Method and apparatus for predicting ignition delay time of compressible flow field auto-ignition process

Abstract

The application provides a compressible flow field self-ignition process ignition delay time prediction method and device, relates to the aircraft ignition prediction technical field, and includes the following steps: monitoring the initial local temperature of the engine inside a hypersonic aircraft before self-ignition operation in real time; self-ignition simulation is carried out through preselected combustion characteristic parameters of a high-compressibility combustion field; in the self-ignition simulation process, the ignition delay time of the hypersonic aircraft is predicted based on the initial local temperature and the preselected combustion characteristic parameters of the high-compressibility combustion field. The application can accurately predict the ignition delay time before ignition, so that the combustion process after ignition can be better controlled, and the occurrence of problems such as unstable combustion is reduced.

Description

Technical Field

[0001] This application relates to the field of aircraft ignition prediction technology, and in particular to a method and apparatus for predicting the ignition delay time in a compressible flow field self-ignition process. Background Technology

[0002] To address key issues such as combustion stability and efficiency within hypersonic vehicles, it is necessary to study and predict the autoignition process within hypersonic vehicles. The main physical quantity affecting the autoignition process from high compressibility and turbulence is the ignition delay time. Accurate prediction of the ignition delay time can better control this instability factor.

[0003] In related technologies, some methods for predicting ignition delay time do not consider the influence of turbulence on the autoignition process, and the applicability of these methods in hypersonic turbulent combustion processes is problematic. Secondly, some current results obtain the influence of turbulence on ignition delay time by analyzing changes in scalar dissipation rate, etc., which makes it difficult to accurately predict ignition delay time. Summary of the Invention

[0004] The purpose of this application is to provide a method and apparatus for predicting the ignition delay time in a compressible flow field self-ignition process, so as to alleviate the above-mentioned technical problems existing in the prior art.

[0005] In a first aspect, the present invention provides a method for predicting the ignition delay time in a compressible flow field self-ignition process, comprising:

[0006] Real-time monitoring of the initial local temperature inside the engine of a hypersonic vehicle before self-ignition;

[0007] Self-ignition simulation is performed using combustion characteristic parameters of a pre-selected highly compressible combustion field. During the self-ignition simulation, the ignition delay time of the hypersonic vehicle is predicted based on the initial local temperature and the combustion characteristic parameters of the pre-selected highly compressible combustion field.

[0008] In an optional implementation, the combustion characteristic parameters of the pre-selected highly compressible combustion field include a first combustion characteristic parameter;

[0009] The first combustion characteristic parameters include at least: characteristic length scale of flame diffusion, turbulence scale, activation energy, gas constant, Taylor-Reynolds number, specific heat capacity, heat released per unit mass of fuel, frequency factor, oxidant mass fraction, fuel density, oxidant molar mass, and Mach number-related parameters.

[0010] In an optional implementation, during the self-ignition simulation, the ignition delay time of the hypersonic vehicle is predicted based on the initial local temperature and combustion characteristic parameters of a pre-selected highly compressible combustion field, including:

[0011] During the self-ignition simulation, the relative scale of the target is determined based on the characteristic length scale of the flame spread and the turbulence scale.

[0012] A first prediction model is constructed based on the initial local temperature, temperature change rate, target relative scale and gas constant, Taylor-Reynolds number, specific heat capacity, heat released per unit mass of fuel, frequency factor, oxidant mass fraction, fuel density, oxidant molar mass, and Mach number-related parameters. The first prediction model is... Among them, l FD η is the characteristic length scale of flame propagation; η is the turbulence scale; T0 is the local temperature at the initial moment; E A As the activation energy, R 0 T is the gas constant; const Re is the rate of temperature change; λ C is the Taylor Reynolds number; V q represents specific heat capacity. F A is the frequency factor, Y O ρ is the mass fraction of the oxidant. F W represents the density of the fuel. O is the molar mass of the oxidant; β and γ(M) are parameters and functions related to the Mach number;

[0013] The ignition delay time of the hypersonic vehicle is predicted using the first prediction model.

[0014] In an optional implementation, the method further includes:

[0015] Based on the initial Damkel number Da before successful ignition t and the corresponding Reynolds number Re t Determine the relative scale of the target.

[0016] In an optional implementation, the target relative scale is determined based on the initial Damkel number and the target Reynolds number before successful ignition, calculated using the following formula:

[0017]

[0018] Where, k FD For the target relative scale, Da t Let Re be the initial Damkel number. t It is the Reynolds number.

[0019] In an optional implementation, the combustion characteristic parameters of the pre-selected highly compressible combustion field include a second combustion characteristic parameter;

[0020] The second combustion characteristic parameter includes at least: flame propagation speed, Taylor-Reynolds number, turbulence scale, activation energy, gas constant, specific heat capacity, heat released per unit mass of fuel, frequency factor, oxidant mass fraction, fuel density, and oxidant molar mass.

[0021] In an optional implementation, during the self-ignition simulation, the ignition delay time of the hypersonic vehicle is predicted based on the initial local temperature and combustion characteristic parameters of a pre-selected highly compressible combustion field, including:

[0022] A second prediction model is constructed based on the initial local temperature, temperature fluctuation parameters, flame propagation velocity, Taylor-Reynolds number, turbulence scale, activation energy, gas constant, specific heat capacity, heat released per unit mass of fuel, frequency factor, oxidant mass fraction, fuel density, and oxidant molar mass. The second prediction model is... Among them, U FD Re represents the flame propagation speed, T' represents the temperature fluctuation, and Re λ η is the Taylor Reynolds number; η is the Kolmogorov scale; T0 is the local temperature at the initial moment; E A As the activation energy, R 0 C is the gas constant; V q represents specific heat capacity. F A is the frequency factor, Y O ρ is the mass fraction of the oxidant. F W represents the density of the fuel. O The molar mass of the oxidant;

[0023] The ignition delay time of the hypersonic vehicle is predicted using the second prediction model.

[0024] In a second aspect, the present invention provides an ignition delay time prediction device for a compressible flow field self-ignition process, comprising:

[0025] The pre-ignition temperature monitoring module is used to monitor the initial local temperature inside the hypersonic vehicle engine in real time before the self-ignition operation.

[0026] The ignition delay time prediction module is used to perform self-ignition simulation using combustion characteristic parameters of a pre-selected highly compressible combustion field. During the self-ignition simulation, the module predicts the ignition delay time of the hypersonic vehicle based on the initial local temperature and the combustion characteristic parameters of the pre-selected highly compressible combustion field.

[0027] Thirdly, the present invention provides an electronic device including a processor and a memory, wherein the memory stores computer-executable instructions that can be executed by the processor, and the processor executes the computer-executable instructions to implement the ignition delay time prediction method for the compressible flow field self-ignition process as described in any of the foregoing embodiments.

[0028] Fourthly, the present invention provides a computer-readable storage medium storing computer-executable instructions, which, when called and executed by a processor, cause the processor to implement the ignition delay time prediction method for the compressible flow field self-ignition process as described in any of the foregoing embodiments.

[0029] The beneficial effects of the method and apparatus for predicting ignition delay time in the compressible flow field self-ignition process provided in this application are as follows:

[0030] The original method for calculating ignition delay time at low Mach numbers without considering turbulence is extended and improved by incorporating the influence of turbulence into the process and simplifying it into specific parameters. A theoretical calculation method for the relative scale of turbulence is presented, which can reasonably estimate the relative scale using the Damker number and the corresponding Reynolds number in the initial state, thus facilitating the prediction of the final ignition delay time. Furthermore, a method is proposed to predict the ignition delay time at higher Mach numbers using results from low Mach numbers, further simplifying the calculation process and reducing computational costs for Mach number ignition delay time. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0032] Figure 1 A flowchart illustrating a method for predicting ignition delay time in a compressible flow field self-ignition process, provided as an embodiment of this application;

[0033] Figure 2 A structural diagram of an ignition delay time prediction device for a compressible flow field self-ignition process provided in this application embodiment;

[0034] Figure 3 A structural diagram of another compressible flow field self-ignition process ignition delay time prediction device provided in an embodiment of this application;

[0035] Figure 4 This is a structural diagram of an electronic device provided in an embodiment of this application. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0037] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0038] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0039] The gas environment surrounding hypersonic vehicles is characterized by extreme temperatures and ultra-high velocities caused by air friction and shock waves. Intense aerodynamic and thermal loads and combustion instabilities constantly jeopardize the vehicle's structure and thrust performance. This is particularly evident in the ignition and combustion processes within the engine. Hypersonic propulsion combustion systems face numerous challenges related to high velocities. These velocities limit the residence time for chemical reactions within the combustion chamber, severely impacting flame propagation. Therefore, in hypersonic propulsion systems, besides the supersonic turbulent combustion induced by forced ignition, the stability of combustion inevitably depends on the autoignition process of the fuel-air mixture. While the autoignition time of most fuel-air mixtures largely depends on temperature, in supersonic turbulent combustion, in addition to the initial high temperature of the incoming flow, it is also affected by localized heating due to viscous dissipation in a highly compressible turbulent field and localized compression caused by shock waves. Since both local dissipation and the impact of shock waves on autoignition are strongly nonlinear coupling problems, their mechanisms are complex and ultimately affect the instability of the entire combustion system. This high-temperature, highly compressible autoignition problem has a significant impact on hypersonic propulsion systems. Therefore, to address key issues such as combustion stability and efficiency within hypersonic vehicles, a detailed study of the autoignition process is needed, analyzing the influence of high compressibility and turbulence on it. The main physical quantity reflecting this influence is the ignition delay time; accurate prediction of the ignition delay time allows for better control of this instability factor.

[0040] Previous research has revealed two main problems in the analysis of ignition delay time. Firstly, simplified ignition processes often neglect the influence of turbulence, focusing only on initial temperature and pressure. A common approach is to use ignition delay time prediction formulas derived from thermal ignition theory. These formulas assume almost constant fuel mass fraction and temperature, ignoring the impact of turbulence on flame core formation and propagation. While this approach is more applicable to premixed low-speed conditions, more detailed analysis is needed for hypersonic turbulent combustion. Secondly, because turbulence's influence on the autoignition process is not monotonically linear, the ignition delay time exhibits uncertainty with variations in turbulence intensity. Current results attribute differences in the final ignition delay time to variations in scalar dissipation rate, but lack a detailed analysis of the physical mechanisms underlying turbulence's influence on the autoignition process, and fail to provide feasible methods for predicting ignition delay time in such highly compressible flow fields.

[0041] In summary, the existing research methods have two main drawbacks. First, some existing simplified methods do not consider the influence of turbulence on the autoignition process, and their applicability in hypersonic turbulent combustion processes is questionable. Second, some current results obtain the influence of turbulence on ignition delay time by analyzing changes in scalar dissipation rate, etc., which makes it difficult to accurately predict the ignition delay time.

[0042] Based on this, embodiments of this application provide a method and apparatus for predicting the ignition delay time in a compressible flow field self-ignition process, which can accurately predict the ignition delay time before ignition, so as to better control the combustion process after ignition and reduce the occurrence of problems such as unstable combustion.

[0043] This application provides a method for predicting the ignition delay time in a compressible flow field self-ignition process. (See also...) Figure 1 As shown, the method mainly includes the following steps:

[0044] Step S110: Real-time monitoring of the initial local temperature inside the hypersonic vehicle engine before the self-ignition operation.

[0045] The aforementioned initial local temperature may include the local temperature of the ignition device inside the hypersonic vehicle engine, which can be obtained by measuring a temperature sensor or other temperature measuring device located at the corresponding position of the ignition device inside the hypersonic vehicle engine.

[0046] In one implementation, real-time monitoring can be performed during a preset period of time before the self-ignition operation. For example, a certain time interval can be selected as the monitoring period, and the local temperature of the ignition device inside the hypersonic vehicle engine before ignition can be accurately obtained by periodically monitoring the temperature.

[0047] Step S120: Self-ignition simulation is performed using combustion characteristic parameters of a pre-selected highly compressible combustion field. During the self-ignition simulation, the ignition delay time of the hypersonic vehicle is predicted based on the initial local temperature and the combustion characteristic parameters of the pre-selected highly compressible combustion field.

[0048] In one implementation, to accurately simulate self-ignition, a local analysis of the combustion field can be performed beforehand. Based on hot ignition theory, it is assumed that a single-step irreversible reaction occurs:

[0049]

[0050] Where F represents fuel, O represents oxidant, P represents reaction product, and k F This is the reaction rate constant. Combining this with the component equation, we know that:

[0051]

[0052] Where ω F w represents the fuel reaction rate. O For the oxidant reaction rate, C F For fuel concentration, C O The concentration of the oxidant is E. A is the frequency factor, and E is the oxidant concentration. A As the activation energy, R 0 Let Y be the gas constant, T be the temperature, and ρ be the density of the gas mixture. F Y represents the fuel mass fraction. O W represents the mass fraction of the oxidant. F W is the molar mass of fuel. O This represents the molar mass of the oxidizing agent.

[0053] From the fuel concentration formula, we know that:

[0054]

[0055] Therefore, combining the above formulas, we can obtain:

[0056]

[0057] Combining the energy equation, we can see that:

[0058]

[0059] Where, q F This represents the heat released per unit mass of fuel. Combining equations 2 and 6, we get:

[0060]

[0061] Parameter ρ F The density and specific heat capacity (C) of fuel are expressed as follows:V It is a constant. In the initial stage of ignition, since the temperature change is very small, we can assume that:

[0062] T=T0(1-εy),ε<<1,y~O(1) (8)

[0063] Where T0 is the local temperature at the initial moment. Therefore, we can conclude that:

[0064]

[0065] Based on the initial conditions (y(t=0)=0), the ignition time τ can be derived. i The solution is:

[0066]

[0067] For the local fuel density ρ in the turbulent combustion field F Dimensional analysis is performed, involving physical processes such as thermodynamics, chemical reaction kinetics, mass transfer, and fluid dynamics, which are significantly influenced by the interaction between chemical reactions and turbulence. Local small flames consume fuel and release heat, altering the thermodynamic state and thus affecting turbulence. The turbulent vortex structure influences flame propagation and local mass transport processes, leading to changes in local chemical reaction kinetics. Since the focus is on analyzing local fuel density, the results of local chemical reaction kinetics and flame diffusion are related to the fuel consumption process through chemical reactions. Therefore, complex chemical reaction kinetic parameters are simplified to characterize the flame diffusion process. By comprehensively analyzing the characteristic parameters related to the turbulent vortex structure, a dimensional expression for local fuel density can be obtained. The main physical processes are analyzed, and the characteristic parameters are selected as follows:

[0068] (a) Diffusion effect: diffusion coefficient D and local temperature T as a function of temperature;

[0069] (b) Flame spread effect: characteristic length scale of flame spread l FD ;

[0070] (c) Turbulence effects: turbulent fluctuation velocity u′, turbulent dissipation rate ε, turbulent integral scale L, kinematic viscosity coefficient v;

[0071] (d) Initial conditions: density ρ0 and temperature T0 at the initial time.

[0072] ρ F =f(D,T,l) FD ,u′,ε,L,ρ0,T0,ν) (11)

[0073] Select ε,L,ρ0,T as feature parameters:

[0074]

[0075] Some parameters also satisfy the following relationship:

[0076]

[0077] ρ=ρ0+dρ,T=T0+dT (14)

[0078]

[0079] In the formula, η is the Kolmogorov scale. Based on Barenblatt's incomplete similarity theory, it is assumed that in compressible turbulence, influenced by factors such as turbulence, the local fuel density and parameters... Not entirely similar, but related to Mach number M or Taylor Reynolds number Re. λ Dissimilar:

[0080]

[0081] Where β and γ(M) are parameters and functions related to the Mach number. It can be inferred that in a relatively compressible turbulent field, due to the interaction between turbulence and chemical reactions, parameter A′ is affected not only by the Mach number but also by the turbulence scale and the flame diffusion scale.

[0082]

[0083] Furthermore, the Zeldovich relationship before ignition shows that:

[0084]

[0085] In the formula, U FD Let ξ represent the flame propagation speed, and ξ be the normal spatial coordinate of the reaction front. Furthermore, the above equation can be equivalently expressed as: The relationship between ignition delay time and temperature is as follows:

[0086]

[0087] Based on the approximation method using the temperature derivative, we can derive:

[0088]

[0089] Among them, l λ Let T represent the Taylor scale of the turbulence, and T′ represent the temperature fluctuation. Combining these two equations, we can obtain:

[0090]

[0091] The denominator can be converted to Since the temperature change is very small before successful ignition, the rate of change over time can be represented by a relatively small constant T. const To approximate.

[0092] The expression for the final ignition delay time is as follows:

[0093]

[0094] This result demonstrates that, unlike simple hot-point ignition theory, in a highly compressible combustion field, the ignition delay time is affected not only by the initial temperature but also by the relative scale. The impact.

[0095] The dimensionless Damker number Da, which characterizes the relative magnitudes of flame propagation time and turbulent flow time during the ignition process. t and the corresponding Reynolds number Re t (Inertial forces and viscous forces in the flow field) indicate that:

[0096] Da t =τ t / τ c =(L ∈ / u rms ) / (l FD / U FD ) (twenty four)

[0097] Re t =u rms L ∈ / ν=(u rms / U FD (L) ∈ / l FD (25)

[0098] Where τ t τ is the characteristic time of turbulent flow. c Flame diffusion characteristic time. L ∈ For the turbulent integral scale, u rms Let be the root mean square velocity of the turbulent flow, where v is the kinematic viscosity, and l satisfies FD =v / U FD By combining equations (24) and (25), we can conclude that:

[0099]

[0100] Furthermore, the relationships between different scales of turbulence show that:

[0101]

[0102] Let relative scale be used From formula (26), we can see that:

[0103]

[0104] Therefore, relative scale This can be determined from the initial Damkel number Da before successful ignition. t and the corresponding Reynolds number Re t To perform theoretical estimation:

[0105]

[0106] Therefore, all variables involved in the final ignition delay time can be estimated from the initial parameters.

[0107] Based on the inventors' research process described above, this application provides two embodiments for determining the ignition delay time, which are described below.

[0108] In one embodiment, the combustion characteristic parameters of the pre-selected highly compressible combustion field include a first combustion characteristic parameter;

[0109] The first combustion characteristic parameters include at least the following: characteristic length scale of flame diffusion, turbulence scale, activation energy, gas constant, Taylor-Reynolds number, specific heat capacity, heat released per unit mass of fuel, frequency factor, oxidant mass fraction, fuel density, oxidant molar mass, and Mach number-related parameters.

[0110] Corresponding to the first combustion characteristic parameter mentioned above, during the self-ignition simulation process, predicting the ignition delay time of the hypersonic vehicle based on the combustion characteristic parameters of the initial local temperature and the pre-selected highly compressible combustion field may include the following steps 1-1 to 1-3:

[0111] Step 1-1: During the self-ignition simulation, the relative scale of the target is determined based on the characteristic length scale and turbulence scale of flame propagation.

[0112] Steps 1-2: Based on the initial local temperature, rate of temperature change, target relative scale, gas constant, Taylor-Reynolds number, specific heat capacity, heat released per unit mass of fuel, frequency factor, oxidant mass fraction, fuel density, oxidant molar mass, and Mach number, a first prediction model is constructed. The first prediction model is... Among them, l FD η is the characteristic length scale of flame propagation; η is the turbulence scale; T0 is the local temperature at the initial moment; E A As the activation energy, R 0 T is the gas constant; const Re is the rate of temperature change; λ C is the Taylor Reynolds number; V q represents specific heat capacity. F A is the frequency factor, Y Oρ is the mass fraction of the oxidant. F W represents the density of the fuel. O is the molar mass of the oxidant; β and γ(M) are parameters and functions related to the Mach number;

[0113] Steps 1-3: Predict the ignition delay time of the hypersonic vehicle using the first prediction model.

[0114] In an optional implementation, the method further includes:

[0115] Based on the initial Damkel number Da before successful ignition t and the corresponding Reynolds number Re t Determine the relative scale of the target.

[0116] In an optional implementation, the target relative scale is determined based on the initial Damker number and the target Reynolds number before successful ignition, and is calculated using the following formula:

[0117]

[0118] Where, k FD For the target relative scale, Da t Let Re be the initial Damkel number. t It is the Reynolds number.

[0119] In summary, since the methods for calculating ignition delay time described above are significantly affected by temperature, relative scale, and Mach number, to further simplify the prediction process and reduce computational costs, experimental or numerical simulations can be performed on relatively simple low-Mach number self-ignition scenarios. This ensures that parameters such as temperature and equivalence ratio remain constant in the initial conditions, only changing the initial Mach number. As shown in the first prediction model, the parameters affected by temperature remain largely unchanged; the main influence comes from the relative scale. Therefore, the ignition delay time at higher Mach numbers can be predicted using this low-Mach number ignition delay time combined with different relative scales, further simplifying the calculation process for ignition delay time prediction.

[0120] In another embodiment, the combustion characteristic parameters of the pre-selected highly compressible combustion field include second combustion characteristic parameters; the second combustion characteristic parameters include at least: flame propagation speed, Taylor-Reynolds number, turbulence scale, activation energy, gas constant, specific heat capacity, heat released per unit mass of fuel, frequency factor, oxidant mass fraction, fuel density, and oxidant molar mass.

[0121] Corresponding to the second combustion characteristic parameter mentioned above, predicting the ignition delay time of a hypersonic vehicle during the self-ignition simulation process based on the combustion characteristic parameters of the initial local temperature and the pre-selected highly compressible combustion field can include the following steps 2-1 and 2-2:

[0122] Step 2-1: Construct a second prediction model based on the initial local temperature, temperature fluctuation parameters, flame propagation velocity, Taylor-Reynolds number, turbulence scale, activation energy, gas constant, specific heat capacity, heat released per unit mass of fuel, frequency factor, oxidant mass fraction, fuel density, and oxidant molar mass. The second prediction model is... Among them, U FD Re represents the flame propagation speed, T' represents the temperature fluctuation, and Re λ η is the Taylor Reynolds number; η is the Kolmogorov scale; T0 is the local temperature at the initial moment; E A As the activation energy, R 0 C is the gas constant. V q represents specific heat capacity. F A is the frequency factor, Y o ρ is the mass fraction of the oxidant. F W represents the density of the fuel. o The molar mass of the oxidant;

[0123] Step 2-2: Predict the ignition delay time of the hypersonic vehicle using the second prediction model.

[0124] In summary, the ignition delay time prediction method adopted in the embodiments of this application combines dimensional analysis with similarity theory to extend and improve the original method of ignition delay time at low Mach numbers that did not consider the influence of turbulence. It adds the influence of turbulence on the process and simplifies it into specific parameters. A theoretical calculation method for the relative scale of turbulence is given, which can reasonably estimate the relative scale from the Damker number and the corresponding Reynolds number in the initial state, so as to facilitate the prediction of the final ignition delay time. A method for predicting the ignition delay time at higher Mach numbers using the results of low Mach numbers is proposed, further simplifying the calculation process and reducing the computational cost of Mach number ignition delay time.

[0125] Based on the above method embodiments, this application also provides an ignition delay time prediction device for compressible flow field self-ignition process, see [link to relevant documentation]. Figure 2 As shown, the device mainly includes the following parts:

[0126] The pre-ignition temperature monitoring module 210 is used to monitor the initial local temperature inside the hypersonic vehicle engine in real time before the self-ignition operation.

[0127] The ignition delay time prediction module 220 is used to perform self-ignition simulation using combustion characteristic parameters of a pre-selected highly compressible combustion field. During the self-ignition simulation, it predicts the ignition delay time of the hypersonic vehicle based on the initial local temperature and the combustion characteristic parameters of the pre-selected highly compressible combustion field.

[0128] In one feasible implementation, the combustion characteristic parameters of the pre-selected highly compressible combustion field include a first combustion characteristic parameter;

[0129] The first combustion characteristic parameters include at least the following: characteristic length scale of flame diffusion, turbulence scale, activation energy, gas constant, Taylor-Reynolds number, specific heat capacity, heat released per unit mass of fuel, frequency factor, oxidant mass fraction, fuel density, oxidant molar mass, and Mach number-related parameters.

[0130] In one feasible implementation, the ignition delay time prediction module 220 is used for:

[0131] In the self-ignition simulation process, the relative scale of the target is determined based on the characteristic length scale and turbulence scale of flame propagation.

[0132] The first prediction model is constructed based on parameters such as initial local temperature, rate of temperature change, target relative scale, gas constant, Taylor-Reynolds number, specific heat capacity, heat released per unit mass of fuel, frequency factor, oxidant mass fraction, fuel density, oxidant molar mass, and Mach number. The first prediction model is... Among them, l FD η is the characteristic length scale of flame propagation; η is the turbulence scale; T0 is the local temperature at the initial moment; E A As the activation energy, R 0 T is the gas constant; const Re is the rate of temperature change; λ C is the Taylor Reynolds number; V q represents specific heat capacity. F A is the frequency factor, Y O ρ is the mass fraction of the oxidant. F W represents the density of the fuel. O is the molar mass of the oxidant; β and γ(M) are parameters and functions related to the Mach number;

[0133] The ignition delay time of the hypersonic vehicle is predicted using the first prediction model.

[0134] In one feasible implementation, see Figure 3 As shown, the above-mentioned device further includes: a relative scale determination module, used for:

[0135] Based on the initial Damkel number Da before successful ignition t and the corresponding Reynolds number Re t Determine the relative scale of the target.

[0136] In one feasible implementation, the relative scale determination module is used to calculate using the following formula:

[0137]

[0138] Where, k FD For the target relative scale, Da t Let Re be the initial Damkel number. t It is the Reynolds number.

[0139] In one feasible implementation, the combustion characteristic parameters of the pre-selected highly compressible combustion field include a second combustion characteristic parameter;

[0140] The second combustion characteristic parameters include at least: flame propagation speed, Taylor-Reynolds number, turbulence scale, activation energy, gas constant, specific heat capacity, heat released per unit mass of fuel, frequency factor, oxidant mass fraction, fuel density, and oxidant molar mass.

[0141] In one feasible implementation, the ignition delay time prediction module 220 is used for:

[0142] A second prediction model is constructed based on the initial local temperature, temperature fluctuation parameters, flame propagation velocity, Taylor-Reynolds number, turbulence scale, activation energy, gas constant, specific heat capacity, heat released per unit mass of fuel, frequency factor, oxidant mass fraction, fuel density, and oxidant molar mass. The second prediction model is as follows: Among them, U FD Re represents the flame propagation speed, T' represents the temperature fluctuation, and Re λ η is the Taylor Reynolds number; η is the Kolmogorov scale; T0 is the local temperature at the initial moment; E A As the activation energy, R 0 C is the gas constant. V q represents specific heat capacity. F A is the frequency factor, Y O ρ is the mass fraction of the oxidant. F W represents the density of the fuel. O The molar mass of the oxidant;

[0143] The ignition delay time of the hypersonic vehicle is predicted using a second prediction model.

[0144] The compressible flow field self-ignition process ignition delay time prediction device provided in this application has the same implementation principle and technical effect as the aforementioned method embodiment. For the sake of brevity, any parts not mentioned in the embodiment of the compressible flow field self-ignition process ignition delay time prediction device can be referred to the corresponding content in the aforementioned compressible flow field self-ignition process ignition delay time prediction method embodiment.

[0145] This application also provides an electronic device, such as... Figure 4The diagram shows the structure of the electronic device 100, which includes a processor 41 and a memory 40. The memory 40 stores computer-executable instructions that can be executed by the processor 41. The processor 41 executes the computer-executable instructions to implement any of the above-mentioned methods for predicting the ignition delay time of the compressible flow field self-ignition process.

[0146] exist Figure 4 In the illustrated embodiment, the electronic device further includes a bus 42 and a communication interface 43, wherein the processor 41, the communication interface 43, and the memory 40 are connected via the bus 42.

[0147] The memory 40 may include high-speed random access memory (RAM) or non-volatile memory, such as at least one disk storage device. Communication between this system network element and at least one other network element is achieved through at least one communication interface 43 (which can be wired or wireless), such as the Internet, wide area network, local area network, metropolitan area network, etc. The bus 42 may be an ISA (Industry Standard Architecture) bus, a PCI (Peripheral Component Interconnect) bus, or an EISA (Extended Industry Standard Architecture) bus, etc. The bus 42 can be divided into address bus, data bus, control bus, etc. For ease of representation, Figure 4 The symbol is represented by a single double-headed arrow, but this does not mean that there is only one bus or one type of bus.

[0148] Processor 41 may be an integrated circuit chip with signal processing capabilities. In implementation, each step of the above method can be completed by the integrated logic circuitry in the hardware of processor 41 or by instructions in software form. Processor 41 can be a general-purpose processor, including a Central Processing Unit (CPU), a Network Processor (NP), etc.; it can also be a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field-Programmable Gate Array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the method disclosed in the embodiments of this application can be directly implemented by a hardware decoding processor, or implemented by a combination of hardware and software modules in the decoding processor. The software modules can reside in random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, or other mature storage media in the art. The storage medium is located in the memory. The processor 41 reads the information in the memory and, in conjunction with its hardware, completes the steps of the compressible flow field self-ignition process ignition delay time prediction method of the aforementioned embodiment.

[0149] This application also provides a computer-readable storage medium storing computer-executable instructions. When these computer-executable instructions are called and executed by a processor, they cause the processor to implement the above-described method for predicting the ignition delay time of the compressible flow field self-ignition process. For specific implementation details, please refer to the foregoing method embodiments, which will not be repeated here.

[0150] The computer program product of the compressible flow field self-ignition process ignition delay time prediction method and apparatus provided in this application includes a computer-readable storage medium storing program code. The instructions included in the program code can be used to execute the methods in the preceding method embodiments. For specific implementation, please refer to the method embodiments, which will not be repeated here.

[0151] Unless otherwise specifically stated, the relative steps, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of this application.

[0152] If a function is implemented as a software functional unit and sold or used as an independent product, it can be stored in a processor-executable, non-volatile, computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0153] In the description of this application, it should be noted that the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0154] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method for predicting the ignition delay time in a compressible flow field self-ignition process, characterized in that, include: Real-time monitoring of the initial local temperature inside the engine of a hypersonic vehicle before self-ignition; Self-ignition simulation is performed using combustion characteristic parameters of a pre-selected highly compressible combustion field. During the self-ignition simulation, the ignition delay time of the hypersonic vehicle is predicted based on the initial local temperature and the combustion characteristic parameters of the pre-selected highly compressible combustion field. The combustion characteristic parameters of the pre-selected highly compressible combustion field include a first combustion characteristic parameter; the first combustion characteristic parameter includes at least: characteristic length scale of flame diffusion, turbulence scale, activation energy, gas constant, Taylor-Reynolds number, specific heat capacity, heat released per unit mass of fuel, frequency factor, oxidant mass fraction, fuel density, oxidant molar mass, and Mach number related parameters. During the self-ignition simulation, the ignition delay time of the hypersonic vehicle is predicted based on the initial local temperature and the combustion characteristic parameters of the pre-selected highly compressible combustion field. This includes: determining the target relative scale based on the characteristic length scale of the flame spread and the turbulence scale during the self-ignition simulation; and constructing a first prediction model based on the initial local temperature, temperature change rate, target relative scale, gas constant, Taylor-Reynolds number, specific heat capacity, heat released per unit mass of fuel, frequency factor, oxidant mass fraction, fuel density, oxidant molar mass, and Mach number-related parameters. The first prediction model is... ;in, The characteristic length scale for flame propagation; For turbulent scales; The local temperature at the initial moment; For activation energy, It is the gas constant; The rate of temperature change; It is the Taylor Reynolds number; Specific heat capacity; This indicates the amount of heat released per unit mass of fuel; , A For frequency factors, This represents the mass fraction of the oxidant. Indicates the density of the fuel. The molar mass of the oxidant; and These are parameters and functions related to the Mach number; the ignition delay time of the hypersonic vehicle is predicted using the first prediction model; The method further includes: based on the initial Damkel number before successful ignition. and the corresponding Reynolds number The relative scale of the target is determined by the following formula: in, For the relative scale of the target Let the initial Damkel number be , It is the Reynolds number.

2. The method for predicting ignition delay time in a compressible flow field self-ignition process according to claim 1, characterized in that, The combustion characteristic parameters of the pre-selected highly compressible combustion field include a second combustion characteristic parameter; The second combustion characteristic parameter includes at least: flame propagation speed, Taylor-Reynolds number, turbulence scale, activation energy, gas constant, specific heat capacity, heat released per unit mass of fuel, frequency factor, oxidant mass fraction, fuel density, and oxidant molar mass.

3. The method for predicting the ignition delay time in a compressible flow field self-ignition process according to claim 2, characterized in that, During the self-ignition simulation, the ignition delay time of the hypersonic vehicle is predicted based on the initial local temperature and combustion characteristic parameters of a pre-selected highly compressible combustion field, including: A second prediction model is constructed based on the initial local temperature, temperature fluctuation parameters, flame propagation velocity, Taylor-Reynolds number, turbulence scale, activation energy, gas constant, specific heat capacity, heat released per unit mass of fuel, frequency factor, oxidant mass fraction, fuel density, and oxidant molar mass. The second prediction model is... ,in, Indicates the speed of flame propagation. T' Indicates temperature fluctuations. It is the Taylor Reynolds number; Kolmogorov scale, The local temperature at the initial moment; For activation energy, It is the gas constant; Specific heat capacity; This indicates the amount of heat released per unit mass of fuel; A is the frequency factor. This represents the mass fraction of the oxidant. Indicates the density of the fuel. The molar mass of the oxidant; The ignition delay time of the hypersonic vehicle is predicted using the second prediction model.

4. A device for predicting the ignition delay time in a compressible flow field self-ignition process, characterized in that, To implement the method of claim 1, the method comprises: The pre-ignition temperature monitoring module is used to monitor the initial local temperature inside the hypersonic vehicle engine in real time before the self-ignition operation. The ignition delay time prediction module is used to perform self-ignition simulation using combustion characteristic parameters of a pre-selected highly compressible combustion field. During the self-ignition simulation, the module predicts the ignition delay time of the hypersonic vehicle based on the initial local temperature and the combustion characteristic parameters of the pre-selected highly compressible combustion field.

5. An electronic device, characterized in that, The method includes a processor and a memory, the memory storing computer-executable instructions that can be executed by the processor, the processor executing the computer-executable instructions to implement the method for predicting the ignition delay time of the compressible flow field self-ignition process as described in any one of claims 1 to 3.

6. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable instructions, which, when invoked and executed by a processor, cause the processor to implement the ignition delay time prediction method for the compressible flow field self-ignition process as described in any one of claims 1 to 3.

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