Cavitation flow numerical calculation key parameter correction method, system, equipment and medium aiming at environmental characteristics of high altitude area
By correcting the key parameters of cavitation flow numerical calculation, the problem of inaccurate cavitation calculation in high-altitude areas was solved, enabling more accurate cavitation performance assessment and protection strategies, and improving the safety and maintenance efficiency of unit operation.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-31
- Publication Date
- 2026-03-24
AI Technical Summary
Existing numerical calculation methods for cavitation flow fail to accurately reflect the environmental differences in high-altitude areas, resulting in inaccurate calculation results and affecting the assessment of unit cavitation performance and protection strategies.
By collecting measured atmospheric pressure data, combining sediment content and cosmic ray radiation intensity, the cavitation pressure value and gas nucleus volume fraction were corrected. The initial radius of the bubble was measured using high-speed photography technology, and then substituted into the Rayleigh-Plesset equation to perform numerical calculations of cavitation flow.
It improves the accuracy of cavitation flow calculations in high-altitude areas, ensures the safety of unit design and operation, reduces the risk of cavitation corrosion, and enables real-time monitoring and maintenance optimization of unit operating status.
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Figure CN121723892A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of high-altitude environmental engineering technology, and particularly relates to a cavitation flow numerical calculation key parameter correction method, system, device and medium for high-altitude environmental characteristics. BACKGROUND
[0002] Cavitation is an inevitable flow phenomenon in hydraulic machinery, and its essence is that the pressure of the internal flow field of the hydraulic machinery is lower than the cavitation pressure of water under certain operating conditions, and bubbles are generated. The cavitation process involves bubble growth and collapse, which can cause a series of problems in hydraulic machinery, including reduced efficiency, vibration and noise of the unit. In addition, complex mechanical, chemical and thermodynamic changes occur during the bubble collapse process, which can cause corrosion effects on the metal wall of the unit, cause serious structural damage, and affect the safe operation of the unit. Therefore, it is necessary to understand and master the cavitation performance of the unit to avoid the occurrence of serious cavitation and erosion and to protect the safety of the unit.
[0003] At present, the cavitation performance of the unit is mainly obtained through model test and numerical calculation, and the two methods complement each other and cooperate to accurately obtain the cavitation performance data of the unit. Numerical calculation has important significance for the cavitation performance calculation of high-altitude pumped storage units due to its low cost and its ability to easily simulate different environmental conditions.
[0004] At present, almost all pumped storage power stations operating globally are located in low-altitude areas, and the environmental factors such as air pressure and temperature in these areas are not much different, so the use of a consistent numerical calculation method has little effect on the results and will not cause significant deviations in the calculation results, but there are large environmental differences between high-altitude and low-altitude areas. If this difference is not corrected, it will lead to the problem of inaccurate calculation using the original cavitation flow numerical calculation method.
[0005] In the existing engineering calculation of hydro-mechanical cavitation flow, the mixture model is usually used to regard the gas-liquid fluid as a whole, and the volume fraction of each of the gas-liquid two phases needs to be calculated. Therefore, a method for describing the gas-liquid two-phase component fraction is needed. The Rayleigh-Plesset equation is the most widely used equation for describing the conversion process between the gas-liquid two phases, and it is the theoretical basis of many existing mainstream cavitation models. These mainstream cavitation models have differences in the expression of the liquid phase evaporation and the gas phase condensation process, but the cavitation pressure pv, the gas nucleus volume fraction a and the bubble initial radius rb in the model are key parameters in the model, which greatly affect the calculation results. In the design calculation of pumped storage power stations at low altitudes, the default uniform value is usually used for these parameters, but in fact, these parameters are closely related to environmental factors such as environmental pressure and temperature. In the low-altitude area, without considering the influence of the environment on the above-mentioned parameters, good calculation results can still be obtained, but the influence of the environment on the above-mentioned parameters increases in the high-altitude area, and needs to be corrected. Therefore, in order to obtain more accurate calculation results of hydro-mechanical cavitation flow in high-altitude environment, the key parameters of the cavitation model based on the Rayleigh-Plesset equation need to be corrected. SUMMARY
[0006] In view of the above existing problems, the present application is proposed.
[0007] Therefore, the present application provides a cavitation flow numerical calculation key parameter correction method for the environmental characteristics of high-altitude areas, and proposes a correction method for the cavitation flow numerical calculation key parameters, so as to improve the accuracy of the cavitation flow calculation in high-altitude areas and ensure the rationality of the cavitation calculation of power stations and units.
[0008] To solve the above technical problems, the present application provides the following technical scheme, a cavitation flow numerical calculation key parameter correction method for the environmental characteristics of high-altitude areas, comprising: collecting the measured data of atmospheric pressure at different altitudes, establishing a segmented fitting relationship between the atmospheric pressure and the altitude, and obtaining the actual atmospheric pressure value of the current area of the power station; by collecting water samples on site and measuring cavitation characteristic parameters, combining with the analysis of silt content, the corrected cavitation pressure value suitable for the local environment is obtained; the distribution characteristics of the gas nucleus in the local water body are measured, and the corrected gas nucleus volume fraction and bubble initial radius are obtained; the corrected parameters are substituted into the cavitation model based on the Rayleigh-Plesset equation, and the cavitation flow numerical calculation is carried out.
[0009] As a preferred scheme of the cavitation flow numerical calculation key parameter correction method for the environmental characteristics of high-altitude areas, the method comprises the following steps: obtaining the actual atmospheric pressure value of the current area of the power station, including linearly fitting the measured atmospheric pressure data of different altitude intervals to obtain the corresponding relationship between the atmospheric pressure and the altitude in each altitude interval.
[0010] As a preferred scheme of the cavitation flow numerical calculation key parameter correction method for the environmental characteristics of high-altitude areas, the method comprises the following steps: obtaining the actual atmospheric pressure value of the current area of the power station, including linearly fitting the measured atmospheric pressure data of different altitude intervals to obtain the corresponding relationship between the atmospheric pressure and the altitude in each altitude interval.
[0011] As a preferred scheme of the cavitation flow numerical calculation key parameter correction method for the environmental characteristics of high-altitude areas, the method comprises the following steps: obtaining the actual atmospheric pressure value of the current area of the power station, including linearly fitting the measured atmospheric pressure data of different altitude intervals to obtain the corresponding relationship between the atmospheric pressure and the altitude in each altitude interval.
[0012] As a preferred scheme of the cavitation flow numerical calculation key parameter correction method for the environmental characteristics of high-altitude areas, the method comprises the following steps: obtaining the actual atmospheric pressure value of the current area of the power station, including linearly fitting the measured atmospheric pressure data of different altitude intervals to obtain the corresponding relationship between the atmospheric pressure and the altitude in each altitude interval. wherein, is the initial cavitation pressure of the water body, is the critical cavitation pressure, is the altitude, is a coefficient obtained by experiment; the cavitation pressure of the water body : wherein, N is a cavitation pressure coefficient, and is between 0 and 1; measuring the relationship between the initial and critical cavitation pressure increments Δp of the water sample containing silt relative to the water sample without silt and the silt content Q: wherein, is the cavitation pressure increment of the water sample containing silt relative to the water sample without silt, is a proportional coefficient, is the silt content in the water body, is an intercept; the cavitation pressure results of the water sample caused by the ionizing radiation of cosmic rays and silt are summarized and calculated to obtain the final cavitation pressure of the water sample: wherein, is the water-like cavitation pressure.
[0013] As a preferred scheme of the cavitation flow numerical calculation key parameter correction method for the environmental characteristics of high altitude areas, wherein: the initial bubble radius includes, through high-speed photography technology to shoot bubble image in water, based on image pixel analysis statistics bubble size distribution, the average bubble radius is calculated as the corrected initial bubble radius. Based on the Rayleigh-Plesset equation, the mass transfer process between the gas-liquid two phases in the cavitation process is calculated, and the growth and collapse of a single bubble is expressed by the following formula: wherein, r b is the initial bubble radius, p b is the bubble surface pressure, p is the pressure at infinity, is the liquid density, ν l is the liquid viscosity coefficient, σ is the liquid surface tension coefficient; p b and p v The relative relationship is used to judge the direction of the conversion between the gas-liquid two phases, when p < p v the liquid evaporates and the bubble grows; when p ≥ p v the gas phase condenses.
[0014] As a preferred scheme of the cavitation flow numerical calculation key parameter correction method for the environmental characteristics of high altitude areas, wherein: the cavitation model based on the Rayleigh-Plesset equation includes the Zwart-Gerber-Belamri model based on the Rayleigh-Plesset equation, and the specific expression form is, wherein, m + is the evaporation equation, m - is the condensation equation, F e , F c are the evaporation coefficient and the condensation coefficient respectively, α nuc is the volume fraction of the gas core in water, α vFor the steam volume fraction.
[0015] The application provides a cavitation flow numerical calculation key parameter correction system for environmental characteristics of high-altitude areas.
[0016] As a preferred scheme of the cavitation flow numerical calculation key parameter correction system for environmental characteristics of high-altitude areas, the system comprises an environmental data acquisition module, an experimental analysis and parameter correction module, a gas core characteristic measurement module and a cavitation flow numerical calculation module. The environmental data acquisition module is used to collect measured data of atmospheric pressure at different altitudes, establish a segmented fitting relationship between the atmospheric pressure and the altitude, and obtain an actual atmospheric pressure value of a region where a power station is located. The experimental analysis and parameter correction module is used to collect water samples on site and measure cavitation characteristic parameters of the water samples, analyze silt content, calculate a corrected cavitation pressure value suitable for a local environment based on a relationship between cosmic ray radiation intensity and the altitude and an influence of the silt content on the cavitation pressure. The gas core characteristic measurement module is used to analyze a number and size distribution of bubbles in a local water body by using high-speed photography technology, analyze non-condensed gas content in the water body and a proportion relationship between the number of bubbles at high and low altitudes, and obtain a corrected gas core volume fraction and an initial bubble radius. The cavitation flow numerical calculation module is used to receive the corrected parameters of the modules and substitute the corrected parameters into a cavitation model based on a Rayleigh-Plesset equation, and perform numerical calculation and simulation analysis of cavitation flow.
[0017] The application provides a computer device, which comprises a memory and a processor, the memory stores a computer program, and the processor implements steps of a cavitation flow numerical calculation key parameter correction method for environmental characteristics of high-altitude areas when executing the computer program.
[0018] The application provides a computer readable storage medium, which stores a computer program, and the computer program implements steps of a cavitation flow numerical calculation key parameter correction method for environmental characteristics of high-altitude areas when being executed by a processor.
[0019] The application can obtain accurate unit cavitation performance, improve the accuracy and precision of cavitation-related calculation in the unit design and selection process, avoid problems such as serious unit cavitation or excessive design margin due to inaccurate cavitation performance, such as selecting too low water suction height; based on accurate unit cavitation performance, the influence of unit cavitation and erosion can be more accurately grasped, and unit cavitation protection strategies can be better developed for more effective operation and maintenance; based on high-precision cavitation flow calculation, a unit operation real-time monitoring system based on multi-physical field simulation can be developed, numerical simulation and parameters obtained by sensors in real machine operation are combined, timely and accurate information of unit operation state is obtained by using digital twinning technology, and the operation quality of the unit is ensured and the maintenance efficiency is improved. BRIEF DESCRIPTION OF DRAWINGS
[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.
[0021] Figure 1 A flowchart of a cavitation flow numerical calculation key parameter correction method for environmental characteristics of high-altitude areas provided by an embodiment of the present application.
[0022] Figure 2 A cavitation pressure diagram of water samples at different altitudes of a cavitation flow numerical calculation key parameter correction method for environmental characteristics of high-altitude areas provided by an embodiment of the present application.
[0023] Figure 3 A bubble recognition mode diagram based on high-speed photography technology of a cavitation flow numerical calculation key parameter correction method for environmental characteristics of high-altitude areas provided by an embodiment of the present application. DETAILED DESCRIPTION
[0024] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application will be described in detail below with reference to the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should be within the scope of protection of the present application.
[0025] Embodiment 1, refer to Figure 1 As the first embodiment of the present application, the embodiment provides a cavitation flow numerical calculation key parameter correction method for environmental characteristics of high-altitude areas, comprising: S1: Collect measured atmospheric pressure data at different altitudes, establish a piecewise fitting relationship between atmospheric pressure and altitude, and obtain the actual atmospheric pressure value of the current area of the power station.
[0026] S2: By collecting water samples on-site and measuring cavitation characteristic parameters, combined with sediment content analysis, a corrected cavitation pressure value suitable for the local environment is obtained.
[0027] S3: Measure the distribution characteristics of gas nuclei in local water bodies to obtain the corrected gas nuclei volume fraction and initial bubble radius.
[0028] S4: Substitute the modified parameters into the cavitation model based on the Rayleigh-Plesset equation to perform numerical calculations of cavitation flow.
[0029] It should be noted that the planning and construction of pumped-storage power stations in high-altitude areas has only begun in recent years, and research on cavitation model correction methods for such projects is still limited. There are no precedents for their use in actual engineering calculations. This invention provides a ZGB model correction scheme for high-altitude environments as follows: The atmospheric pressure value of the power station's location is calculated using measured atmospheric pressure values or a more accurate relationship between atmospheric pressure and altitude. Experimental methods are used to sample the power station's drinking water source in the area, measuring the initial and critical cavitation pressure values, and analyzing the sediment content and material composition. Based on the sediment content and material composition, a coefficient N is obtained, and the final cavitation pressure value is calculated. Finally, the average gas nucleus content and size in the water body of the power station's location are measured experimentally, and statistical principles are used to obtain the characteristic gas nucleus volume fraction α and initial gas nucleus radius r for that region, replacing the default values in the cavitation model.
[0030] Example 2, refer to Figure 2 and Figure 3 This is one embodiment of the present invention. Based on the above embodiment, a method for correcting key parameters of cavitation flow numerical calculation for environmental characteristics of high-altitude areas is provided.
[0031] Furthermore, in this embodiment, step S1 collects measured atmospheric pressure data at different altitudes, establishes a piecewise fitting relationship between atmospheric pressure and altitude, and obtains the actual atmospheric pressure value of the current area of the power station. Specific details include: Establish atmospheric pressure p a Correction for the relationship with altitude H. Using existing measured atmospheric pressure values from different regions, the relationship between air pressure and altitude is fitted. Based on existing results, the altitude range of 0-5km is divided into three segments, and each segment is fitted with a linear relationship, as shown in the following formula. This form is more accurate than fitting with the same function form. Where ∇ represents a specific altitude.
[0032] In an optional embodiment, establishing a piecewise fitting relationship between atmospheric pressure and altitude can also be achieved through moving average smoothing fitting. Specifically, the altitude is divided into fixed intervals, and the average atmospheric pressure of each altitude point and all data points within a certain range adjacent to it is calculated. This average value is used as the representative pressure value for that altitude point. Using the smoothed data points, a one-time overall linear regression is performed using the least squares method across the entire 0-5km altitude range, directly obtaining a single linear equation describing the change of atmospheric pressure with altitude.
[0033] In another alternative embodiment, establishing a piecewise fit between atmospheric pressure and altitude can also be achieved through exponential smoothing trend fitting. Specifically, a smoothed value is calculated for each original data point, which is a weighted average of its own observation value and the smoothed value of the previous data point. By adjusting the weighting coefficients, the strength of the smoothing can be controlled, thereby filtering out short-range fluctuations while preserving the overall trend. The new data sequence obtained after exponential smoothing is then subjected to overall linear fitting across the entire 0-5 km altitude range, resulting in a single linear relationship model.
[0034] Furthermore, in this embodiment, step S2 involves collecting water samples on-site and measuring cavitation characteristic parameters, combined with sediment content analysis, to obtain a corrected cavitation pressure value suitable for the local environment. Specific steps include S201-S203: S201: This invention addresses cavitation pressure p v The correction is based on existing experimental conclusions: the ionization intensity of cosmic rays and the sediment content in the water body affect the cavitation pressure p of the water body. v This has the most significant impact because the formation of the intrinsic gas nuclei that cause cavitation occurs is through two pathways: the accumulation of energy from radiation and the carrying of gas through gaps on the surface of solid particles.
[0035] Figure 2 This demonstrates the cavitation pressure p of clear water (which can be considered as water without sediment). v The value increases almost linearly with altitude, which is a result of the increased cosmic ray ionization intensity with increasing altitude. Current experimental measurements involve collecting water samples from various regions, sealing them simply, and then conducting the experiments in laboratories at low altitudes. Differences in transportation and testing environments compared to the actual locations of the water samples inevitably affect the cavitation results, potentially leading to inaccuracies. Therefore, two solutions are proposed: S202: In a low-altitude experimental environment, to simulate the intensity of cosmic ray irradiation in high-altitude areas, the experiment was conducted by continuously irradiating water for a certain period of time. Experiments were conducted directly using experimental equipment set up in high-altitude areas.
[0036] Through experimental measurements, the functional relationships between the initial and critical cavitation pressures pi and pc of sediment-free water bodies and altitude H were obtained: in, The initial pressure of the water body, The critical cavitation pressure, For altitude, The coefficients obtained from the experiment; Cavitation pressure of water: Where N is the cavitation pressure coefficient, which is between 0 and 1; The relationship between cavitation pressure and altitude of sediment-free water samples calculated above is applicable to water samples from different altitude regions and has universal applicability.
[0037] S203: The effect of sediment content on cavitation pressure in water samples is closely related to the size, shape, and hardness of the sediment, therefore specific analysis and calculation are required for different regions. Sediment was collected from local rivers at the power station site, and the relationship between the increase in primary and critical cavitation pressure ∆p of sediment-containing water samples relative to sediment-free water samples and the sediment content Q was measured in the laboratory. in, The cavitation pressure increment of the sediment-containing water sample relative to the sediment-free water sample. This is the proportionality coefficient. The sediment content in the water body. The intercept; Finally, the cavitation pressure results of the water sample caused by both cosmic ionizing radiation and sediment were combined and calculated to obtain the final cavitation pressure of the water sample: in, The cavitation pressure of the water sample.
[0038] In the above methods, the formula for the change in cavitation pressure of water samples caused by cosmic ray radiation is commonly used. Based on existing measurement results, p can be obtained. v The relationship between sediment content and altitude H is discussed, but the impact of sediment content on cavitation pressure requires experimental measurement and analysis specific to each power plant. If analysis results from power plants with similar sediment characteristics are available, their existing data can also be utilized.
[0039] Furthermore, in this embodiment of the application, step S3 measures the distribution characteristics of gas nuclei in the local water body to obtain the corrected gas nuclei volume fraction and the initial radius of the bubbles. Specific steps include S301-S302: S301: Volume fraction α of gas nuclei and bubble radius in water r b Correction. Gas nuclei in water mainly include non-condensable gases, such as oxygen and nitrogen from the air, and water vapor excited by external energy (mainly cosmic rays). Previous correction methods only considered the non-condensable gas portion, using Henry's Law to calculate the volume fraction α1 of non-condensable gases in water, without considering the excited water vapor portion. Since water vapor is difficult to measure, this invention uses a comparative method, employing a high-speed camera and a sheet-light laser to capture the number of bubbles in water bodies at high and low altitudes (simulating high-altitude water bodies in a laboratory by irradiation with X-rays or actual high-altitude water bodies). The ratio k of the number of bubbles in multiple sets of these two types of water bodies is compared. The total number of bubbles α1k is then calculated.
[0040] In an optional embodiment, the total gas nucleus volume fraction can also be calculated using a turbidimeter reading ratio method. Specifically, the turbidity values of the two water bodies are measured separately using a turbidimeter. The turbidimeter provides a reading by measuring the intensity of light scattering by suspended particles (including microbubbles) in the water, which can reflect the overall abundance of gas nuclei in the water to some extent. Multiple sets of turbidity values from the two water bodies are recorded, and their average ratio is calculated. This ratio is used as a proxy parameter for the ratio k of the number of bubbles.
[0041] In another alternative embodiment, the total gas nucleus volume fraction can be calculated using a static image sedimentation analysis ratio method. Specifically, a water sample is injected into a transparent standard graduated cylinder and allowed to stand for a period of time, allowing larger air bubbles to rise and escape, while retaining most of the micro-air nuclei. A single static photograph of the water body in the middle of the graduated cylinder is taken using a standard high-resolution digital camera (non-high-speed) against a dark background with a fixed light source to avoid image blurring caused by rapid bubble movement. The two sets of static images of the water body are then subjected to grayscale and contrast analysis on a computer. It is assumed that the overall intensity of the bright spots representing air nuclei in the image is correlated with the number of air nuclei. The average grayscale or contrast ratio of multiple sets of images is calculated as an estimate of the ratio k of the number of bubbles.
[0042] For bubble radius r b This method uses the pixel count of each bubble image as the basis for determining its size, and finally calculates the average bubble size. , where n is the number of bubbles counted and r is the radius of each bubble. Figure 3 The paper demonstrates a bubble identification method based on high-speed photography for analyzing bubble content and initial radius in water.
[0043] In an optional embodiment, the bubble radius can also be calculated using a fixed sample size, specifically, by pre-setting a fixed and reasonable statistical sample size n. The first 100 well-defined, non-overlapping bubbles are randomly or sequentially selected from the image for analysis. For each selected bubble, its apparent maximum size (e.g., longest and shortest axes) in different directions is measured, and then the arithmetic mean is calculated as the bubble's "equivalent diameter," without strictly fitting its shape to a circle and determining the precise radius.
[0044] In another alternative embodiment, the bubble radius can also be calculated through hierarchical statistics. Specifically, a visual grading method is used to roughly divide the bubbles into 3 to 5 levels according to their size. The approximate number of bubbles in each level is counted. A representative radius value is assigned to each size level, and a weighted average of these representative radii is calculated based on the number of bubbles in each level. This weighted average is taken as the average bubble radius r. b .
[0045] S302: Existing cavitation models are mainly based on the Rayleigh-Plesset equation to calculate the mass transfer process between the gas and liquid phases during cavitation, as shown in the following equation, which can be used to describe the growth and collapse of a single bubble: in, r b Let the initial radius of the bubble be 1. p b The surface pressure of the bubble. p Pressure at infinity For the density of the liquid, ν l Liquid viscosity coefficient, σ It is the surface tension coefficient of the liquid; p b and p v The relative relationship is used to determine the direction of the transition between the gas and liquid phases. p < p v When the liquid evaporates, the bubbles grow; when p ≥ p v At that time, the gas phase condenses.
[0046] Furthermore, in this embodiment, step S4 substitutes the modified parameters into the cavitation model based on the Rayleigh-Plesset equation to perform numerical calculations of cavitation flow. Specific steps include S401-S402: S401: Current calculations typically use the saturated vapor pressure of 20°C water (0.24 mH₂O) as the pressure for the liquid-to-gas phase transition, or take 3540 Pa as the cavitation pressure (the recommended value for cavitation flow calculations in the general-purpose fluid dynamics software ANSYS CFX). Such values have minimal deviation for low-altitude areas, but the actual cavitation pressure deviates significantly from this value as altitude increases. Existing scientific research has demonstrated that the cavitation pressure of water bodies at high altitudes differs significantly from that at low altitudes due to the combined effects of cosmic ray ionization intensity, sediment content, and environmental pressure.
[0047] S402: The Rayleigh-Plesset equation is a widely used equation in engineering to calculate the interphase transition process. The mainstream cavitation models based on it include the Singhal model, the Zwart-Gerber-Belamri model, and the Scherrand-Sauer model, which are currently the three major mainstream cavitation models widely used in academia and engineering. In these mainstream cavitation models, the nucleus volume fraction α and the initial nucleus radius r are the core parameters that determine the initiation and development of cavitation, and have a decisive impact on the calculation results of cavitation flow. Taking the ZGB model as an example, its specific expression is as follows: Where m+ is the evaporation equation, m- is the condensation equation, and F e F c These are the evaporation coefficient and condensation coefficient, typically taken as 50 and 0.01 respectively; p v It is the critical pressure for cavitation, which is generally taken as the saturated vapor pressure at 20°C. α nuc It is the volume fraction of gas nuclei in water. These represent the vapor volume fraction, with default values of 5 × 10⁻⁴ and 10⁻⁶, respectively. Currently, in engineering calculations, these parameters are generally kept at their default values, but the vapor core volume fraction α... nuc The volume fraction of the gas nucleus and the initial radius r of the bubble b It is also closely related to environmental factors. Therefore, when calculating cavitation flow in high-altitude environments, it is necessary to modify the cavitation model to avoid large deviations in the calculation.
[0048] In an optional embodiment, the cavitation model parameters can also be corrected using an empirical lookup table method. Specifically, an empirical database is established to extensively collect and organize published academic literature and engineering reports, containing data on the gas nucleus volume fraction obtained by various methods at different altitudes. This data is then correlated with the corresponding altitudes, summarized, and averaged to create a simple "altitude-recommended gas nucleus volume fraction" lookup table. When performing cavitation flow calculations for a specific power plant, the altitude of the power plant location is first determined. By looking up the table, interpolation is used to determine the corresponding recommended α value at that altitude. nuc value.
[0049] Example 3 is the third embodiment of the present invention, which differs from the previous two embodiments in that: This embodiment also provides a key parameter correction system for numerical calculation of cavitation flow for environmental characteristics of high-altitude areas, including: an environmental data acquisition module, an experimental analysis and parameter correction module, a gas core characteristic measurement module, and a cavitation flow numerical calculation module. The environmental data acquisition module is used to collect measured atmospheric pressure data at different altitudes, establish a piecewise fitting relationship between atmospheric pressure and altitude, and obtain the actual atmospheric pressure value of the area where the power station is located. The experimental analysis and parameter correction module is used to collect water samples on site and measure their cavitation characteristic parameters. Combined with sediment content analysis, based on the relationship between cosmic ray radiation intensity and altitude and the influence of sediment content on cavitation pressure, the module calculates the corrected cavitation pressure value applicable to the local environment. The gas nucleus characteristic measurement module is used to capture and analyze the number and size distribution of bubbles in local water bodies using high-speed photography technology. Combined with the analysis of non-condensable gas content in water and the ratio of the number of bubbles in water bodies at high and low altitudes, the corrected gas nucleus volume fraction and the initial radius of the bubbles are obtained. The cavitation flow numerical calculation module is used to receive the parameters corrected by the above modules, and substitute them into the cavitation model based on the Rayleigh-Plesset equation to perform numerical calculation and simulation analysis of cavitation flow.
[0050] This embodiment also provides an electronic device, including: a memory and a processor; the memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions to realize the method for correcting key parameters of cavitation flow numerical calculation for environmental characteristics of high-altitude areas proposed in the above embodiment.
[0051] This embodiment also provides a storage medium storing a computer program that, when executed by a processor, implements a method for correcting key parameters of cavitation flow numerical calculation for environmental characteristics of high-altitude regions, as proposed in the above embodiment.
[0052] The storage medium proposed in this embodiment and the method for correcting key parameters of cavitation flow numerical calculation for high-altitude environmental characteristics proposed in the above embodiments belong to the same inventive concept. Technical details not described in detail in this embodiment can be found in the above embodiments, and this embodiment has the same beneficial effects as the above embodiments.
[0053] Based on the above description of the implementation methods, those skilled in the art can clearly understand that the present invention can be implemented using software and necessary general-purpose hardware, and of course, it can also be implemented using hardware. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as a computer floppy disk, read-only memory (ROM), random access memory (RAM), flash memory, hard disk, or optical disk, etc., including several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods of the various embodiments of the present invention.
[0054] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.
Claims
1. A method for correcting key parameters in numerical calculation of cavitation flow in high-altitude environments, characterized by: include, Collect measured atmospheric pressure data at different altitudes, establish a piecewise fitting relationship between atmospheric pressure and altitude, and obtain the actual atmospheric pressure value of the current area of the power station. By collecting water samples on-site and measuring cavitation characteristic parameters, combined with sediment content analysis, a corrected cavitation pressure value suitable for the local environment was obtained. The distribution characteristics of gas nuclei in local water bodies were measured to obtain the corrected gas nuclei volume fraction and the initial radius of the bubbles. The modified parameters were substituted into the cavitation model based on the Rayleigh-Plesset equation to perform numerical calculations of cavitation flow.
2. The method for correcting key parameters of cavitation flow numerical calculation for environmental characteristics in high-altitude areas as described in claim 1, characterized in that: The process of obtaining the actual atmospheric pressure value of the current area of the power station includes linearly fitting the measured atmospheric pressure data of different altitude ranges to obtain the correspondence between atmospheric pressure and altitude in each altitude range.
3. The method for correcting key parameters in numerical calculation of cavitation flow for environmental characteristics in high-altitude areas as described in claim 2, characterized in that: The process of obtaining a corrected cavitation pressure value suitable for the local environment involves analyzing the relationship between cosmic ray radiation intensity and altitude, as well as the influence of sediment content and material composition in the water body on cavitation pressure, to comprehensively obtain a cavitation pressure value that reflects the characteristics of the local environment.
4. The method for correcting key parameters in numerical calculation of cavitation flow for high-altitude environments as described in claim 3, characterized in that: The process of obtaining the corrected gas nucleus volume fraction involves comparing the ratio of the number of air bubbles in water bodies at high and low altitudes, and combining this with an analysis of the content of non-condensable gases in the water, to obtain the corrected gas nucleus volume fraction.
5. The method for correcting key parameters in numerical calculation of cavitation flow for high-altitude environments as described in claim 4, characterized in that: The corrected cavitation pressure value includes, through experimental measurements, obtaining the functional relationship between the initial and critical cavitation pressures of sediment-free water bodies and altitude. in, The initial pressure of the water body, The critical cavitation pressure, For altitude, The coefficients obtained from the experiment; Cavitation pressure of water : Where N is the cavitation pressure coefficient, which is between 0 and 1; The relationship between the increase in primary and critical cavitation pressure ∆p of sediment-laden water samples relative to sediment-free water samples and sediment content Q was measured: in, The cavitation pressure increment of the sediment-containing water sample relative to the sediment-free water sample. This is the proportionality coefficient. The sediment content in the water body. The intercept; The cavitation pressure results of the water sample caused by cosmic ionizing radiation and sediment were combined and calculated to obtain the final cavitation pressure of the water sample: in, The cavitation pressure of the water sample.
6. The method for correcting key parameters in numerical calculation of cavitation flow for environmental characteristics in high-altitude areas as described in claim 5, characterized in that: The initial bubble radius is obtained by capturing images of bubbles in water using high-speed photography technology, analyzing and statistically distributing bubble size based on image pixels, and calculating the average bubble radius as the corrected initial bubble radius. The mass transfer process between the gas and liquid phases during cavitation is calculated based on the Rayleigh-Plesset equation, and the growth and collapse of a single bubble are expressed by the following formula: in, r b Let the initial radius of the bubble be 1. p b The surface pressure of the bubble. p Pressure at infinity For the density of the liquid, ν l Liquid viscosity coefficient, σ It is the surface tension coefficient of the liquid; p b and p v The relative relationship is used to determine the direction of the transition between the gas and liquid phases. p < p v When the liquid evaporates, the bubbles grow; when p ≥ p v At that time, the gas phase condenses.
7. The method for correcting key parameters in numerical calculation of cavitation flow for environmental characteristics in high-altitude areas as described in claim 6, characterized in that: The cavitation model based on the Rayleigh-Plesset equations includes the Zwart-Gerber-Belamri model based on the Rayleigh-Plesset equations, specifically expressed as follows: Where, m + For the evaporation equation, m - For the condensation equation, F e F c These are the evaporation coefficient and the condensation coefficient, respectively. α nuc It is the volume fraction of gas nuclei in water. α v This represents the volume fraction of steam.
8. A key parameter correction system for numerical calculation of cavitation flow in high-altitude areas, employing the method for correcting key parameters for numerical calculation of cavitation flow in high-altitude areas as described in any one of claims 1 to 7, characterized in that... include: The module includes an environmental data acquisition module, an experimental analysis and parameter correction module, a gas core characteristic measurement module, and a cavitation flow numerical calculation module. The environmental data acquisition module is used to collect measured atmospheric pressure data at different altitudes, establish a piecewise fitting relationship between atmospheric pressure and altitude, and obtain the actual atmospheric pressure value of the area where the power station is located. The experimental analysis and parameter correction module is used to collect water samples on site and measure their cavitation characteristic parameters. Combined with sediment content analysis, based on the relationship between cosmic ray radiation intensity and altitude and the influence of sediment content on cavitation pressure, it calculates a corrected cavitation pressure value applicable to the local environment. The gas nucleus characteristic measurement module is used to capture and analyze the number and size distribution of bubbles in local water bodies using high-speed photography technology. Combined with the analysis of non-condensable gas content in water and the ratio of the number of bubbles in water bodies at high and low altitudes, the corrected gas nucleus volume fraction and the initial radius of the bubbles are obtained. The cavitation flow numerical calculation module is used to receive the parameters corrected by the above modules, and substitute them into the cavitation model based on the Rayleigh-Plesset equation to perform numerical calculation and simulation analysis of cavitation flow.
9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method for correcting key parameters of cavitation flow numerical calculation for environmental characteristics of high-altitude areas, as described in any one of claims 1 to 7.
10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the method for correcting key parameters of cavitation flow numerical calculation for environmental characteristics of high-altitude areas, as described in any one of claims 1 to 7.