Aircraft plume spectral radiation characteristic modeling, solving method, system and terminal under gas-solid coupling

Abstract

The present application belongs to the technical field of aircraft plume spectral radiation characteristic analysis, and discloses a gas-solid coupling aircraft plume spectral radiation characteristic modeling, solving method, system and terminal. Based on the radiation transmission theory, the plume radiation transmission mechanism under the coupling of gas molecules and alumina solid particles is introduced to model the gas-solid coupling aircraft plume spectral radiation transmission equation. The calculation module of the gas-solid coupling plume optical parameter is added in the classical spherical harmonic discrete coordinate method to realize the solution of the gas-solid coupling aircraft plume spectral radiation transmission characteristic. In the modeling of the aircraft plume spectral radiation characteristic, the coupling effect between the gas molecules and the solid particles is considered, and the gas-solid coupling aircraft plume spectral radiation transmission equation is derived in theory. The calculation module of the gas-solid coupling plume optical parameter is added in the classical spherical harmonic discrete coordinate method, and the solution algorithm for calculating the gas-solid coupling aircraft plume spectral radiation transmission characteristic is proposed.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of aircraft plume spectral radiation characteristic analysis, and particularly relates to a method, system and terminal for modeling and solving aircraft plume spectral radiation characteristics under gas-solid coupling. BACKGROUND

[0002] The aircraft plume is generally composed of products after fuel combustion, un-combusted fuel and gas molecules in the atmosphere, and main components thereof are carbon dioxide, water, hydrogen, oxygen, carbon, nitrogen and aluminum oxide particles. Since the plume temperature is high, the gas components therein are often in a thermal chemical non-equilibrium state, and after multi-component gas collision, a series of complex physical and chemical processes such as internal energy level excitation, ionization, dissociation and recombination will occur, and during this period, certain gases will perform spectral radiation (for example, carbon dioxide at 4.1 μm-4.5 μm and water at 2.5 μm-3.1 μm will generate infrared spectral radiation) at certain specific wave bands. In addition, under high temperature and high pressure, the aluminum oxide particles and gas molecules in the plume will produce a series of coupling effects, thereby changing the absorption characteristics, emission characteristics and scattering characteristics of the plume.

[0003] Hyun Jae Nam, Oh Joon Kwon published Infrared radiation modeling of NO, OH, CO, H2O, and CO2 for emissivity / radiance prediction at high temperature, which uses the structured radiation analysis package SPRADIAN07 and gas molecule spectral parameters to design an infrared radiation transmission model of NO, OH, CO, H2O and CO2 molecules based on the line-by-line method, and calculates the infrared spectral radiation characteristics of the rocket plume. However, the scattering and radiation characteristics of the aluminum oxide particles in the plume are not considered, so the spectral radiation intensity of the plume will be underestimated.

[0004] Ju Yong Ko, Euntaek Lee et al. published Influence of optical properties of alumina particles on the radiative base heating from solid rocket plume, which studies the change of the solid rocket plume radiation characteristics with the optical properties of aluminum oxide particles, but does not consider the influence of the gas molecules and solid particles and their coupling effects on the spectral radiation characteristics of the aircraft plume.

[0005] Quentin Binauld, Jean-Michel Lamet, et al. published "Numerical simulation of radiation in high altitude solid propellant rocket plumes." This paper studies the momentum and energy exchange between gas molecules and aluminum oxide particles in the plume. They argue that the coupling between gas molecules and solid particles in the plume affects the medium properties of the plume flow field, and thus the plume's radiation characteristics. Therefore, they recommend that gas-solid coupling be fully considered when modeling the radiation of solid propellant rocket plumes. However, they do not theoretically provide a spectral radiation transfer equation for a vehicle plume under gas-solid coupling, nor do they provide a corresponding solution algorithm.

[0006] In the tail flame of an aircraft, a series of coupling effects will occur between solid particles and gas molecules at high temperatures, which will form new tail flame medium parameters (including absorption characteristics, emission characteristics and scattering characteristics), thereby changing the spectral radiation characteristics of the tail flame. In the current research on the spectral radiation characteristics of the tail flame of an aircraft, some scholars only consider the spectral radiation characteristics of the gas in the tail flame, or only consider the radiation characteristics and scattering characteristics of solid particles. In the spectrum containing gas radiation, the infrared spectral radiation characteristics of the tail flame of an aircraft are mainly determined by the spectral radiation characteristics of the gas; if only the thermal radiation and scattering characteristics of solid particles are considered, the infrared spectral radiation characteristics of the tail flame will be significantly distorted; if only the gas radiation characteristics in the tail flame are considered, and the gas-solid coupling effect is ignored, the spectral radiation intensity of the tail flame will be underestimated. Some scholars have studied the influence of the two-phase flow formed by gas molecules and solid particles in the tail flame and the coupling effect between them on the radiation transmission characteristics of the tail flame, and pointed out that the coupling effect between solid particles and gas molecules in the tail flame cannot be ignored.

[0007] However, the current research progress on the spectral radiation characteristics of aircraft tail plumes under gas-solid coupling has not yet resulted in a mature and complete spectral radiation transfer equation in theory, nor has there been a corresponding available solution algorithm.

[0008] The existing problems and defects of the prior art: at present, in the research on the spectral radiation characteristics of the aircraft plume, the infrared spectral radiation characteristics of the aircraft plume in the spectrum containing gas radiation is mainly determined by the spectral radiation characteristics of the gas. In order to simplify the complexity of the problem, most scholars only consider the gas radiation in the plume, and some scholars only consider the particle radiation and scattering characteristics. Although the model is simplified, and when only considering gas molecules or only considering solid particles, there is a relatively complete spectral radiation transfer equation and its solving algorithm, but only considering gas molecules or solid particles will have a large error. Especially when only considering the thermal radiation and scattering characteristics of solid particles, the infrared spectral radiation characteristics of the plume will be distorted. When only considering gas molecules, the infrared spectral radiation intensity of the plume will be underestimated. This cannot well approximate the real plume, and cannot achieve better accuracy. Even some scholars have pointed out that the coupling effect between gas molecules and solid particles is very important for the spectral radiation of the aircraft plume, but they have not given the spectral radiation transfer equation and its solving algorithm.

[0009] The technical problem caused is that in the research on the spectral radiation characteristics of the aircraft plume, there is no simple and effective method to consider the gas molecules and solid particles and the coupling effect between them, and there is no simple and effective algorithm to calculate the spectral radiation intensity of the plume under the gas-solid coupling effect, which cannot well approximate the real plume and cannot achieve better accuracy. SUMMARY

[0010] In view of the problems existing in the prior art, the present application provides a gas-solid coupling aircraft plume spectral radiation characteristics modeling, solving method, system and terminal, especially relates to a gas-solid coupling aircraft plume spectral radiation characteristics solving method, system, medium, equipment and terminal under gas-solid coupling.

[0011] The present application is realized in this way, a gas-solid coupling aircraft plume spectral radiation characteristics modeling and its solving method, the gas-solid coupling aircraft plume spectral radiation characteristics solving method comprises: based on the radiation transfer theory, the plume radiation transfer mechanism under the coupling of gas molecules and alumina solid particles is introduced, the spectral radiation transfer equation of the aircraft plume under gas-solid coupling is modeled; the calculation module of the optical parameter of the plume after gas-solid coupling is added in the classical spherical harmonic discrete coordinate method, and the solving of the spectral radiation transfer characteristics of the aircraft plume under gas-solid coupling is realized.

[0012] ①Based on the radiation transfer theory, the plume radiation transfer mechanism under the coupling of gas molecules and alumina solid particles is introduced, and the spectral radiation transfer equation of the aircraft plume under gas-solid coupling is modeled;

[0013] ② A calculation module for the optical parameters of the tail plume after gas-solid coupling is added to the classical spherical harmonic discrete ordinate method to solve the spectral radiation transmission characteristics of the aircraft tail plume under gas-solid coupling.

[0014] In the first part, on the basis of the radiation transfer equation, the tail plume radiation transfer mechanism under the coupling of gas molecules and solid particles was introduced. Through a series of derivations, the final aircraft tail plume radiation transfer equation under gas-solid coupling was obtained.

[0015] In step ②, the traditional spherical harmonic discrete ordinate method (SHDOM) is used to add a calculation module for the optical parameters of the tail flame after gas-solid coupling to the algorithm. In this way, the SHDOM can be used to solve the radiation transfer equation under gas-solid coupling derived in step ①.

[0016] Furthermore, the radiation transfer equation of the aircraft tail plume under the modeling of gas-solid coupling includes:

[0017] Based on classical radiative transfer theory and incorporating the radiative transfer mechanism of coupled gas molecules and solid particles, a radiative transfer equation applicable to the tail plume of an aircraft under gas-solid coupling is modeled. Within a small region within the tail plume, the material components participating in spectral radiation are spherical aluminum oxide particles, and the gas molecules are specific gas molecules that radiate spectrally outward in a specific wavelength band. A differential volume is taken at position s in the direction of radiation transmission Ω, with a cross section dA and a length ds. Let the spectral radiation intensity in the direction of Ω at position s be I. λ (s,Ω), then the outgoing spectral radiation intensity in the Ω direction at s+ds is I λ (s,Ω)+dI λ (s,Ω).

[0018] According to the different spectral radiation mechanisms of gas molecules and solid particles in the tail plume under gas-solid coupling, the increment of spectral radiation intensity dI λ (s,Ω) is expressed as five components:

[0019] (1) Spectral radiation intensity emitted by gas molecules By default, in the state of local thermodynamic equilibrium, Kirchhoff's theorem is satisfied;

[0020]

[0021] (2) Spectral radiation intensity absorbed by gas molecules in, is the emissivity of the gas, is the absorption coefficient of gas molecules;

[0022] (3) Spectral radiation intensity emitted by solid particles

[0023]

[0024] (4) The spectral radiance intensity absorbed and scattered by the solid particles is the spectral radiance intensity of extinction

[0025] (5) The spectral radiance intensity scattered by the particles in other unit volume into the calculated unit volume in the direction of Ω is:

[0026]

[0027] wherein, is the absorption coefficient of the solid particles, is the scattering coefficient of the solid particles, is the extinction coefficient of the solid particles, and Φ particles (s; λ; Ω'→Ω) is the scattering phase function of the solid particles;

[0028] Since the gas and the solid particles in the same differential volume are in local thermodynamic equilibrium by default, the temperatures of the gas and the solid particles are the same T particles = T gas = T, the spectral radiation transfer equation of the plume under the gas-solid coupling is:

[0029]

[0030] Further, the modeling of the radiation transfer equation of the plume of the aircraft under the gas-solid coupling further comprises:

[0031] The following parameters are defined for describing the medium properties of the plume under the gas-solid coupling:

[0032] (1) The absorption coefficient of the medium under the gas-solid coupling and

[0033] (2) The extinction coefficient of the medium under the gas-solid coupling and

[0034]

[0035] (3) The scattering albedo of the medium under the gas-solid coupling and

[0036]

[0037] Therefore, the spectral radiation transfer equation of the plume under the gas-solid coupling can be expressed as:

[0038]

[0039] Further, the method for solving the spectral radiation characteristics of the plume of the aircraft under the gas-solid coupling comprises the following steps:

[0040] Step one, get the physical parameters of the aircraft plume and divide the calculation domain of the plume into grids;

[0041] Get the physical parameters of the plume, which are needed as input parameters when calculating the spectral radiation characteristics. Grid division is the discretization of the calculation domain, which is divided into grids to facilitate subsequent calculations.

[0042] Step two, calculate the medium parameters after gas-solid coupling at each grid point;

[0043] During modeling, the medium parameters after gas-solid coupling are calculated to obtain the medium parameters under gas-solid coupling as input data to calculate the spectral radiation intensity at each grid point.

[0044] Step three, determine the integral path k and the calculation grid point i, and calculate the spectral radiation intensity I λ (i,Ω) at grid point i in the discrete coordinate system;

[0045] Before calculating the spectral radiation intensity, the integral path and the initial grid point i to start calculation need to be determined to determine the starting path of calculation and the position of the grid point. According to the initial condition, the spectral radiation intensity I λ (i,Ω) at the initial grid point i is calculated to calculate the spectral radiation source function at grid point i.

[0046] Step four, according to the alumina particle thermal radiation source function, the gas molecule radiation source function and the internal scattering source function at grid point i, solve the spectral radiation source function at grid point i under gas-solid coupling in the spherical harmonic coordinate system, and convert the spectral radiation source function at grid point i to the discrete coordinate system;

[0047] In the spherical harmonic coordinate system, the integral term of the radiation transfer equation under gas-solid coupling can be calculated more conveniently. The spectral radiation source function at grid point i under gas-solid coupling is calculated, and then converted to the discrete coordinate system to calculate the spectral radiation intensity at grid point i+1.

[0048] Step five, solve the radiation intensity along the detection direction Ω through a small differential volume of the plume spectral radiation transfer equation in the discrete coordinate system, and give the spectral radiation intensity I λ (i+1,Ω) at grid point i+1 along the detection direction Ω through a small differential volume;

[0049] This step can calculate the spectral radiation intensity at the next grid point i+1 along the integral path, which provides data for calculating the spectral radiation intensity at the grid point on the boundary.

[0050] Step six, repeat steps three to five for each grid cell along the integral path in the detection direction until the boundary nodes of the aircraft plume calculation domain are calculated, and the spectral radiation intensity on the boundary grid points is stored;

[0051] This step is to calculate the spectral radiation intensity along the grid points on the integral path, and save the spectral radiation intensity of the grid points on the boundary for subsequent calculation of the spectral radiation intensity distribution in the observation direction Ω.

[0052] Step seven, complete the calculation of the spectral radiation intensity on all integral paths, and output the final spectral radiation intensity result of the plume.

[0053] This step is to calculate the spectral radiation intensity of all grid points on the integral path in the entire calculation domain, so that the spectral radiation intensity distribution of the entire plume in the observation direction Ω can be obtained.

[0054] Further, the aircraft plume physical parameter acquisition in step one includes: acquiring the calculation domain size, temperature distribution, pressure distribution, gas molar fraction distribution, alumina particle size distribution and density distribution of the plume through the aircraft plume flow field data; the domain size includes length, width and height.

[0055] The grid division of the calculation domain of the plume includes: determining the grid size in the plume calculation domain and the related physical parameters in each grid, and the related physical parameters include the temperature, pressure, gas molar fraction, alumina particle size and density of each grid point.

[0056] Further, the calculation of the medium parameters after gas-solid coupling in each grid point in step two includes: based on the Mie theory and the gas spectral radiation model, calculating the absorption coefficient, extinction coefficient, scattering albedo and scattering phase function of the alumina particles of the medium after gas-solid coupling in each grid point.

[0057] Another object of the present application is to provide an aircraft plume spectral radiation characteristic modeling and solving system applying the aircraft plume spectral radiation characteristic solving method under gas-solid coupling, and the aircraft plume spectral radiation characteristic modeling and solving system comprises:

[0058] The physical parameter acquisition module is used for acquiring the aircraft plume physical parameters;

[0059] The grid division module is used for dividing the calculation domain of the plume into grids;

[0060] The medium parameter calculation module is used for calculating the medium parameters after gas-solid coupling in each grid point;

[0061] a spectral radiation intensity calculation module for determining the integral path k and the calculated grid point i, and calculating the spectral radiation intensity I of the grid point i in the discrete coordinate system λ (i,Ω); for solving the radiation intensity of the plume spectral radiation transfer equation along the detection direction Omega through a small differential volume in the discrete coordinate system, and giving the spectral radiation intensity I at the grid point i+1 along the detection direction Omega through a small differential volume λ (i+1,Ω);

[0062] a spectral radiation source function solving module for solving the spectral radiation source function of the grid point i in the spherical harmonic coordinate system according to the alumina particle thermal radiation source function, the gas molecule radiation source function and the internal scattering source function of the grid point i, and converting the spectral radiation source function of the grid point i to the discrete coordinate system;

[0063] a boundary grid point spectral radiation intensity calculation and storage module for repeating the spectral radiation intensity calculation module for each grid unit along the integral path of the detection direction until the calculation of the boundary node of the aircraft plume calculation domain is completed, and storing the spectral radiation intensity on the boundary grid point;

[0064] a result output module for completing the calculation of the spectral radiation intensity on all integral paths, and outputting the final plume spectral radiation intensity result.

[0065] Another object of the present application is to provide a computer device comprising a memory and a processor, the memory storing a computer program, the computer program being executed by the processor to make the processor execute the steps of the aircraft plume spectral radiation characteristic solving method under the gas-solid coupling.

[0066] Another object of the present application is to provide a computer readable storage medium storing a computer program, the computer program being executed by a processor to make the processor execute the steps of the aircraft plume spectral radiation characteristic solving method under the gas-solid coupling.

[0067] Another object of the present application is to provide an information data processing terminal for realizing the aircraft plume spectral radiation characteristic modeling and solving system under the gas-solid coupling.

[0068] In combination with the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solutions to be protected by the present application are analyzed from the following aspects:

[0069] First, in view of the technical problems existing in the prior art and the difficulty of solving the problems, the technical solution to be protected by the application and the results and data in the research and development process are closely combined, and the technical problems solved by the technical solution of the application and some creative technical effects brought about after the problems are solved are analyzed in detail and profoundly. The specific description is as follows:

[0070] Based on the radiation transmission theory, the present application introduces the plume radiation transmission mechanism under the coupling of gas molecules and alumina solid particles, models the plume spectral radiation transmission equation under the coupling of gas and solid, adds a calculation module of plume optical parameters after the coupling of gas and solid in the classical spherical harmonic discrete coordinate method, and proposes a solving method which can be used to calculate the spectral radiation transmission characteristics of the plume of the aircraft under the coupling of gas and solid.

[0071] In the research on the spectral radiation characteristics of the plume of the aircraft, if only the thermal radiation and scattering characteristics of the solid particles are considered, the infrared spectral radiation characteristics of the plume will be obviously distorted, and if only the radiation characteristics of the gas in the plume are considered and the coupling effect of gas and solid is ignored, the spectral radiation intensity of the plume will be underestimated. Therefore, only considering the gas molecules or the solid particles cannot well analyze the spectral radiation characteristics of the plume of the aircraft.

[0072] At present, the research on the spectral radiation characteristics of the plume of the aircraft under the coupling of gas and solid has not yet had a mature and complete spectral radiation transmission equation in theory, and has not yet had a corresponding available solving algorithm in algorithm. Therefore, the present application considers the gas molecules and the solid particles and the coupling effect therebetween in the modeling of the spectral radiation characteristics of the plume of the aircraft, and derives the spectral radiation transmission equation of the plume of the aircraft under the coupling of gas and solid in theory. Moreover, the present application adds a calculation module of plume optical parameters after the coupling of gas and solid in the classical spherical harmonic discrete coordinate method, and proposes a solving algorithm which can be used to calculate the spectral radiation transmission characteristics of the plume of the aircraft under the coupling of gas and solid.

[0073] Second, the technical solution to be protected by the application has the technical effects and advantages, which are described in detail as follows, from the perspective of the product as a whole:

[0074] The present application develops a modeling of the spectral radiation characteristics of the plume of the aircraft under the coupling of gas and solid and a corresponding solving algorithm in view of the fact that the research on the spectral radiation characteristics of the plume of the aircraft under the coupling of gas and solid has not yet had a mature and complete spectral radiation transmission equation in theory and has not yet had a corresponding available solving algorithm in algorithm.

[0075] Third, the creativity of the claims of the present application is also reflected in the following important aspects:

[0076] (1) The technical solution of the present application fills the technical gap in the industry at home and abroad:

[0077] Even now, scholars have proposed that the coupling of gas molecules and solid particles is necessary (or important) in the study of the spectral radiation characteristics of the plume. However, the research on the spectral radiation characteristics of the plume under the gas-solid coupling has not yet had a mature and complete spectral radiation transfer equation in theory, and has not had a corresponding available solving algorithm in algorithm.

[0078] The technical scheme of the present application derives the spectral radiation transfer equation of the spectral radiation characteristics of the plume under the gas-solid coupling, and gives a corresponding available solving algorithm. Therefore, the technical scheme of the present application increases the spectral radiation transfer equation related modeling in the field of the spectral radiation characteristics of the plume under the gas-solid coupling, and can solve the given spectral radiation transfer equation under the gas-solid coupling through the given algorithm.

[0079] (2) The technical scheme of the present application solves the technical problems that people have always been eager to solve but have always failed to succeed:

[0080] At present, since many scholars only consider gas molecules or solid particles in the study of the spectral radiation characteristics of the plume, and cannot consider the coupling between the two and model and calculate it, it is found that the spectral radiation characteristics of the plume cannot be better approximated in the calculation of the spectral radiation characteristics of the plume. Therefore, the technical scheme of the present application can solve the modeling and calculation problems of the spectral radiation characteristics of the plume under the gas-solid coupling, which are expected to be solved, so that the spectral radiation characteristics of the plume under the gas-solid coupling can be more conveniently calculated. BRIEF DESCRIPTION OF DRAWINGS

[0081] In order to more clearly illustrate the technical scheme of the embodiments of the present application, the drawings needed to be used in the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0082] Figure 1 is a flow chart of the method for solving the spectral radiation characteristics of the plume under the gas-solid coupling provided by the embodiments of the present application;

[0083] Figure 2 is a principle diagram of the method for solving the spectral radiation characteristics of the plume under the gas-solid coupling provided by the embodiments of the present application;

[0084] Figure 3 is a schematic diagram of the spectral radiation transfer process of a differential volume in the plume under the gas-solid coupling provided by the embodiments of the present application;

[0085] Figure 4Figure is a schematic diagram of a process for solving aircraft plume spectral radiation characteristics under gas-solid coupling provided by the embodiment of the present application; wherein figure (a) is the physical property of the plume, figure (b) is the modeling of the plume calculation domain, and figure (c) is the solved plume spectral radiation intensity.

[0086] Figure 5 Figure is a physical property diagram of Black Brant sounding rocket plume infrared radiation intensity at a detection angle of 112 degrees provided by the embodiment of the present application; wherein figure (a) is the Black Brant sounding rocket plume infrared spectral radiation intensity given in the literature, and figure (b) is the Black Brant sounding rocket plume infrared spectral radiation intensity solved by using the technical solution of the present application.

[0087] Figure 6 The embodiment of the present application provides a comparison diagram of Black Brant sounding rocket plume infrared spectral radiation intensity.

[0088] Figure 7 The embodiment of the present application provides an atmospheric transmittance diagram from the rocket plume to the DRDC spectral imaging sensor.

[0089] Figure 8 The embodiment of the present application provides a comparison diagram of DRDC experimental measurement data and infrared radiation data of the plume under gas-solid coupling. DETAILED DESCRIPTION

[0090] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application will be further described in detail below in combination with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application.

[0091] In view of the problems existing in the prior art, the present application provides a modeling, solving method, system and terminal for aircraft plume spectral radiation characteristics under gas-solid coupling, which will be described in detail below in combination with the drawings.

[0092] I. Explanation of Embodiments. In order to enable those skilled in the art to fully understand how the present application is specifically implemented, this part is an explanation of the embodiments of the technical scheme of the claims.

[0093] As shown in Figure 1 The solving method for aircraft plume spectral radiation characteristics under gas-solid coupling provided by the embodiment of the present application comprises the following steps:

[0094] S101, obtaining the physical parameters of the aircraft plume and performing grid division on the calculation domain of the plume;

[0095] S102, calculating the medium parameters after gas-solid coupling in each grid point;

[0096] S103, determine the integration path k and the calculated grid point i, and calculate the spectral radiation intensity I of the grid point i in the discrete coordinate system λ (i,Ω);

[0097] S104, solving the spectral radiation source function of grid point i under gas-solid coupling in a spherical harmonic coordinate system based on the aluminum oxide particle thermal radiation source function, gas molecule radiation source function, and internal scattering source function at grid point i, and converting the spectral radiation source function of grid point i into a discrete coordinate system;

[0098] S105, solve the tail plume spectrum radiation transfer equation in the discrete coordinate system along the detection direction Ω through a small differential volume of radiation intensity, and give the spectral radiation intensity I at the grid point i+1 along the detection direction Ω through a small differential volume λ (i+1,Ω);

[0099] S106, repeating S103 to S105 for each grid cell on the integral path along the detection direction until the calculation is completed at the boundary node of the aircraft tail flame calculation domain, and storing the spectral radiation intensity at the boundary grid point;

[0100] S107, completing the calculation of the spectral radiation intensity on all integral paths, and outputting the final tail flame spectral radiation intensity result.

[0101] As a preferred embodiment, Figure 2 As shown, the method for solving the spectral radiation characteristics of the aircraft tail flame under gas-solid coupling provided by the embodiment of the present invention specifically includes the following steps:

[0102] 1. Modeling the radiative transfer equation of the aircraft tail plume under gas-solid coupling

[0103] The plume of an aircraft is typically an axisymmetric medium with emission, absorption, and scattering properties, in which both gas molecules and solid particles participate in radiative transfer. Therefore, based on classical radiative transfer theory and incorporating the radiative transfer mechanism of coupled gas molecules and solid particles, we develop a radiative transfer equation applicable to the plume of an aircraft under gas-solid coupling.

[0104] like Figure 3 The figure shows the material components involved in the spectral radiation within a tiny region of the tail flame. Here, the solid particles are spherical aluminum oxide particles, and the gas molecules are specific gas molecules that radiate spectrally outward in a specific wavelength band. At position s and in the radiation transmission direction Ω, a differential volume is taken with a cross section dA and a length ds. Let the spectral radiation intensity in the direction of Ω at position s be I λ (s,Ω), then the outgoing spectral radiation intensity in the Ω direction at s+ds is I λ (s,Ω)+dI λ (s,Ω).

[0105] According to the different spectral radiation mechanism of gas molecules and solid particles in the plume under the gas-solid coupling, the increment of spectral radiation intensity dI λ (s,Ω) can be expressed as the following five components:

[0106] (1) The spectral radiation intensity emitted by gas molecules By default, in the local thermodynamic equilibrium state, the Kirchhoff's law is satisfied;

[0107]

[0108] (2) The spectral radiation intensity absorbed by gas molecules Wherein, is the emission coefficient of gas, is the absorption coefficient of gas molecules.

[0109] (3) The spectral radiation intensity emitted by solid particles

[0110]

[0111] (4) The spectral radiation intensity absorbed and scattered by solid particles, that is, the spectral radiation intensity of extinction

[0112] (5) The scattering spectral radiation intensity of particles in other unit volumes to the calculated unit volume in the direction of Ω:

[0113]

[0114] Wherein, is the absorption coefficient of solid particles, is the scattering coefficient of solid particles, is the extinction coefficient of solid particles, and Φ particles (s; λ; Ω'→Ω) is the scattering phase function of solid particles.

[0115] Since the same differential volume is in the local thermodynamic equilibrium state by default, the gas and solid particles in it have the same temperature T particles = T gas = T, the spectral radiation transfer equation of the plume under the gas-solid coupling can be obtained as:

[0116]

[0117] In order to further express the medium properties of the plume under the gas-solid coupling, the following parameters are defined:

[0118] (1) The absorption coefficient of the medium under the gas-solid coupling And

[0119] (2) The extinction coefficient of the medium under the gas-solid coupling and

[0120]

[0121] (3) The scattering albedo of the medium under the gas-solid coupling and

[0122]

[0123] Therefore, the spectral radiation transfer equation of the plume under the gas-solid coupling can be expressed as:

[0124]

[0125] 2. The solving algorithm for the spectral radiation characteristics of the plume of an aircraft under the gas-solid coupling

[0126] After theoretically deriving the spectral radiation transfer equation of the plume under the gas-solid coupling in item 1, a related program for solving the spectral radiation transfer equation will be developed from the algorithmic perspective. In the calculation of the radiation transfer equation, the traditional spherical harmonic discrete ordinate method is the most widely used deterministic solving algorithm, which is mainly used in the past for calculating the infrared and visible radiation transfer characteristics of the atmosphere. The calculation idea is to combine the discretization and gridding of the atmosphere with the spherical harmonic coordinates to accelerate the calculation speed of the scattering integral, and then to solve the radiation intensity of the atmosphere by solving the source function in each grid on the detection path.

[0127] In the currently widely used spherical harmonic discrete ordinate algorithm program, the radiation source can only calculate the solar radiation and the thermal radiation, and the internal scattering source mainly considers the scattering characteristics of aerosol particles, water or ice crystal particles. However, the radiation source in the plume of an aircraft is mainly the thermal radiation of alumina particles and the spectral radiation of gas molecules, and the solar radiation is usually not considered; the internal scattering source mainly studies the scattering characteristics of alumina particles. Therefore, based on the traditional spherical harmonic discrete ordinate method, a solving algorithm for calculating the spectral radiation characteristics of the plume of an aircraft under the gas-solid coupling is proposed.

[0128] In the new algorithm, the spectral radiation mechanism under the gas-solid coupling will be introduced, and the calculation module of the optical parameters of the plume after the gas-solid coupling will be added. The plume is discretized and gridded and combined with the spherical harmonic coordinates, and the spectral radiation characteristics of the plume of an aircraft under the gas-solid coupling are finally solved by calculating the source function in each grid on the transmission path. Figure 4 The solving process of the spectral radiation characteristics of the plume of an aircraft under the gas-solid coupling proposed in the embodiment of the present application is given. In order to highlight the internal structure of the plume, only the left half structure of the plume is depicted in the figure, and the solving domain in the actual calculation is the entire plume.

[0129] In combination with Figure 4The specific steps of the aircraft plume spectral radiation characteristic solving algorithm under the gas-solid coupling proposed by the embodiment of the present application are as follows:

[0130] Step one: aircraft plume physical parameter acquisition

[0131] Through the aircraft plume flow field data, the physical parameters of the calculation domain size (length, width and height) of the plume, temperature distribution, pressure distribution, gas molar fraction distribution, alumina particle size distribution and density distribution are acquired;

[0132] Step two: grid division of the calculation domain of the plume

[0133] The grid size in the plume calculation domain and the related physical parameters in each grid are determined, mainly including the temperature, pressure, gas molar fraction, alumina particle size and density of each grid point;

[0134] Step three: calculation of the medium parameters after the gas-solid coupling in each grid point

[0135] Based on the Mie theory and the gas spectral radiation model, the absorption coefficient, the extinction coefficient, the scattering albedo and the scattering phase function of the alumina particles of the medium after the gas-solid coupling in each grid point are calculated;

[0136] Step four: determination of the integral path k and the calculation grid point i, and calculation of the spectral radiation intensity I of the grid point i in the discrete coordinate system λ (i,Ω);

[0137] Step five: based on the alumina particle thermal radiation source function, the gas molecule radiation source function and the internal scattering source function of the grid point i, the spectral radiation source function of the grid point i under the gas-solid coupling is solved in the spherical harmonic coordinate system, and the spectral radiation source function of the grid point i is converted to the discrete coordinate system;

[0138] Step six: the radiation intensity of the plume spectral radiation transfer equation along the detection direction Ω through a small differential volume in the discrete coordinate system is solved, and the spectral radiation intensity I of the grid point i+1 along the detection direction Ω through a small differential volume is given λ (i+1,Ω).

[0139] Step seven: along the integral path of the detection direction, the steps four to six are repeated for each grid unit until the calculation of the boundary node of the aircraft plume calculation domain is completed, and the spectral radiation intensity on the boundary grid point is stored.

[0140] Step eight: the calculation of the spectral radiation intensity on all integral paths is completed, and the final plume spectral radiation intensity result is output.

[0141] The aircraft plume spectral radiation characteristic modeling and solving system provided by the embodiment of the present application comprises:

[0142] a physical parameter acquisition module, configured to acquire a physical parameter of a jet plume of a vehicle;

[0143] a mesh division module, configured to divide a calculation domain of the jet plume into meshes;

[0144] a medium parameter calculation module, configured to calculate a medium parameter after gas-solid coupling in each mesh point;

[0145] a spectral radiation intensity calculation module, configured to determine an integral path k and a mesh point i of calculation, and calculate a spectral radiation intensity I λ (i,Ω) of the mesh point i in a discrete coordinate system, and give a spectral radiation intensity I λ (i+1,Ω) of a mesh point i+1 along a detection direction Ω through a small differential volume in the spectral radiation transfer equation of the jet plume in the discrete coordinate system;

[0146] a spectral radiation source function solving module, configured to solve a spectral radiation source function of the mesh point i in the spherical harmonic coordinate system according to an alumina particle thermal radiation source function, a gas molecule radiation source function and an internal scattering source function of the mesh point i, and convert the spectral radiation source function of the mesh point i to the discrete coordinate system;

[0147] a boundary mesh point spectral radiation intensity calculation and storage module, configured to repeat the spectral radiation intensity calculation module for each mesh unit along the integral path of the detection direction, until the calculation of a boundary node of the calculation domain of the jet plume is completed, and store the spectral radiation intensity on the boundary mesh point;

[0148] a result output module, configured to complete the calculation of the spectral radiation intensity along all the integral paths, and output a final spectral radiation intensity result of the jet plume.

[0149] II. Application Examples. In order to prove the creativity and technical value of the technical scheme of the present application, this part is an application example of the technical scheme of the claims on a specific product or related technology.

[0150] Based on the results of the Black Brant sounding rocket launch experiment at White Sands in 1997, the spectral radiation transfer equation and the solving algorithm of the jet plume of the vehicle under gas-solid coupling are simulated and calculated by using the technical scheme of the present application to simulate and calculate the infrared spectral radiation characteristics of the Black Brant sounding rocket jet plume, and compared with the experimental results. The related data is Infrared signature modelling of a rocket jet plume-comparison with flight measurements published by VRialland, A Guy, etc.

[0151] The following conclusions can be drawn:

[0152] (1) The physical characteristics of the simulated infrared spectral radiation intensity of the plume according to the technical scheme of the present application are consistent with the experimental data of the infrared spectral radiation intensity of the plume, that is, the plume length is all within 45 m, and the maximum of the radiation intensity is all within the range of 17 m to 20 m from the nozzle, which preliminarily proves the effectiveness and accuracy of the spectral radiation transfer model of the plume under the gas-solid coupling of the aircraft according to the modeling of the technical scheme of the present application.

[0153] (2) In the spectral range containing gas radiation, the infrared spectral radiation characteristics of the plume are mainly determined by the spectral radiation characteristics of the gas; if only the thermal radiation and scattering characteristics of the solid particles are considered, the infrared spectral radiation characteristics of the plume will be significantly distorted; if only the radiation characteristics of the gas in the plume are considered and the gas-solid coupling effect is ignored, the spectral radiation intensity of the plume will be underestimated. In summary, when studying the spectral radiation characteristics of the plume, the complex spectral radiation mechanism generated by the gas-solid coupling effect needs to be studied in depth, which further proves that it is very necessary to model the spectral radiation transfer model of the plume under the gas-solid coupling of the aircraft.

[0154] (3) The infrared spectral radiation intensity of the Black Brant sounding rocket plume under the gas-solid coupling simulated according to the technical scheme of the present application is consistent with the experimental measurement results of DRDC, which finally proves that the spectral radiation transfer equation and the solving algorithm of the plume under the gas-solid coupling according to the modeling of the technical scheme of the present application are effective and accurate when studying the spectral radiation characteristics of the plume.

[0155] III. Evidence of the effects of the embodiments. The embodiments of the present application have achieved some positive effects in the process of research and development or use, and indeed have great advantages compared with the prior art. The following contents are described in combination with the data and graphs of the test process.

[0156] The flow field data of the Black Brant sounding rocket are obtained from the above-mentioned literature, including the calculation domain size of the plume, the temperature distribution, the gas composition, the particle size and the particle density distribution of the aluminum oxide particles.

[0157] According to the above initial conditions, the infrared spectral radiation intensity of the Black Brant sounding rocket plume in the 2 μm to 5.2 μm band is simulated and calculated at intervals of 0.2 μm by using the spectral radiation transfer equation and the solving algorithm of the plume under the gas-solid coupling according to the modeling, and the relevant simulation results are as follows:

[0158] (1) The physical characteristics of the infrared spectral radiation intensity of the rocket plume are consistent

[0159] From the above simulation results, it can be seen that the infrared spectral radiation intensity of the Black Brant sounding rocket plume under the gas-solid coupling according to the modeling is consistent with the experimental data of DRDC, which further proves that the spectral radiation transfer equation and the solving algorithm of the plume under the gas-solid coupling according to the modeling are effective and accurate when studying the spectral radiation characteristics of the plume. Figure 5(a) in the figure, when the detection angle is 112 degrees (the rocket head direction is 0 degree, and the tail direction is 180 degrees), the maximum value of the infrared spectral radiation intensity of the Black Brant sounding rocket exhaust plume is in the range of 17m to 20m away from the nozzle, and the length of the exhaust plume is 45m. Figure 5 (b) in the figure, the maximum value of the infrared spectral radiation intensity of the Black Brant sounding rocket exhaust plume simulated by the technical scheme of the application is also in the range of 17m to 20m away from the nozzle, and the length of the exhaust plume is 45m. According to the above comparative analysis, it can be known that the spectral radiation transmission model of the aircraft exhaust plume under the gas-solid coupling established by the technical scheme of the application is accurate.

[0160] (2) The infrared spectral radiation intensity results of the rocket exhaust plume are consistent

[0161] According to Figure 6 , it can be known that, in the infrared waveband, the emission spectral line range of the H2O gas molecule is 2.5μm to 3.1μm, the emission spectral line range of the HCl gas molecule is 3.3μm to 4μm, the emission spectral line range of the CO2 gas molecule is 4.1μm to 4.5μm, and the emission spectral line range of the CO gas molecule is 5μm to 5.2μm. When only the thermal radiation and scattering characteristics of the alumina solid particles are considered, the infrared spectral radiation intensity of the exhaust plume is very small; when only the gas radiation characteristics are considered, the infrared spectral radiation intensity of the exhaust plume is obviously increased, and the spectral radiation intensity is increased with the increase of the gas radiation intensity; when the radiation characteristics of the alumina solid particles and the gas molecules after mutual coupling (i.e. the radiation characteristics under the gas-solid coupling) are considered, the infrared spectral radiation intensity of the exhaust plume will be greater than the radiation intensity when only the gas radiation is considered.

[0162] Therefore, in the spectrum containing the gas radiation, the infrared spectral radiation characteristics of the exhaust plume are mainly determined by the spectral radiation characteristics of the gas; but if only the gas radiation characteristics in the exhaust plume are considered, and the gas-solid coupling effect is ignored, the spectral radiation intensity of the exhaust plume will be underestimated. In addition, according to Figure 6 , it can be known that the infrared radiation intensity of the exhaust plume under the gas-solid coupling calculated by the technical scheme of the application is in good agreement with the infrared radiation intensity of the exhaust plume in the literature, which can further prove that the spectral radiation transmission equation of the aircraft exhaust plume under the gas-solid coupling modeled by the technical scheme of the application and the algorithm proposed are effective and accurate in solving the spectral radiation characteristics of the exhaust plume.

[0163] (3) The simulation results are consistent with the measurement results of the DRDC spectral imaging experiment

[0164] Figure 7The atmospheric transmittance from the rocket plume to the DRDC spectral imager is given in the Black Brant sounding rocket launch experiment at White Sands in 1997. To compare the simulation data with the experimental measurement data, only need to multiply the infrared spectral radiance intensity of the plume under the gas-solid coupling simulated by the technical scheme of the present application by the atmospheric transmittance from the rocket plume to the DRDC spectral imaging sensor. Figure 8 The comparison results of the DRDC spectral experimental measurement data and the simulation data of the literature and the technical scheme of the present application are given.

[0165] According to Figure 7 and Figure 8 It can be seen that the atmospheric transmittance of the water and carbon dioxide spectral absorption band tends to 0, so the peak value of the spectral radiance intensity will appear in the 4.5 μm-5 μm band range when the spectral imaging instrument is used to experimentally measure the infrared radiation characteristics of the plume, and this conclusion is also embodied in the simulation results of the technical scheme of the present application. In addition, compared with the simulation results of the literature without considering the gas-solid coupling, the simulation results of the technical scheme of the present application are more similar to the DRDC experimental measurement results, which further proves the effectiveness and accuracy of the spectral radiation transfer equation and solving algorithm of the plume under the gas-solid coupling built by the technical scheme of the present application.

[0166] It should be noted that the embodiments of the present application can be realized by hardware, software or a combination of software and hardware. The hardware part can be realized by using special logic; the software part can be stored in a memory and executed by a suitable instruction execution system, such as a microprocessor or a specially designed hardware. Those skilled in the art can understand that the above-mentioned devices and methods can be realized by using computer executable instructions and / or included in processor control code, such as provided on a carrier medium, such as a magnetic disk, CD or DVD-ROM, a programmable memory, such as a read-only memory (firmware), or a data carrier, such as an optical or electronic signal carrier. The devices of the present application and their modules can be realized by hardware circuits, such as very large scale integrated circuits or gate arrays, semiconductors, such as logic chips, transistors, or programmable hardware devices, such as field programmable gate arrays, programmable logic devices, etc. They can also be realized by software executed by various types of processors, or by a combination of the above-mentioned hardware circuits and software, such as firmware.

[0167] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and any modification, equivalent replacement and improvement made by those skilled in the art within the technical scope disclosed by the present application shall be covered within the protection scope of the present application.

Claims

1. A method for solving the spectral radiation characteristics of aircraft plume under gas-solid coupling, characterized in that, The aircraft plume spectral radiation characteristic solving method under the gas-solid coupling comprises the following steps: Based on the classical radiation transfer theory, and combined with the radiation transfer mechanism of the gas molecules and solid particles coupling, the radiation transfer equation of the aircraft exhaust plume under the gas-solid coupling is established. In a small region within the set exhaust plume, the solid particles are spherical alumina particles, and the gas molecules are specific gas molecules that perform spectral radiation outward in a specific wave band. A differential volume is taken at position s and in the radiation transfer direction Ω, with a cross section of dA and a length of ds. Let the spectral radiation intensity in the direction Ω at s be I λ (s,Ω), then the outgoing spectral radiation intensity in the direction Ω at s+ds is I λ (s,Ω)+dI λ (s,Ω). The radiation transfer equation of the aircraft plume under the gas-solid coupling is established by introducing a plume radiation transfer mechanism under the gas molecule and the alumina solid particle coupling based on a radiation transfer theory; The radiation transfer equation of the aircraft plume under the gas-solid coupling is established by introducing a plume radiation transfer mechanism under the gas molecule and the alumina solid particle coupling based on a radiation transfer theory; (1) Absorption coefficient of a medium under gas-solid coupling and (2) Extinction coefficient of medium under gas-solid coupling and (3) Scattering albedo of a medium under gas-solid coupling and The following parameters are defined for describing the medium properties of the plume under the gas-solid coupling: where is the absorption coefficient of the solid particles, is the absorption coefficient of the gas molecules, is the scattering coefficient of the solid particles, Φ particles (s; λ; Ω'→Ω) is the scattering phase function of the solid particles.

2. The method according to claim 1, wherein, Therefore, the spectral radiation transfer equation of the plume under the gas-solid coupling can be expressed as: According to the different spectral radiation mechanism of gas molecules and solid particles in the plume under gas-solid coupling, the increment dI of spectral radiation intensity is λ (s,Ω) is expressed as five components: (1) the spectral radiance intensity emitted by the gas molecules By default, in the local thermodynamic equilibrium state, the Kirchhoff's law is satisfied; (2) the spectral radiance intensity absorbed by the gas molecules wherein, is the emission coefficient of the gas, is the absorption coefficient of the gas molecules; (3) The spectral radiance intensity emitted by the solid particles (4) The spectral radiance intensity absorbed and scattered by the solid particles is the spectral radiance intensity of extinction The radiation transfer equation of the aircraft plume under the gas-solid coupling is established by introducing a plume radiation transfer mechanism under the gas molecule and the alumina solid particle coupling based on a radiation transfer theory; wherein is the absorption coefficient of the solid particles, is the scattering coefficient of the solid particles, is the extinction coefficient of the solid particles, and Φ particles (s; λ; Ω'→Ω) is the scattering phase function of the solid particles; Since the gas and solid particles in the same differential volume are in local thermodynamic equilibrium, the temperature of the gas and solid particles is the same T particles = T gas = T, the spectral radiation transfer equation of the plume under the gas-solid coupling is obtained as 3. The method according to claim 1, wherein, (5) the scattering spectral radiation intensity of the particles in other unit volumes in the medium into the calculated unit volume in the Ω direction: The aircraft plume spectral radiation characteristic solving method under the gas-solid coupling comprises the following steps: Step one, obtaining the physical parameters of the aircraft plume and performing grid division on the calculation domain of the plume; Step three, determine the integral path k and the calculated grid point i, and calculate the spectral radiance I of the grid point i in the discrete coordinate system λ (i,Ω); Step two, calculating the medium parameters after the gas-solid coupling in each grid point; Step five, the spectral radiation transfer equation of the plume is solved along the detection direction Ω through a small differential volume of radiation intensity under the discrete coordinate system, and the spectral radiation intensity I at the grid point i+1 along the detection direction Ω through a small differential volume is given λ (i+1,Ω). Step four, solving the spectral radiation source function of the grid point i under the gas-solid coupling in the spherical harmonic coordinate system according to the alumina particle thermal radiation source function, the gas molecule radiation source function and the internal scattering source function of the grid point i, and converting the spectral radiation source function of the grid point i to the discrete coordinate system; Step six, repeating steps three to five for each grid element along the integral path of the detection direction until the calculation of the boundary nodes of the aircraft plume calculation domain is completed, and storing the spectral radiation intensity on the boundary grid points; 4. The method according to claim 3, wherein, Step seven, completing the calculation of the spectral radiation intensity on all integral paths, and outputting the final spectral radiation intensity result of the plume. The physical parameter acquisition of the aircraft plume in step one comprises: obtaining the physical parameters of the calculation domain size, temperature distribution, pressure distribution, gas molar fraction distribution, alumina particle size distribution and density distribution of the plume through the flow field data of the aircraft plume; the calculation domain size comprises length, width and height; 5. The method according to claim 3, wherein, The grid division on the calculation domain of the plume comprises: determining the grid size in the plume calculation domain and the related physical parameters in each grid, the related physical parameters comprising the temperature, pressure, gas molar fraction, alumina particle size and density of each grid point.

6. A system for modeling and solving the spectral radiation characteristics of a vehicle plume, which applies the method for solving the spectral radiation characteristics of a vehicle plume under the gas-solid coupling according to any one of claims 1 to 5, characterized in that, The calculation of the medium parameters after the gas-solid coupling in each grid point in step two comprises: calculating the absorption coefficient, extinction coefficient, scattering albedo of the medium after the gas-solid coupling and the scattering phase function of the alumina particles in each grid point based on the Mie theory and the gas spectral radiation model. The aircraft plume spectral radiation characteristic modeling and solving system comprises: A physical parameter acquisition module for acquiring the physical parameters of the aircraft plume; A grid division module for performing grid division on the calculation domain of the plume; A medium parameter calculation module for calculating the medium parameters after the gas-solid coupling in each grid point; a spectral radiance calculation module for determining the integral path k and the calculated grid point i and calculating the spectral radiance I of the grid point i in the discrete coordinate system λ (i,Ω) ; for solving the plume spectral radiance transfer equation along the detection direction Ω through a small differential volume and giving the spectral radiance I at the grid point i+1 along the detection direction Ω through a small differential volume λ (i+1,Ω) ; a spectral radiation source function solving module, configured to solve the spectral radiation source function of the grid point i in the spherical harmonic coordinate system according to the alumina particle thermal radiation source function, the gas molecule radiation source function and the internal scattering source function of the grid point i under the gas-solid coupling, and convert the spectral radiation source function of the grid point i to the discrete coordinate system; a boundary grid point spectral radiation intensity calculating and storing module, configured to repeat the spectral radiation intensity calculating module and the spectral radiation source function solving module for each grid unit on the integral path in the detection direction until the calculation of the boundary node of the aircraft plume calculation domain is completed, and store the spectral radiation intensity on the boundary grid point; a result output module, configured to complete the calculation of the spectral radiation intensity on all the integral paths and output the final spectral radiation intensity result of the plume.

7. A computer device, characterized by The computer device comprises a memory and a processor, and the memory stores a computer program. When the computer program is executed by the processor, the processor executes the steps of the aircraft plume spectral radiation characteristic solving method under the gas-solid coupling according to any one of claims 1 to 5.

8. A computer readable storage medium, storing a computer program. When the computer program is executed by a processor, the processor executes the steps of the aircraft plume spectral radiation characteristic solving method under the gas-solid coupling according to any one of claims 1 to 5.

9. An information data processing terminal, characterized by The information data processing terminal is used to implement the aircraft plume spectral radiation characteristic modeling and solving system according to claim 6.

Images