Flame surface simulation method and device for supersonic combustion

Abstract

The invention relates to the technical field of computational fluid mechanics and combustion science, in particular to a flame surface simulation method and device for supersonic combustion, and the method comprises the steps: solving a continuity equation, a momentum equation, a mixing fraction equation and an energy equation in a supersonic cold state mixing process; obtaining a mixing fraction distribution, a pressure distribution and a mixture total internal energy distribution; calculating a one-dimensional flame to construct a four-dimensional table of at least one mixing fraction-progress variable-oxidant side total internal energy-pressure based on the one-dimensional flame; and acquiring progress variable information of the supersonic combustion based on the four-dimensional table to obtain a flame surface simulation result of the supersonic combustion. According to the method, two control variables of pressure and oxidant side total internal energy can be introduced on the basis of a traditional small flame model according to the characteristics of supersonic combustion, and an Euler random field method is introduced to describe a joint probability density distribution function between the control variables, so that the influence of a preset probability density function is reduced, and the calculation precision is improved.

Description

Technical Field

[0001] The present application relates to the technical fields of computational fluid dynamics and combustion, and in particular to a method and device for simulating a flame surface of supersonic combustion. Background Art

[0002] In the related technology, the combustion models currently used for supersonic combustion are mainly divided into two categories, namely, models based on transport probability density distribution functions and models based on flame thickening. Among them, the model based on transport probability density distribution functions directly solves the probability density distribution function of the unresolved part, and the chemical reaction rate is directly obtained by integrating the chemical reaction mechanism. Therefore, when the transport probability density distribution function model is combined with a detailed chemical reaction mechanism, it will bring a lot of computational time. Therefore, the transport probability density distribution function model can only be used in combination with simplified or skeleton chemical reaction mechanisms. The model technology based on flame thickening artificially increases the thickness of the flame front by adding a flame thickening factor to the component and energy transport equations, so a coarser grid can be used to resolve the entire flame front.

[0003] In order to reduce the amount of calculation, the transport probability density distribution function model and the flame thickening model are usually used in conjunction with the flame surface low-dimensional table building method. The flame surface low-dimensional table building method assumes that the time scale of the chemical reaction during the combustion process is very short relative to the time scale of the turbulence, so the combustion mainly occurs in a thin reaction layer, which can be regarded as a one-dimensional flame structure, that is, the turbulent combustion flame is composed of a series of laminar combustion superpositions. For example, in the small flame generation manifold model (a flame surface low-dimensional table building method), the laminar flame structure can be solved by solving the one-dimensional laminar flame equation and mapping the calculation results to the space of control parameters such as the mixture fraction and the flame progress variable, and then the thermochemical state quantities are tabulated. In the three-dimensional turbulent combustion simulation, it is only necessary to solve the transport equations of these control parameters, and the thermochemical state quantities can be interpolated from the small flame library, thereby avoiding solving the temperature / component transport equations and complex chemical reaction source term calculations, and the required amount of calculation is greatly reduced. Since the one-dimensional laminar flame has a small amount of calculation, detailed chemical reaction mechanisms can be used. However, current small flame models all rely on a preset subgrid probability density distribution function, for example, assuming that the probability density distribution function of the unresolved part of the mixture fraction follows a typical delta function or beta function. It is unknown whether this assumption is reasonable in supersonic combustion, which brings uncertainty to the simulation results.

[0004] However, in the related technology, the transport probability density distribution function model cannot apply the detailed chemical reaction mechanism due to the limitation of computational complexity, which reduces the accuracy of numerical simulation to a certain extent. The small flame model can consider the detailed chemical reaction mechanism, but a simple distribution function needs to be used for the unresolved sub-grid probability density distribution function, and the joint probability density distribution function between different control variables cannot be considered. The calculation accuracy is low and needs to be solved urgently. Summary of the invention

[0005] The present application provides a flame surface simulation method, device, electronic device and storage medium for supersonic combustion to solve the problem in related technologies that the transport probability density distribution function model cannot apply the detailed chemical reaction mechanism due to the limitation of the calculation amount, which reduces the accuracy of numerical simulation to a certain extent. The small flame model can consider the detailed chemical reaction mechanism, but a simple distribution function needs to be used for the unresolved sub-grid probability density distribution function, and the joint probability density distribution function between different control variables cannot be considered, resulting in low calculation accuracy and other problems.

[0006] The first aspect of the present application provides a flame surface simulation method for supersonic combustion, comprising the following steps: solving the continuity equation, momentum equation, mixture fraction equation and energy equation in the supersonic cold mixing process to obtain the mixture fraction distribution, pressure distribution and total internal energy distribution of the mixture in the supersonic cold mixing process; calculating a one-dimensional flame based on the mixture fraction distribution, the pressure distribution and the total internal energy distribution of the mixture to construct at least one four-dimensional table of mixture fraction-progress variable-oxidant side total internal energy-pressure based on the one-dimensional flame; acquiring the progress variable information of the supersonic combustion based on the four-dimensional table, and obtaining the flame surface simulation result of the supersonic combustion according to the progress variable information.

[0007] Optionally, in one embodiment of the present application, the solution of the continuity equation, momentum equation, mixture fraction equation and energy equation in the supersonic cold mixing process includes: establishing target initial conditions and target boundary conditions; based on the target initial conditions and the target boundary conditions, solving the continuity equation, momentum equation, mixture fraction equation and energy equation in the supersonic cold mixing process through a target turbulence model.

[0008] Optionally, in one embodiment of the present application, the calculating of the one-dimensional flame based on the mixture fraction distribution, the pressure distribution and the total internal energy distribution of the mixture includes: establishing different pressure conditions, different oxidant side temperatures and different stretching rates; calculating the one-dimensional flame based on the mixture fraction distribution, the pressure distribution and the total internal energy distribution of the mixture under the different pressure conditions, different oxidant side temperatures and different stretching rates.

[0009] Optionally, in one embodiment of the present application, the obtaining of the progress variable information of the supersonic combustion based on the four-dimensional table includes: solving the mixture fraction equation, the progress variable equation, and the transport equation of the total internal energy in the supersonic combustion process, so as to obtain the mixture fraction-progress variable-total internal energy sub-grid joint probability density distribution through the Euler random field equation; based on the four-dimensional table, the progress variable information of the supersonic combustion is obtained in combination with the mixture fraction-progress variable-total internal energy sub-grid joint probability density distribution.

[0010] Optionally, in one embodiment of the present application, the expressions of the continuity equation, momentum equation, mixture fraction equation and energy equation are:

[0011]

[0012]

[0013] in, The wavy line represents the Favre filter average (also known as density-weighted average, a common averaging method in fluid dynamics), and the horizontal line represents the spatial filter average. is the density, t is the time, x j is the component of the position vector in the j direction, is the component of velocity in the i direction, is the component of velocity in the j direction, is the filtered stress tensor, is the stress tensor of the subgrid, is the Bilger mixed fraction, D eff is the effective mass diffusion coefficient, is the total internal energy of the mixture, is the viscous heat dissipation of the subgrid, Γ eff is the effective energy diffusion coefficient, K is the kinetic energy, It's pressure. is the sensible enthalpy of the mixture.

[0014] Optionally, in one embodiment of the present application, the expression of the Euler random field equation is:

[0015]

[0016] in, is the density, is the nth random field, is the convection term, represents molecular diffusion and turbulent transport in the subgrid, is a small-scale mixing term, is the chemical reaction source term.

[0017] The second aspect of the present application provides a flame surface simulation device for supersonic combustion, characterized in that it includes: a solution module, used to solve the continuity equation, momentum equation, mixture fraction equation and energy equation in the supersonic cold mixing process, so as to obtain the mixture fraction distribution, pressure distribution and total internal energy distribution of the mixture in the supersonic cold mixing process; a calculation module, used to calculate a one-dimensional flame based on the mixture fraction distribution, the pressure distribution and the total internal energy distribution of the mixture, so as to construct at least one four-dimensional table of mixture fraction-progress variable-oxidant side total internal energy-pressure based on the one-dimensional flame; a simulation module, used to obtain the progress variable information of supersonic combustion based on the four-dimensional table, and obtain the flame surface simulation result of the supersonic combustion according to the progress variable information.

[0018] Optionally, in one embodiment of the present application, the solution module includes: a first establishment unit, used to establish target initial conditions and target boundary conditions; a first solution unit, used to solve the continuity equation, momentum equation, mixture fraction equation and energy equation in the supersonic cold mixing process through a target turbulence model based on the target initial conditions and the target boundary conditions.

[0019] Optionally, in one embodiment of the present application, the calculation module includes: a second establishment unit, used to establish different pressure conditions, different oxidant side temperatures and different stretching rates; a calculation unit, used to calculate the one-dimensional flame based on the mixture fraction distribution, the pressure distribution and the total internal energy distribution of the mixture under the different pressure conditions, different oxidant side temperatures and different stretching rates.

[0020] Optionally, in one embodiment of the present application, the simulation module includes: a second solving unit, used to solve the mixture fraction equation, the progress variable equation, and the transport equation of the total internal energy in the supersonic combustion process, so as to obtain the mixture fraction-progress variable-total internal energy sub-grid joint probability density distribution through the Euler random field equation; an acquisition unit, used to obtain the progress variable information of the supersonic combustion based on the four-dimensional table and in combination with the mixture fraction-progress variable-total internal energy sub-grid joint probability density distribution.

[0021] Optionally, in one embodiment of the present application, the expressions of the continuity equation, momentum equation, mixture fraction equation and energy equation are:

[0022]

[0023] in, The wavy line represents the Favre filter average (also known as density-weighted average, a common averaging method in fluid dynamics), and the horizontal line represents the spatial filter average. is the density, t is the time, xj is the component of the position vector in the j direction, is the component of velocity in the i direction, is the component of velocity in the j direction, is the filtered stress tensor, is the stress tensor of the subgrid, is the Bilger mixed fraction, D eff is the effective mass diffusion coefficient, is the total internal energy of the mixture, is the viscous heat dissipation of the subgrid, Γ eff is the effective energy diffusion coefficient, K is the kinetic energy, It's pressure. is the sensible enthalpy of the mixture.

[0024] Optionally, in one embodiment of the present application, the expression of the Euler random field equation is:

[0025]

[0026] in, is the density, is the nth random field, is the convection term, represents molecular diffusion and turbulent transport in the subgrid, is a small-scale mixing term, is the chemical reaction source term.

[0027] The third aspect of the present application provides an electronic device, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the flame surface simulation method for supersonic combustion as described in the above embodiment.

[0028] A fourth aspect of the present application provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, which, when executed by a processor, implements the flame surface simulation method for supersonic combustion as described above.

[0029] The fifth aspect of the present application provides a computer program product, including a computer program, which, when executed, is used to implement the flame surface simulation method of supersonic combustion as described above.

[0030] The embodiment of the present application can calculate a one-dimensional flame to construct a four-dimensional table of mixture fraction-progress variable-total internal energy on the oxidant side-pressure, obtain the progress variable information of supersonic combustion, and obtain the flame surface simulation result of supersonic combustion. Thus, according to the characteristics of supersonic combustion, on the basis of the small flame model of the traditional mixture fraction-progress variable, two control variables, pressure and total internal energy on the oxidant side, are introduced, and the Euler random field method is introduced to describe the joint probability density distribution function between the control variables, reducing the influence of the preset probability density function and improving the calculation accuracy. Thus, the problem that the transport probability density distribution function model in the related art cannot apply the detailed chemical reaction mechanism due to the limitation of the calculation amount, which reduces the accuracy of the numerical simulation to a certain extent, and the small flame model can consider the detailed chemical reaction mechanism, but a simple distribution function needs to be used for the unresolved sub-grid probability density distribution function, and the joint probability density distribution function between different control variables cannot be considered, and the calculation accuracy is low.

[0031] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0033] Figure 1 A flow chart of a flame surface simulation method for supersonic combustion provided according to an embodiment of the present application;

[0034] Figure 2 A schematic diagram of pressure distribution of an embodiment of the present application is shown in FIG.

[0035] Figure 3 A schematic diagram of the scattered distribution of total internal energy and mixture fraction according to an embodiment of the present application;

[0036] Figure 4 A schematic diagram of the scattered distribution of pressure and mixture fraction according to an embodiment of the present application;

[0037] Figure 5 This is a schematic diagram of boundary conditions for an embodiment of the present application;

[0038] Figure 6 A schematic diagram of constructing a four-dimensional table of mixture fraction-progress variable-oxidant side internal energy-pressure according to an embodiment of the present application;

[0039] Figure 7 This is a schematic diagram comparing temperature curves at different flow direction positions according to an embodiment of the present application;

[0040] Figure 8 This is a schematic diagram comparing mainstream velocity curves at different flow direction positions according to an embodiment of the present application;

[0041] Fig. 9 It is a structural schematic diagram of a flame surface simulation device for supersonic combustion according to an embodiment of the present application;

[0042] Fig.10 Schematic diagram of the structure of an electronic device according to an embodiment of the present application.

[0043] Reference numerals:

[0044] 10-flame surface simulation device for supersonic combustion: 100-solving module, 200-calculation module and 300-simulation module; 1001-memory, 1002-processor and 1003-communication interface. DETAILED DESCRIPTION

[0045] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0046] The flame surface simulation method and device of supersonic combustion of the embodiment of the present application are described below with reference to the accompanying drawings. In view of the related art mentioned in the above background technology, the transport probability density distribution function model cannot apply the detailed chemical reaction mechanism due to the limitation of the amount of calculation, which reduces the accuracy of the numerical simulation to a certain extent. The small flame model can consider the detailed chemical reaction mechanism, but for the unresolved sub-grid probability density distribution function, a simple distribution function needs to be used, and the joint probability density distribution function between different control variables cannot be considered, and the calculation accuracy is low. The present application provides a flame surface simulation method for supersonic combustion, in which a one-dimensional flame can be calculated to construct a four-dimensional table of mixture fraction-progress variable-oxidant side total internal energy-pressure, obtain the progress variable information of supersonic combustion, and obtain the flame surface simulation result of supersonic combustion. In this way, according to the characteristics of supersonic combustion, on the basis of the traditional small flame model of mixture fraction-progress variable, two control variables of pressure and oxidant side total internal energy are introduced, and the Euler random field method is introduced to describe the joint probability density distribution function between the control variables, reducing the influence of the preset probability density function and improving the calculation accuracy. As a result, the problem in the related technology that the transport probability density distribution function model cannot apply the detailed chemical reaction mechanism due to the limitation of calculation amount, which reduces the accuracy of numerical simulation to a certain extent is solved. The small flame model can consider the detailed chemical reaction mechanism, but a simple distribution function needs to be used for the unresolved sub-grid probability density distribution function, and it cannot consider the joint probability density distribution function between different control variables, resulting in low calculation accuracy, etc.

[0047] Specifically, Figure 1 A flow chart of a method for simulating a flame surface of supersonic combustion provided in an embodiment of the present application.

[0048] like Figure 1 As shown, the flame surface simulation method of supersonic combustion includes the following steps:

[0049] In step S101, the continuity equation, momentum equation, mixture fraction equation and energy equation in the supersonic cold mixing process are solved to obtain the mixture fraction distribution, pressure distribution and total internal energy distribution of the mixture in the supersonic cold mixing process. The expressions of the continuity equation, momentum equation, mixture fraction equation and energy equation can be expressed as follows:

[0050]

[0051] in, The wavy line represents the Favre filter average (also known as density-weighted average, a common averaging method in fluid dynamics), and the horizontal line represents the spatial filter average. is the density, t is the time, x jis the component of the position vector in the j direction, is the component of velocity in the i direction, is the component of velocity in the j direction, is the filtered stress tensor, is the stress tensor of the subgrid, is the Bilger mixed fraction, D eff is the effective mass diffusion coefficient, is the total internal energy of the mixture, is the viscous heat dissipation of the subgrid, Γ eff is the effective energy diffusion coefficient, K is the kinetic energy, It's pressure. is the sensible enthalpy of the mixture.

[0052] It can be understood by professionals in this technical field that supersonic combustion is a combustion technology based on the principles of supercharging and inertial compression. Its main feature is to accelerate air to supersonic speed and high temperature for combustion, thereby greatly improving the combustion efficiency of fuel and achieving the purpose of reducing energy consumption and reducing pollution.

[0053] Supersonic combustion is widely used in ramjets of hypersonic vehicles, but there are still some technical difficulties in the actual application of ramjets, such as ignition in supersonic airflow, flame stability under high Mach number flow, etc. It is very difficult to study the above problems from an experimental perspective, including experimental equipment and test methods. Therefore, numerical simulation is an effective means to study supersonic combustion in ramjets. However, simulating supersonic combustion requires a series of models, such as turbulence models, combustion models, chemical reaction kinetics simulation, high-precision shock wave capture format, etc.

[0054] Since there are unresolved thermodynamic variables in both Reynolds average simulation and large eddy simulation, such as component mass fraction, temperature, etc., but the Reynolds average or filtered average thermodynamic variables cannot be used to directly calculate the averaged chemical reaction rate, because the chemical reaction rate is a nonlinear function of thermodynamic variables such as component mass fraction and temperature, it is necessary to use a combustion model to consider the contribution of the pulsation of thermodynamic variables to the average chemical reaction rate. Based on this, the embodiments of the present application can be explained based on, but not limited to, the combustion model.

[0055] In some embodiments, in order to ensure the accuracy of simulation and design, the present application can solve the continuity equation, momentum equation, mixture fraction equation and energy equation in the supersonic cold mixing (cold fuel / oxidizer mixing) process to effectively understand the physical and chemical behavior of the fluid in the combustion chamber.

[0056] Taking large eddy simulation as an example, the present application can first solve the continuity equation, momentum equation, mixture fraction equation and energy equation through cold flow simulation. The specific equation form can be expressed as follows:

[0057]

[0058] in, The wavy line represents the Favre filter average, and the horizontal line represents the spatial filter average. is the density, t is the time, x j is the component of the position vector in the j direction, is the component of velocity in the i direction, is the component of velocity in the j direction, is the filtered stress tensor, is the stress tensor of the subgrid, is the Bilger mixed fraction, D eff is the effective mass diffusion coefficient, is the total internal energy of the mixture, is the viscous heat dissipation of the subgrid, Γ eff is the effective energy diffusion coefficient, K is the kinetic energy, It's pressure. is the sensible enthalpy of the mixture.

[0059] Specifically, the continuity equation can be understood here as the mass conservation equation, which describes that the increase or decrease in mass in a fluid microelement per unit time is equal to the mass flowing into or out of the volume of the microelement in the same time. In supersonic combustion, since the fluid flows at an extremely high speed, the accurate calculation of mass conservation helps to understand the fluid dynamics and combustion process, thereby ensuring that the mass of the fluid does not appear or disappear during the combustion process, thereby maintaining the continuity and stability of the flow.

[0060] The momentum equation describes the change in momentum of a fluid during its flow, including momentum transfer caused by pressure, gravity, and other external forces. In supersonic combustion, the high-speed motion of the fluid will produce significant momentum changes, which directly affect the stability and efficiency of combustion. By analyzing the momentum equation, the trajectory, velocity distribution, and pressure distribution of the fluid in the combustion chamber can be predicted.

[0061] The mixture fraction equation describes how well the fuel and oxidant are mixed in a flow. In supersonic combustion, the fuel mixes with an oxidant (such as air) at extremely high speeds, and by solving the mixture fraction equation, we can understand the spatial distribution of the fuel during the combustion process.

[0062] The energy equation describes the transfer and conversion of energy during combustion, including the interaction between thermal energy, kinetic energy, and chemical energy. In supersonic combustion, the high temperature and high pressure combustion environment generates a large amount of heat energy, which needs to be effectively utilized or managed to ensure the stability and efficiency of combustion. By solving the energy equation, the temperature distribution in the combustion chamber, the heat transfer path, and the energy conversion efficiency can be analyzed.

[0063] After solving the continuity equation, momentum equation, mixture fraction equation and energy equation respectively, the mixture fraction distribution, pressure distribution and total internal energy distribution of the mixture in the supersonic combustion process under cold conditions can be obtained. Figure 2 The figure shows a schematic diagram of pressure distribution of an embodiment of the present application.

[0064] Also, due to the reflection of the shock wave on the upper and lower walls, a shock wave train structure is formed in the combustion chamber, which will cause uneven pressure distribution in space. At the same time, the shock wave will also bring about changes in the total internal energy of the mixture. Figure 3 This is a schematic diagram of the scattered distribution of total internal energy and mixture fraction according to an embodiment of the present application. Figure 4 This is a schematic diagram of the scattered distribution of pressure and mixture fraction according to an embodiment of the present application, as shown in FIG. Figure 3 and Figure 4 As shown in the figure, the scattered distribution of the mixture fraction-total internal energy and the mixture fraction-pressure in the combustion chamber are respectively shown. Among them, under cold flow, the mixture fraction is the mass fraction of the fuel.

[0065] Optionally, in one embodiment of the present application, solving the continuity equation, momentum equation, mixture fraction equation and energy equation in the supersonic cold mixing process includes: setting target initial conditions and target boundary conditions; based on the target initial conditions and target boundary conditions, solving the continuity equation, momentum equation, mixture fraction equation and energy equation in the supersonic cold mixing process through a target turbulence model.

[0066] In the actual implementation process, in order to effectively ensure the accuracy of simulating supersonic combustion, the present application can set target initial conditions and target boundary conditions to provide a clear starting point and boundary for the simulation process.

[0067] Among them, the target initial conditions can be understood as a certain starting point set during the simulation process, including but not limited to key parameters such as the initial temperature, pressure, velocity, and component concentration of the fluid, which helps to ensure the accuracy and reliability of subsequent simulation results and facilitates result analysis and optimization. The target boundary conditions define the external environment of the simulation area and the behavior of the fluid at the boundary, such as the distribution and change law of parameters such as velocity, temperature, pressure, and component concentration, thereby limiting the scope of the simulation and the impact of boundary conditions on the internal flow and combustion process.

[0068] It should be noted that the specific target initial conditions and target boundary conditions can be set by professional and technical personnel in this field according to actual conditions or needs or reasonably set through experiments. The embodiments of this application are only for illustrative purposes and are not specifically limited.

[0069] For example, the embodiments of the present application may adopt a suitable turbulence model, such as a single equation k model, based on the finite volume method, and the convection flux in space adopts a second-order Godunov type central format with a Van Leer limiter, and the diffusion term is discretized using a second-order central difference format; in time, a second-order backward format may be adopted. Taking the hydrogen blunt body supersonic combustion of the German Aerospace Center as an example, Figure 5 The figure is a schematic diagram of boundary conditions of an embodiment of the present application.

[0070] Step S102, calculating a one-dimensional flame based on the mixture fraction distribution, the pressure distribution and the total internal energy distribution of the mixture, so as to construct at least one four-dimensional table of mixture fraction-progress variable-oxidant side total internal energy-pressure based on the one-dimensional flame.

[0071] In other embodiments, in order to more conveniently read relevant information in the supersonic combustion process, the present application can establish a four-dimensional table of mixture fraction-progress variable-oxidant side total internal energy-pressure. Wherein, the four-dimensional table of mixture fraction-progress variable-oxidant side total internal energy-pressure can be obtained from a one-dimensional flame calculated from the mixture fraction distribution, pressure distribution and mixture total internal energy distribution.

[0072] Next, the one-dimensional flame calculation process is further explained.

[0073] Optionally, in one embodiment of the present application, a one-dimensional flame is calculated based on the mixture fraction distribution, pressure distribution and total internal energy distribution of the mixture, including: establishing different pressure conditions, different oxidant side temperatures and different stretching rates; under different pressure conditions, different oxidant side temperatures and different stretching rates, the one-dimensional flame is calculated based on the mixture fraction distribution, pressure distribution and total internal energy distribution of the mixture.

[0074] In certain embodiments, in order to include all possible states of the mixture in the process of building a table based on one-dimensional flame chemistry (a four-dimensional table of mixing fraction-progress variable-total internal energy on the oxidant side-pressure), the present application can use different pressures, different oxidant side temperatures (Tox) and different stretching rates for simulation when calculating the one-dimensional flame.

[0075] Still taking large eddy simulation as an example, Figure 3 As shown in , when the lower limit of Tox is 300K and the upper limit is 600K, most of the mixture states can be included. Figure 4As shown, when the lower limit of p is 0.4 bar and the upper limit is 1.8 bar, it is a state that can also include most mixtures. Among them, between the upper and lower limits, the temperature interval is 20K and the pressure interval is 0.1 bar.

[0076] Next, we calculate the one-dimensional (opposing) flame. The fuel side is hydrogen, the oxidant side is gaseous water, oxygen and nitrogen, with mass fractions of 0.032, 0.736 and 0.232 respectively, the pressure is 1 bar, and the temperature of the oxidant side is 300 K. -1 Start calculating the steady-state flame, continuously increase the stretch rate, and simulate the steady-state flame under different stretch rates until the steady-state flame solution no longer converges, that is, reaches the critical flameout stretch rate. Continue to solve the transient flame at the critical flameout stretch rate until the flame is completely extinguished.

[0077] At this point, the embodiment of the present application can obtain the chemical table information of the mixture fraction-progress variable at a pressure of 1 bar and an oxidant side temperature of 300K. The progress variable can be defined as M is the molar mass of the component. Then, keeping the pressure at 1 bar constant, change the temperature on the oxidant side from 300 K to 600 K at intervals of 20 K. After the above calculations are completed, change the pressure again from 0.1 bar to 1.8 bar at intervals of 0.1 bar.

[0078] Finally, a four-dimensional table of mixture fraction-progress variable-total internal energy on the oxidant side-pressure is constructed, such as Figure 6 As shown, it is a schematic diagram of constructing a four-dimensional table of mixture fraction-progress variable-total internal energy on the oxidant side-pressure according to an embodiment of the present application.

[0079] It should be noted that the total internal energy of the mixture is directly solved in the large eddy simulation in the embodiment of the present application, but the control variable used in establishing the four-dimensional table is the total internal energy on the oxidant side, so it is also necessary to convert the total internal energy of the mixture to the total internal energy on the oxidant side. The formula can be expressed as follows:

[0080]

[0081] Among them, E ox represents the total internal energy on the oxidant side, E fu Represents the total internal energy on the fuel side.

[0082] Because the total internal energy does not change during the combustion process, it is assumed here that the total internal energy contribution of the fuel side is constant, and the changes in internal energy brought about by the flow are attributed to the oxidant side. According to the above equation, the solution format can be consistent with the cold state solution.

[0083] Step S103, obtaining the progress variable information of the supersonic combustion based on the four-dimensional table, and obtaining the flame surface simulation result of the supersonic combustion according to the progress variable information.

[0084] As a possible implementation method, after establishing a four-dimensional table of mixture fraction-progress variable-total internal energy on the oxidant side-pressure, the present application can read the progress variable information of the chemical reaction source term from the four-dimensional table to obtain the flame surface simulation results of supersonic combustion based on this information.

[0085] For example, the present application can use the established four-dimensional table of mixture fraction-progress variable-oxidant side internal energy-pressure in large eddy simulation, and solve the continuity equation and momentum equation again, as well as the mixture fraction (Z), progress variable (Y c ), total internal energy (E a )’s transport equation, etc., to realize reading the progress variable information of the chemical reaction source term from the table.

[0086] After obtaining the progress variable information of the relevant chemical reaction source term, the embodiment of the present application can obtain the flame surface simulation result of supersonic combustion based on the progress variable information. Figure 7 As shown, it is a schematic diagram of temperature curve comparison at different flow positions of an embodiment of the present application, and Figure 8 , which is a schematic diagram comparing mainstream velocity curves at different flow direction positions according to an embodiment of the present application.

[0087] Optionally, in one embodiment of the present application, obtaining progress variable information of supersonic combustion based on a four-dimensional table includes: solving the mixture fraction equation, the progress variable equation, and the transport equation of the total internal energy in the supersonic combustion process, so as to obtain the mixture fraction-progress variable-total internal energy sub-grid joint probability density distribution through the Euler random field equation; based on the four-dimensional table, combining the mixture fraction-progress variable-total internal energy sub-grid joint probability density distribution to obtain the progress variable information of supersonic combustion.

[0088] Based on the relevant descriptions of other embodiments, it can be understood that when reading the progress variable information of the chemical reaction source term from the four-dimensional table, it is necessary to solve the mixture fraction equation, the progress variable equation, and the transport equation of the total internal energy in the supersonic combustion process on the basis of solving the continuity equation and the momentum equation again, so as to obtain the mixture fraction-progress variable-total internal energy sub-grid joint probability density distribution, and then combine with the four-dimensional table to obtain the progress variable information of the chemical reaction source term of supersonic combustion.

[0089] For example, to use the constructed table in large eddy simulation, the embodiment of the present application needs to solve the continuity equation and the momentum equation, where the equation forms of the continuity equation and the momentum equation are consistent with equations (1) and (2). In order to read the progress variable information of the chemical reaction source term from the table, the embodiment of the present application also needs to solve the mixture fraction (Z), progress variable (Y c ), total internal energy (E a ) transport equation. Additionally, the pressure in the embodiments of the present application can be obtained from density calculation according to, but not limited to, the ideal gas equation.

[0090] It should be noted that the thermophysical property data of the mixture (viscosity, mass diffusion coefficient, energy diffusion coefficient, etc.) in the embodiment of the present application are not directly read from the four-dimensional table, but are calculated from the total internal energy transported and the mass fraction of the components read from the four-dimensional table. This method of calculating the thermophysical property data of the mixture can better consider the influence of flow compressibility.

[0091] Furthermore, in order to better consider ZY c -E a The sub-grid joint probability density distribution, the embodiment of the present application can use the Euler random field method to solve the probability density transport function, which can be expressed as follows:

[0092]

[0093] in,

[0094] In the Euler random field model, the average value and high-order moment of a random vector are obtained by ensemble averaging a series of related Euler random fields. In the embodiment of the present application, this random vector is composed of the mixing fraction (Z), the progress variable (Y c ), total internal energy (E a ). For example, the average Among them, N F represents the number of random fields, is the nth random field, x is the spatial position coordinate, t is the time, C is the convection term, D represents molecular diffusion and sub-grid turbulent transport, is a small-scale mixing term, is the chemical reaction source term, is the Wiener term, dW i (n) Represents the incremental direction in the Wiener process (also known as the Wiener process or Brownian motion process, which is a random process with continuous time parameters and continuous state space). Different random fields have different values, but the same random field has the same value in space. C φis the parameter in the mean-exchanging small-scale mixing model, ω sgs is the subgrid turbulence frequency. Generally in large eddy simulations, C φ The value can be 2, N F The possible value is 8.

[0095] According to the flame surface simulation method of supersonic combustion proposed in the embodiment of the present application, a one-dimensional flame can be calculated to construct a four-dimensional table of mixture fraction-progress variable-total internal energy on the oxidant side-pressure, obtain the progress variable information of supersonic combustion, and obtain the flame surface simulation result of supersonic combustion. Thus, according to the characteristics of supersonic combustion, on the basis of the small flame model of traditional mixture fraction-progress variable, two control variables, pressure and total internal energy on the oxidant side, are introduced, and the Euler random field method is introduced to describe the joint probability density distribution function between the control variables, reducing the influence of the preset probability density function and improving the calculation accuracy. Thus, the problem that the transport probability density distribution function model in the related art cannot apply the detailed chemical reaction mechanism due to the limitation of the calculation amount, which reduces the accuracy of the numerical simulation to a certain extent, and the small flame model can consider the detailed chemical reaction mechanism, but a simple distribution function needs to be used for the unresolved sub-grid probability density distribution function, and the joint probability density distribution function between different control variables cannot be considered, and the calculation accuracy is low.

[0096] Next, the flame surface simulation device for supersonic combustion proposed in accordance with an embodiment of the present application will be described with reference to the accompanying drawings.

[0097] Fig. 9 It is a schematic structural diagram of a flame surface simulation device for supersonic combustion according to an embodiment of the present application.

[0098] like Fig. 9 As shown, the flame surface simulation device 10 of supersonic combustion includes: a solution module 100 , a calculation module 200 and a simulation module 300 .

[0099] The solution module 100 is used to solve the continuity equation, momentum equation, mixture fraction equation and energy equation in the supersonic cold mixing process to obtain the mixture fraction distribution, pressure distribution and total internal energy distribution of the mixture in the supersonic cold mixing process.

[0100] The calculation module 200 is used to calculate the one-dimensional flame based on the mixture fraction distribution, the pressure distribution and the total internal energy distribution of the mixture, so as to construct at least one four-dimensional table of mixture fraction-progress variable-oxidant side total internal energy-pressure based on the one-dimensional flame.

[0101] The simulation module 300 is used to obtain the progress variable information of the supersonic combustion based on the four-dimensional table, and obtain the flame surface simulation result of the supersonic combustion according to the progress variable information.

[0102] Optionally, in one embodiment of the present application, the solution module 100 includes: a first establishment unit and a first solution unit.

[0103] Wherein, the first setting unit is used to set up target initial conditions and target boundary conditions;

[0104] The first solving unit is used to solve the continuity equation, momentum equation, mixture fraction equation and energy equation in the supersonic cold mixing process through the target turbulence model based on the target initial condition and the target boundary condition.

[0105] Optionally, in one embodiment of the present application, the calculation module 200 includes: a second establishment unit and a calculation unit.

[0106] Among them, the second setting unit is used to set up different pressure conditions, different oxidant side temperatures and different stretching rates.

[0107] The calculation unit is used to calculate the one-dimensional flame based on the mixture fraction distribution, pressure distribution and total internal energy distribution of the mixture under different pressure conditions, different oxidant side temperatures and different stretching ratios.

[0108] Optionally, in one embodiment of the present application, the simulation module 300 includes: a second solving unit and an acquiring unit.

[0109] Among them, the second solving unit is used to solve the mixture fraction equation, progress variable equation, and total internal energy transport equation in the supersonic combustion process, so as to obtain the mixture fraction-progress variable-total internal energy sub-grid joint probability density distribution through the Euler random field equation.

[0110] The acquisition unit is used to acquire the progress variable information of supersonic combustion based on a four-dimensional table and in combination with the mixed fraction-progress variable-total internal energy sub-grid joint probability density distribution.

[0111] Optionally, in one embodiment of the present application, the expressions of the continuity equation, the momentum equation, the mixture fraction equation and the energy equation can be expressed as follows:

[0112]

[0113] in, The wavy line represents the Favre filter average (also known as density-weighted average, a common averaging method in fluid dynamics), and the horizontal line represents the spatial filter average. is the density, t is the time, x j is the component of the position vector in the j direction, is the component of velocity in the i direction, is the component of velocity in the j direction, is the filtered stress tensor, is the stress tensor of the subgrid, is the Bilger mixed fraction, D eff is the effective mass diffusion coefficient, is the total internal energy of the mixture, is the viscous heat dissipation of the subgrid, Γ eff is the effective energy diffusion coefficient, K is the kinetic energy, It's pressure. is the sensible enthalpy of the mixture.

[0114] It should be noted that the aforementioned explanation of the embodiment of the flame surface simulation method for supersonic combustion is also applicable to the flame surface simulation device for supersonic combustion of this embodiment, and will not be repeated here.

[0115] According to the flame surface simulation device for supersonic combustion proposed in the embodiment of the present application, a one-dimensional flame can be calculated to construct a four-dimensional table of mixture fraction-progress variable-total internal energy on the oxidant side-pressure, obtain the progress variable information of supersonic combustion, and obtain the flame surface simulation result of supersonic combustion. Thus, according to the characteristics of supersonic combustion, on the basis of the small flame model of the traditional mixture fraction-progress variable, two control variables, pressure and total internal energy on the oxidant side, are introduced, and the Euler random field method is introduced to describe the joint probability density distribution function between the control variables, reducing the influence of the preset probability density function and improving the calculation accuracy. Thus, the problem that the transport probability density distribution function model in the related art cannot apply the detailed chemical reaction mechanism due to the limitation of the calculation amount, which reduces the accuracy of the numerical simulation to a certain extent, and the small flame model can consider the detailed chemical reaction mechanism, but a simple distribution function needs to be used for the unresolved sub-grid probability density distribution function, and the joint probability density distribution function between different control variables cannot be considered, and the calculation accuracy is low.

[0116] Fig.10 A schematic diagram of the structure of an electronic device provided in an embodiment of the present application. The electronic device may include:

[0117] A memory 1001 , a processor 1002 , and a computer program stored in the memory 1001 and executable on the processor 1002 .

[0118] When the processor 1002 executes the program, the flame surface simulation method for supersonic combustion provided in the above embodiment is implemented.

[0119] Furthermore, the electronic device further comprises:

[0120] The communication interface 1003 is used for communication between the memory 1001 and the processor 1002 .

[0121] The memory 1001 is used to store computer programs that can be executed on the processor 1002 .

[0122] The memory 1001 may include a high-speed RAM memory, and may also include a non-volatile memory (non-volatile memory), such as at least one disk memory.

[0123] If the memory 1001, the processor 1002 and the communication interface 1003 are implemented independently, the communication interface 1003, the memory 1001 and the processor 1002 can be connected to each other through a bus and communicate with each other. The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus. The bus can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, Fig.10 Only one thick line is used in the diagram, but this does not mean that there is only one bus or only one type of bus.

[0124] Optionally, in a specific implementation, if the memory 1001, the processor 1002 and the communication interface 1003 are integrated on a chip, the memory 1001, the processor 1002 and the communication interface 1003 can communicate with each other through an internal interface.

[0125] The processor 1002 may be a central processing unit (CPU), or an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of the present application.

[0126] An embodiment of the present application also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the flame surface simulation method for supersonic combustion as described above.

[0127] An embodiment of the present application also provides a computer program product, including a computer program, which can run computer instructions. When the computer instructions are executed by a processor, the flame surface simulation method for supersonic combustion provided in the embodiment of the present application is implemented.

[0128] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or N embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0129] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, "N" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0130] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, fragment or portion of code comprising one or N executable instructions for implementing the steps of a custom logical function or process, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in reverse order depending on the functions involved, which should be understood by technicians in the technical field to which the embodiments of the present application belong.

[0131] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in combination with these instruction execution systems, devices or apparatuses. For the purpose of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in combination with these instruction execution systems, devices or apparatuses. More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or N wirings (electronic devices), a portable computer disk box (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), a fiber optic device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically by optically scanning the paper or other medium and then editing, interpreting or processing in other suitable ways as necessary and then storing it in a computer memory.

[0132] It should be understood that the various parts of the present application can be implemented by hardware, software, firmware or a combination thereof. In the above embodiment, the N steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. If implemented by hardware, as in another embodiment, it can be implemented by any one or a combination of multiple of the following technologies known in the art: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0133] A person skilled in the art may understand that all or part of the steps in the method for implementing the above-mentioned embodiment may be completed by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, which, when executed, includes one or a combination of the steps of the method embodiment.

[0134] In addition, each functional unit in each embodiment of the present application may be integrated into a processing module, or each unit may exist physically separately, or two or more units may be integrated into one module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of a software functional module. If the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it may also be stored in a computer-readable storage medium.

[0135] The storage medium mentioned above may be a read-only memory, a magnetic disk or an optical disk, etc. Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limiting the present application. A person of ordinary skill in the art may change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A method for simulating a flame surface of supersonic combustion, characterized in that: The following steps are involved: Solving the continuity equation, momentum equation, mixture fraction equation and energy equation in the supersonic cold mixing process to obtain the mixture fraction distribution, pressure distribution and total internal energy distribution of the mixture in the supersonic cold mixing process; Calculating a one-dimensional flame based on the mixture fraction distribution, the pressure distribution and the mixture total internal energy distribution to construct at least one four-dimensional table of mixture fraction-progress variable-oxidant side total internal energy-pressure based on the one-dimensional flame; The progress variable information of the supersonic combustion is acquired based on the four-dimensional table, and the flame surface simulation result of the supersonic combustion is obtained according to the progress variable information.

2. The method according to claim 1, characterized in that The method for solving the continuity equation, momentum equation, mixture fraction equation and energy equation in the supersonic cold mixing process includes: Establish target initial conditions and target boundary conditions; Based on the target initial condition and the target boundary condition, the continuity equation, momentum equation, mixture fraction equation and energy equation in the supersonic cold mixing process are solved by a target turbulence model.

3. The method according to claim 1, characterized in that The calculating of the one-dimensional flame based on the mixture fraction distribution, the pressure distribution and the total internal energy distribution of the mixture comprises: Establish different pressure conditions, different oxidant side temperatures, and different stretching rates; The one-dimensional flame is calculated based on the mixture fraction distribution, the pressure distribution and the total internal energy distribution of the mixture under the different pressure conditions, the different oxidant side temperatures and the different stretching ratios.

4. The method according to claim 1, characterized in that: The obtaining of progress variable information of supersonic combustion based on the four-dimensional table includes: Solving the mixture fraction equation, the progress variable equation, and the transport equation of the total internal energy in the supersonic combustion process, so as to obtain the mixture fraction-progress variable-total internal energy subgrid joint probability density distribution through the Euler random field equation; Based on the four-dimensional table, the progress variable information of the supersonic combustion is obtained in combination with the mixture fraction-progress variable-total internal energy sub-grid joint probability density distribution.

5. The method according to claim 1, characterized in that: The expressions of the continuity equation, momentum equation, mixture fraction equation and energy equation are: in, The wavy line represents the Favre filter average, and the horizontal line represents the spatial filter average. is the density, t is the time, x j is the component of the position vector in the j direction, is the component of velocity in the i direction, is the component of velocity in the j direction, is the filtered stress tensor, is the stress tensor of the subgrid, is the Bilger mixed fraction, D eff is the effective mass diffusion coefficient, is the total internal energy of the mixture, is the viscous heat dissipation of the subgrid, Γ eff is the effective energy diffusion coefficient, K is kinetic energy, It's pressure. is the sensible enthalpy of the mixture.

6. The method according to claim 4, characterized in that The expression of the Euler random field equation is: in, is the density, is the nth random field, is the convection term, represents molecular diffusion and turbulent transport in the subgrid, is a small-scale mixing term, is the chemical reaction source term.

7. A flame surface simulation device for supersonic combustion, characterized in that: include: A solution module, used for solving the continuity equation, momentum equation, mixture fraction equation and energy equation in the supersonic cold mixing process, so as to obtain the mixture fraction distribution, pressure distribution and total internal energy distribution of the mixture in the supersonic cold mixing process; A calculation module, configured to calculate a one-dimensional flame based on the mixture fraction distribution, the pressure distribution and the mixture total internal energy distribution, so as to construct at least one four-dimensional table of mixture fraction-progress variable-oxidant side total internal energy-pressure based on the one-dimensional flame; The simulation module is used to obtain the progress variable information of the supersonic combustion based on the four-dimensional table, and obtain the flame surface simulation result of the supersonic combustion according to the progress variable information.

8. An electronic device, characterized in that: include: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the flame surface simulation method for supersonic combustion according to any one of claims 1 to 6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: The program is executed by a processor to implement the flame surface simulation method for supersonic combustion as described in any one of claims 1 to 6.

10. A computer program product, comprising a computer program, characterized in that When the computer program is executed, it is used to implement the flame surface simulation method for supersonic combustion as described in any one of claims 1-6.

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