Method and device for simulating cloud cavitation evolution process

Abstract

The present invention provides a method and device for simulating the evolution process of cloud cavitation, which can effectively simulate the transformation from sheet cavitation to cloud cavitation and the growth and collapse processes of cloud cavitation in cavitating flows. The method for simulating the evolution process of cloud cavitation includes: Step 1, setting the initial calculation field; Step 2, calculating the interphase mass transfer rate during the cavitation process through a user-defined function (UDF), using a region to represent the region where sheet cavitation collapses into cloud cavitation, and exporting the grid node position coordinates of this region; Step 3, calculating the mass of non-condensable gas in the bubble and the bubble diameter when sheet cavitation is converted into cloud cavitation through the UDF; Step 4, generating a bubble injection file for the CFD-DPM coupling model through the UDF and setting relevant parameters; Step 5, incrementing the time step by 1, calculating the cloud cavitation flow under CFD-DPM coupling, and simultaneously solving the R-P equation through the UDF to control the change in bubble diameter; Step 6, repeating Steps 2 to 5 until the calculation duration requirement is met.

Description

Technical Field

[0001] The present invention belongs to the technical field of engineering computational fluid dynamics simulation, and particularly relates to a method and device for simulating the evolution process of cloud cavitation. Background Technique

[0002] Cavitation is an important and complex hydrodynamic phenomenon that widely exists in hydraulic machinery, ship propellers, and water conservancy projects, and has always been the focus and difficulty in the field of hydrodynamics research. In complex cavitation flows, according to the cavitation form, it can be divided into sheet cavitation and cloud cavitation. Sheet cavitation is generally harmless, while cloud cavitation will cause severe noise and vibration, and long-term action will also lead to cavitation erosion on the surface of hydraulic machinery, reducing the equipment life. At the same time, the local high temperature, high pressure, and micro-jet effects during the collapse of cloud cavitation can be utilized. For example, aquatic algae, bacteria, etc. can be killed through cavitation, as well as ultrasonic cleaning, etc. Whether it is to reduce the damage of cavitation or study the application of cavitation, it is necessary to deeply analyze the generation, development, and collapse processes of cloud cavitation. However, traditional cavitation models highly depend on the grid size, and the results obtained with different grid sizes are different; moreover, there are defects in the conversion mechanism, and it is impossible to study or can only study the process of a part of large-scale bubbles transforming into cloud cavitation; thus, it is impossible to effectively simulate the generation, development, and collapse processes of cloud cavitation. Summary of the Invention

[0003] The present invention is made to solve the above problems, and aims to provide a method and device for simulating the evolution process of cloud cavitation, which can effectively simulate the transformation from sheet cavitation to cloud cavitation and the growth and collapse processes of cloud cavitation in cavitation flow.

[0004] In order to achieve the above object, the present invention adopts the following solutions:

[0005] <Method>

[0006] As Figure 1 shown, the present invention provides a method for simulating the evolution process of cloud cavitation, which is characterized by including the following steps:

[0007] Step 1, taking the cavitation region represented by the gas volume fraction as the initial calculation field;

[0008] Step 2, calculating the interphase mass transfer rate during the cavitation process through a user-defined function (UDF) Adopting the region representing the area where sheet cavitation collapses into cloud cavitation, and exporting the grid node position coordinates of the region;

[0009] Step 3, calculating the mass of non-condensable gas and the bubble diameter inside the bubble when sheet cavitation is converted into cloud cavitation through UDF; the calculation formulas for the bubble mass and diameter are as follows:

[0010]

[0011]

[0012] Wherein, V is the volume of the grid where it is located, and ρ g is the density of the non-condensable gas, and p g , p v are respectively the partial pressures of the non-condensable gas and the vapor in the bubble; p l is the pressure at the grid where the bubble particles are located; is the liquid surface tension coefficient; R0 is the initial diameter of the bubble; R g is the gas constant; T is the temperature;

[0013] Step 4: Generate a bubble injection file for the CFD-DPM coupling model through UDF and set relevant parameters;

[0014] Step 5: Increment the time step by 1, calculate the cloud cavitation flow under CFD-DPM coupling, and simultaneously solve the R-P equation through UDF to control the change in the bubble diameter;

[0015] Step 6: Repeat Steps 2 to 5 until the calculation duration requirement is met.

[0016] Preferably, the cloud cavitation evolution process simulation method provided by the present invention may further have the following characteristics. In Step 2, The calculation formula is as follows:

[0017]

[0018] When P ≤ P v :

[0019]

[0020] When P ≥ P v :

[0021]

[0022] Wherein, m + , m - are respectively the mass transfer rates of the steam bubble growth and collapse; P v is the saturated vapor pressure of the liquid; P is the far-field pressure; α v is the gas volume fraction at the grid node; R B is the initial particle size of the bubble; F vap is the evaporation coefficient; F cond is the condensation coefficient; α nuc is the volume fraction of nucleation sites; ρ v , ρ lare the densities of the gas phase and the liquid phase, respectively.

[0023] Preferably, the cloud cavitation evolution process simulation method provided by the present invention may further have the following characteristics: In step 4, the particles are regarded as bubbles, and the calculation between CFD and DPM is carried out by one-way coupling without considering the collision between bubbles; the bubble injection adopts the File injection method, and the injection position coordinates and various parameters of the bubbles are defined through a file with the suffix.inj; the DEFINE_ON_DEMAND macro in Fluent is used to calculate and generate the injection file, and the position coordinates are determined by the methods described in steps 2 and 3, and the bubble parameters are calculated.

[0024] Preferably, the cloud cavitation evolution process simulation method provided by the present invention may further have the following characteristics: In step 5, the coupled calculation is carried out. During the calculation process, the change of the bubble diameter is controlled by solving the R-P equation through the UDF macro DEFINE_DPM_LAW.

[0025] Preferably, the cloud cavitation evolution process simulation method provided by the present invention may further have the following characteristics: In step 5, the bubble wall velocity during the growth and collapse of the bubble is obtained by solving the following equation:

[0026]

[0027] where R is the bubble radius, ρ l is the liquid phase density, p ∞ (t) is the ambient pressure at time t, μ is the dynamic viscosity of the liquid phase. In this model, p v is the saturation vapor pressure.

[0028] <Device>

[0029] Furthermore, the present invention also provides a cloud cavitation evolution process simulation device that can automatically implement the above <Method>. It is characterized in that it includes:

[0030] An initial field setting unit that uses the cavitation region represented by the gas volume fraction as the calculation initial field;

[0031] A mass transfer and position setting unit that calculates the interphase mass transfer rate during the cavitation process through a user-defined function UDF Adopt The region represents the region where sheet cavitation collapses into cloud cavitation, and exports The grid node position coordinates of the region;

[0032] A bubble parameter calculation unit that calculates the mass of the non-condensable gas inside the bubble and the bubble diameter when the sheet cavitation is converted into cloud cavitation through UDF; the calculation formulas for the bubble mass and diameter are as follows:

[0033]

[0034] In the formula, V is the volume of the grid where it is located, and ρ g is the density of the non-condensable gas, and p g , p v are the partial pressures of the non-condensable gas and steam in the bubble respectively; p l is the pressure at the grid where the bubble particle is located; is the liquid surface tension coefficient; R0 is the initial diameter of the bubble; R g is the gas constant; T is the temperature;

[0035] The bubble generation setting unit generates a bubble injection file for the CFD-DPM coupling model through UDF and sets relevant parameters;

[0036] The coupling calculation unit increments the time step by 1, calculates the cloud cavitation flow under CFD-DPM coupling, and simultaneously solves the R-P equation through UDF to control the change of the bubble diameter;

[0037] The iteration unit enables the mass transfer and position setting unit, the bubble parameter calculation unit, the bubble generation setting unit, and the coupling calculation unit to continue the loop process (calculate the parameters of subsequent time steps) until the calculation duration requirement is met;

[0038] The control unit is communicatively connected to the initial field setting unit, the mass transfer and position setting unit, the bubble parameter calculation unit, the bubble generation setting unit, the coupling calculation unit, and the iteration unit, and controls their operations.

[0039] Preferably, the cloud cavitation evolution process simulation device provided by the present invention may further include: a dynamic demonstration unit communicatively connected to the control unit, and generating a two-dimensional or three-dimensional dynamic view of the cloud cavitation evolution process according to the cloud cavitation evolution process data obtained by the initial field setting unit, the mass transfer and position setting unit, the bubble parameter calculation unit, the bubble generation setting unit, the coupling calculation unit, and the iteration unit.

[0040] Preferably, the cloud cavitation evolution process simulation device provided by the present invention may further include: an input display unit communicatively connected to the control unit, for allowing a user to input operation instructions and performing corresponding displays.

[0041] Preferably, the cloud cavitation evolution process simulation device provided by the present invention may further have the following feature: in the mass transfer and position setting unit, The calculation formula is as follows:

[0042]

[0043] When P ≤ P v :

[0044]

[0045] When P ≥ P v :

[0046]

[0047] In the formula, m + , m - are the mass transfer rates of steam bubble growth and collapse respectively; P v is the saturation vapor pressure of the liquid; P is the far-field pressure; α v is the gas-phase volume fraction at the grid node; R B is the initial particle size of the bubble; F vap is the evaporation coefficient; F cond is the condensation coefficient; α nuc is the volume fraction of nucleation sites; ρ v , ρ l are the densities of the gas phase and the liquid phase respectively.

[0048] Preferably, the cloud cavitation evolution process simulation device provided by the present invention may further have the following characteristics: In the bubble parameter calculation unit, one-way coupling is used for calculation between CFD and DPM, and the collision between bubbles is not considered; The bubble injection adopts the File injection method, and the injection position coordinates and various parameters of the bubbles are defined through a file with the suffix.inj; The DEFINE_ON_DEMAND macro in Fluent is used to calculate and generate the injection file, and the position coordinates are determined and the bubble parameters are calculated by the methods described in steps 2 and 3.

[0049] Preferably, the cloud cavitation evolution process simulation device provided by the present invention may further have the following characteristics: In the bubble generation setting unit, the bubble wall velocity during the growth and collapse of the bubble is obtained by solving the following equation:

[0050]

[0051] In the formula, R is the bubble radius, ρ l is the liquid phase density, p ∞ (t) is the ambient pressure at time t, μ is the dynamic viscosity of the liquid phase, and in this model, p v is the saturation vapor pressure.

[0052] Functions and effects of the invention

[0053] The cloud cavitation evolution process simulation method and device provided by the present invention fully consider the transformation process from sheet cavitation to cloud cavitation and the development and collapse process of cloud cavitation in cavitation flow, determine the bubble release position, initial bubble diameter and mass, and realize the change of the bubble's own diameter with the ambient pressure and the damage effect of bubble collapse on the surrounding wall surface. The calculation result is independent of the grid size, not affected by the grid size, and can simulate the process of bubble transformation into cloud cavitation at all scales, making up for the deficiency that the existing cavitation model cannot simulate and calculate cloud cavitation. It can obtain a cavitation flow field that more conforms to physical reality, can accurately simulate the generation, development and collapse process of cloud cavitation in cavitation flow, as well as the microscopic mechanism and development process of cloud cavitation, and can be used to quantitatively predict the damage effect of cloud cavitation collapse on surrounding objects, providing new ideas and scientific basis for predicting cavitation damage in fluid machinery, studying the microscopic mechanism of cavitation erosion and its application in practice. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 It is a flow chart of the cloud cavitation evolution process simulation method related to the present invention;

[0055] Figure 2 It is a schematic diagram of the computational domain and related boundary conditions of the jet pump type cavitation generator example related to the embodiment of the present invention;

[0056] Figure 3 It is a schematic diagram of the cloud cavitation bubble diameter distribution of the jet pump type cavitation generator related to the embodiment of the present invention;

[0057] Figure 4 It is a comparison diagram of the cloud cavitation experiment and numerical simulation effects of the jet pump type cavitation generator related to the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0058] The following will describe in detail the specific implementation schemes of the cloud cavitation evolution process simulation method and device related to the present invention with reference to the accompanying drawings.

[0059] <Embodiment>

[0060] As Figure 2 shown, in this embodiment, the example is: the diameter D0 of the jet pump nozzle is 8 mm, the diameter D th of the throat is 16 mm, the length L th of the throat is 96 mm, the diffusion tube angle β is 12°, the working fluid flow rate is 1.74 L / s, the suction fluid flow rate is 1.45 L / s, and the outlet pressure is 129.33 KPa. For this example, the cloud cavitation evolution process simulation method of the present invention is used to simulate the cloud cavitation evolution process, specifically as follows:

[0061] Step 1: Use the cavitation region represented by the gas volume fraction as the initial calculation field.

[0062] The interfacial mass transfer equation of the cavitation model based on the Eulerian view is as follows:

[0063]

[0064] In the formula, the subscript v represents the gas phase; m + and m - are the mass transfer rates of steam bubble growth and collapse respectively; a v is the gas phase volume fraction; ρ v is the density of the gas phase; V v represents the gas phase velocity.

[0065] The ZGB cavitation model is adopted for relevant calculations. In this model, m + and m - are calculated by the following formulas:

[0066] When P ≤ P v :

[0067]

[0068] When P ≥ P v :

[0069]

[0070] In the formula, P v is the saturated vapor pressure of the liquid; P is the far-field pressure at the local grid; R B is the initial particle size of the bubble, taking 10 -6 m; F vap is the evaporation coefficient, taking 50, and F cond is the condensation coefficient, taking 0.01; α nuc is the volume fraction of nucleation sites, taking 5×10 -4 ; ρ v and ρ l are the densities of the gas phase and the liquid phase respectively.

[0071] Step 2: Calculate the interfacial mass transfer rate during the cavitation process through UDF and export the grid node coordinates of the region.

[0072] In the ZGB cavitation model, the interfacial mass transfer rate is used to represent the conversion between the gas phase and the liquid phase. The expression is as follows:

[0073]

[0074] In the formula, m + and m -are the mass transfer rates of steam bubble growth and collapse, respectively. The calculation formulas are shown in formulas (2) and (3).

[0075] The positions represent areas of net reduction of vapor phase in the cavitation region, i.e., areas where sheet cavitation collapses into cloud cavitation, and the subsequent release of gas particles in these areas represents cloud cavitation.

[0076] Step 3: Calculate the mass of non-condensable gas in the bubble and the bubble diameter when sheet cavitation is converted into cloud cavitation through UDF.

[0077] Bubbles composed of non-condensable gases are used to represent cloud cavitation particles, and the content of non-condensable gases released during the collapse of cavitation is calculated.

[0078] The nucleation point volume fraction a is used in the ZGB cavitation model. nuc To indicate the existence of cavitation nuclei, according to the interphase mass transfer rate The definition of and the volume of the grid in which it is located, calculate the mass of the non-condensable gas released in a single grid at time t, as shown below:

[0079]

[0080] In the formula, V represents the volume of the grid, ρ g represents the density of the non-condensable gas, p g 、p v are the partial pressures of the non-condensable gas and vapor in the bubble; p l is the pressure of the liquid outside the bubble, which is the pressure at the grid where the bubble particles are located in the present invention; T is the surface tension coefficient of the liquid; R0 is the initial diameter of the bubble; R g is the gas constant, which is only related to the type of gas. In this example, nitrogen is selected as the non-condensable gas, and the gas constant is 296.8 J / (kg·K); T is the temperature, in K.

[0081] The initial bubble diameter can be calculated by combining equations (6) and (7).

[0082] Step 4: Generate the particle injection file of the CFD-DPM coupling model through UDF and set relevant parameters.

[0083] The calculation is performed using one-way coupling between CFD and DPM (discrete phase model), and the collision between particles (bubbles are regarded as particles) is not considered. The particle injection adopts the file injection method, and the injection position coordinates and various parameters of the particles are defined by the file with the suffix .inj. The DEFINE_ON_DEMAND macro in Fluent is used to calculate and generate the injection file. The calculation method of the injection coordinates and particle parameters can be found in steps 2 and 3.

[0084] Step 5: Increment the time step by 1, calculate the cloud cavitation flow under CFD-DPM coupling, and simultaneously solve the R-P equation (Rayleigh-Plesset equation) through UDF to control the change in bubble diameter.

[0085] The above steps are all setup work before calculation. Step 5 will start the coupled calculation. During the calculation, the change in bubble diameter is controlled by solving the R-P equation through the UDF macro DEFINE_DPM_LAW.

[0086]

[0087] In the formula, R is the bubble radius, ρ l is the liquid-phase density, p ∞ (t) is the ambient pressure at time t, μ is the dynamic viscosity of the liquid phase; in this model, p v is equal to the saturated vapor pressure.

[0088] The algorithm form for solving the above equations is as follows:

[0089]

[0090] In the formula, h R is the step size, i represents the number of equations in the differential equation system. In the present invention, i takes 1, 2. h R is set to 10 - 8 s, and the solution result has the best accuracy.

[0091] Step 6: Repeat Steps 2 to 5 until the required calculation duration is reached.

[0092] All calculation steps in the present invention can be completed in the software Fluent. Since particles (bubbles) are injected at each step during the calculation, the calculation process and parameter settings can be controlled through Fluent text commands.

[0093] In this embodiment, a one-way coupling is adopted between the DPM model and the CFD calculation. The drag force, acceleration force, and fluid inhomogeneity force acting on the particles are all considered. The grid node coordinates of the sheet cavitation collapse position and the mass of the non-condensable gas are calculated and exported. Gas particles are released at the obtained coordinates and the particle size is changed according to the ambient pressure. From Figure 3 It can be seen that the method proposed in the present invention can well simulate the transition from sheet cavitation to cloud cavitation and the change process of the cloud cavitation bubble diameter with the fluid pressure. The bubble has a larger diameter at the initial stage, and as the bubble moves downstream gradually, the bubble diameter in the diffuser tube continuously decreases with the increase in pressure. Figure 4It is a comparison diagram between the numerical simulation results and the experimental measurements. As can be seen from the figure, the numerical method proposed by the present invention can effectively capture the morphology of cloud cavitation, improving the deficiencies of the existing cavitation models.

[0094] In summary, the simulation method for the cloud cavitation evolution process proposed by the present invention can preferably simulate the generation, development and collapse processes of cloud cavitation in cavitation flow, fully considering the influence of non-condensable gas on the cavitation morphology, making up for the shortcoming that traditional cavitation models cannot simulate cloud cavitation, and making the calculated cavitation flow field more in line with physical reality. The present invention provides a new idea for studying the microscopic mechanism of cloud cavitation and predicting the destructive effect of cloud cavitation on surrounding objects.

[0095] Furthermore, in this embodiment, a simulation device for the cloud cavitation evolution process that can automatically implement the above method of the present invention is also provided. The device includes an initial field setting unit, a mass transfer and position setting unit, a bubble parameter calculation unit, a bubble generation setting unit, a coupling calculation unit, an iteration unit, a dynamic demonstration unit, an input display unit, and a control unit.

[0096] The initial field setting unit executes the content described in step 1 above, using the cavitation region represented by the gas volume fraction as the calculation initial field.

[0097] The mass transfer and position setting unit executes the content described in step 2 above, calculating the interphase mass transfer rate during cavitation through a user-defined function UDF. Adopt The region represents the region where sheet cavitation collapses into cloud cavitation, and exports The grid node position coordinates of the region.

[0098] The bubble parameter calculation unit executes the content described in step 3 above, calculating the mass of non-condensable gas in the bubble and the bubble diameter when sheet cavitation is converted into cloud cavitation through UDF.

[0099] The bubble generation setting unit executes the content described in step 4 above, generating a bubble injection file for the CFD-DPM coupling model through UDF and setting relevant parameters.

[0100] The coupling calculation unit executes the content described in step 5 above, adding 1 to the time step, calculating the cloud cavitation flow under CFD-DPM coupling, and simultaneously solving the R-P equation through UDF to control the change of the bubble diameter.

[0101] The iteration unit executes the content described in step 6 above, repeating (looping) steps 2 to 5 until the calculation duration requirement is met.

[0102] The dynamic demonstration unit is communicatively connected to the control unit, and generates a two-dimensional or three-dimensional dynamic view of the cloud cavitation evolution process according to the cloud cavitation evolution process data obtained by the initial field setting unit, the mass transfer and position setting unit, the bubble parameter calculation unit, the bubble generation setting unit, the coupling calculation unit, and the iteration unit.

[0103] The input display unit is communicatively connected to the control unit, and is used for allowing a user to input operation instructions and performing corresponding displays. For example, the input, output data, and processing processes of each unit are displayed in the form of text, tables, or graphs.

[0104] The control unit is communicatively connected to the initial field setting unit, the mass transfer and position setting unit, the bubble parameter calculation unit, the bubble generation setting unit, the coupling calculation unit, the iteration unit, the dynamic demonstration unit, and the input display unit, and controls their operations.

[0105] The above embodiments are merely illustrative examples of the technical solutions of the present invention. The cloud cavitation evolution process simulation method and device involved in the present invention are not limited solely to the content described in the above embodiments, but are subject to the scope defined by the claims. Any modifications, supplements, or equivalent replacements made by those skilled in the art to the present invention on the basis of this embodiment are within the scope protected by the claims of the present invention.

Claims

1. A method for simulating the evolution process of cloud cavitation, characterized in that, It includes the following steps: Step 1: Use the cavitation region expressed by the gas-phase volume fraction as the initial field for calculation; Step 2, calculate the interphase mass transfer rate during the cavitation process through the user-defined function UDF , adopt The region represents the region where sheet cavitation collapses into cloud cavitation, and export The grid node position coordinates of the region; Step 3: Calculate the mass of the non-condensable gas in the bubble and the bubble diameter when sheet cavitation is converted into cloud cavitation through UDF; the calculation formulas for the bubble mass and diameter are as follows: （3-1） （3-2） （3-3） In the formula, V is the volume of the grid where it is located, is the density of the gas phase, is the volume fraction of nucleation sites, is the density of the non-condensable gas, 、 are the partial pressures of the non-condensable gas and vapor in the bubble, respectively; is the pressure at the grid where the bubble particles are located; is the liquid surface tension coefficient; is the initial diameter of the bubble; is the gas constant; T is the temperature; Step 4: Generate the bubble injection file for the CFD-DPM coupling model through UDF and set the relevant parameters; Step 5: Increment the time step by 1, calculate the cloud cavitation flow under CFD-DPM coupling, and at the same time solve the R-P equation through UDF to control the change of the bubble diameter; Step 6: Repeat Step 2 to Step 5 until the calculation duration requirement is met.

2. The method for simulating the cloud cavitation evolution process according to claim 1, characterized in that: Among them, In step 2, The calculation formula is as follows: （2-1） When : （2-2） When : （2-3） Wherein, and are the mass transfer rates of steam bubble growth and collapse, respectively; is the saturated vapor pressure of the liquid; is the far-field pressure; is the gas-phase volume fraction at the grid node; is the initial particle size of the bubble; is the evaporation coefficient; is the condensation coefficient; is the nucleation site volume fraction; and are the densities of the gas phase and the liquid phase, respectively.

3. The method for simulating the cloud cavitation evolution process according to claim 1, characterized in that: Among them, In Step 4, one-way coupling is used for calculation between CFD and DPM, and the collision between bubbles is not considered; the bubble injection adopts the File injection method, and the injection position coordinates and various parameters of the bubbles are defined through the file with the suffix.inj; the DEFINE_ON_DEMAND macro in Fluent is used to calculate and generate the injection file, and the method described in Step 2 and Step 3 is used to determine the position coordinates and calculate the bubble parameters.

4. The method for simulating the cloud cavitation evolution process according to claim 1, characterized in that: Among them, In Step 5, coupling calculation is performed. During the calculation process, the R-P equation is solved through the UDF macro DEFINE_DPM_LAW to control the change of the bubble diameter.

5. The method for simulating the cloud cavitation evolution process according to claim 1, characterized in that: Among them, In Step 5, the bubble wall velocity during the growth and collapse process of the bubble is obtained by solving the following equation: （5） In the formula, is the bubble radius, is the liquid-phase density, is the ambient pressure at time t, μ is the dynamic viscosity of the liquid phase. In this model, is the saturation vapor pressure.

6. Cloud cavitation evolution process simulation device, characterized in that, It includes: Initial field setting part: Use the cavitation region expressed by the gas-phase volume fraction as the initial field for calculation; Mass transfer and position setting section, which calculates the interfacial mass transfer rate during cavitation through a user-defined function (UDF). , and uses the region to represent the region where sheet cavitation collapses into cloud cavitation, and exports the grid node position coordinates of the region; Bubble parameter calculation part: Calculate the mass of the non-condensable gas in the bubble and the bubble diameter when sheet cavitation is converted into cloud cavitation through UDF; the calculation formulas for the bubble mass and diameter are as follows: （3-1） （3-2） （3-3） In the formula, V is the volume of the grid where it is located, is the density of the gas phase, is the volume fraction of nucleation sites, is the density of the non-condensable gas, and are the partial pressures of the non-condensable gas and vapor in the bubble, respectively; is the pressure at the grid where the bubble particles are located; is the liquid surface tension coefficient; is the initial diameter of the bubble; is the gas constant; T is the temperature; Bubble generation setting part: Generate the bubble injection file for the CFD-DPM coupling model through UDF and set the relevant parameters; Coupling calculation part: Increment the time step by 1, calculate the cloud cavitation flow under CFD-DPM coupling, and at the same time solve the R-P equation through UDF to control the change of the bubble diameter; Iteration part: Make the mass transfer and position setting part, the bubble parameter calculation part, the bubble generation setting part, and the coupling calculation part perform cyclic processing until the calculation duration requirement is met; Control part: Communicates and is connected to the initial field setting part, the mass transfer and position setting part, the bubble parameter calculation part, the bubble generation setting part, the coupling calculation part, and the iteration part, and controls their operations.

7. The cloud cavitation evolution process simulation device according to claim 6, characterized in that, It further includes: Dynamic demonstration part: Communicates and is connected to the control part, and generates a two-dimensional or three-dimensional dynamic view of the cloud cavitation evolution process according to the cloud cavitation evolution process data obtained by the initial field setting part, the mass transfer and position setting part, the bubble parameter calculation part, the bubble generation setting part, the coupling calculation part, and the iteration part.

8. The cloud cavitation evolution process simulation device according to claim 6, characterized in that, It further includes: An input display unit, communicatively connected to the control unit, is configured to enable a user to input an operation instruction and perform corresponding display.

9. The cloud cavitation evolution process simulation device according to claim 6, wherein: Among them, In the bubble parameter calculation unit, one-way coupling is adopted between CFD and DPM for calculation, and the collision between bubbles is not considered; the bubble injection adopts the File injection method, and the injection position coordinates and various parameters of the bubbles are defined through a file with the suffix.inj; the DEFINE_ON_DEMAND macro in Fluent is used to calculate and generate the injection file, and the methods described in steps 2 and 3 are used to determine the position coordinates and calculate the bubble parameters.

10. The cloud cavitation evolution process simulation device according to claim 6, wherein: Among them, In the bubble generation setting unit, the bubble wall velocity during the growth and collapse processes of the bubbles is obtained by solving the following equation: （5） In the formula, is the bubble radius, is the liquid phase density, is the environmental pressure at time t, μ is the dynamic viscosity of the liquid phase. In this model, is the saturated vapor pressure.

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