A hydraulic design method for submarine drainage pipes under waterways

Abstract

The present invention provides a hydraulic design method for submarine drainage pipes under waterways, which is applicable to the field of marine engineering. The method includes preliminary work preparation, obtaining a local head loss formula, determining unknown parameters using a computational fluid dynamics numerical method, obtaining a complete head loss formula and applying it. By considering siltation and flow rate changes, local head losses are reduced, and a multi-objective optimization design is adopted to improve pipeline performance and economy. With the help of the application of computational fluid dynamics, the scientific nature of the design is enhanced, thereby promoting the development of marine engineering technology.

Description

Technical Field

[0001] The invention relates to a hydraulic design method for a submarine drainage pipe passing under a waterway, and is applicable to the field of marine engineering. Background Art

[0002] The Darcy formula is currently widely used in hydraulic calculations for long-distance water pipelines. Its applicability is wider than that of the Scherz formula and the Hezen-Williams formula. Before using the Darcy formula, the value of the drag coefficient along the pipeline must be determined. For pipeline flow, the mainstream design approach abroad uses the Collebrook formula. This formula is applicable to water flowing through the hydraulically smooth, turbulent transition, and squared resistance regions of the pipeline, and is applicable over a Reynolds number range of 4000 to 108. Extensive experimental results have shown that the drag coefficient along the pipeline calculated using the Collebrook formula agrees well with actual resistance tests on commercial circular pipes. This formula is widely used internationally, particularly in Europe. However, existing hydraulic calculation formulas cannot address the issues of siltation and velocity changes at the upper arch of the underpass.

[0003] Therefore, the present invention studies the design method of the head loss of the underpass, additionally considers the siltation and head loss at the upper arch, considers the influence of the underpass when designing the water level of the surge tank, and proposes a calculation formula for the head loss of the underpass. Summary of the Invention

[0004] The purpose of the present invention is to propose a hydraulic design method for submarine drainage pipes passing under waterways. Taking into account the hydraulic loss calculation theory of underwater waterways, a hydraulic design method for "U"-shaped pipes is formed, which helps to reduce the local head loss of water pressure and is suitable for the hydraulic design of submarine pipelines passing under waterways.

[0005] The purpose of the present invention can be achieved by taking the following technical solutions:

[0006] S101 preliminary work preparation;

[0007] The preliminary work preparation includes data collection, on-site investigation and determination of design objectives. The data collection includes topographic, geological and hydrological data of the channel under which the submarine drainage pipe passes. The on-site investigation includes surveying the channel under which the pipe passes and determining design parameters. The determination of design objectives includes determining the design flow rate and flow velocity of the submarine drainage pipe under the channel.

[0008] S102 obtains the local head loss correction formula;

[0009] The local head loss correction formula is obtained by taking into account the factors of siltation and flow velocity change of the underpass in the hydraulic design of the submarine drainage pipe under the underpass. The local head loss correction formula is shown in formula (1).

[0010] (1)

[0011] Where, is the local head loss under the channel, is the changing flow velocity at the underpass, is the local water loss coefficient at the elbow, is the coefficient of siltation and velocity change in the underpass, and g is the acceleration due to gravity.

[0012] S103 uses computational fluid dynamics numerical methods to determine unknown parameters;

[0013] The method of determining unknown parameters by using a computational fluid dynamics numerical method comprises the following steps:

[0014] a) Establish an analytical model. Based on the basic equations of fluid mechanics, establish a mathematical analysis model suitable for the specific conditions of the underpass.

[0015] b) Grid division: Grid division is performed on the flow area in the pipeline to ensure that the grid quality and density can meet the accuracy requirements and reduce calculation errors.

[0016] c) Set boundary conditions and initial conditions to determine the initial flow rate, velocity, and interaction boundary conditions between the pipeline and the surrounding environment.

[0017] d) Numerical solution: numerical methods are used to solve and obtain relevant parameters of the fluid in the pipeline, including flow velocity, pressure and flow rate in the pipeline.

[0018] e) Verify the calculation results to ensure the rationality and accuracy of the simulation results, and use the calculation results to determine the sedimentation and flow velocity change coefficients of the underpass in formula (1) ;

[0019] S104 obtains the complete head loss formula and applies it;

[0020] The method of obtaining and applying the complete head loss formula includes the following steps:

[0021] a) Change the coefficient based on the determined sedimentation and flow velocity of the underpass Substitute into formula (1) to obtain the complete head loss correction formula,

[0022] b) Apply the complete head loss correction formula to the design of drainage pipes under the waterway and perform specific technical calculations.

[0023] c) Based on the calculation results, a multi-objective optimization method is used to adjust the design parameters, including the diameter, material and layout parameters of the pipe, to achieve the best drainage effect.

[0024] Furthermore, in the above step S103, the numerical method includes a finite volume method and a finite difference method.

[0025] Furthermore, in the above step S104, the step of adjusting the design parameters using the multi-objective optimization method is as follows:

[0026] a) data preparation, including obtaining relevant data based on the calculation results, wherein the relevant data includes design parameters and model output parameters, wherein the design parameters include the diameter, material, and layout parameters of the pipeline, and the model output parameters include head loss. The data preparation also includes data cleaning and data normalization;

[0027] b) Construct a multi-objective optimization neural network structure;

[0028] c) Define the loss function, use relevant data to train the model, and obtain a trained model;

[0029] d) Use a multi-objective optimization algorithm to optimize the design parameters, use the trained model as the objective function, and calculate the model output parameter values ​​under different inputs.

[0030] e) Set constraints on the model output parameter values ​​and optimize them to obtain a design parameter combination that meets the requirements.

[0031] Furthermore, the multi-objective optimization neural network structure includes an input layer, a hidden layer, and an output layer. The activation function of the hidden layer uses a scaled linear activation function. The formula of the scaled linear activation function is formula (2),

[0032] (2)

[0033] Where a is a fixed parameter with a value of 0.01, and b is a fixed parameter with a value of 0.5.

[0034] The present invention has the following beneficial effects: By proposing a head loss calculation formula applicable to underpasses, it takes into account the effects of siltation and flow velocity variations, making hydraulic design more accurate and effectively addressing the shortcomings of existing hydraulic calculation formulas under the specific conditions of underpasses, particularly the head loss problem at the upper arch. By employing a multi-objective optimization approach to adjust design parameters, the drainage pipeline can be optimized to the greatest extent possible while meeting flow and velocity requirements, improving pipeline performance and economic efficiency. This balance of multiple design factors results in a more reasonable final design. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a flow chart of a hydraulic design method for a submarine drainage pipe under a waterway according to the present invention; DETAILED DESCRIPTION

[0036] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments given here are only used to illustrate and explain the present invention and cannot be used to limit the present invention.

[0037] The following is a specific embodiment of a hydraulic design method for a submarine drainage pipe passing under a waterway.

[0038] S101 preliminary work preparation;

[0039] The preliminary work preparation includes data collection, on-site investigation and determination of design objectives. The data collection includes topographic, geological and hydrological data of the channel under which the submarine drainage pipe passes. The on-site investigation includes surveying the channel under which the pipe passes and determining design parameters. The determination of design objectives includes determining the design flow rate and flow velocity of the submarine drainage pipe under the channel.

[0040] S102 obtains the local head loss correction formula;

[0041] The local head loss correction formula is obtained by taking into account the factors of siltation and flow velocity change of the underpass in the hydraulic design of the submarine drainage pipe under the underpass. The local head loss correction formula is shown in formula (1).

[0042] (1)

[0043] Where, is the local head loss in the underpass, is the changing flow velocity at the underpass, is the local water loss coefficient at the elbow, is the coefficient of siltation and velocity change in the underpass, and g is the acceleration due to gravity.

[0044] S103 uses computational fluid dynamics numerical methods to determine unknown parameters;

[0045] The method of determining unknown parameters by using a computational fluid dynamics numerical method comprises the following steps:

[0046] a) Establish an analytical model. Based on the basic equations of fluid mechanics, establish a mathematical analysis model suitable for the specific conditions of the underpass.

[0047] b) Grid division: Grid division is performed on the flow area in the pipeline to ensure that the grid quality and density can meet the accuracy requirements and reduce calculation errors.

[0048] c) Set boundary conditions and initial conditions to determine the initial flow rate, velocity, and interaction boundary conditions between the pipeline and the surrounding environment.

[0049] d) Numerical solution: numerical methods are used to solve and obtain relevant parameters of the fluid in the pipeline, including flow velocity, pressure and flow rate in the pipeline.

[0050] e) Verify the calculation results to ensure the rationality and accuracy of the simulation results, and use the calculation results to determine the sedimentation and flow velocity change coefficients of the underpass in formula (1) ;

[0051] Furthermore, in the above step S103, the numerical method includes a finite volume method and a finite difference method.

[0052] S104 obtains the complete head loss formula and applies it;

[0053] The method of obtaining and applying the complete head loss formula includes the following steps:

[0054] a) Change the coefficient based on the determined sedimentation and flow velocity of the underpass Substitute into formula (1) to obtain the complete head loss correction formula,

[0055] b) Apply the complete head loss correction formula to the design of drainage pipes under the waterway and perform specific technical calculations.

[0056] c) Based on the calculation results, a multi-objective optimization method is used to adjust the design parameters, including the diameter, material and layout parameters of the pipe, to achieve the best drainage effect.

[0057] Furthermore, in the above step S104, the step of adjusting the design parameters using the multi-objective optimization method is as follows:

[0058] a) data preparation, including obtaining relevant data based on the calculation results, wherein the relevant data includes design parameters and model output parameters, wherein the design parameters include the diameter, material, and layout parameters of the pipeline, and the model output parameters include head loss. The data preparation also includes data cleaning and data normalization;

[0059] b) Construct a multi-objective optimization neural network structure;

[0060] c) Define the loss function, use relevant data to train the model, and obtain a trained model;

[0061] d) Use a multi-objective optimization algorithm to optimize the design parameters, use the trained model as the objective function, and calculate the model output parameter values ​​under different inputs.

[0062] e) Set constraints on the model output parameter values ​​and optimize them to obtain a design parameter combination that meets the requirements.

[0063] Furthermore, the multi-objective optimization neural network structure includes an input layer, a hidden layer, and an output layer. The activation function of the hidden layer uses a scaled linear activation function. The formula of the scaled linear activation function is formula (2),

[0064] (2)

[0065] Where a is a fixed parameter with a value of 0.01, and b is a fixed parameter with a value of 0.5.

[0066] In the above embodiment, the present invention discloses a hydraulic design method for a submarine drainage pipe under a waterway, including preliminary work preparation, obtaining a local head loss formula, determining unknown parameters using a computational fluid dynamics numerical method, obtaining a complete head loss formula and applying it; by considering siltation and flow rate changes, reducing local head losses, and adopting a multi-objective optimization design, the pipeline performance and economy are improved, and with the help of the application of computational fluid dynamics, the scientific nature of the design is enhanced, thereby promoting the development of marine engineering technology.

[0067] The above description is a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A hydraulic design method for a submarine drainage pipe under a waterway, characterized in that: The following steps are involved: S101 preliminary work preparation; S102 obtains the local head loss correction formula; S103 uses computational fluid dynamics numerical methods to determine unknown parameters; S104 obtains the complete head loss formula and applies it; The preliminary work preparation includes data collection, on-site investigation and determination of design objectives. The data collection includes topographic, geological and hydrological data of the channel under which the submarine drainage pipe passes. The on-site investigation includes surveying the channel under which the pipe passes and determining design parameters. The determination of design objectives includes determining the design flow rate and flow velocity of the submarine drainage pipe under the channel. The local head loss correction formula is obtained by taking into account the factors of siltation and flow velocity change of the underpass in the hydraulic design of the submarine drainage pipe under the underpass. The local head loss correction formula is shown in formula (1). （1） Where, is the local head loss under the channel, is the changing flow velocity at the underpass, is the local water loss coefficient at the elbow, is the coefficient of siltation and velocity change of the underpass, g is the acceleration of gravity; The method of determining unknown parameters by using a computational fluid dynamics numerical method comprises the following steps: a) Establish an analytical model. Based on the basic equations of fluid mechanics, a mathematical analysis model suitable for the specific conditions of the underpass is established; b) Grid division: Grid the flow area in the pipeline to ensure that the grid quality and density can meet the accuracy requirements and reduce calculation errors; c) Set boundary conditions and initial conditions to determine the initial flow rate and velocity of the system, as well as the boundary conditions for the interaction between the pipeline and the surrounding environment; d) Numerical solution, using numerical methods to solve and obtain relevant parameters of the fluid in the pipeline, including flow velocity, pressure and flow rate in the pipeline; e) Verify the calculation results to ensure the rationality and accuracy of the simulation results, and use the calculation results to determine the sedimentation and flow velocity change coefficients of the underpass in formula (1) ; The method of obtaining and applying the complete head loss formula includes the following steps: a) Change the coefficient based on the determined sedimentation and flow velocity of the underpass Substitute into formula (1) to obtain the complete head loss correction formula; b) Apply the complete head loss correction formula to the design of drainage pipes under the waterway and perform specific technical calculations; c) Based on the calculation results, a multi-objective optimization method is used to adjust the design parameters, including the diameter, material and layout parameters of the pipe, to achieve the best drainage effect.

2. The hydraulic design method for a submarine drainage pipe under a waterway according to claim 1 is characterized in that: In step S103, the numerical method includes a finite volume method and a finite difference method.

3. The hydraulic design method for a submarine drainage pipe under a waterway according to claim 1 is characterized in that: In step S104, the step of adjusting the design parameters using the multi-objective optimization method is as follows: a) data preparation, including obtaining relevant data based on the calculation results, wherein the relevant data includes design parameters and model output parameters, wherein the design parameters include the diameter, material, and layout parameters of the pipeline, and the model output parameters include head loss. The data preparation also includes data cleaning and data normalization; b) Construct a multi-objective optimization neural network structure; c) Define the loss function, use relevant data to train the model, and obtain a trained model; d) Use a multi-objective optimization algorithm to optimize the design parameters, use the trained model as the objective function, and calculate the model output parameter values ​​under different inputs. e) Set constraints on the model output parameter values ​​and optimize them to obtain a design parameter combination that meets the requirements.

4. The hydraulic design method for a submarine drainage pipe under a waterway according to claim 3 is characterized in that: The multi-objective optimization neural network structure includes an input layer, a hidden layer and an output layer. The activation function of the hidden layer uses a scaled linear activation function. The formula of the scaled linear activation function is formula (2): （2） Where a is a fixed parameter with a value of 0.01, and b is a fixed parameter with a value of 0.5.

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