Method, device and equipment for calculating design length of weir behind siphon well and medium

Abstract

This application provides a method, apparatus, equipment, and medium for calculating the design length of a siphon well weir. The method includes: first, obtaining the structural and operational parameters of the siphon well overflow weir; then, based on the structural and operational parameters, calculating the maximum total head of the overflow weir according to the overflow weir discharge capacity formula, and determining the design jet length based on the maximum total head; next, calculating the bubble diameter based on bubble dynamics theory and operational parameters, and substituting the bubble diameter into the dynamic buoyancy expression to obtain the bubble buoyancy; further, calculating the horizontal movement distance of the bubble under the action of the water flow based on the relative relationship between the bubble buoyancy and the water flow velocity, and determining the maximum air-carrying length by traversing the water depth fluctuation range behind the weir; finally, adding the design jet length and the maximum air-carrying length to obtain the total design length of the siphon well weir. This method improves the stability and safety of the hydraulic operation of the siphon well.

Description

Technical Field

[0001] This application relates to the interdisciplinary field of hydraulic engineering and fluid mechanics, and in particular to a method, device, equipment and medium for calculating the design length of a siphon well weir. Background Technology

[0002] Siphon wells are core hydraulic structures in nuclear power plants, thermal power plants, and industrial circulating water systems. They are primarily used to control water levels and maintain negative pressure at the condenser outlet through the siphon effect, thereby reducing the head requirements of circulating water pumps and significantly reducing energy consumption. In nuclear power plant circulating cooling water systems, siphon wells regulate water levels through overflow weirs. When water flows over the overflow weir, a drop occurs due to the difference in water levels between upstream and downstream, causing the water to come into violent contact with air and resulting in a hydraulic jump, which entrains a large number of air bubbles into the water. These bubbles move downstream under the influence of the water flow and gradually rise to the surface due to buoyancy. If the bubbles do not escape sufficiently behind the weir, they may form air pockets after entering the siphon section, reducing the effective flow area and causing the drainage flow rate to deviate from the design conditions. In more serious cases, the accumulation of bubbles may cause cavitation problems, damaging the siphon well structure and threatening the operational safety of the nuclear power plant. Therefore, a method for calculating the design length of the siphon well after the porous energy dissipation weir is urgently needed to improve the safety and economy of siphon wells.

[0003] In existing technologies, the calculation method for the design length of a siphon well weir mainly relies on empirical formulas or traditional hydraulic models. Specifically, the method typically involves first estimating the head at the weir crest based on the weir type (e.g., thin-walled weir) and maximum discharge flow rate using the discharge capacity formula. Then, the horizontal projection length of the water jet is calculated using empirical coefficients as the basis for the design length downstream of the weir. Simultaneously, for the length of the bubble-entrained region, the water flow is generally simplified to a single-phase uniform flow. Assuming that the upward velocity of the bubble is constant during its ascent, the entrained length is estimated by multiplying the average cross-sectional velocity by the bubble's ascent time. Finally, the length of the water jet and the entrained length are simply added together, and the total design length downstream of the weir is determined by combining engineering experience margins.

[0004] However, existing calculation methods suffer from problems such as large design deviations and high risk of air resistance. Summary of the Invention

[0005] This application provides a method, apparatus, equipment, and medium for calculating the design length of the siphon well weir, in order to solve the problems of large design deviations and high risk of air resistance in the prior art.

[0006] In a first aspect, embodiments of this application provide a method for calculating the design length of a siphon well weir, including:

[0007] Obtain the structural parameters and operating condition parameters of the siphon well overflow weir;

[0008] Based on the structural parameters and operating condition parameters, the maximum total head of the overflow weir is calculated according to the overflow weir discharge capacity formula, and the design water tongue length is determined based on the maximum total head.

[0009] The bubble diameter is calculated based on bubble dynamics theory and the operating parameters, and the bubble diameter is substituted into the dynamic buoyancy velocity expression to obtain the bubble buoyancy velocity.

[0010] Based on the relative relationship between the bubble's rising velocity and the water flow velocity, the horizontal movement distance of the bubble under the action of the water flow is calculated, and the maximum air-carrying length is determined by traversing the water depth fluctuation range behind the weir.

[0011] The total design length of the siphon well weir is obtained by adding the designed water tongue length to the maximum air-carrying length.

[0012] In one possible implementation, the structural parameters include at least the weir width and the weir height;

[0013] The operating parameters include at least the maximum drainage flow, the water depth behind the weir, and the hydraulic gradient.

[0014] In one possible implementation, the step of calculating the maximum total head of the overflow weir based on the structural parameters and operating condition parameters according to the overflow weir discharge capacity formula, and determining the design jet length based on the maximum total head, includes:

[0015] Establish the relationship between flow rate and head at the weir crest based on the overflow capacity formula;

[0016] Substituting the maximum drainage flow rate into the aforementioned formula yields the initial value of the weir crest head.

[0017] Calculate the cross-sectional area in front of the weir based on the weir width and the water depth in front of the weir, and calculate the flow velocity in front of the weir based on the cross-sectional area in front of the weir.

[0018] The total head is iteratively corrected based on the flow velocity in front of the weir to obtain the maximum total head.

[0019] The maximum water tongue length is calculated based on the relationship between the maximum total head and the water tongue length, and the design water tongue length is obtained by adding the maximum water tongue length to the preset safety margin.

[0020] In one possible implementation, the step of calculating the bubble diameter based on bubble dynamics theory and the operating condition parameters, and substituting the bubble diameter into the dynamic buoyancy velocity expression to obtain the bubble buoyancy velocity, includes:

[0021] A bubble diameter calculation model is established based on water surface tension, fluid density, and water flow turbulence dissipation rate to calculate the characteristic bubble diameter.

[0022] Based on the bubble size distribution pattern, the diameter of the characteristic bubble is multiplied by a preset proportional coefficient to obtain the initial diameter of the bubble;

[0023] A bubble dynamic equilibrium model is established based on the force balance relationship of bubbles moving in water. The bubble dynamic equilibrium model includes gravity, buoyancy, water flow resistance and surface tension.

[0024] The bubble dynamics equilibrium model was fitted based on historical experimental data to obtain the correlation expression between bubble rising velocity and bubble diameter, water density and surface tension coefficient.

[0025] The bubble's rising speed is calculated based on the correlation expression and the initial diameter of the bubble.

[0026] In one possible implementation, the calculation process for the water flow turbulence dissipation rate includes:

[0027] The frictional velocity is determined based on the energy equation and hydraulic gradient of uniform flow in the flume.

[0028] The turbulent dissipation rate is calculated using the frictional velocity and the von Kármán constant.

[0029] In one possible implementation, calculating the horizontal distance the bubble travels under the influence of the water flow, based on the relative relationship between the bubble's rising velocity and the water flow velocity, includes:

[0030] The time it takes for the bubble to rise is calculated based on the bubble's rising speed and the height it rises above the water surface.

[0031] Calculate the average flow velocity at the cross-section behind the weir based on the maximum drainage flow rate and the weir width;

[0032] The horizontal distance the bubble travels under the influence of the water flow is calculated based on the average flow velocity of the cross-section and the bubble's ascent time.

[0033] In one possible implementation, determining the maximum air-carrying length by traversing the water depth fluctuation range after the weir includes:

[0034] Within the range of water depth fluctuations behind the weir, each water depth condition is traversed with a preset step size.

[0035] For each water depth condition, the horizontal movement distance of the bubble is calculated based on the product of the flow velocity behind the weir and the bubble's ascent time, wherein the bubble's ascent time is obtained by integrating the bubble's ascent velocity along the water depth.

[0036] The maximum horizontal movement distance of the air bubble under each water depth condition is determined as the maximum air-carrying length.

[0037] Secondly, embodiments of this application provide a device for calculating the design length of a siphon well weir, comprising:

[0038] The acquisition module is used to acquire the structural parameters and operating condition parameters of the siphon well overflow weir;

[0039] The first determining module is used to calculate the maximum total head of the overflow weir based on the structural parameters and operating condition parameters, according to the overflow weir discharge capacity formula, and to determine the design water tongue length based on the maximum total head.

[0040] The first calculation module is used to calculate the bubble diameter based on bubble dynamics theory and the operating condition parameters, and to substitute the bubble diameter into the dynamic buoyancy expression to obtain the bubble buoyancy.

[0041] The second determining module is used to calculate the horizontal movement distance of the bubble under the action of the water flow based on the relative relationship between the bubble's rising speed and the water flow velocity, and to determine the maximum air-carrying length by traversing the water depth fluctuation range behind the weir.

[0042] The second calculation module is used to add the designed water tongue length to the maximum air-carrying length to obtain the total designed length of the siphon well weir.

[0043] In one possible implementation, the structural parameters include at least the weir width and the weir height;

[0044] The operating parameters include at least the maximum drainage flow, the water depth behind the weir, and the hydraulic gradient.

[0045] In one possible implementation, the first determining module is specifically used for:

[0046] Establish the relationship between flow rate and head at the weir crest based on the overflow capacity formula;

[0047] Substituting the maximum drainage flow rate into the aforementioned formula yields the initial value of the weir crest head.

[0048] Calculate the cross-sectional area in front of the weir based on the weir width and the water depth in front of the weir, and calculate the flow velocity in front of the weir based on the cross-sectional area in front of the weir.

[0049] The total head is iteratively corrected based on the flow velocity in front of the weir to obtain the maximum total head.

[0050] The maximum water tongue length is calculated based on the relationship between the maximum total head and the water tongue length, and the design water tongue length is obtained by adding the maximum water tongue length to the preset safety margin.

[0051] In one possible implementation, the second computing module is specifically used for:

[0052] A bubble diameter calculation model is established based on water surface tension, fluid density, and water flow turbulence dissipation rate to calculate the characteristic bubble diameter.

[0053] Based on the bubble size distribution pattern, the diameter of the characteristic bubble is multiplied by a preset proportional coefficient to obtain the initial diameter of the bubble;

[0054] A bubble dynamic equilibrium model is established based on the force balance relationship of bubbles moving in water. The bubble dynamic equilibrium model includes gravity, buoyancy, water flow resistance and surface tension.

[0055] The bubble dynamics equilibrium model was fitted based on historical experimental data to obtain the correlation expression between bubble rising velocity and bubble diameter, water density and surface tension coefficient.

[0056] The bubble's rising speed is calculated based on the correlation expression and the initial diameter of the bubble.

[0057] In one possible implementation, the calculation process for the water flow turbulence dissipation rate includes:

[0058] The frictional velocity is determined based on the energy equation and hydraulic gradient of uniform flow in the flume.

[0059] The turbulent dissipation rate is calculated using the frictional velocity and the von Kármán constant.

[0060] In one possible implementation, calculating the horizontal distance the bubble travels under the influence of the water flow, based on the relative relationship between the bubble's rising velocity and the water flow velocity, includes:

[0061] The time it takes for the bubble to rise is calculated based on the bubble's rising speed and the height it rises above the water surface.

[0062] Calculate the average flow velocity at the cross-section behind the weir based on the maximum drainage flow rate and the weir width;

[0063] The horizontal distance the bubble travels under the influence of the water flow is calculated based on the average flow velocity of the cross-section and the bubble's ascent time.

[0064] In one possible implementation, the second determining module is specifically used for:

[0065] Within the range of water depth fluctuations behind the weir, each water depth condition is traversed with a preset step size.

[0066] For each water depth condition, the horizontal movement distance of the bubble is calculated based on the product of the flow velocity behind the weir and the bubble's ascent time, wherein the bubble's ascent time is obtained by integrating the bubble's ascent velocity along the water depth.

[0067] The maximum horizontal movement distance of the air bubble under each water depth condition is determined as the maximum air-carrying length.

[0068] Thirdly, embodiments of this application provide an electronic device, including: a memory and a processor;

[0069] The memory stores computer-executed instructions;

[0070] The processor executes computer execution instructions stored in the memory, causing the processor to perform the first aspect and / or various possible implementations of the first aspect as described above.

[0071] Fourthly, embodiments of this application provide a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, are used to implement the first aspect and / or various possible implementations of the first aspect.

[0072] The method, apparatus, equipment, and medium for calculating the design length of the siphon well weir provided in this application, during the design process of the uniform flow section after the siphon well weir, firstly obtain the structural parameters and operating condition parameters of the overflow weir of the siphon well; then, based on the structural parameters and operating condition parameters, establish a functional relationship between the flow rate and the head at the weir crest using the overflow weir discharge capacity formula, and calculate the head at the weir crest in conjunction with the maximum discharge flow rate, while considering the influence of the upstream flow velocity on the total head for correction, thereby obtaining the maximum total head of the overflow weir under the design conditions; then, calculate the maximum length of the water tongue formed by the water tongue ejection after the weir based on the relationship between the maximum total head and the trajectory of the water tongue; and on this basis, determine the design length of the water tongue in conjunction with the safety margin to ensure that the water flow after the weir has sufficient space to complete the water tongue landing and initial diffusion before entering the uniform flow section; after obtaining the length of the water tongue, further analyze the water flow aeration process based on bubble dynamics theory, establish a bubble diameter calculation model based on parameters such as water surface tension, fluid density, and water flow turbulence dissipation rate, calculate the characteristic bubble diameter, and then calculate the characteristic bubble diameter based on the gas... The initial diameter of the bubble is determined by the bubble size distribution law. Then, the bubble diameter is substituted into the expression for the dynamic buoyancy velocity of the bubble to obtain the buoyancy velocity of the bubble in the water body, thus characterizing the bubble's mobility in the water flow. Based on this, according to the relative relationship between the bubble's buoyancy velocity and the flow velocity behind the weir, the horizontal movement distance of the bubble carried by the water flow during its buoyancy is calculated. That is, the horizontal migration range of the bubble in the water flow is determined by the bubble's buoyancy time and the average flow velocity of the cross section. Furthermore, the maximum air-carrying length is determined by traversing the possible water depth fluctuation range behind the weir, thus reflecting the bubble's residence range in the water flow under the most unfavorable aeration conditions. Finally, the design water tongue length and the maximum air-carrying length are added to obtain the total design length of the uniform flow section behind the weir of the siphon well. This ensures that the length of the uniform flow section behind the weir can meet the spatial requirements for water tongue diffusion and ensure that the aerated bubbles fully float to the surface before entering the subsequent siphon section. This effectively avoids the adverse effects of bubbles entering the siphon system on the stable operation of the siphon, improving the stability and safety of the hydraulic operation of the siphon well. Attached Figure Description

[0073] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0074] Figure 1 A flowchart illustrating the method for calculating the design length of the siphon well weir provided in this application embodiment. Figure 1 ;

[0075] Figure 2 A flowchart illustrating the method for calculating the design length of the siphon well weir provided in this application embodiment. Figure 2 ;

[0076] Figure 3 A schematic diagram of the structure of the siphon well weir design length calculation device provided in the embodiments of this application;

[0077] Figure 4 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application.

[0078] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0079] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0080] Siphon wells are core hydraulic structures in nuclear power plants, thermal power plants, and industrial circulating water systems. They are primarily used to control water levels and maintain negative pressure at the condenser outlet through the siphon effect, thereby reducing the head requirements of circulating water pumps and significantly reducing energy consumption. In nuclear power plant circulating cooling water systems, siphon wells regulate water levels through overflow weirs. When water flows over the overflow weir, a drop occurs due to the difference in water levels between upstream and downstream, causing the water to come into violent contact with air and resulting in a hydraulic jump, which entrains a large number of air bubbles into the water. These bubbles move downstream under the influence of the water flow and gradually rise to the surface due to buoyancy. If the bubbles do not escape sufficiently behind the weir, they may form air pockets after entering the siphon section, reducing the effective flow area and causing the drainage flow rate to deviate from the design conditions. In more serious cases, the accumulation of bubbles may cause cavitation problems, damaging the siphon well structure and threatening the operational safety of the nuclear power plant. Therefore, a method for calculating the design length of the siphon well after the porous energy dissipation weir is urgently needed to improve the safety and economy of siphon wells.

[0081] In existing technologies, the calculation method for the design length of a siphon well weir mainly relies on empirical formulas or traditional hydraulic models. Specifically, the method typically involves first estimating the head at the weir crest based on the weir type (e.g., thin-walled weir) and maximum discharge flow rate using the discharge capacity formula. Then, the horizontal projection length of the water jet is calculated using empirical coefficients as the basis for the design length downstream of the weir. Simultaneously, for the length of the bubble-entrained region, the water flow is generally simplified to a single-phase uniform flow. Assuming that the upward velocity of the bubble is constant during its ascent, the entrained length is estimated by multiplying the average cross-sectional velocity by the bubble's ascent time. Finally, the length of the water jet and the entrained length are simply added together, and the total design length downstream of the weir is determined by combining engineering experience margins.

[0082] However, existing calculation methods do not consider the effects of bubble diameter changes and water flow shear on the buoyancy, resulting in design parameters that cannot reflect the actual movement of the bubbles. Furthermore, they neglect the complex characteristics of the gas-liquid two-phase flow after aeration, leading to the lack of a collaborative calculation model for the water tongue length and the entrained gas length, resulting in deviations between the design results and actual requirements. Finally, existing methods do not establish a dynamic relationship between turbulent dissipation rate, bubble diameter, buoyancy, and design length, making it impossible to improve design accuracy through parameter optimization.

[0083] By analyzing the hydraulic characteristics of the aerated water flow behind the weir, the inventors discovered that the movement of bubbles in the water flow is not only affected by buoyancy, but also by a combination of factors such as water flow shear, turbulent structure, and changes in bubble size. Furthermore, changes in bubble diameter will further affect the rising speed of the bubbles and their migration distance in the water flow. Therefore, traditional design methods based solely on empirical parameters or single hydraulic conditions are difficult to accurately reflect the motion characteristics of actual gas-liquid two-phase flow. Therefore, this application proposes a method for calculating the design length of the siphon well weir. This method first obtains the structural and operational parameters of the overflow weir, and then uses the overflow weir discharge capacity formula to calculate the maximum total head of the overflow weir under design conditions, thereby determining the design length of the water tongue formed behind the weir. Subsequently, combining bubble dynamics theory, a bubble diameter prediction model is established using parameters such as water surface tension, fluid density, and turbulent dissipation rate to calculate the bubble diameter. Furthermore, considering the shearing effect of the water flow, a dynamic bubble buoyancy expression is established to obtain a bubble buoyancy velocity that better reflects actual hydraulic conditions. Further, based on the relative relationship between the bubble buoyancy velocity and the water flow velocity, the horizontal movement distance formed by the bubble being carried by the water flow during its buoyancy process is calculated. The maximum air-carrying length under the most unfavorable conditions is determined by traversing the range of water depth variations behind the weir. Finally, the design water tongue length and the maximum air-carrying length are coupled and added together to obtain the total design length of the uniform flow section behind the siphon well weir. Through the above technical solution, this application establishes a dynamic correlation between turbulent dissipation rate, bubble diameter, bubble rising velocity and the design length after the weir, so that the determination of the length of the uniform flow section after the weir can more accurately reflect the actual motion law of the aerated water flow, thereby improving the rationality and calculation accuracy of the design parameters, reducing the deviation between the design results and the actual operation requirements, and helping to improve the stability and safety of the siphon well system.

[0084] The technical solution of this application and how the technical solution of this application solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.

[0085] Figure 1 A flowchart illustrating the method for calculating the design length of the siphon well weir provided in this application embodiment. Figure 1 ;like Figure 1 As shown, the method includes:

[0086] S101. Obtain the structural parameters and operating condition parameters of the siphon well overflow weir.

[0087] In one possible implementation, the structural parameters include at least the weir width and weir height; the operating parameters include at least the maximum drainage flow, the water depth behind the weir, and the hydraulic gradient.

[0088] It should be noted that the structural parameters of the siphon well overflow weir are used to characterize the geometric boundary conditions of the overflow weir body and its adjacent flow areas, while the operating condition parameters are used to characterize the boundary states affecting the discharge, aeration, and bubble transport behavior during actual operation. The structural parameters include at least: weir width B (unit: m), weir height P (unit: m), and overflow weir type (in this embodiment, a rectangular thin-walled weir is used as a typical operating condition). Additionally, they may include the weir crest elevation, the cross-sectional dimensions of the downstream uniform flow section, and the inlet position of the downstream siphon section. The operating condition parameters include at least: maximum drainage flow rate. (Unit: m³ / s), water depth fluctuation range z behind the weir (unit: m), hydraulic gradient J (dimensionless), water density (unit: seawater at room temperature ), surface tension coefficient of water (Unit: N / m, 0.074 N / m is taken at room temperature of 20℃), hydrodynamic viscosity (Unit: Pa·s, taken at room temperature 20℃) ), gravitational acceleration g (value 9.81) ), von Kármán constant (Value 0.41). An overflow weir is a hydraulic structure used to control the upstream water level and allow water to flow freely over the weir crest; structural parameters are a set of data that quantitatively describes the spatial shape, geometric dimensions, and relative position of a structure; operating condition parameters are the actual operating status data of equipment or system under different loads, water levels, and flow rates; the water depth fluctuation range behind the weir is a continuous range of values ​​from the lowest possible operating water depth to the highest possible operating water depth, which directly determines the bubble's upward path length and residence time.

[0089] Taking a siphon well project that uses a rectangular thin-walled weir as the overflow control structure, the relevant design parameters are shown in Table 1 below:

[0090] Table 1. Engineering Design and Related Calculation Parameters for Siphon Wells

[0091]

[0092] In practice, structural parameters can be imported from 3D design models, as-built drawings, parametric modeling files, or on-site measurement data. Operating condition parameters can be obtained from historical operating databases, design specifications, online monitoring systems, numerical simulation boundary condition input files, or through manual input. In one possible embodiment, the executing entity first establishes a parameter acquisition interface, automatically parsing static parameters such as weir width, weir crest elevation, and downstream cross-sectional dimensions from BIM (Building Information Modeling) models or CAD (Computer-Aided Design) drawings, and converting them into a unified structural parameter table. Simultaneously, it retrieves upstream water levels, downstream water levels, and circulating water flow records under different unit loads from the plant monitoring system, performs noise reduction, outlier removal, and time alignment on the raw data, generating an operating condition parameter set that corresponds one-to-one with the structural parameters. In an exemplary implementation, to ensure the accuracy of subsequent calculations, the executing entity also performs integrity checks and dimensional unification processing on the collected data, such as converting water levels to the same elevation benchmark, flow rates to cubic meters per second, and lengths to meters. If a parameter is missing, it is supplemented based on common engineering design knowledge. For example, when the weir type coefficient is not directly provided on site, it can be selected based on the weir cross-sectional shape, inlet contraction, and the corresponding value range in commonly used hydraulic engineering design manuals, and its rationality is verified in conjunction with similar projects. Furthermore, regarding the fluctuation characteristics in the operating condition parameters, the embodiments of this application can construct operating condition sets according to rated operating condition, variable load operating condition, start-stop transition operating condition, and abnormal fluctuation operating condition, so that subsequent analysis covers the main boundary conditions in actual operation. The standardized input parameter set formed by this step not only provides a basis for the calculation of the maximum total head, but also establishes a unified data source for the subsequent calculation of bubble diameter, buoyancy velocity, and maximum air-carrying length. Based on the above analysis, it can be seen that by simultaneously incorporating structural dimensions and dynamic operating boundaries, the operating condition mismatch problem caused by calculating based on only a single static geometric parameter can be avoided, thus making the entire design length solution process engineering feasible and adaptable to operating conditions.

[0093] S102. Based on structural parameters and operating condition parameters, calculate the maximum total head of the overflow weir according to the overflow weir discharge capacity formula, and determine the design water tongue length based on the maximum total head.

[0094] In one possible implementation, firstly, a relationship between flow rate and weir crest head is established based on the overflow weir discharge capacity formula; then, the maximum discharge flow rate is substituted into the relationship to obtain the initial value of the weir crest head; next, the cross-sectional area in front of the weir is calculated based on the weir width and the water depth in front of the weir, and the flow velocity in front of the weir is calculated based on the cross-sectional area in front of the weir; then, the total head is iteratively corrected based on the flow velocity in front of the weir to obtain the maximum total head; finally, the maximum flow tongue length is calculated based on the relationship between the maximum total head and the flow tongue length, and the maximum flow tongue length is added to the preset safety margin to obtain the design flow tongue length.

[0095] In practical implementation, a functional relationship between flow rate and crest head is first established based on the overflow weir discharge capacity formula. This formula can employ empirical discharge expressions for thin-walled or broad-crested weirs, and is parameterized by incorporating weir width, flow coefficient, and gravitational acceleration. Substituting the maximum discharge flow rate into this formula yields the initial crest head. Then, the cross-sectional area in front of the weir is calculated based on the weir width and the water depth upstream. When boundary contraction exists in the cross-section upstream of the weir, a correction factor is introduced to adjust the area. Subsequently, the flow velocity upstream of the weir is obtained by dividing the maximum discharge flow rate by the cross-sectional area in front of the weir. This velocity is then iteratively updated using the total head correction relationship, gradually approximating the value that satisfies the discharge balance condition until the deviation between two adjacent calculations is less than a preset threshold, thus obtaining the maximum total head. The maximum water tongue length is further calculated based on the analytical relationship or empirical fitting relationship between the maximum total head and the water tongue length, and a preset safety margin is added on it to obtain the final design water tongue length. The safety margin can be determined by a fixed length or by the fluctuation amplitude of the operating condition. In practical applications, this parameter can also be selected by other values, which is not limited in this embodiment.

[0096] This calculation method uses the maximum drainage flow rate as the control input and corrects the total head by adjusting the inlet velocity, ensuring that the head calculation results take into account both flow conditions and actual flow regime changes. The length of the jet head is then calculated by back-calculating from the maximum total head, avoiding the accumulation of errors caused by single substitutions. By adding a safety margin to the theoretical maximum jet head, operational fluctuations and design uncertainties can be further covered, making the obtained downstream length of the weir more in line with engineering safety requirements.

[0097] The specific calculation process is as follows: First, establish the relationship between the flow rate and the head at the crest of the weir based on the formula for the discharge capacity of a thin-walled weir:

[0098]

[0099] Where Q is the weir flow rate (unit: m³ / s). 3 / s); is the flow coefficient, with a value of 0.617; H is the head at the crest of the weir (in meters); g is the acceleration due to gravity (value 9.81 m / s²).

[0100] In the calculation, the effect of velocity head is first ignored, and then... Substituting into the formula and transforming it, we can obtain the initial estimate of the total head at the weir crest:

[0101]

[0102] Subsequently, the cross-sectional area in front of the weir was calculated based on the geometric relationship of the cross-section in front of the weir. :

[0103]

[0104]

[0105] in, This represents the cross-sectional area in front of the weir, in m². The water depth in front of the weir (gradual transition section) is expressed in meters (m).

[0106] Then, the maximum flow velocity in front of the weir is calculated based on the maximum drainage flow rate and the cross-sectional area in front of the weir:

[0107]

[0108] in, The maximum flow velocity upstream of the weir is expressed in m / s.

[0109] Furthermore, the velocity head is calculated based on the maximum flow velocity in front of the weir:

[0110]

[0111] Flow rate head Substituting the values ​​into the total head correction relation, the total head is iteratively corrected until the deviation between two adjacent calculations is less than a preset threshold, thus obtaining the maximum total head. .

[0112] After obtaining the maximum total head, the maximum jet length L is calculated based on the free overflow jet motion relationship of the thin-walled weir:

[0113]

[0114] in, A comprehensive correction factor of 0.88 is used, where P is the weir height. Finally, a preset safety margin (e.g., 10%) is added to obtain the final design water jet length. .

[0115] In one exemplary embodiment, when B=11m, , At that time, the maximum total head is obtained through iterative correction. The maximum water jet length was calculated to be 5.47m. After further considering a 10% safety margin, the design water jet length was obtained. .

[0116] It is understandable that by adopting this implementation method, the calculation accuracy of the maximum total head of the overflow weir and the design length of the water tongue can be improved, the adaptability of the results to different drainage conditions and changes in the water depth in front of the weir can be enhanced, and the risks of water tongue overrun, gas retention and local flow instability caused by insufficient length can be reduced, thereby improving the reliability and safety margin of the siphon well weir downstream structure design.

[0117] S103. Calculate the bubble diameter based on bubble dynamics theory and operating condition parameters, and substitute the bubble diameter into the dynamic buoyancy expression to obtain the bubble buoyancy.

[0118] It should be understood that, in the embodiments of this application, bubble dynamics theory is used to describe the generation, breakup, coalescence, stress, and migration of bubbles in aerated water flow. The bubble diameter is a key parameter reflecting the bubble size, directly affecting the buoyancy, drag, and added mass effect experienced by the bubble. The dynamic buoyancy velocity expression is a functional relationship used to characterize the real-time rising speed of a bubble relative to the liquid phase under specific fluid properties, local turbulent conditions, and scale conditions. Unlike the approach of simplifying the bubble buoyancy velocity to a fixed empirical constant, the embodiments of this application introduce the bubble diameter as an intermediate variable into the calculation link, so that the bubble buoyancy capability is dynamically updated with changes in operating conditions.

[0119] It should be noted that this step establishes a dynamic relationship between bubble diameter and buoyancy; the specific calculation process is detailed in [link to calculation]. Figure 2 The examples are described below, and the overall logic is given here but will not be elaborated upon.

[0120] Based on turbulent dissipation rate Obtain the characteristic bubble diameter The initial diameter of the bubbles behind the weir was obtained by introducing the bubble diameter distribution law. For detailed derivation, see Figure 2 Example: When the bubble diameter d > 1.3 mm, the Reynolds number Re > 600 ( (where the dynamic viscosity is that of water), the gravity term can be ignored, and the drag coefficient in the turbulent region... Approximately constant, the bubble is approximately spherical due to surface tension. The expression for the bubble's upward velocity is obtained from force balance and fitting experimental data:

[0121]

[0122] in, The rising velocity of the bubble (m / s); is the surface tension coefficient of water (N / m);

[0123] Water density ( ); d is the initial diameter of the bubble (m); g is the acceleration due to gravity ( ).

[0124] S104. Based on the relative relationship between the bubble's rising speed and the water flow velocity, calculate the horizontal movement distance of the bubble under the action of the water flow, and determine the maximum air-carrying length by traversing the water depth fluctuation range behind the weir.

[0125] In this embodiment, the movement of bubbles in the downstream water flow can be decomposed into horizontal movement with the mainstream liquid phase and vertical movement relative to the liquid phase, which together determine how far the bubbles can be transported before escaping the water. The water flow velocity refers to the average velocity or cross-sectional representative velocity of the liquid phase in the downstream mainstream area; the bubble rising velocity is the vertical migration velocity of the bubble relative to the liquid phase; the horizontal movement distance refers to the horizontal distance the bubble moves under the carrying action of the water flow from entering the downstream aeration zone until it rises to the free liquid surface and escapes; the entrainment length refers to the effective flow length where significant bubble entrainment still exists downstream of the weir. Since changes in the downstream water depth directly alter the vertical distance and residence time required for the bubbles to rise, the horizontal movement distance of the same type of bubble is not the same under different water depth conditions, with a specific water depth often corresponding to the most unfavorable bubble retention range.

[0126] In the specific implementation process, the flow velocity is first calculated based on the cross-sectional dimensions of the flow path behind the weir and the flow rates under various operating conditions. For cases where the cross-section varies significantly along the flow path, the area behind the weir can be discretized into several computational units, and the local velocity can be calculated for each unit. For cases with a relatively uniform flow field, a one-dimensional approximation can be made using the cross-sectional average velocity. Subsequently, the time required for the bubble to rise to the free surface is calculated based on the bubble's rising velocity and the current water depth. The rising time is then multiplied by the local horizontal velocity to obtain the horizontal distance traveled by the bubble under the given water depth. When considering the attenuation of flow velocity along the flow path, turbulent diffusion, and bubble size evolution, a piecewise integration method can be used to obtain the horizontal distance traveled. That is, the bubble diameter, rising velocity, and local velocity are updated in each small time step, and the horizontal displacement of each time step is accumulated to obtain results that better reflect the actual flow pattern.

[0127] In one possible embodiment, to cover water level fluctuations during actual operation, the water depth fluctuation range behind the weir is traversed and calculated. The traversal method can be either equally spaced discrete sampling or adaptive traversal with denser sampling in highly sensitive areas. Specifically, the minimum operating water depth, maximum operating water depth, and water depth step size are first set, generating multiple candidate water depth values ​​sequentially. Then, for each candidate water depth, the ascent time and horizontal movement distance calculation are repeatedly performed to form a curve showing the correspondence between water depth and air-carrying length. Finally, the largest horizontal movement distance is selected from all results as the maximum air-carrying length. If the discrete characteristics of the bubble swarm at different particle sizes are considered, the corresponding air-carrying length can also be calculated for multiple representative bubble diameters, and the outer boundary of the envelope can be taken as the maximum air-carrying length. Through this traversal process, the most unfavorable water depth conditions that are easily overlooked by traditional average operating condition methods can be identified. This step is crucial for solving the problem of insufficient design length because it directly addresses the quantitative identification of bubble retention and air resistance risks.

[0128] Specifically, this step determines the farthest horizontal distance that the bubble can be carried by the water flow before escaping, i.e., the air-carrying length. .

[0129] First, the flow velocity behind the weir is calculated. , (unit: m / s) is the cross-sectional average velocity of the aerated water flow downstream of the overflow weir, derived from the formulas for the downstream flow area and the cross-sectional average velocity:

[0130]

[0131]

[0132] Where B is the width of the weir; z is the water depth behind the weir; The cross-sectional area of ​​the flow path; The average flow velocity is the cross-section behind the weir.

[0133] Furthermore, due to the rising speed of the bubbles As the water depth changes, the ascent time is the integral of the vertical path:

[0134]

[0135] in, The initial position of the bubble, in meters (m). This represents the speed at which the bubble rises.

[0136] Finally, the horizontal distance (air-carrying length) that the bubble travels from its generation location to its exit from the water surface can be calculated as follows:

[0137]

[0138] in, The initial height of the bubble above the water surface. ,when When the water depth changes, an integral form is used. Accumulate horizontal displacement.

[0139] In the specific implementation process, the water depth fluctuation range z∈ behind the weir is first defined. and with a preset step size The process iterates through all water depth conditions. For each candidate water depth value, the above steps are executed sequentially. After iterating through all water depth conditions, the maximum horizontal movement distance in all conditions is determined as the maximum air-carrying length.

[0140] In one exemplary embodiment, when the water depth z behind the weir is in the range of 1.5m to 8.0m, the calculation is performed in increments of 0.1m, resulting in 66 calculation cases. The calculation results show that as z increases, the average flow velocity behind the weir gradually decreases from 2.30m / s to 0.43m / s, while the bubble rise height... As the z-value increases, the influence of both on the horizontal movement distance exhibits an inverse synergistic relationship. Further ensemble analysis reveals that when z=1.5m, although the bubble's buoyancy height is minimal, the average flow velocity behind the weir is at its maximum, thus maximizing the bubble's horizontal movement distance, corresponding to the most unfavorable condition. Under this condition, the time for the bubble to surface is t=6.26s; further calculations yield the maximum air-carrying length. =14.4m. This step allows for the analysis of the vertical upward floating process and the horizontal transport process of the bubble on the same time scale, and identifies the most unfavorable water depth conditions through a traversal approach.

[0141] It is understandable that by establishing the relative motion relationship between bubble uplift and horizontal transport, and searching for the most unfavorable air-carrying length within the water depth fluctuation range behind the weir, the problem of insufficient coverage caused by designing based on a single typical water depth can be avoided. This significantly improves the adaptability of the siphon well's post-weir length design to extreme operating conditions and reduces the risk of bubbles entering the downstream siphon section and forming air pockets, air resistance, and flow instability.

[0142] S105 adds the designed water tongue length to the maximum air-carrying length to obtain the total designed length of the siphon well weir.

[0143] It should be understood that, in the embodiments of this application, the total design length refers to the total effective length required to be configured from the overflow weir control position along the downstream flow direction to the position where the bubble escape requirement is met. This total length is composed of the area covered by the water jet after the upstream section crosses the weir and the maximum transport area where bubbles may continue to exist in the downstream aerated water flow. The design water jet length reflects the initial projection and ingress influence range of the water flow after crossing the weir, and the maximum air-carrying length reflects the additional flow distance that bubbles may still be carried forward under the most unfavorable operating conditions. In a physical sense, the two correspond to the downstream aeration formation stage and the bubble escape completion stage, respectively. Therefore, adding the two together yields the total downstream design length that covers the entire risk section.

[0144] In practice, the design water tongue length output from S102 and the maximum air-carrying length output from S104 are first received. After verifying the dimensionality consistency of the two, a summation calculation is performed to generate the total design length of the siphon well weir. The specific formula is as follows:

[0145]

[0146] In the formula: The total design length after the overflow weir (unit: m); Design water jet length (unit: m); The length of the air-carrying vessel (unit: m).

[0147] In the specific implementation process, the design water tongue length output by S102 is received first. and the maximum air-carrying length of S104 output After verifying the dimensionality of the two quantities, they are summed to generate the final design total length. In an exemplary embodiment, the design water tongue length is obtained according to S102. The maximum gas-carrying length is obtained from S104. ,therefore: The final design length of the siphon well weir was determined to be 20.4m.

[0148] In one possible embodiment, for ease of engineering application, the results can be further compared with existing civil engineering design boundaries, siphon section layout locations, equipment maintenance space, and structural safety margin requirements. If the calculated total design length is less than the minimum safe length allowed by the existing structural layout, it is output according to the safe length; if the calculation result exceeds the existing layout boundary, a design adjustment prompt is automatically generated, suggesting modification of the length of the flow equalization section after the weir, adjustment of the siphon section inlet location, or re-optimization of the weir parameters. For example, a complete calculation report can also be output, including an input parameter table, maximum total head, design water tongue length, bubble diameter, dynamic buoyancy velocity, water depth traversal curve, maximum air-carrying length, and final total design length, for designers to review and archive.

[0149] The method for calculating the design length of the siphon well weir provided in this application involves first obtaining the structural and operational parameters of the overflow weir during the design of the uniform flow section. Then, based on these parameters, a functional relationship between the flow rate and the head at the weir crest is established using the overflow weir discharge capacity formula. The head at the weir crest is calculated in conjunction with the maximum discharge flow rate, while also considering the influence of the upstream velocity on the total head. This yields the maximum total head of the overflow weir under design conditions. Next, the maximum length of the water jet formed by the jet after the weir is calculated based on the relationship between the maximum total head and the trajectory of the water jet. The design length of the water jet is then determined by incorporating a safety margin to ensure sufficient space for the water flow after the weir to complete the water jet's impact and initial diffusion before entering the uniform flow section. After obtaining the water jet length, the aeration process is further analyzed based on bubble dynamics theory. A bubble diameter calculation model is established based on parameters such as water surface tension, fluid density, and turbulent dissipation rate. The characteristic bubble diameter is calculated, and the bubble size distribution is then considered. The initial diameter of the bubble is determined by a certain rule. This bubble diameter is then substituted into the expression for the bubble's dynamic buoyancy velocity to obtain its buoyancy velocity in the water body, thus characterizing the bubble's movement capability in the water flow. Based on this, the horizontal movement distance of the bubble carried by the water flow during its ascent is calculated according to the relative relationship between the bubble's buoyancy velocity and the flow velocity behind the weir. This is achieved by determining the bubble's horizontal migration range in the water flow through the bubble's ascent time and the average flow velocity of the cross-section. Further calculations are performed within the possible water depth fluctuation range behind the weir to determine the maximum air-carrying length, reflecting the bubble's retention range in the water flow under the most unfavorable aeration conditions. Finally, the designed water tongue length and the maximum air-carrying length are added to obtain the total design length of the uniform flow section behind the weir in the siphon well. This ensures that the length of the uniform flow section after the weir meets the spatial requirements for water tongue diffusion while also ensuring that the aerated bubbles fully float to the surface before entering the subsequent siphon section. This effectively prevents bubbles from entering the siphon system and negatively impacting the stable operation of the siphon, improving the stability and safety of the siphon well's hydraulic operation.

[0150] In one possible implementation, the bubble's ascent time is first calculated based on its rising speed and the height it rises above the water surface; then, the average flow velocity at the cross-section behind the weir is calculated based on the maximum drainage flow rate and the weir width; finally, the horizontal distance the bubble travels under the influence of the water flow is calculated based on the average flow velocity at the cross-section and the bubble's ascent time.

[0151] It should be understood that, in this embodiment, the bubble buoyancy height refers to the vertical distance from the bubble to the free water surface when it enters the water body behind the weir. This distance can be determined by the local water depth behind the weir, the initial location of the bubble, and the thickness of the hydraulic jump aeration layer. The bubble buoyancy velocity is the average vertical migration velocity of the bubble under the combined effects of still water buoyancy, resistance, and turbulent disturbances, characterizing the bubble's ability to detach from the water body. The average flow velocity at the cross-section behind the weir refers to the average horizontal flow velocity formed after the maximum discharge flow passes through the cross-section corresponding to the weir width, used to characterize the water flow's ability to carry bubbles.

[0152] In the calculation, the bubble's ascent velocity is first combined with its ascent height above the water surface, and the ascent time is obtained by dividing the ascent height by the ascent velocity. When the ascent velocity varies with water depth, the ascent process in different water layers can also be integrated to obtain an ascent time that more closely reflects the actual flow pattern. Then, the average flow velocity at the cross-section behind the weir is calculated based on the maximum discharge flow rate and the weir width, where the maximum discharge flow rate is used as a known input, and the weir width is used as the control width for the flow. If necessary, the cross-sectional area can be determined by combining the water depth behind the weir to ensure that the average flow velocity reflects the actual cross-sectional conditions. Finally, the average cross-sectional velocity is multiplied by the bubble's ascent time to obtain the horizontal distance the bubble travels under the influence of the water flow. This distance characterizes the scale of horizontal transport of the bubble before it completes its vertical escape.

[0153] Understandably, by employing the above method, the vertical upward floating process of bubbles and the horizontal transport process downstream of the weir can be analyzed on the same time scale, thereby more accurately determining the migration range of bubbles in the downstream flow field. This calculation result can be directly used to determine the subsequent air-carrying length, ensuring that the designed length downstream of the weir covers the most unfavorable bubble retention area, reducing the risk of air resistance after bubbles enter the siphon section, and improving the operational stability and safety of the siphon well under different drainage conditions.

[0154] In one possible implementation, the maximum air-carrying length is determined by traversing the water depth fluctuation range behind the weir, including:

[0155] First, within the water depth fluctuation range behind the weir, each water depth condition is traversed with a preset step size; then, for each water depth condition, the horizontal movement distance of the bubble is calculated based on the product of the water flow velocity behind the weir and the bubble's rising time; finally, the maximum value of the horizontal movement distance of the bubble in each water depth condition is determined as the maximum air-carrying length.

[0156] The bubble's ascent time is obtained by integrating the bubble's ascent velocity along the water depth.

[0157] It should be understood that the water depth fluctuation range behind the weir is used to characterize the possible water depth range behind the siphon well under different operating loads, downstream water level disturbances, and the influence of backflow. The preset step size is used to limit the traversal interval in order to achieve a balance between calculation accuracy and calculation efficiency. The bubble buoyancy velocity refers to the instantaneous velocity of a bubble rising vertically in the water under the action of buoyancy, and its value can change with water depth. The bubble buoyancy time refers to the time required for a bubble to rise from its current water depth position to the water surface. It is obtained by integrating the buoyancy velocities corresponding to different water depths, and can reflect the actual retention characteristics of bubbles in stratified water bodies. The downstream flow velocity refers to the average horizontal transport velocity of the water flow under the working condition of the bubble's location. It can be calculated from the flow rate and cross-sectional area under this working condition, or obtained from numerical hydraulic calculation results. The maximum air-carrying length is used to characterize the maximum horizontal migration distance that a bubble behind the weir may reach under the action of water flow. Its value is directly related to the safe arrangement length of the downstream uniform flow section or siphon section.

[0158] In practical implementation, the lower and upper limits of the water depth fluctuation range behind the weir can be determined first based on historical operating data, design boundary conditions, and safety margins. Then, discrete water depth values ​​are sequentially taken as traversal conditions according to a preset step size. For each water depth condition, the flow velocity behind the weir is calculated first by combining the flow rate and cross-sectional geometry under that condition. Then, an integral expression is established based on the buoyancy distribution of the bubble within the corresponding water depth range to obtain the time it takes for the bubble to rise from its current position to the water surface. This time is then multiplied by the flow velocity to obtain the horizontal movement distance of the bubble under that condition. After traversing all water depth conditions, the horizontal movement distances are compared, and the maximum value is taken as the maximum air-carrying length, thus covering the most unfavorable water depth conditions. This method avoids the bias caused by estimating solely based on average water depth or a single typical water depth, thereby improving the adaptability and reliability of the design length behind the weir.

[0159] Understandably, incorporating the velocity changes caused by water depth fluctuations and the changes in bubble rise time into the same calculation framework, and identifying the working condition where the bubble migrates the furthest horizontally through point-by-point searching, the range of air entrainment behind the weir can be controlled based on this furthest value. This allows the maximum air entrainment length to more closely approximate the actual gas-liquid two-phase flow state, reducing the risks of bubble retention, gas resistance formation, and local flow instability, and providing a more accurate basis for determining the total design length behind the siphon well weir.

[0160] It should be noted that the specific calculation process in this embodiment has been described in detail in the above embodiments, and will not be repeated here.

[0161] Figure 2 A flowchart illustrating the method for calculating the design length of the siphon well weir provided in this application embodiment. Figure 2 ;like Figure 2 As shown, in this embodiment... Figure 1Based on the examples, the process of calculating the bubble rising speed is described in detail, and the method includes:

[0162] S201. Establish a bubble diameter calculation model based on water surface tension, fluid density, and water flow turbulence dissipation rate, and calculate the characteristic bubble diameter.

[0163] Among them, water surface tension is used to characterize the ability of the gas-liquid interface to resist breakup and deformation, fluid density is used to reflect the inertial influence of water on the bubble buoyancy process, and water flow turbulence dissipation rate is used to characterize the control effect of local turbulence on the bubble breakup scale.

[0164] In one possible implementation, the calculation process for the turbulent dissipation rate of the water flow includes:

[0165] First, the frictional velocity is determined based on the energy equation and hydraulic gradient of uniform flow in the flume; then, the turbulent dissipation rate is calculated using the frictional velocity and the von Kármán constant.

[0166] The energy equation for uniform flow in a flume characterizes the relationship between head loss and average velocity, while the hydraulic gradient characterizes the degree of energy attenuation per unit length. Frictional velocity is an important hydraulic parameter reflecting the intensity of near-wall shear, which can be inversely calculated based on water depth, velocity, roughness, and gradient conditions. The von Kármán constant is an empirical coefficient characterizing the logarithmic distribution of turbulence. In the near-wall analysis of an open flume, its value is matched with the flow regime characteristics to establish the conversion relationship between frictional velocity and turbulent dissipation.

[0167] Specifically, the frictional velocity is first derived using the uniform flow energy equation in the water tank:

[0168]

[0169] in, ρ is the frictional velocity (m / s); g is the acceleration due to gravity (9.81). z represents the water depth behind the weir, and j represents the hydraulic gradient.

[0170] Furthermore, the turbulent dissipation rate is obtained from the frictional velocity and the von Kármán constant:

[0171]

[0172] in, Frictional velocity (unit: m / s) is the von Kármán constant, with a value of 0.41.

[0173] Specifically, based on the balance between bubble surface tension and turbulent shear force, the characteristic bubble diameter is obtained from the prediction equation:

[0174]

[0175] Among them, The characteristic bubble diameter, It is a proportionality constant. The surface tension coefficient of water. For fluid density, The value represents the turbulent dissipation rate per unit mass. This model can reflect the dynamic impact of changes in turbulence intensity on the bubble scale under different operating conditions.

[0176] Understandably, this calculation process utilizes directly obtainable hydraulic gradient and uniform flow energy equations to establish an engineering-based path for determining turbulent dissipation rate. This allows turbulence intensity parameters to no longer rely on local instantaneous quantities that are difficult to measure directly, but rather to be stably reflected through frictional velocity. This provides reliable turbulent input parameters for bubble diameter calculation, thereby improving the accuracy of bubble rise velocity and entrainment length predictions, and enhancing the adaptability of the calculated design length after the siphon weir to different operating conditions.

[0177] S202. Based on the bubble size distribution pattern, multiply the characteristic bubble diameter by a preset proportional coefficient to obtain the initial bubble diameter.

[0178] Among them, the characteristic bubble diameter is used to represent the representative size of the bubble group under a given working condition, and the preset scaling factor is used to convert the characteristic particle size into an initial particle size that matches the actual bubble distribution.

[0179] In this embodiment, the characteristic bubble diameter is only used to reflect the overall scale characteristics of the bubble swarm. However, in a real gas-entrained field, bubble size is usually discretely distributed, and the probability of bubbles of different sizes appearing is not the same. Experimental studies have shown that in the highly turbulent gas-entrained region behind the weir, the frequency of small-diameter bubbles is significantly higher than that of large-diameter bubbles. Therefore, this embodiment further combines the statistical distribution law of bubble size to proportionally correct the characteristic bubble diameter to obtain an initial bubble diameter that better matches the characteristics of the actual bubble swarm.

[0180] In the specific implementation process, based on a large number of water tank experiments and field observations, one-quarter of the characteristic bubble diameter was selected as the representative initial bubble diameter, that is:

[0181]

[0182] Where d is the initial diameter of the bubble. The characteristic bubble diameter is defined as follows: In practice, the characteristic bubble diameter is first obtained according to S201, and then the initial bubble diameter used for kinetic analysis is calculated using a scaling factor. For example, when the characteristic bubble diameter is 16.92 mm, the initial bubble diameter is approximately 4.23 mm.

[0183] It should be understood that this step allows the bubble size parameters to more closely approximate the dominant particle size distribution characteristics in real aerated water flow, avoiding the problem of calculation results being too large or too small due to directly using the average particle size, thereby improving the consistency between the bubble dynamics model and actual operating conditions.

[0184] S203. Establish a bubble dynamic equilibrium model based on the force balance relationship of bubbles moving in water.

[0185] The bubble dynamics equilibrium model includes gravity, buoyancy, water flow resistance, and surface tension, which are used to describe the balance relationship between various forces acting on the bubble during vertical motion.

[0186] It should be understood that, in this embodiment, the process of bubbles rising in water is a typical gas-liquid two-phase flow dynamics problem, and its motion is affected by buoyancy, gravity, water flow resistance, and surface tension. As the bubble size and local flow field change, the force state of the bubble will also change. Therefore, it is necessary to establish a bubble dynamic equilibrium model to uniformly describe the bubble motion process.

[0187] In practical implementation, the forces acting on the bubble include gravity, buoyancy, water flow resistance, and surface tension. In the turbulent region (d>1.3mm, Re>600), gravity can be ignored, and the resistance term is:

[0188]

[0189] in, Water density (unit: ); Bubble diameter (unit: m); The drag coefficient, (Unit: m / s).

[0190] It should be understood that this step establishes the correlation between bubble size, drag characteristics, and buoyancy behavior, enabling subsequent dynamic buoyancy velocity calculations to simultaneously reflect changes in bubble size and flow field disturbances, thereby improving the model's adaptability to real gas-mixed flow patterns.

[0191] S204. Fit the bubble dynamics equilibrium model based on historical experimental data to obtain the correlation expression between the bubble rising speed and the bubble diameter, water density and surface tension coefficient.

[0192] Historical experimental data can come from water tank tests, field observation data, or numerical simulation results, so that the correlation expression can reflect the bubble rising pattern under different working conditions.

[0193] It should be understood that, in this embodiment, the movement of bubbles in actual water flow is affected by a variety of complex factors such as local turbulence, bubble deformation, wake disturbance, and bubble coalescence, making it difficult to fully and accurately describe the bubble's buoyancy using only the theoretical force balance equations. Therefore, this embodiment further incorporates historical experimental data to modify and fit the bubble dynamics balance model, thereby obtaining a dynamic buoyancy velocity correlation expression applicable to engineering conditions.

[0194] In the specific implementation process, firstly, water tank test data, field observation data, or numerical simulation results are obtained under different water depths, flow velocities, and bubble sizes. Then, a nonlinear regression method is used to correlate parameters such as bubble diameter, water density, and surface tension with the experimentally measured buoyancy velocity, establishing a dynamic buoyancy velocity expression:

[0195]

[0196] in, Let d be the dynamic rising velocity of the bubble, and d be the initial diameter of the bubble. For water density, is the surface tension coefficient.

[0197] For example, in a certain seawater circulation system, when the water density is 1025... When the surface tension coefficient is 0.074 N / m, the range of bubble rising velocity obtained by fitting is approximately 0.24 m / s to 0.27 m / s.

[0198] Understandably, this step allows for the integration of theoretical mechanical models with actual experimental laws, enabling the dynamic buoyancy expression to not only have physical meaning but also good engineering applicability and adaptability to operating conditions, thereby improving the reliability of subsequent air-carrying length prediction results.

[0199] S205. Calculate the bubble's rising speed based on the correlation expression and the initial diameter of the bubble.

[0200] In this embodiment, the bubble's buoyancy velocity is a key parameter determining its residence time and horizontal migration distance in the downstream flow. A higher buoyancy velocity allows the bubble to quickly escape the water surface; conversely, a lower velocity makes it more likely to be carried by the current into the subsequent siphon section. Therefore, this embodiment calculates the bubble's buoyancy capability under different operating conditions based on the dynamic buoyancy velocity expression established in S204.

[0201] In the specific implementation process, the initial diameter of the bubble output by S202 is first obtained; then, the initial bubble diameter, water density, and surface tension parameters are substituted into the dynamic buoyancy velocity expression to obtain the bubble buoyancy velocity under the corresponding working condition. Further, the bubble buoyancy time is calculated based on the bubble buoyancy velocity and the bubble's buoyancy height above the water surface.

[0202] Understandably, this step enables dynamic quantitative analysis of bubble buoyancy, allowing bubble residence time to be updated in real time as flow field conditions change. This provides an accurate basis for determining the maximum entrainment length and the total design length after the siphon well weir, and reduces the risk of air resistance and flow instability caused by bubbles entering the siphon section.

[0203] Figure 3 This is a schematic diagram of the structure of the siphon well weir design length calculation device provided in the embodiments of this application; as shown. Figure 3 As shown, the device includes:

[0204] The acquisition module 301 is used to acquire the structural parameters and operating condition parameters of the siphon well overflow weir;

[0205] The first determining module 302 is used to calculate the maximum total head of the overflow weir based on the structural parameters and operating condition parameters, according to the overflow weir discharge capacity formula, and to determine the design water tongue length based on the maximum total head.

[0206] The first calculation module 303 is used to calculate the bubble diameter based on bubble dynamics theory and operating condition parameters, and to substitute the bubble diameter into the dynamic buoyancy expression to obtain the bubble buoyancy.

[0207] The second determining module 304 is used to calculate the horizontal movement distance of the bubble under the action of the water flow based on the relative relationship between the bubble's rising speed and the water flow velocity, and to determine the maximum air-carrying length by traversing the water depth fluctuation range behind the weir.

[0208] The second calculation module 305 is used to add the designed water tongue length to the maximum air-carrying length to obtain the total designed length of the siphon well weir.

[0209] In one possible implementation, the structural parameters include at least the weir width and the weir height;

[0210] Operating parameters should include at least the maximum drainage flow, the water depth behind the weir, and the hydraulic gradient.

[0211] In one possible implementation, the first determining module 302 is specifically used for:

[0212] Establish the relationship between flow rate and head at the weir crest based on the overflow capacity formula;

[0213] Substituting the maximum drainage flow rate into the formula yields the initial value of the weir crest head.

[0214] Calculate the cross-sectional area in front of the weir based on the weir width and the water depth in front of the weir, and then calculate the flow velocity in front of the weir based on the cross-sectional area in front of the weir.

[0215] The total head is iteratively corrected based on the flow velocity in front of the weir to obtain the maximum total head.

[0216] The maximum water tongue length is calculated based on the relationship between the maximum total head and the water tongue length, and the design water tongue length is obtained by adding the maximum water tongue length to the preset safety margin.

[0217] In one possible implementation, the first computing module 303 is specifically used for:

[0218] A bubble diameter calculation model is established based on water surface tension, fluid density, and water flow turbulence dissipation rate to calculate the characteristic bubble diameter.

[0219] Based on the bubble size distribution pattern, the initial bubble diameter is obtained by multiplying the characteristic bubble diameter by a preset scaling factor.

[0220] A bubble dynamic equilibrium model is established based on the force balance relationship of bubbles moving in water. The bubble dynamic equilibrium model includes gravity, buoyancy, water flow resistance and surface tension.

[0221] Based on historical experimental data, the bubble dynamics equilibrium model was fitted to obtain the correlation expression between the bubble rising speed and the bubble diameter, water density and surface tension coefficient.

[0222] The bubble's rising speed is calculated based on the correlation expression and the initial diameter of the bubble.

[0223] In one possible implementation, the calculation process for the turbulent dissipation rate of the water flow includes:

[0224] The frictional velocity is determined based on the energy equation and hydraulic gradient of uniform flow in the flume.

[0225] The turbulent dissipation rate was calculated using the frictional velocity and the von Kármán constant.

[0226] In one possible implementation, the first computing module 303 includes:

[0227] The time it takes for the bubble to rise is calculated based on the bubble's rising speed and the height it rises above the water surface.

[0228] Calculate the average flow velocity at the cross-section behind the weir based on the maximum drainage flow rate and the weir width;

[0229] The horizontal distance the bubble travels under the influence of water flow is calculated based on the average flow velocity of the cross section and the bubble's ascent time.

[0230] In one possible implementation, the second determining module 304 is specifically used for:

[0231] Within the range of water depth fluctuations behind the weir, each water depth condition is traversed with a preset step size.

[0232] For each water depth condition, the horizontal movement distance of the bubble is calculated based on the product of the flow velocity behind the weir and the bubble's ascent time, where the bubble's ascent time is obtained by integrating the bubble's ascent velocity along the water depth.

[0233] The maximum horizontal movement distance of the air bubble under each water depth condition is determined as the maximum air-carrying length.

[0234] The siphon well weir design length calculation device provided in this application embodiment can execute the method provided in the above method embodiment. Its implementation principle and technical effect are similar, and will not be described in detail here.

[0235] Figure 4 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. Figure 4 As shown, the electronic device 40 provided in this embodiment includes at least one processor 401 and a memory 402. Optionally, the device 40 further includes a communication component 403. The processor 401, memory 402, and communication component 403 are connected via a bus 404.

[0236] In a specific implementation, at least one processor 401 executes computer execution instructions stored in memory 402, causing at least one processor 401 to perform the above-described method.

[0237] The specific implementation process of processor 401 can be found in the above method embodiments, and its implementation principle and technical effect are similar. It will not be repeated here.

[0238] In the above embodiments, it should be understood that the processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), etc. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the method disclosed in this invention can be directly implemented by a hardware processor, or implemented by a combination of hardware and software modules within the processor.

[0239] The memory may include random access memory (RAM) and may also include non-volatile memory (NVM), such as at least one disk storage device.

[0240] The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. Buses can be categorized as address buses, data buses, control buses, etc. For ease of illustration, the buses shown in the accompanying drawings are not limited to a single bus or a single type of bus.

[0241] This application also provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, implement the above-described method.

[0242] The aforementioned readable storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk. The readable storage medium can be any available medium accessible to a general-purpose or special-purpose computer.

[0243] An exemplary readable storage medium is coupled to a processor, enabling the processor to read information from and write information to the readable storage medium. Of course, the readable storage medium can also be a component of the processor. The processor and the readable storage medium can reside in an Application Specific Integrated Circuit (ASIC). Alternatively, the processor and the readable storage medium can exist as discrete components in the device.

[0244] The division of units is merely a logical functional division; in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be indirect coupling or communication connection through some interfaces, devices, or units, and may be electrical, mechanical, or other forms.

[0245] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0246] In addition, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0247] If a function is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0248] Those skilled in the art will understand that all or part of the steps of the above-described method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When executed, the program performs the steps of the above-described method embodiments; and the aforementioned storage medium includes various media capable of storing program code, such as ROM, RAM, magnetic disks, or optical disks.

[0249] Finally, it should be noted that other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A method for calculating the design length of a siphon well weir, characterized in that, include: Obtain the structural parameters and operating condition parameters of the siphon well overflow weir; Based on the structural parameters and operating condition parameters, the maximum total head of the overflow weir is calculated according to the overflow weir discharge capacity formula, and the design water tongue length is determined based on the maximum total head. The bubble diameter is calculated based on bubble dynamics theory and the operating parameters, and the bubble diameter is substituted into the dynamic buoyancy velocity expression to obtain the bubble buoyancy velocity. Based on the relative relationship between the bubble's rising velocity and the water flow velocity, the horizontal movement distance of the bubble under the action of the water flow is calculated, and the maximum air-carrying length is determined by traversing the water depth fluctuation range behind the weir. The total design length of the siphon well weir is obtained by adding the designed water tongue length to the maximum air-carrying length.

2. The method according to claim 1, characterized in that, The structural parameters include at least the weir width and weir height; The operating parameters include at least the maximum drainage flow, the water depth behind the weir, and the hydraulic gradient.

3. The method according to claim 2, characterized in that, The calculation of the maximum total head of the overflow weir based on the structural parameters and operating condition parameters, according to the overflow weir discharge capacity formula, and the determination of the design jet length based on the maximum total head, includes: Establish the relationship between flow rate and head at the weir crest based on the overflow capacity formula; Substituting the maximum drainage flow rate into the aforementioned formula yields the initial value of the weir crest head. Calculate the cross-sectional area in front of the weir based on the weir width and the water depth in front of the weir, and calculate the flow velocity in front of the weir based on the cross-sectional area in front of the weir. The total head is iteratively corrected based on the flow velocity in front of the weir to obtain the maximum total head. The maximum water tongue length is calculated based on the relationship between the maximum total head and the water tongue length, and the design water tongue length is obtained by adding the maximum water tongue length to the preset safety margin.

4. The method according to claim 1, characterized in that, The calculation of the bubble diameter based on bubble dynamics theory and the operating condition parameters, and the substitution of the bubble diameter into the dynamic buoyancy velocity expression to obtain the bubble buoyancy velocity, includes: A bubble diameter calculation model is established based on water surface tension, fluid density, and water flow turbulence dissipation rate to calculate the characteristic bubble diameter. Based on the bubble size distribution pattern, the diameter of the characteristic bubble is multiplied by a preset proportional coefficient to obtain the initial diameter of the bubble; A bubble dynamic equilibrium model is established based on the force balance relationship of bubbles moving in water. The bubble dynamic equilibrium model includes gravity, buoyancy, water flow resistance and surface tension. The bubble dynamics equilibrium model was fitted based on historical experimental data to obtain the correlation expression between bubble rising velocity and bubble diameter, water density and surface tension coefficient. The bubble's rising speed is calculated based on the correlation expression and the initial diameter of the bubble.

5. The method according to claim 4, characterized in that, The calculation process of the water flow turbulence dissipation rate includes: The frictional velocity is determined based on the energy equation and hydraulic gradient of uniform flow in the flume. The turbulent dissipation rate is calculated using the frictional velocity and the von Kármán constant.

6. The method according to claim 2, characterized in that, The calculation of the horizontal distance the bubble travels under the influence of the water flow, based on the relative relationship between the bubble's rising velocity and the water flow velocity, includes: The time it takes for the bubble to rise is calculated based on the bubble's rising speed and the height it rises above the water surface. Calculate the average flow velocity at the cross-section behind the weir based on the maximum drainage flow rate and the weir width; The horizontal distance the bubble travels under the influence of the water flow is calculated based on the average flow velocity of the cross-section and the bubble's ascent time.

7. The method according to claim 2, characterized in that, The determination of the maximum air-carrying length by traversing the water depth fluctuation range after the weir includes: Within the range of water depth fluctuations behind the weir, each water depth condition is traversed with a preset step size. For each water depth condition, the horizontal movement distance of the bubble is calculated based on the product of the flow velocity behind the weir and the bubble's ascent time, wherein the bubble's ascent time is obtained by integrating the bubble's ascent velocity along the water depth. The maximum horizontal movement distance of the air bubble under each water depth condition is determined as the maximum air-carrying length.

8. A device for calculating the design length of a siphon well weir, characterized in that, include: The acquisition module is used to acquire the structural parameters and operating condition parameters of the siphon well overflow weir; The first determining module is used to calculate the maximum total head of the overflow weir based on the structural parameters and operating condition parameters, according to the overflow weir discharge capacity formula, and to determine the design water tongue length based on the maximum total head. The first calculation module is used to calculate the bubble diameter based on bubble dynamics theory and the operating condition parameters, and to substitute the bubble diameter into the dynamic buoyancy expression to obtain the bubble buoyancy. The second determining module is used to calculate the horizontal movement distance of the bubble under the action of the water flow based on the relative relationship between the bubble's rising speed and the water flow velocity, and to determine the maximum air-carrying length by traversing the water depth fluctuation range behind the weir. The second calculation module is used to add the designed water tongue length to the maximum air-carrying length to obtain the total designed length of the siphon well weir.

9. An electronic device, characterized in that, include: Memory, processor; The memory stores computer-executed instructions; The processor executes computer execution instructions stored in the memory, causing the processor to perform the method as described in any one of claims 1-7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable instructions, which, when executed by a processor, are used to implement the method as described in any one of claims 1-7.

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