geomorphic feature data collected in S1. This usually involves importing elevation data into the software and generating a three-dimensional terrain model. The seafloor slope and elevation data are extracted from S1. The terrain construction formula is: Among them, Δz is the elevation difference between adjacent points, and Δx is the horizontal distance between adjacent points; The sediment characteristic data (particle size distribution, density, settling velocity) collected in S1 are input into the model to simulate the transport and deposition process of sediment under the action of reciprocating flow; Sediment characteristic input: Where v is the dynamic viscosity of water, ρ w is the density of water and g is the gravitational acceleration vector.

6. The fluid dynamics simulation test method for scour protection of offshore wind turbine pile foundations under reciprocating flow according to claim 1 is characterized by: In step S3, the actual single pile foundation diameter is 3-6m, and a scaled model pile foundation is arranged in the water tank. The size and spacing of the scaled model pile foundation are scaled by 1:10-15 according to the actual situation, and the scaled model pile foundation diameter is 30-40cm.

7. The fluid dynamics simulation test method for scour protection of offshore wind power pile foundations under reciprocating flow according to claim 6 is characterized by: In step S3, the angle of the human-shaped submerged dike is 10°-20°, the length is 1-3 times the diameter of the pile foundation, the distance between the human-shaped submerged dike and the pile foundation is 1-4 times the diameter of the pile foundation, and the width is 1-2 times the diameter of the pile foundation. The material of the human-shaped submerged dike is usually permeable material or impermeable material.

8. The fluid dynamics simulation test method for scour protection of offshore wind power pile foundations under reciprocating flow according to claim 1 is characterized by: In step S4, the water tank experiment is: Build the experimental environment: The specifications of the water tank are as follows: the water tank size is 20m long, 4m wide, and 2m high; Prepare acoustic Doppler current meters, pressure sensors, displacement sensors, and materials for simulating sediment internally; use multi-beam bathymetric system data to build a corresponding seafloor terrain model in the water tank to ensure that the slope and landform characteristics meet actual conditions; Fine sand with simulated particle size distribution of 0.01-0.1 mm, accounting for 40%-60% of the total sediment, is evenly laid on the bottom of the water tank. The high proportion of fine sand can simulate the suspension and transportation characteristics of sediment; Medium sand of 0.1-1 mm accounts for 25% to 35% of the total sediment. The particle size of medium sand is larger, the sedimentation speed is faster, and the scouring effect on the submerged dike is more significant; Coarse sand larger than 1 mm accounts for 15% to 25% of the total sediment. Coarse sand has the largest particle size, the fastest sedimentation rate, and the greatest impact on the local scouring of the submerged dike. And the sediment density range is set at 2.55g / cm 3 Up to 2.65g / cm 3 ,This density range reflects the specific gravity of different types of sediment, which is crucial for simulating the movement and deposition behavior of sediment in water flow; The measurement equipment was installed in the experiment, and water level meters, flow meters, pressure sensors and displacement sensors were installed in the water tank to ensure that the effect of the reciprocating flow on the submerged dike could be monitored in real time; By starting a bidirectional pump to simulate reciprocating water flow, the set water flow conditions are generated to ensure that the flow rate and direction of the water flow are stably converted according to a fixed cycle. ; The test water level was set at 0.05m-0.2m. This range takes into account extreme conditions such as extreme tide levels and storm surge water increase and decrease, covering mild to severe sea conditions to ensure that the submerged dike design can cope with different reciprocating flow conditions; The period range of the water flow is set at 1.5s-3s, reflecting the periodic changes of the reciprocating flow, which is crucial for simulating the impact effect of the reciprocating flow on the submerged dike; The flow velocity range is set at 0.16m / s-0.48m / s. This range simulates tidal currents of different intensities, which is very important for evaluating the stability and scour protection effect of the submerged dike under different flow velocity conditions.

9. The fluid dynamics simulation test method for scour protection of offshore wind power pile foundations under reciprocating flow according to claim 1 is characterized by: In step s4, the execution steps of the water tank experiment are: S41, start the bidirectional pump, gradually increase the flow rate to the set value, and ensure the water flow is stable; S42. Use ADV or other current meters to measure velocity profiles at different locations in the flume, including before, after, and on both sides of the submerged dike; record time series of velocity data to capture dynamic changes in reciprocating flow and velocity; S43. Pressure sensors and displacement sensors installed on the submerged dike and pile foundation record the changes in water pressure and the displacement of the submerged dike and pile foundation to evaluate their stability; S44. Use a depth sounder to regularly measure the scour depth before and after the submerged dike, and evaluate the changes in the scour extent by measuring the size of the scour pit.

10. The fluid dynamics simulation test method for scour protection of offshore wind power pile foundations under reciprocating flow according to claim 1, characterized in that: In step S6, S61. Arrange the data of flume experiments and numerical simulations to ensure the consistency of time series, spatial positions and measurement parameters; Use interpolation or fitting methods to align experimental and simulated data in time and space Among them, (x1, y1) and (x2, y2) are two known plane points, and (x, y) is the plane coordinate of the required value point; S62. Use statistical methods to assess the significance of differences; t-test: in, is the mean S of the two groups of samples pcoled is the combined standard deviation, n1 and n2 are the sample sizes; S63, numerical simulation model optimization; Among them, ρ is density, u is velocity vector, p is pressure, g is gravitational acceleration, and μ is dynamic viscosity; Also considering the turbulence effect, the corresponding optimization is: where k is the turbulent kinetic energy, ∈ is the turbulent dissipation rate, μ i is the turbulent viscosity, P k is the turbulence generation term, C 1∈ , C 2∈ , σ k , σ ∈ is the model constant; S64. Use error analysis methods to evaluate the differences between simulation results and experimental data Among them, y i is the experimental data, is the simulated data, and n is the number of data points.

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