CN116070540A

CN116070540A - Method, system and related device for determining flow field parameters of compressible two-phase flow

Info

Publication number: CN116070540A
Application number: CN202211620787.2A
Authority: CN
Inventors: 陈伟; 喻岩; 李东坡; 乔骄; 柯玉祥; 王一淼
Original assignee: Avic Chengdu Uav System Co ltd
Current assignee: Avic Chengdu Uav System Co ltd
Priority date: 2022-12-15
Filing date: 2022-12-15
Publication date: 2023-05-05

Abstract

The application discloses a method, a system and a related device for determining flow field parameters of compressible two-phase flow, and belongs to the technical field of two-phase flow analysis. The method for determining the flow field parameters of the compressible two-phase flow comprises the following steps: dividing a target flow field into a plurality of tetrahedral units, and initializing the target flow field; determining a flow control equation of a target flow field, and performing space discrete operation and time discrete operation on the flow control equation; solving a flow control equation subjected to space discrete operation and time discrete operation, and processing an interface unit by a real virtual fluid method to further generate flow field information of a target flow field at the next moment; and solving the discrete VOF transport equation so as to determine the two-phase flow interface of the target flow field at the next moment. The method and the device can reduce the iteration times and the calculated amount for determining the flow field parameters of the compressible two-phase flow and improve the conservation in the calculation of the compressible two-phase flow.

Description

Method, system and related device for determining flow field parameters of compressible two-phase flow

Technical Field

The present disclosure relates to the field of two-phase flow analysis, and in particular, to a method, a system, and a related device for determining flow field parameters of a compressible two-phase flow.

Background

Two-phase flow is a research hotspot in computational fluid mechanics, wherein compressible two-phase flow plays an important role in many fields, such as underwater ignition of missiles, underwater explosion, supercavitation of high-speed underwater vehicles and other scenes, and flow field parameters of the compressible two-phase flow need to be analyzed.

At present, a Level-set capturing interface is mainly used for determining flow field parameters in the related technology, although the method can better capture discontinuities, the conservation is poor, large volume loss is usually caused after a plurality of iterations, the Level-set function needs to be reinitialized after each iteration, the calculated amount is large, and if phenomena such as crushing, fusion and the like occur on the interface in calculation, the Level-set method is difficult to capture accurately.

Therefore, how to reduce the number of iterations and the amount of computation for determining the flow field parameters of the compressible two-phase flow and to improve the conservation in the computation of the compressible two-phase flow are technical problems that a person skilled in the art needs to solve at present.

Disclosure of Invention

The invention aims to provide a method for determining flow field parameters of a compressible two-phase flow, a system for determining flow field parameters of the compressible two-phase flow, a storage medium and electronic equipment, which can reduce the iteration times and the calculated amount for determining the flow field parameters of the compressible two-phase flow and improve the conservation in the calculation of the compressible two-phase flow.

In order to solve the above technical problems, the present application provides a method for determining flow field parameters of a compressible two-phase flow, the method comprising:

step 1: determining a target flow field of a target object when the target object moves in the compressible two-phase fluid;

step 2: dividing the target flow field into a plurality of tetrahedral units, and initializing the target flow field at T _n Flow field information and volume fraction of moment;

step 3: determining a flow control equation of the target flow field, and performing space discrete operation and time discrete operation on the flow control equation;

step 4: solving a flow control equation passing through the space discrete operation and the time discrete operation to obtain a flow control equation in T _n Flux on the control plane of the time of day non-interface unit; wherein the non-interface unit is not positioned in the target flow field at T _n Tetrahedral units of the two-phase flow interface at the moment;

step 5: processing the interface unit by a real virtual fluid method and solving at T _n Flux on the control surface of the interface unit at the moment; wherein the interface unit is positioned at the T of the target flow field _n Tetrahedral units of the two-phase flow interface at the moment;

step 6: according to T _n Generating the target flow field at T by the flux on the control surfaces of the non-interface unit and the interface unit at the moment _n+1 Flow field information of moment;

step 7: solving a discrete VOF transport equation to obtain T of all tetrahedral units _n+1 Determining the volume fraction and the interfacial normal vector of the moment, and determining the T of the target flow field according to the volume fraction and the interfacial normal vector _n+1 A two-phase flow interface at a moment;

step 8: judging whether an iteration termination condition is reached; if yes, outputting the T _n+1 Flow field information of time and the T _n+1 A two-phase flow interface at a moment; if not, adding 1 to the value of n, and proceeding to step 4.

Optionally, performing a spatial discrete operation and a time discrete operation on the flow control equation includes:

performing space discrete operation on the flow control equation by a finite volume method;

the flow control equation is time-discrete operated by the second order finger-Kutta method.

Optionally, solving a flow control equation through the spatially discrete operation and the time discrete operation to obtain a value at T _n Flux on the control surface of the time of day non-interface cell, comprising:

solving a flow control equation through the space discrete operation and the time discrete operation by an AUSM+ -UP method to obtain a flow control equation in T _n And the flux on the control surface of the non-interface unit at the moment.

Optionally, the interface unit is processed by a real virtual fluid method and solved at T _n The flux on the control surface of the interface unit at the moment comprises:

and carrying out interface boundary processing on the interface unit by a real virtual fluid method, and solving the flux on the control surface of the interface unit by using an interface boundary processing result.

Optionally, the solution of the discretized VOF transport equation obtains all tetrahedral units at T _n+1 The volume fraction of time and the interfacial normal vector include:

solving a discrete VOF transport equation to obtain the volume flux of the control surface of the tetrahedral unit;

solving the tetrahedral unit at T according to the volume flux of the control surface of the tetrahedral unit _n+1 A volume fraction of time;

according to the tetrahedral unit at T _n+1 Solving the volume fraction of the moment to obtain the T of the tetrahedron unit _n+1 Interfacial normal vector of time.

Optionally, the determining whether the iteration termination condition is met includes:

judgment T _n Whether the moment is a preset moment or not; t (T) _n+1 And T is _n The difference value of (2) is an iteration period;

if yes, judging that the iteration termination condition is reached;

if not, judging that the iteration termination condition is not met.

Optionally, the determining the target flow field of the target object when moving in the compressible two-phase fluid includes:

determining a target flow field of the propeller when the propeller moves in the compressible two-phase fluid; wherein the compressible two-phase fluid is water and air, respectively;

correspondingly, at the output of the T _n+1 Flow field information of time and the T _n+1 After the two-phase flow interface at the moment, the method further comprises:

according to said T _n+1 Flow field information of time and the T _n+1 Calculating the mechanical damage grade of the propeller at the moment through a two-phase flow interface;

and adjusting the blade shape of the propeller according to the mechanical damage level.

The application also provides a flow field parameter determination system of a compressible two-phase flow, the system comprising:

the flow field determining module is used for determining a target flow field when a target object moves in the compressible two-phase fluid;

an initialization module for dividing the target flow field into a plurality of tetrahedral units and initializing the target flow field at T _n Flow field information and volume fraction of moment;

the discrete processing module is used for determining a flow control equation of the target flow field and performing space discrete operation and time discrete operation on the flow control equation;

A first flux determination module for solving a flow control equation through the spatially discrete operation and the time discrete operation to obtain a flux value at T _n Flux on the control plane of the time of day non-interface unit; wherein the non-interface unit is not positioned in the target flow field at T _n Tetrahedral units of the two-phase flow interface at the moment;

a second throughput determination module for passing trueReal virtual fluid method processes interface unit and solves at T _n Flux on the control surface of the interface unit at the moment; wherein the interface unit is positioned at the T of the target flow field _n Tetrahedral units of the two-phase flow interface at the moment;

a flow field information updating module for updating the flow field information according to the time of T _n Generating the target flow field at T by the flux on the control surfaces of the non-interface unit and the interface unit at the moment _n+1 Flow field information of moment;

an interface updating module for solving the discretized VOF transport equation to obtain all tetrahedral units in T _n+1 Determining the volume fraction and the interfacial normal vector of the moment, and determining the T of the target flow field according to the volume fraction and the interfacial normal vector _n+1 A two-phase flow interface at a moment;

the iteration judging module is used for judging whether an iteration termination condition is reached; if yes, outputting the T _n+1 Flow field information of time and the T _n+1 A two-phase flow interface at a moment; if not, adding 1 to the value of n, and entering the processing flow of the discrete processing module.

The present application also provides a storage medium having stored thereon a computer program which, when executed, performs the steps performed by the flow field parameter determining method for compressible two-phase flow described above.

The application also provides electronic equipment, which comprises a memory and a processor, wherein the memory stores a computer program, and the processor realizes the steps executed by the flow field parameter determining method of the compressible two-phase flow when calling the computer program in the memory.

The application provides a flow field parameter determining method of a compressible two-phase flow, which comprises the following steps: step 1: determining a target flow field of a target object when the target object moves in the compressible two-phase fluid; step 2: dividing the target flow field into a plurality of tetrahedral units, and initializing the target flow field at T _n Flow field information and volume fraction of moment; step 3: determining a flow control equation of the target flow field, and performing space discrete operation and time on the flow control equationPerforming discrete operation; step 4: solving a flow control equation passing through the space discrete operation and the time discrete operation to obtain a flow control equation in T _n Flux on the control plane of the time of day non-interface unit; wherein the non-interface unit is not positioned in the target flow field at T _ni Tetrahedral units of the two-phase flow interface at the moment; step 5: processing the interface unit by a real virtual fluid method and solving at T _n Flux on the control surface of the interface unit at the moment; wherein the interface unit is positioned at the T of the target flow field _n Tetrahedral units of the two-phase flow interface at the moment; step 6: according to T _n Generating the target flow field at T by the flux on the control surfaces of the non-interface unit and the interface unit at the moment _n+1 Flow field information of moment; step 7: solving a discrete VOF transport equation to obtain T of all tetrahedral units _n+1 Determining the volume fraction and the interfacial normal vector of the moment, and determining the T of the target flow field according to the volume fraction and the interfacial normal vector _n+1 A two-phase flow interface at a moment; step 8: judging whether an iteration termination condition is reached; if yes, outputting the T _n+1 Flow field information of time and the T _n+1 A two-phase flow interface at a moment; if not, adding 1 to the value of n, and proceeding to step 4.

After determining a target flow field when a target object moves in compressible two-phase fluid, the method divides the target flow field into a plurality of tetrahedral units and initializes the target flow field. After initializing a target flow field, determining flow field information and a two-phase flow interface at each moment in an iterative calculation mode, and solving a flow control equation subjected to space discrete operation and time discrete operation in an iterative process to obtain a flow control equation in T _n Flux on the control plane of the time of day non-interface unit; the application also processes the interface unit by a real virtual fluid method and solves the problem at T _n Flux on the control surface of the interface unit at the moment to further obtain the target flow field at T _n+1 The time flow field information is also solved by the application for the discrete VOF transport equation to obtain all tetrahedral units in T _n+1 Time of day bodyThe integration number and the interfacial normal vector are used for determining the T of the target flow field according to the volume fraction and the interfacial normal vector _n+1 A two-phase flow interface at time. The iteration process combines the VOF method with the real virtual flow method, and solves the compressible two-phase flow. Compared with a compressible two-phase flow algorithm based on a Level-set method in the related art, the method simplifies the calculation process, improves the processing capacity of interface fusion and interface crushing, and therefore, the method can reduce the iteration times and the calculation amount for determining the flow field parameters of the compressible two-phase flow and improves the conservation in the calculation of the compressible two-phase flow. The application also provides a flow field parameter determining system of a compressible two-phase flow, a storage medium and an electronic device, which have the beneficial effects and are not repeated here.

Drawings

For a clearer description of the embodiments of the present application, the drawings that are needed in the embodiments will be briefly described, it being apparent that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

Fig. 1 is a flow chart of a method for determining flow field parameters of a compressible two-phase flow according to an embodiment of the present application;

FIG. 2 is a schematic diagram of a high-level format structure according to an embodiment of the present application;

fig. 3 is a schematic solution diagram of a normal direction of a VOF interface according to an embodiment of the present application;

FIG. 4 is a schematic diagram illustrating a classification of an interface unit according to an embodiment of the present disclosure;

FIG. 5 is a schematic diagram of an interface volume flux solution provided in an embodiment of the present application;

FIG. 6 is a schematic diagram illustrating the establishment of two-phase flow interface boundary conditions according to an embodiment of the present disclosure;

FIG. 7 is a schematic illustration of a virtual fluid architecture according to an embodiment of the present disclosure;

FIG. 8 is a schematic diagram of an interface capturing effect recovered after spherical deformation according to an embodiment of the present application;

FIG. 9 is a schematic diagram illustrating an interface capturing effect of spherical shear deformation according to an embodiment of the present disclosure;

FIG. 10 is a graph showing the results of the numerical values of the shock tube in the density dimension and the exact solution according to the embodiment of the present application;

FIG. 11 is a graph showing the results of the water shock tube values in the pressure dimension versus the exact solution provided in the embodiments of the present application;

FIG. 12 is a graph showing the results of the values of the shock tube in the velocity dimension and the exact solution according to the embodiment of the present application;

FIG. 13 is a shock wave and helium bubble interaction interface contour plot provided in an embodiment of the present application;

fig. 14 is a cross-sectional density cloud of symmetric interactions between shock waves and helium bubbles according to an embodiment of the present application.

Detailed Description

For the purposes of making the objects, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is apparent that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the present disclosure, are within the scope of the present disclosure.

Referring now to fig. 1, fig. 1 is a flowchart of a method for determining flow field parameters of a compressible two-phase flow according to an embodiment of the present application.

The specific steps may include:

s101: determining a target flow field of a target object when the target object moves in the compressible two-phase fluid;

the present embodiment can be applied to a computer having a hydrodynamic computing function. The target object can be a missile, a propeller, an aircraft and the like, the compressible two-phase fluid is a flow system consisting of two compressible fluids, and the compressible two-phase fluid comprises a main-phase fluid and a secondary-phase fluid. The fluid in the compressible two-phase fluid may be: any two of water, air, nitrogen, oxygen, carbon dioxide, gasoline, liquid metal, and the like.

When the target object moves in the compressible two-phase fluid, a compressible two-phase flow field is formed, and the compressible two-phase flow field in the specific area can be selected as the target flow field.

S102: dividing the target flow field into a plurality of tetrahedral units, and initializing the target flow field at T _n Flow field information and volume fraction of moment;

after the target flow field is determined, the embodiment may divide the target flow field to obtain a plurality of tetrahedral units. As a possible implementation, the present embodiment may divide the target flow field into a plurality of tetrahedral units having the same shape and size.

The embodiment can also initialize the target flow field at T _n The flow field information at the moment comprises information of density, pressure, speed and the like, the volume fraction is used for describing flow field attributes (primary phase fluid or secondary phase fluid) of the tetrahedron units, and the flow field attributes are used for describing that the tetrahedron units are tetrahedron units corresponding to the primary phase fluid or tetrahedron units corresponding to the secondary phase fluid. The flow field information and volume fraction are collectively referred to as flow field parameters.

As a possible implementation manner, the embodiment can determine T through the movement speed of the target object and the environmental flow field parameters of the compressible two-phase fluid _n Initializing an initial value of a target flow field at time, and initializing the target flow field at T based on the initial value _n Flow field information and volume fraction of time. The n represents the sequence number of the update time, and the T corresponding to the flow field information and the volume fraction is initialized _n Time instant, i.e. initial time instant T ₁ 。

The target flow field comprises a main phase fluid and a secondary phase fluid, the flow field information is initialized, namely flow field information (such as speed, density and pressure) is assigned to each tetrahedron unit, and meanwhile volume fraction is assigned to each unit, wherein the volume fraction of the main phase fluid is assigned to 1, the volume fraction of the secondary phase fluid is assigned to 0, and the rest flow field information is given according to the true numerical value of the flow field where the tetrahedron unit is located at the initial moment.

S103: determining a flow control equation of the target flow field, and performing space discrete operation and time discrete operation on the flow control equation;

in this embodiment, an Euler equation may be selected as a flow control equation of the target flow field, so that a space discrete operation and a time discrete operation are performed on the flow control equation, thereby converting the solution of the flow control equation into the solution of the flux on the control plane of the unit.

S104: solving a flow control equation passing through the space discrete operation and the time discrete operation to obtain a flow control equation in T _n Flux on the control plane of the time of day non-interface unit;

the embodiment can determine the two-phase flow interface of the target flow field, and further solve the flow control equation subjected to the space discrete operation and the time discrete operation to obtain the flow control equation in T _n Flux on the control plane of the time of day non-interface cell. The two-phase flow interface is the interface between the primary phase fluid and the secondary phase fluid in the target flow field. The control surface refers to the surface of the tetrahedral unit, and the flux of the control surface includes velocity flux, density flux, pressure flux, and the like.

Specifically, in this embodiment, the solution of the flow control equation through the space discrete operation and the time discrete operation may be performed by the ausm+ -UP method, so as to obtain the flow control equation at T _n And the flux on the control surface of the non-interface unit at the moment. The ausm+ -UP method is an improvement of the windward vector flux split format (AUSM), i.e. a dissipative term is added to the traditional AUSM format.

The tetrahedral unit in the target flow field comprises a non-interface unit and an interface unit, wherein the non-interface unit is not positioned in the target flow field at T _n Tetrahedral units of the two-phase flow interface at the moment; the interface unit is positioned at the T of the target flow field _n Tetrahedral units of the two-phase flow interface at the moment. The present embodiment can be based on the flow field genusDetermining interface unit, and solving the space discrete and time discrete flow control equation to obtain T _n And the flux on the control surface of the non-interface unit in the target flow field at the moment.

S105: processing the interface unit by a real virtual fluid method and solving at T _n Flux on the control surface of the interface unit at the moment;

the method comprises the steps of processing an interface unit in a target flow field by a real virtual fluid method, and then carrying out flux solution on a control surface of the interface unit to obtain a target flow field in T _n And the flux on the control surface of the interface unit at the moment. Specifically, in this embodiment, the interface boundary processing may be performed on the interface unit by using a real virtual fluid method, and the flux on the control surface of the interface unit may be solved by using the result of the interface boundary processing.

S106: according to T _n Generating the target flow field at T by the flux on the control surfaces of the non-interface unit and the interface unit at the moment _n+1 Flow field information of moment;

after T has been solved for _n Based on the flux of the control surface of the time non-interface unit, can be combined with T _n Obtaining T from flux on control surface of interface unit _n Flux of all tetrahedral units in the time target flow field, and then according to T _n The flux of all tetrahedral units in the moment target flow field is obtained in T _n+1 Flow field information of time. T (T) _n+1 Time is T _n Time next to time, T _n+1 Time and T _n The time difference of the moments is an iterative period (e.g., 1 millisecond or 10 milliseconds) of the flow field parameters.

Updating of flow field information can be achieved through the operations of S104, S105 and S106, namely: will T _n The flow field information at the moment is updated to be T _n+1 Flow field information of time.

S107: solving a discrete VOF transport equation to obtain T of all tetrahedral units _n+1 Determining the volume fraction and the interfacial normal vector of the moment, and determining the T of the target flow field according to the volume fraction and the interfacial normal vector _n+1 Two phases of timeA flow interface;

wherein, the target flow field can also be at T before the step _n And dispersing the VOF transport equation at the moment to obtain a discrete form of the VOF transport equation, so that the solution of the VOF transport equation is converted into the solution of the volume flux flowing through each control surface of the unit.

The step can solve the discretized VOF transport equation to obtain all tetrahedral units in T _n+1 The volume fraction of the time and the interfacial normal vector. Specifically, the volume flux of the control surface can be solved in the step, and T is obtained according to the solving result of the volume flux _n+1 The volume fraction of each tetrahedron unit at the moment, then solving the normal vector of the interface in the interface unit according to the volume fraction of each tetrahedron unit, and reconstructing T according to the normal vector and the volume fraction of the interface in the interface unit _n+1 The two-phase flow interface (i.e., the interface of two fluids) at the moment.

Updating of the two-phase flow interface can be achieved by the operation of S107, namely: will T _n Updating the two-phase flow interface at the moment to T _n+1 A two-phase flow interface at time.

S108: judging whether an iteration termination condition is reached; if yes, go to step S109; if not, 1 is added to the value of n, and the process proceeds to S104.

The step may determine whether the current iteration state reaches an iteration termination condition, where the iteration termination condition may be a time termination condition or a frequency termination condition. Specifically, the embodiment can judge the time T corresponding to the current updated flow field information and the two-phase flow interface _n Whether it is a preset time (or later); if yes, judging that the current iteration state reaches an iteration termination condition; if not, judging that the current iteration state does not reach the iteration termination condition. The embodiment can judge whether the iteration times of the current updated flow field information and the two-phase flow interface are preset times (or more than the preset times); if yes, judging that the current iteration state reaches an iteration termination condition; if not, judging that the current iteration state does not reach the iteration termination condition.

Specifically, if the iteration termination condition is not met, the flow field attribute (i.e. belonging to the primary phase fluid or belonging to the secondary phase fluid) of each unit after the solution can be determined according to the volume fraction value obtained in the iteration termination condition.

S109: outputting the T _n+1 Flow field information of time and the T _n+1 A two-phase flow interface at a moment;

wherein, T is obtained _n+1 After the flow field information and the two-phase flow interface are obtained at the moment, the embodiment can analyze the motion state of the target object by utilizing the flow field information and the two-phase flow interface to obtain the motion state analysis result of the target object.

Specifically, in a scene in the missile underwater gas jet (namely, the target object is a missile), gas bubbles can be generated in water (at the moment, compressible two-phase fluid comprises water and gas bubbles), pressure oscillation and other accidents can be caused by the action of a complex wave system structure in the gas bubbles, change information of the gas bubbles can be determined according to flow field information obtained through iteration and two-phase flow interfaces, and then corresponding adjustment (such as adjustment of depth when the missile is ignited and launched underwater) is performed on the missile according to the change information.

In an underwater navigation body scene (i.e. the target object is a navigation body), drag reduction can be achieved through active ventilation (at the moment, the compressible two-phase fluid comprises water and bubbles), package distribution information of the bubbles on the navigation body can be determined according to flow field information obtained through iteration and two-phase flow interfaces, and then ventilation of the navigation body can be adjusted according to the package distribution information.

In a scenario where a ship sails in water through a propeller (i.e., a target object is the propeller), small bubbles are generated around the propeller when the propeller rotates and collapse rapidly (at this time, the compressible two-phase fluid comprises water and bubbles), the propeller is mechanically damaged under the conditions, and the damage level of the propeller can be determined according to flow field information obtained through iteration and a two-phase flow interface, so that the blade shape of the propeller is optimized. Specifically, the present embodiment may determine a target flow field of the propeller as it moves in the compressible two-phase fluid; wherein the compressible two-phase fluid is water and air, respectively; at the output of the T _n+1 Flow field information of time and the methodT _n+1 After the two-phase flow interface at the moment, the T can be also adopted _n+1 Flow field information of time and the T _n+1 Calculating the mechanical damage grade of the propeller at the moment through a two-phase flow interface; and adjusting the blade shape of the propeller according to the mechanical damage level. The mechanical damage grade is used for describing the damage degree of the compressible two-phase fluid, and the blade shape corresponding to each mechanical damage grade can be preset in the embodiment, so that the blade shape of the propeller is determined and adjusted based on the corresponding relation; specifically, the present embodiment can adjust the blade type shape of the propeller in the design file of the propeller so as to produce the propeller according to the design file.

After determining a target flow field when a target object moves in a compressible two-phase fluid, the embodiment divides the target flow field into a plurality of tetrahedral units and initializes the target flow field. After initializing a target flow field, the embodiment determines flow field information and two-phase flow interface at each moment in an iterative calculation mode, and solves a flow control equation subjected to space discrete operation and time discrete operation in an iterative process to obtain a flow control equation at T _n Flux on the control plane of the time of day non-interface unit; the present embodiment also processes the interface element by a true virtual fluid method and solves at T _n Flux on the control surface of the interface unit at the moment to further obtain the target flow field at T _n+1 The embodiment also solves the discrete VOF transport equation to obtain all tetrahedral units in T according to the flow field information at the moment _n+1 Determining the volume fraction and the interfacial normal vector of the moment, and determining the T of the target flow field according to the volume fraction and the interfacial normal vector _n+1 A two-phase flow interface at time. The iteration process combines the VOF method with the real virtual flow method, and solves the compressible two-phase flow. Compared with a compressible two-phase flow algorithm based on a Level-set method in the related art, the method simplifies the calculation process, improves the processing capacity of interface fusion and interface crushing, and therefore, the method can reduce the iteration times and the calculation amount for determining the flow field parameters of the compressible two-phase flow, and provides Conservation in highly compressible two-phase flow calculations.

As a further introduction to the corresponding embodiment of fig. 1, spatial and temporal dispersion may be performed by: spatially discrete manipulation of the flow control equation by a finite volume method (Finite Volume Method); the flow control equation is time-discrete operated by a second order finger-Kutta method.

As a further introduction to the corresponding embodiment of FIG. 1, the above-described embodiment may solve for T by _n+1 Volume fraction of time and interfacial normal vector: solving a discrete VOF transport equation to obtain the volume flux of the control surface of the tetrahedral unit; solving the tetrahedral unit at T according to the volume flux of the control surface of the tetrahedral unit _n+1 A volume fraction of time; according to the tetrahedral unit at T _n+1 Solving the volume fraction of the moment to obtain the T of the tetrahedron unit _n+1 Interfacial normal vector of time.

The flow described in the above embodiment is explained below by way of an embodiment in practical application.

Current two-phase flow interface capture algorithms employ a large number of Level-set (Level-set) and fluid volume fraction (VOF) methods. The method can better capture the discontinuity, but has poor conservation, so that the method always causes larger volume loss after multiple iterations, the Level-set function needs to be reinitialized after each iteration, the calculated amount is larger, and the Level-set method is difficult to accurately capture if the phenomena such as crushing, fusion and the like occur to the interface in calculation. The VOF method has the characteristics of good conservation, small calculated amount and the like, and has more advantages in the aspects of processing broken interfaces and interface fusion. Aiming at interface reconstruction of the VOF method, more SLIC methods and PLIC methods are adopted. The SLIC method replaces the two-phase flow interface in the unit by a line segment or a plane parallel to the coordinate plane, the precision is low, and the PLIC method approximates the two-phase flow interface of each unit by an inclined sectional plane, so the precision is high. In the current calculation method for compressible two-phase fluid, the Level-set and virtual fluid methods are mostly combined for solving. Solutions to the problem of combining the PLIC-VOF method with the virtual fluid method for compressible two-phase flow do not exist.

In order to improve the volume conservation in the solving process of the compressible two-phase flow, reduce the volume loss and improve the capturing capacity of a crushing interface and a fusion interface, the embodiment provides a compressible two-phase flow algorithm based on a PLIC-VOF method so as to obtain flow field parameters of a compressible two-phase flow field. The embodiment is based on tetrahedral units, adopts a segmented planar approximation method (PLIC) to reconstruct a two-phase flow interface, and adopts a single non-split Euler geometric algorithm to solve the volume flux of VOF. The flow control equation (Euler equation) adopts a finite volume method to carry out space dispersion, the control surface flux is solved by an AUSM+ -UP method, and the time dispersion adopts a second-order Runge-Kutta method. The interface boundary is processed by using a real virtual flow method (RGFM), and then a compressible flow field solver and a VOF solver are combined to establish a set of compressible two-phase flow algorithm, and the specific implementation flow is as follows:

step 1: selecting an Euler equation as a flow control equation;

step 2: performing space dispersion on a flow control equation by adopting a finite volume method, and initializing a flow field;

step 3: performing time dispersion by adopting a second-order Runge-Kutta method;

step 4: solving flux on a control surface of the non-interface unit by adopting an AUSM+ -UP method;

Step 5: discretizing a VOF transport equation;

step 6: reconstructing an interface;

the interface reconstruction process is as follows: initializing the volume fraction of a flow field, wherein the volume fraction of a main phase fluid is 1, and the volume fraction of a secondary phase fluid is 0; representing an interface normal vector by a volume fraction gradient, and solving the normal vector by adopting a moving particle semi-implicit Method (MPS); dividing an interface grid into 3 types, and solving the intersection point coordinates of the interface and the grid unit to determine the position of the interface; the volume flux flowing through each unit is solved by a geometric cutting method, the volume flux is subtracted from the volume of the main phase fluid at the time n, and the volume flux is divided by the volume of the unit, so that the unit volume fraction at the time n+1 is obtained.

Step 7: interface boundary processing is carried out through a real virtual fluid method (RGFM), fluid flux of an interface unit is solved, and global flow field variables are updated to obtain flow field information at the time of n+1.

Step 8: and updating the flow field attribute, namely updating the flow field of each unit according to the obtained volume fraction at the time n+1, if the volume fractions of the unit and surrounding units are both greater than 0.5, considering the fluid attribute as a main phase fluid, and if the volume fractions of the unit and surrounding units are both less than 0.5, considering the fluid attribute as a secondary phase fluid, and remaining units retain the original fluid attribute.

Specifically, the flow control equation is described as follows:

the flow control equation adopts an Euler equation, the integral form of the flow control equation is shown as a formula (1), and the flow control equation adopts a finite volume method to carry out space dispersion.

In formula (1), V is the volume of the tetrahedral unit (i.e., control volume),

is the outer boundary of a tetrahedral unit, +.>

Let dV denote the differential of volume, dA denote the differential of area, and the conservation variable U and the non-sticking flux F are defined as follows:

ρ, p, E in formula (2) are the density, pressure, total specific internal energy of the fluid, u, v and w are the velocity components in the three directions of X, Y, Z, n _x 、n _y N is as follows _z Is the division of the normal direction n of the control surface in the three directions X, Y, ZAmount of the components. Wherein the normal velocity is defined as formula (3), and the relationship between the total specific internal energy E and the specific internal energy E is shown as formula (4). X, Y, Z three directions are three coordinate axis directions of a space rectangular coordinate system.

u _n ＝un _x +vn _y +wn _z ； (3)

And (5) adopting a Stiffen gas state equation, as shown in a formula (5). P in the formula _c Is an expansion pressure constant, and γ is the specific heat ratio.

Specifically, the implementation process of the space dispersion is as follows:

with the finite volume method based on the lattice-lattice format, each state variable is stored at the cell centroid, dividing the computational domain (i.e., the aforementioned target flow field) into a number of tetrahedral cells that do not overlap each other, with conservation of integration in each tetrahedral cell. Since the volume of each tetrahedral unit does not change with time, i represents the number of the tetrahedral unit, formula (1) can be written as formula (6):

For integration of the non-stick flux over the cell control surface, equation (6) can be written as equation (7):

wherein R is _i As a residual, it is defined as shown in formula (8):

A _ij the area of the common control surface between two adjacent tetrahedral units i and j can be replaced by the flux in the center of the control surface, thus the flux on the control surface can be written approximately as formula (9):

F _ij represents the non-stick flux on the common plane of tetrahedral unit i and tetrahedral unit j.

Specifically, the second-order finger-Kutta method performs time discrete description on the flow control equation as follows:

the formula (10) can be obtained by performing time derivative dispersion on the formula (1):

where V is the volume of the tetrahedral unit,

is the average value of the state variables of tetrahedral unit i, U _i Is the value of the state variable at the centroid of the tetrahedral unit, equation (10) can be written as equations (11) and (12):

the superscript n or n+1 of each letter in the formula (12) indicates the time n or the time n+1, and Δt indicates the time step, that is, the time difference between the time n and the time n+1 (the above iterative period).

Considering two-step time dispersion for equation (12) can yield equations (13) and (14):

L _h a function representing a state variable U, the argument being U, can be expressed as

Specifically, the control plane flux solution is described as follows:

And solving flux on the control surface by adopting an AUSM+ -up method, and constructing second-order precision on the control surface.

The AUSM+ -UP format for flux calculation can be written as formulas (15) - (17), where M _ij Mach number at the interface of two units, defined as formula (18), a _ij Is the speed of sound at the interface of the two units.

In the above formula

Flow field variable, indicated by (16), on the left side of the two cell interface, (-)>

A flow field variable represented by formula (16) on the right side of the two cell interface; p represents pressure, ρ _L Representing the density, ρ, at the left side of the two cell interface _R Representing the density to the right of the two cell interface; m is M _L Representing Mach number, M, on the left side of the two cell interface _R Representing the Mach number on the right side of the two cell interface;

And->

The meaning of the formula (23) is->

Has the meaning of formula (20), K _p 、f _a And sigma represents a first coefficient, a second coefficient and a third coefficient for modifying the dissipation term.

Pressure flux P _ij The calculation formula of (2) is as follows:

and->

As a function of M, K _u Representing the correction coefficient, u _R Indicating the velocity to the right of the two cell interface, u _L Indicating the velocity to the left of the two cell interface.

Each of the formulae (18) and (19) is defined as follows:

on the upper partMiddle q _L Represents the sum of squares, q, of the speeds of the three directions to the left of the two-element interface _R The sum of the squares of the speeds of the three directions to the right of the two cell interface is shown.

q ² ＝u ² +v ² +w ² ； (21)

In the above-mentioned method, the step of,

representing the square of the mach number of the incoming stream.

Referring to fig. 2, fig. 2 is a schematic diagram of a higher-order format structure according to an embodiment of the present application, in which P in fig. 2 ₀ 、P ₁ 、P ₂ And P ₃ The numbers of the tetrahedral units are shown, A, B, C indicates the points of the tetrahedral units, and the numbers of the tetrahedral units are shown in the tetrahedral unit P ₀ In omega ₁ Representing the main phase fluid, Ω ₂ Representing minor phase fluid, the variable reconstruction value at any point (x, y, z) can be represented as formula (25):

in the above, (x) ₀ ，y ₀ ，z ₀ ) Representing tetrahedral units P ₀ Is defined by the center of gravity coordinates of (c),

representing the gradient of the variable, Δr represents the point-to-point vector.

Specifically, the VOF discretizes the transport equation as follows:

a volume-integral scalar field function f (x, t) is defined for each fluid, as shown in the following equation:

the volume fraction F of the main phase fluid in each cell is calculated as shown in the following formula.

V in formula (27) _c The transport equation representing the volume of the cell, the VOF scalar function f (x, t), is shown in equation (28).

In the above-mentioned method, the step of,

representing the Nabla operator.

Discretizing formula (28) can result in:

in which A _k Is the area of the kth face of the cell, n _k Is the external normal direction of the kth plane of the unit, V _nk For the normal velocity of the kth face of the unit, V _c Is the unit volume. The problem can be translated by equation (29) into a net volumetric flux through the various control planes of the cell that solves the VOF scalar function.

Specifically, the description of the interface reconstruction is as follows:

VOF initialization: and assigning the volume fraction of all units in the flow field to enable the volume fraction of the main phase fluid to be 1 and the volume fraction of the secondary phase fluid to be 0.

(1) Solving the normal direction of an interface: the gradient of the volume fraction is adopted to replace the normal direction, and the moving particle semi-implicit Method (MPS) is solved, as shown in fig. 3, fig. 3 is a schematic diagram of solving the normal direction of the VOF interface provided by the embodiment of the present application, F ₀ Representing the volume fraction of the cells to be solved for normal, 1, 2, 3 representing cell vertices, F ₁ 、F ₂ 、F ₃ Representing the volume fraction of the cell vertices.

As shown in formula (30), and the solution formula of the MPS method is shown in formula (31), which specifies that the direction from the inside of the main phase fluid to the outside of the main phase fluid is positive.

In the above, (x) _p ，y _p ，z _p ) Representing the coordinates of the individual vertices of the cell,

representing the average of the volume fractions of all cells co-located with a certain vertex of the cell.

(2) Interface position determination: each cell vertex is numbered, as indicated by A, B, C, D, to ensure that vertex a is within the main phase fluid and to divide the cell into 3 types, as shown in fig. 4, fig. 4 is a schematic diagram of a classification of interface cells provided in an embodiment of the present application. In fig. 4, (a) is a first type of unit, (b) is a second type of unit, (c) is a third type of unit, and A, B, C, D, E, F, G, H, I, J, K, L is a point on a tetrahedral unit. The classification method comprises the following steps: a plane is drawn through vertex B with a given normal vector n, as shown in fig. 4 (a). The intersection points of the plane with AC and AD are F and E, respectively. The volume ratio of tetrahedral ABEF to ABCD can be written as formula (32).

V _ABEF Representing the volume of tetrahedral ABEF, V _ABCD Representing the volume of tetrahedral ABCD, S _AEF Represents the area of triangle AEF, S _ACD Representing the area of the triangular ACD. Assuming a plane passing point A, the normal vector of the plane is the normal direction of the two-phase flow interface in the unit, d _B 、d _C 、d _D The distance from point B, C, D to the plane.

Likewise, a plane is drawn through vertex C with a given normal vector n. The intersection points of the plane with DA and DB are L and K, respectively, as shown in FIG. 4 (c). The volume ratio of tetrahedral DCKL to ABCD can be written as formula (33).

V _DCKL Representing the volume of tetrahedral DCKL, V _ABCD Representing the volume of tetrahedral ABCD, S _DKL Represents the area of triangle DKL, S _ABD Representing the area of triangle ABD. If the fluid volume fraction F of the unit is less than or equal to F _B The first type of unit, if F is more than or equal to 1-F _C If the unit is the third type, if the unit is the second type, special cases will also occur in the calculation. If d _B =0, then f _B =0, points E and F collapse to the top point a. The following formulas are also valid for these special cases. It is only to be noted that in order to avoid the occurrence of the case where the denominator is 0, in actual programming, d needs to be explicitly set _C ＝d _B ＝d _A The case of =0 is classified in the third class, and let f _C =1 and d will be _D ＝d _C ＝d _B The conditions of (2) are classified into the second category, and let f _B ＝1。

After classifying the units, solving the coordinates of the intersection points of the interface and the tetrahedral units for each unit type, solving the coordinates of the point G, H, I for the first and third types of units, and solving the coordinates of the point G, H, I, J for the second type of units, so that the position of the interface can be determined.

(3) Solving unit volume flux: knowing the volume fraction at time n requires solving the volume flux at time n to obtain the volume fraction at time n+1. Taking a first type of grid as an example to describe a solution method of volume flux, as shown in fig. 5, fig. 5 is a schematic diagram of solution of interfacial volume flux according to an embodiment of the present application. The volumetric flux solutions for the remaining mesh facets are similar.

Assuming that the intersections of a plane mu parallel to the plane ABD and the cell sides are P1, P2 and P3, the distance between the plane mu and the plane ABD is V _n *Δt，V _n For the normal speed of the plane to be solved, Δt is the time step, only V is calculated _n In the case of an out-of-plane normal direction, the principal phase fluid taken by that plane is the volumetric flux exiting at that plane. Let h _H Is the distance from point H to face ABD. If h _H ＜V _n * Δt, the flux flowing out is the whole main phase fluid V _AGHI If h _H ＞V _n * Δt, the flux out of the face ABD is the shaded volume in fig. 5. The volume fraction flux of the remaining faces of the cell is obtained by the same method, and then integrated, so that the volume flux flowing out of the whole cell can be obtained. Then subtracting the volume flux of the main phase fluid flowing out from the main phase fluid of the unit at the time n to obtain the volume of the main phase fluid at the time n+1, and dividing the volume of the main phase fluid by the unit volume to obtain the volume fraction of the unit at the time n+1.

Specifically, the construction process of the interface boundary condition is as follows: in the computation of compressible two-phase flow, because the physical properties of the media at two sides of the interface are very different, a break is generated, and if the convection flux is directly obtained for the interface unit, non-physical oscillation is caused, and even computation divergence is caused. In order to accurately solve the problem of discontinuity of the interface, the interface unit needs to be processed. The patent adopts a real virtual fluid method (RGFM) with better strong intermittent solvency to carry out interface boundary treatment.

The schematic diagrams of boundary condition structures on two sides of the interface are shown in fig. 6 and fig. 7, fig. 6 is a schematic diagram of establishing boundary conditions of a two-phase flow interface provided in an embodiment of the present application, and fig. 7 is a schematic diagram of virtual fluid structure provided in an embodiment of the present application. In fig. 6 a represents fluid a, a represents a virtual of fluid aFluid, U _A Representing the state variable of the fluid A, S _A Representing the entropy, V of fluid A _A Indicating the velocity of the fluid A, P _A Indicating the pressure of fluid a. B represents fluid B, B represents a virtual fluid of fluid B, U _B Representing a state variable of the fluid B, S _B Representing the entropy of fluid B, V _B Indicating the velocity of the fluid B, P _B Indicating the pressure of fluid B. In FIG. 7 e ^L And e ^R Respectively representing the names of the left and right units of the interface, U ^L And U ^R State variables representing the left and right elements of the interface,

and->

Representing intermediate state variables obtained by solving the Riemann problem of left and right states of a unit

Three physical quantities of density ρ, velocity V and pressure P are defined, and at time n, in order to determine the density, velocity and pressure of the fluid in the region a at time n+1, a virtual unit of the region a needs to be assigned. For the one-dimensional case at the two-phase flow interface location, there is a break in entropy for physical reasons, but the pressure and velocity are continuous, so the pressure and velocity of the fluid in the virtual cell in zone a can be directly assigned to the pressure and velocity of the fluid in the cell in zone B. Because entropy is intermittent, its value in a virtual cell can be determined by extrapolation, as follows:

in the above formula, S represents the entropy of the fluid.

For the two-dimensional and three-dimensional cases, tangential velocity is increased, which is described here by way of example in two dimensions. The interpolation is performed along the normal direction of the interface, so that the normal speed and the pressure are continuous, the tangential speed and the density are intermittent, the processing of the normal speed, the pressure and the entropy can be referred to the one-dimensional condition, and other variables need to be solved additionally.

Assume state variables U of cells on both sides of interface ^L，R As shown in formula (35).

U ^L，R ＝[p ^L，R ，V ^L，R ，ρ ^L，R ]； (35)

The velocity of the interface in equation (35) is composed of normal and tangential velocity components, as shown in equation (36):

in the above-mentioned method, the step of,

represents normal velocity, n represents normal direction vector, +.>

Representing tangential velocity, τtangential direction vector.

The state variables of the cells on both sides of the interface are projected to the normal direction of the interface as shown in formula (37), then the Riemann problem is solved to reconstruct new interface state variables, which are recombined from the Riemann problem solution and the intermediate state of tangential velocity as shown in formula (38).

The subscript I in equation (38) represents the intermediate state variable resulting from the Riemann problem, and then the state variables of the cells on both sides of the interface are updated with the Riemann solution. The information of the virtual stream element can be obtained by extrapolation of the updated state variables of the element. After the virtual fluid cell is constructed, the fluid flux of the interface cell is solved.

Specifically, the procedure for updating the flow field properties is as follows:

dividing all computing units into two regions Ω ₁ And omega ₂ Each cell centroid corresponds to a fluid medium state defined by formula (39):

the volume fraction can be reconstructed according to equation (40):

in the formula (40), the (i ', j') is a unit adjacent to the unit, alpha and beta are 1 or 2, and are not equal, traversing the unit with the volume fraction of 0 and 1 near the interface, and considering the fluid property as omega if the volume fractions of the unit and the surrounding units are both larger than 0.5 ₁ If the unit volume fraction and the surrounding unit volume fraction are both less than 0.5, the fluid property is considered to be Ω ₂ The remaining cells retain the original fluid properties.

Referring to fig. 8 to 14, fig. 8 is a schematic diagram of an interface capturing effect of recovery after spherical deformation provided in an embodiment of the present application, fig. 9 is a schematic diagram of an interface capturing effect of spherical shear deformation provided in an embodiment of the present application, fig. 10 is a graph of a water shock tube value result and an accurate solution comparison in a density dimension provided in an embodiment of the present application, fig. 11 is a graph of a water shock tube value result and an accurate solution comparison in a pressure dimension provided in an embodiment of the present application, fig. 12 is a graph of a water shock tube value result and an accurate solution comparison in a velocity dimension provided in an embodiment of the present application, fig. 13 is a graph of a shock and helium bubble interaction interface equivalent surface provided in an embodiment of the present application, and fig. 14 is a cross-sectional density cloud of a shock and helium bubble interaction symmetry provided in an embodiment of the present application. In fig. 10, the abscissa indicates the length of dimensionless (total length is 1), and the ordinate indicates the density; exact-density represents the Exact solution of density, density represents the numerical solution (i.e., the density numerical solution calculated by the method in this example). In fig. 11, the abscissa indicates the dimensionless length (total length is 1), and the ordinate indicates the pressure. Exact-p represents the Exact solution of pressure, and p represents the numerical solution of pressure. In fig. 12, the abscissa represents the dimensionless length (total length is 1), the ordinate represents the velocity, exact-u represents the Exact solution of the velocity, and u represents the numerical solution of the velocity. Density is shown as Density in FIG. 14. E in fig. 11 and 12 represents a scientific counting method.

The PLIC-VOF method is combined with a real virtual flow method (RGFM), so that the solving of the compressible two-phase flow is realized, and the method is popularized to the calculation of a three-dimensional flow field based on tetrahedral units, and a compressible two-phase flow solving algorithm is formed. Compared with the traditional compressible two-phase flow algorithm based on the Level-set method, the method simplifies the calculation process, reduces the number of calculation iterations, improves the processing capacity for interface fusion and interface crushing, and increases the conservation in the calculation of the compressible two-phase flow.

The embodiment of the application also provides a flow field parameter determining system of a compressible two-phase flow, which can comprise:

a second flux determination module for processing the interface unit by a real virtual fluid method and solving at T _n Flux on control surface of interface unit at momentThe method comprises the steps of carrying out a first treatment on the surface of the Wherein the interface unit is positioned at the T of the target flow field _n Tetrahedral units of the two-phase flow interface at the moment;

After determining a target flow field when a target object moves in a compressible two-phase fluid, the embodiment divides the target flow field into a plurality of tetrahedral units and initializes the target flow field. After initializing a target flow field, the embodiment determines flow field information and two-phase flow interface at each moment in an iterative calculation mode, and solves a flow control equation subjected to space discrete operation and time discrete operation in an iterative process to obtain a flow control equation at T _n Flux on the control plane of the time of day non-interface unit; the present embodiment also processes the interface element by a true virtual fluid method and solves at T _n Flux on the control surface of the interface unit at the moment to further obtain the target flow field at T _n+1 The embodiment also solves the discrete VOF transport equation to obtain all tetrahedral units in T according to the flow field information at the moment _n+1 Determining the volume fraction and the interfacial normal vector of the moment, and determining the T of the target flow field according to the volume fraction and the interfacial normal vector _n+1 A two-phase flow interface at time. The iteration process combines the VOF method with the real virtual stream method, thereby realizing the aim of compressing two streamsAnd solving the phase flow. Compared with a compressible two-phase flow algorithm based on a Level-set method in the related art, the method simplifies the calculation process, improves the processing capacity of interface fusion and interface crushing, and therefore, the method can reduce the iteration times and the calculation amount for determining the flow field parameters of the compressible two-phase flow and improves the conservation in the calculation of the compressible two-phase flow.

Further, the process of performing the space discrete operation and the time discrete operation on the flow control equation by the discrete processing module includes: performing space discrete operation on the flow control equation by a finite volume method; the flow control equation is time-discrete operated by the second order finger-Kutta method.

Further, the first flux determination module solves a flow control equation through the spatial discrete operation and the time discrete operation to obtain a value at T _n The process of flux on the control surface of the time of day non-interface unit includes: solving a flow control equation through the space discrete operation and the time discrete operation by an AUSM+ -UP method to obtain a flow control equation in T _n And the flux on the control surface of the non-interface unit at the moment.

Further, the second throughput determination module processes the interface unit by a true virtual fluid method and solves at T _n The process of flux on the control surface of the interface unit at the moment comprises: and carrying out interface boundary processing on the interface unit by a real virtual fluid method, and solving the flux on the control surface of the interface unit by using an interface boundary processing result.

Further, the interface updating module solves the discrete VOF transport equation to obtain all tetrahedral units in T _n+1 The process of the volume fraction of the moment and the interfacial normal vector comprises the following steps: solving a discrete VOF transport equation to obtain the volume flux of the control surface of the tetrahedral unit; solving the tetrahedral unit at T according to the volume flux of the control surface of the tetrahedral unit _n+1 A volume fraction of time; according to the tetrahedral unit at T _n+1 Solving the volume fraction of the moment to obtain the T of the tetrahedron unit _n+1 Time of dayIs defined by the interface normal vector of (a).

Further, the process of judging whether the iteration termination condition is reached by the iteration judging module comprises the following steps: judgment T _n Whether the moment is a preset moment or not; t (T) _n+1 And T is _n The difference value of (2) is an iteration period; if yes, judging that the iteration termination condition is reached; if not, judging that the iteration termination condition is not met.

Further, the process of determining the target flow field by the flow field determining module when the target object moves in the compressible two-phase fluid comprises the following steps: determining a target flow field of the propeller when the propeller moves in the compressible two-phase fluid; wherein the compressible two-phase fluid is water and air, respectively;

correspondingly, the method further comprises the steps of:

an adjusting module for outputting the T _n+1 Flow field information of time and the T _n+1 After the two-phase flow interface at the moment, according to the T _n+1 Flow field information of time and the T _n+1 Calculating the mechanical damage grade of the propeller at the moment through a two-phase flow interface; and adjusting the blade shape of the propeller according to the mechanical damage level.

Since the embodiments of the system portion and the embodiments of the method portion correspond to each other, the embodiments of the system portion refer to the description of the embodiments of the method portion, which is not repeated herein.

The present application also provides a storage medium having stored thereon a computer program which, when executed, performs the steps provided by the above embodiments. The storage medium may include: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a random access Memory (Random Access Memory, RAM), a magnetic disk, or an optical disk, or other various media capable of storing program codes.

The application also provides an electronic device, which may include a memory and a processor, where the memory stores a computer program, and the processor may implement the steps provided in the foregoing embodiments when calling the computer program in the memory. Of course the electronic device may also include various network interfaces, power supplies, etc.

In the description, each embodiment is described in a progressive manner, and each embodiment is mainly described by the differences from other embodiments, so that the same similar parts among the embodiments are mutually referred. For the system disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant points refer to the description of the method section. It should be noted that it would be obvious to those skilled in the art that various improvements and modifications can be made to the present application without departing from the principles of the present application, and such improvements and modifications fall within the scope of the claims of the present application.

It should also be noted that in this specification, relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.

Claims

1. A method for determining flow field parameters of a compressible two-phase flow, comprising:

2. The method of determining flow field parameters for a compressible two-phase flow of claim 1, wherein performing spatially and time discrete operations on the flow control equation comprises:

3. Flow field parameter determination of a compressible two-phase flow according to claim 1The method is characterized in that the flow control equation passing through the space discrete operation and the time discrete operation is solved to obtain a flow control equation in T _n Flux on the control surface of the time of day non-interface cell, comprising:

4. The method of determining flow field parameters for a compressible two-phase flow according to claim 1, wherein the interface unit is processed by a true virtual fluid method and solved at T _n The flux on the control surface of the interface unit at the moment comprises:

5. The method for determining flow field parameters of a compressible two-phase flow according to claim 1, wherein the solving of the discretized VOF transport equation yields all tetrahedral units at T _n+1 The volume fraction of time and the interfacial normal vector include:

6. The method of determining flow field parameters for a compressible two-phase flow according to claim 1, wherein said determining whether an iteration termination condition is reached comprises:

judgment T _n Whether or not the moment isPresetting a moment; t (T) _n+1 And T is _n The difference value of (2) is an iteration period;

if yes, judging that the iteration termination condition is reached;

If not, judging that the iteration termination condition is not met.

7. The method of determining flow field parameters of a compressible two-phase flow according to claim 1, wherein the determining a target flow field of a target object moving in a compressible two-phase fluid comprises:

8. A flow field parameter determination system for a compressible two-phase flow, comprising:

A first flux determination module for solving a flow control equation through the spatially discrete operation and the time discrete operation to obtain a flux value at T _n Flux on the control plane of the time of day non-interface unit; which is a kind ofWherein the non-interface unit is not positioned in the target flow field at T _n Tetrahedral units of the two-phase flow interface at the moment;

a second flux determination module for processing the interface unit by a real virtual fluid method and solving at T _n Flux on the control surface of the interface unit at the moment; wherein the interface unit is positioned at the T of the target flow field _n Tetrahedral units of the two-phase flow interface at the moment;

9. An electronic device comprising a memory and a processor, the memory having a computer program stored therein, the processor, when calling the computer program in the memory, implementing the steps of the method for determining flow field parameters of a compressible two-phase flow according to any one of claims 1 to 7.

10. A storage medium having stored therein computer executable instructions which when loaded and executed by a processor perform the steps of the method for determining flow field parameters of a compressible two phase flow as claimed in any one of claims 1 to 7.