Waterpower design method for undercrossing channel seabed drainage pipe

Abstract

The invention provides a waterpower design method for an undercrossing channel seabed drainage pipe, which is suitable for the field of ocean engineering and comprises the following steps: preparing early-stage work, obtaining a local head loss formula, determining unknown parameters by adopting a computational fluid mechanics numerical method, and obtaining and applying a complete head loss formula. By considering sedimentation and flow velocity change, reducing local head loss and adopting multi-objective optimization design, pipeline performance and economical efficiency are improved, and by means of application of computational fluid mechanics, design scientificity is enhanced, and development of the ocean engineering technology is promoted.

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] At present, Darcy's formula is widely used in hydraulic calculations of long-distance water pipelines. Its scope of application is wider than that of the Scherzy formula and the Hezen-Williams formula. Before using the Darcy formula, the value of the water resistance coefficient along the pipeline must be determined first. For pipeline flow, the mainstream design abroad uses the Colebrooke formula. The formula is applicable to the hydraulic smooth zone, turbulent transition zone and square resistance zone of water flow in the pipeline. The applicable Reynolds number range is 4000-108. A large number of test results show that the water resistance coefficient along the pipeline solved by the Colebrooke formula is well matched with the actual commercial circular pipe resistance test. The formula is widely used abroad, especially in Europe. However, the existing hydraulic calculation formula cannot solve the problems of siltation and flow velocity changes at the upper arch of the underpass channel.

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

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

[0005] The purpose of the present invention can be achieved by adopting 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 topographical, geological and hydrological data of the channel under which the submarine drainage pipe passes. The on-site investigation includes surveying the channel under the channel 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 considering the factors of siltation and flow velocity change of the underpass in the hydraulic design of the underpass submarine drainage pipe, and the local head loss correction formula is obtained as shown in formula (1):

[0010]

[0011] In the formula, h j is the local head loss of the underpass, v1 is the changing flow velocity at the underpass, ζ is the local water loss coefficient at the elbow, and α is the siltation and flow velocity change coefficient of the underpass.

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

[0013] The method of using computational fluid dynamics numerical method to determine the unknown parameters 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, using numerical methods to solve and obtain relevant parameters of the fluid in the pipeline, the relevant parameters include flow velocity, pressure and flow rate in the pipeline,

[0018] e) verifying the calculation results to ensure the rationality and accuracy of the simulation results, and using the calculation results to determine the siltation and velocity change coefficient α of the underpass in the formula (1);

[0019] S104 obtain the complete head loss formula and apply it;

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

[0021] a) According to the determined siltation of the underpass and the velocity change coefficient α, substitute it 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) According to the calculation results, a multi-objective optimization method is used to adjust the design parameters, which include the diameter, material and layout parameters of the pipe, so as 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 by using the multi-objective optimization method is:

[0026] a) data preparation, including obtaining relevant data according to 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, and 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 carry out model training, and obtain a trained model;

[0029] d) Adopt multi-objective optimization algorithm to optimize 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 (1):

[0032]

[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 suitable for the underpass, the influence of siltation and flow velocity changes is taken into account, so that the hydraulic design is more accurate, and the shortcomings of the existing hydraulic calculation formula under the specific conditions of the underpass are effectively solved, especially the head loss problem at the upper arch. By adopting a multi-objective optimization method, the design parameters are adjusted, so that the drainage pipeline can be optimized to the greatest extent on the basis of meeting the flow and flow velocity requirements, improve the performance and economy of the pipeline, take into account multiple design factors, and make the final design scheme more reasonable. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0036] The specific embodiments of the present invention are described in detail below in conjunction with 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 method for hydraulic design of 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 topographical, geological and hydrological data of the channel under which the submarine drainage pipe passes. The on-site investigation includes surveying the channel under the channel 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 considering the factors of siltation and flow velocity change of the underpass in the hydraulic design of the underpass submarine drainage pipe, and the local head loss correction formula is obtained as shown in formula (1):

[0042]

[0043] In the formula, h j is the local head loss of the underpass, v1 is the changing flow velocity at the underpass, ζ is the local water loss coefficient at the elbow, and α is the siltation and flow velocity change coefficient of the underpass.

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

[0045] The method of using computational fluid dynamics numerical method to determine the unknown parameters 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, using numerical methods to solve and obtain relevant parameters of the fluid in the pipeline, the relevant parameters include flow velocity, pressure and flow rate in the pipeline,

[0050] e) verifying the calculation results to ensure the rationality and accuracy of the simulation results, and using the calculation results to determine the siltation and velocity change coefficient α of the underpass in the formula (1);

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

[0052] S104 obtain the complete head loss formula and apply it;

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

[0054] a) According to the determined siltation of the underpass and the velocity change coefficient α, substitute it 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) According to the calculation results, a multi-objective optimization method is used to adjust the design parameters, which include the diameter, material and layout parameters of the pipe, so as to achieve the best drainage effect.

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

[0058] a) data preparation, including obtaining relevant data according to 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, and 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 carry out model training, and obtain a trained model;

[0061] d) Adopt multi-objective optimization algorithm to optimize 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 (1):

[0064]

[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 performance and economy of the pipeline 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 principle of the present invention should be included in the protection scope 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 obtain the complete head loss formula and apply it; The preliminary work preparation includes data collection, on-site investigation and determination of design objectives. The data collection includes topographical, geological and hydrological data of the channel under which the submarine drainage pipe passes. The on-site investigation includes surveying the channel under the channel 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 considering the factors of siltation and flow velocity change of the underpass in the hydraulic design of the underpass submarine drainage pipe, and the local head loss correction formula is obtained as shown in formula (1): In the formula, h j is the local head loss of the underpass, v1 is the changing flow velocity at the underpass, ζ is the local water loss coefficient at the elbow, and α is the siltation and flow velocity change coefficient of the underpass; 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, establish a mathematical analysis model suitable for the specific conditions of the underpass; 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; c) Set boundary conditions and initial conditions to determine the initial flow rate and velocity of the system, as well as the boundary conditions of 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, the relevant parameters including flow velocity, pressure and flow rate in the pipeline; e) verifying the calculation results to ensure the rationality and accuracy of the simulation results, and using the calculation results to determine the siltation and velocity change coefficient α of the underpass in the formula (1); The method of obtaining and applying the complete head loss formula includes the following steps: a) Substitute the determined siltation and velocity change coefficient α of the underpass 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) According to the calculation results, a multi-objective optimization method is used to adjust the design parameters, which include the diameter, material and layout parameters of the pipe, so as 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: a) data preparation, including obtaining relevant data according to 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, and 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 carry out model training, and obtain a trained model; d) Adopt multi-objective optimization algorithm to optimize 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. A hydraulic design method for a submarine drainage pipe under a waterway according to claim 3, characterized in that: The multi-objective optimization neural network structure comprises 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 (1): 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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