CN108647419B

CN108647419B - Low-altitude flame infrared radiation characteristic estimation method and device along with height change

Info

Publication number: CN108647419B
Application number: CN201810413157.5A
Authority: CN
Inventors: 包醒东; 毛宏霞; 吴杰; 郑立; 董雁冰
Original assignee: Beijing Institute of Environmental Features
Current assignee: Beijing Institute of Environmental Features
Priority date: 2018-05-03
Filing date: 2018-05-03
Publication date: 2022-01-28
Anticipated expiration: 2038-05-03
Also published as: CN108647419A

Abstract

The invention relates to the technical field of data processing, and provides a low-altitude flame infrared radiation characteristic estimation method and device along with height change, wherein the method comprises the following steps: acquiring jet flame flow field characteristic parameters under a first height and a second height based on simulation, and calculating the infrared radiation intensity of jet flames under the first height and the second height; calculating the jet flame flow field scale changing along with the height to be estimated according to jet flame flow field characteristic parameters under the first height and the second height obtained by simulation, and obtaining an infrared radiation intensity function changing along with the height to be estimated according to the jet flame flow field scale changing along with the height to be estimated and the spectral absorption coefficient of each subarea; and correcting by a formula to obtain the flame infrared radiation intensity. The method can realize the rapid estimation of the low-altitude flame infrared radiation characteristic along with the height change, and solves the problem of low calculation efficiency of the flame flow field and the radiation characteristic based on a detailed modeling method in the prior art.

Description

Low-altitude flame infrared radiation characteristic estimation method and device along with height change

Technical Field

The invention relates to the technical field of data processing, in particular to a low-altitude flame infrared radiation characteristic estimation method and device along with height change.

Background

When the rocket engine is designed, the full-flow state of the rocket engine needs to be ensured, the expansion ratio (the ratio of the outlet pressure of the spray pipe to the ambient pressure) of the engine is about 1, when the rocket is launched and emptied from the ground, the expansion ratio is increased along with the reduction of the ambient pressure in the flying process, the engine is basically in a slight under-expansion state and an under-expansion state, and the rocket is in a gradual acceleration state. The reburning effect is an important parameter influencing the infrared radiation characteristic of the jet flame, the reburning effect is determined by the recovery temperature, the component concentration and the blending parameter, the expansion ratio is larger along with the increase of the height, the loss after the Mach disk is larger, the recovery temperature after the expansion is further reduced, the oxygen concentration is reduced along with the height, on the other hand, the jet flame outlet speed (about 2000m/s to 3000m/s) is higher along with the increase of the rocket speed, the speed difference is smaller, the blending is weaker, and under the assumed condition, the reburning effect is weakened along with the increase of the height and is characterized as the reduction of the highest temperature.

Thus, the low-altitude flame infrared radiation characteristics differ with changes in height. The flow field and radiation characteristics obtained under a certain typical height based on the simulation method have higher calculation time cost and lower efficiency, so the method is not suitable for estimating the low-altitude flame infrared radiation characteristics at all heights.

Disclosure of Invention

The invention aims to solve the technical problem that the calculation efficiency of a jet flame flow field and radiation characteristics based on a detailed modeling method in the prior art is low, and provides a low-altitude jet flame infrared radiation characteristic estimation method and device along with height change, which can quickly and effectively realize estimation.

In order to solve the technical problem, the invention provides a low-altitude flame infrared radiation characteristic estimation method along with height change, which comprises the following steps:

obtaining jet flame flow field characteristic parameters under a first height and a second height based on simulation, and calculating the infrared radiation intensity I of jet flames under the first height and the second height_template(H₁) And I_template(H₂)；

Calculating the jet flame flow field scale changing with the height to be estimated according to jet flame flow field characteristic parameters under the first height and the second height obtained by simulation, and obtaining an infrared radiation intensity function I changing with the height H to be estimated according to the jet flame flow field scale changing with the height to be estimated and the spectral absorption coefficient of each subarea_new(H)；

The jet flame infrared radiation intensity I is obtained by the following formula:

wherein, I_new(H₁) And I_new(H₂) Respectively is the first height H₁And a second height H₂Substitution of infrared radiationIntensity function I_new(H) The infrared radiation intensity obtained is then determined.

Optionally, the calculating a jet flame flow field dimension varying with the height to be estimated according to the jet flame flow field characteristic parameters at the first height and the second height obtained by the simulation includes:

calculating the corresponding expansion ratio N according to the height to be estimated_PRSelecting the expansion ratio N at the first height and the second height_PR1And N_PR2The middle and closest height is used as a basic template, and the maximum equivalent radius R of the jet flame of the basic template is calculated according to the jet flame flow field characteristic parameters of the basic template_templateLength equivalent to that of the jet flame L_template；

The maximum equivalent radius R of the jet flame according to the basic template_templateLength equivalent to that of the jet flame L_templateCalculating the jet flame flow field dimension which changes along with the height H to be estimated by the following formula:

wherein R is_newMaximum equivalent radius of the flame for the height H variation to be estimated, L_newFor equivalent length of the jet, N, as a function of the height H to be estimated_PRAnd N_{PR_template}For the expansion ratio of the height to be estimated and the expansion ratio of the base form, f (U)_∞template) And g (U)_∞template) And the accompanying flow velocity U of the basic template_∞templateAs the accompanying flow velocity U_∞Substituting into the high-speed accompanying flow influence function f (U)_∞) And g (U)_∞) To obtain k_LAnd k_RIs the fitting constant.

Optionally, the high speed companion flow influence function f (U)_∞) And g (U)_∞) Respectively as follows:

wherein, U_∞To accompany the velocity of the flow, U^*Is the limit expansion rate of the jet flame, and

γ_exitis specific heat ratio at the outlet of the engine, R is the gas constant, T_exitIs the engine nozzle exit temperature.

Optionally, the infrared radiation intensity function I varying with the height H to be estimated is obtained according to the jet flame flow field scale varying with the height to be estimated and the spectral absorption coefficient of each partition_new(H) The method comprises the following steps:

calculating the spectral absorption coefficient of each jet flow field subarea according to the jet flow field scale changed along with the height H to be estimated;

obtaining an infrared radiation intensity function I which changes along with the height H to be estimated according to the spectral absorption coefficient of each jet flame flow field subarea_new(H)。

Optionally, the function is dependent on accompanying flow velocity U_∞Calculating the spectral absorption coefficient of each jet flow field partition by the changed jet flow field scale, wherein the calculation comprises the following steps:

calculating the spectral absorption coefficient of the area according to the outlet parameters of the jet pipe engine in the outlet area of the flow field;

calculating the spectral absorption coefficient of the region according to the flow field parameters of the incoming flow influence region;

according to a first height H₁And a second height H₂The flow field parameters of the reburning area with the height H to be estimated are calculated, and the spectral absorption coefficient of the reburning area is calculated according to the flow field parameters of the reburning area.

Optionally, said first height H₁And a second height H₂The flow field parameter calculation of the reburning zone of the height H to be estimated comprises the following steps:

(1) the reburning zone being calculated by the formulaTemperature T_afterburning：

T_afterburning＝T_{1_max}+(T_{2_max}-T_{1_max})(H-H₁)/(H₂-H₁)；

Wherein T is_{1_max}Is a first height H₁Maximum temperature in the form of (1), T_{2_max}Is a second height H₂Maximum temperature in the template of (1);

(2) the pressure P of the reburning zone is calculated by the following formula_afterburning：

P_afterburning＝0.5*(P₁(x″,0)+P₂(x″′,0))；

Wherein P is₁(x', 0) is a first height H₁At a position corresponding to the maximum temperature in the template, P₂(x' ", 0) is a second height H₂The pressure at the position corresponding to the maximum temperature value in the template;

(3) the density ρ of the reburning zone is calculated by the following formula_afterburning：

ρ_afterburning＝0.5*(ρ₁(x″,0)+ρ₂(x″′,0))；

Where ρ is₁(x', 0) is a first height H₁The density, p, of the location corresponding to the temperature maximum in the template₂(x' ", 0) is a second height H₂The density of the position corresponding to the maximum temperature value in the template;

(4) the velocity U of the reburning zone is calculated by the following formula_afterburning：

U_afterburning＝0.5*(U₁(x″,0)+U₂(x″′,0))；

Wherein U is₁(x', 0) is a first height H₁Speed of the position corresponding to the maximum temperature value in the template, U₂(x' ", 0) is a second height H₂The speed of the position corresponding to the maximum temperature value in the template;

CO in the reburning zone is calculated by the following formula₂Component mass concentration X_{CO2_afterburning}：

X_{CO2_afterburning}＝(X_{1_co2}(x″,0)-X_{1_co2}(x′，0))*α_afterburning/α₁+X_{1_co2}(x′,0)；

Wherein, X_{1_co2}(x', 0) is a first height H₁At the (x', 0) position of the template of (A)₂Mass concentration of component X_{1_co2}(x', 0) is a first height H₁At the (x', 0) position CO in the template₂Mass concentration of the components, wherein (x', 0) is a first height H₁The mass concentration X of OH component in the template_{1_OH}Position where (x,0) is not less than 0, alpha_afterburningAccording to the velocity U of the reburning zone_afterburningAnd temperature T of the reheat zone_afterburningCalculated entrainment coefficient, α₁According to a first height H₁Speed U of the position corresponding to the maximum temperature value in the template₁(x', 0) and temperature T_{1_max}(ii) a calculated entrainment coefficient; the mass concentration X of the CO component in the reburning area is calculated by the same method_{CO_afterburning}And H₂Mass concentration X of O component_{H2O_afterburning}。

The invention also provides a low-altitude flame infrared radiation characteristic pre-estimating device along with the height change, which comprises: the device comprises a simulation unit, a change estimation unit and an intensity correction unit;

the simulation unit obtains jet flame flow field characteristic parameters under a first height and a second height based on simulation, and calculates the infrared radiation intensity I of jet flames under the first height and the second height_template(H₁) And I_template(H₂)；；

The change pre-estimating unit is used for calculating the jet flame flow field scale changing along with the height to be estimated according to jet flame flow field characteristic parameters under the first height and the second height obtained by simulation, and obtaining an infrared radiation intensity function I changing along with the height H to be estimated according to the jet flame flow field scale changing along with the height to be estimated and the spectral absorption coefficient of each subarea_new(H)；

The intensity correction unit is used for

wherein, I_new(H₁) And I_new(H₂) Respectively is the first height H₁And a second height H₂Substitution into an infrared radiation intensity function I_new(H) The infrared radiation intensity obtained is then determined.

Optionally, the change estimation unit is configured to perform the following operations to calculate the flow field dimension of the flame as a function of the height to be estimated:

Optionally, the variation estimation unit is configured to perform the following operation to change the infrared radiation intensity function I with the height H to be estimated_new(H)：

obtaining an infrared radiation intensity function I which changes along with the height H to be estimated according to the spectral absorption coefficient of each jet flame flow field subarea_new(U_∞)。

The method and the device for estimating the infrared radiation characteristic of the low-altitude flame along with the height change, provided by the embodiment of the invention, have the following beneficial effects:

1. according to the method, the flow field and radiation change rules under the condition of different altitudes can be solved based on the infrared radiation intensity of the flame at the first height and the second height obtained by simulation and the infrared radiation intensity function which is obtained based on the self-emission principle and changes along with the height to be estimated, the flame infrared radiation characteristic of each height can be rapidly estimated, and the problem of low calculation efficiency of the flame flow field and radiation characteristic based on a detailed modeling method in the prior art is solved.

2. The invention constructs a jet flame flow field scale correction formula, and can calculate the jet flame flow field scale which changes along with the height H to be estimated according to the jet flame flow field scale of the basic template, thereby converting the simulation result under the fixed height into different altitudes H, and being convenient for solving the infrared radiation characteristics of different altitudes.

3. The invention also fits a high-speed adjoint flow influence function f (U) by analyzing the statistical characteristics of the jet flame flow field_∞) And g (U)_∞) The jet flow field size of the low-altitude jet flow field along with the velocity U of the accompanying flow is obtained by the formula_∞The change rule of (2).

4. The invention estimates the intensity I of the infrared radiation at a new height H_new(HH) after the above, to obtain a spectral radiation intensity with higher accuracy, I obtained by simulation was further used_new(H₁) And I_template(H₂) And correcting to calculate the spectral radiation intensity at different heights with higher precision.

Drawings

FIG. 1 is a flow chart of a method for estimating the infrared radiation characteristic of a low-altitude flame according to the variation of height according to an embodiment of the present invention;

FIG. 2 is a schematic view of a low altitude flame flow field;

FIGS. 3a and 3b are graphs of a fitted low altitude flame infrared radiation characteristic in accordance with the present invention;

FIG. 4 is a plot of predicted distribution characteristics of a low-altitude flame flow field according to the present disclosure;

FIG. 5 is a schematic diagram of an apparatus for estimating the infrared radiation characteristic of a low-altitude flame according to a fifth embodiment of the present invention;

in the figure: 501: a simulation unit; 502: a change estimation unit; 503: and an intensity correction unit.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

Example one

As shown in fig. 1, the method for estimating the infrared radiation characteristic of the low-altitude flame according to the embodiment of the invention may include the following steps:

step S101: obtaining a first height H based on simulation₁And a second height H₂The characteristic parameters of the lower jet flame flow field are calculated, and the first height H is calculated₁And a second height H₂Intensity of infrared radiation of lower jet flame I_template(H₁) And I_template(H₂)；

Step S102: calculating the jet flame flow field scale changing with the height to be estimated according to jet flame flow field characteristic parameters under the first height and the second height obtained by simulation, and obtaining an infrared radiation intensity function I changing with the height H to be estimated according to the jet flame flow field scale changing with the height to be estimated and the spectral absorption coefficient of each subarea_new(H)；H₁≤H≤H₂；

Step S103: the jet flame infrared radiation intensity I is obtained by the following formula:

The method for estimating the infrared radiation characteristic of the low-altitude flame changing along with the height, provided by the embodiment of the invention, can be used for solving the flow field and radiation change rule under the condition of different altitudes based on the infrared radiation intensity of the flame at the first height and the second height obtained by simulation and the infrared radiation intensity function changing along with the height to be estimated obtained based on the self-emission principle, and can be used for rapidly estimating the infrared radiation characteristic of the flame at each height.

Example two

Based on the method for estimating the infrared radiation characteristic of the low-altitude flame with height variation provided in the first embodiment, the first height H is obtained based on simulation in step S101₁And a second height H₂The characteristic parameters of the lower jet flame flow field are calculated, and the first height H is calculated₁And a second height H₂Intensity of infrared radiation of lower jet flame I_template(H₁) And I_template(H₂) The process of (2) can be specifically realized by the following modes:

a1 simulating two different heights (first height H) based on CFD + + method and using engine nozzle outlet parameters and environment parameters as input₁A second height H₂) And (3) jet flame flow field characteristic parameters under the conditions. First height H in the present invention₁A second height H₂And the height H to be estimated both refer to the altitude. Wherein the engine nozzle exit parameters include: nozzle exit radius R_{exit_template}Outlet pressure P_{exit_template}Outlet temperature T_{exit_template}Outlet density ρ_{exit_template}Outlet velocity U_{exit_template}Specific heat ratio at outlet gamma_{exit_template}And mass concentration of the components (e.g. co)₂Mass fraction

co mass fraction x_{coexit_template}、h₂o mass fraction

). The environmental parameters include: pressure P of accompanying flow_{∞_template}Temperature T of the accompanying stream_{∞_template}And accompanying flow velocity U_{∞_template}. The characteristic parameters of the jet flame flow field comprise: temperature T (X, y), pressure P (X, y), density ρ (X, y), component mass concentration distribution X (X, y), where X and y represent the position in the flow field, respectively, the above parameters characterizing the parameters varying with position. In the present invention, subscript template represents template, exit represents export, and ∞ represents environmental companion stream.

Wherein the altitude is a first altitude H₁When the corresponding ambient pressure is P_∞1Ambient temperature T_∞1And the incoming flow velocity U_∞1At this time, the expansion ratio N_PR1＝P_exit/P_∞1(ii) a When the altitude is the second altitude H₂When the corresponding ambient pressure is P_∞2Ambient temperature T_∞2And the incoming flow velocity U_∞2At this time, the expansion ratio N_PR2＝P_exit/P_∞2。

A2, taking characteristic parameters of the jet flame flow field as input, solving the absorption coefficient of gas in the jet flame flow field based on a line-by-line integration method, solving the radiation transmission equation of the jet flame flow field based on an apparent light method (LOS), and obtaining two different heights (a first height H)₁And a second height H₂) The intensity of the infrared radiation (i.e., the intensity of the spectral radiation) of the jet flame. The invention can adopt CFD + + and line-by-line integration and LOS method to simulate the jet flame flow field and the template of the infrared radiation characteristic under the typical height, extract the characteristic parameter of the jet flame flow field, and is beneficial to obtaining the infrared radiation intensity function I which changes along with the height H to be estimated subsequently_new(H) In that respect The invention does not limit the concrete form of the template, and the flow field and radiation characteristics obtained by simulation or actual measurement under typical speed and typical two heights can be used as the template.

EXAMPLE III

On the basis of the method for estimating the infrared radiation characteristic of the low-altitude flame with height change provided in the second embodiment, the step S102 is a process of calculating the flame flow field dimension with height change to be estimated according to the flame flow field characteristic parameters at the first height and the second height obtained by simulation, and the method can be specifically implemented by the following steps:

b1, calculating the corresponding expansion ratio N according to the height to be estimated_PRSelecting the expansion ratio N at the first height and the second height_PR1And N_PR2The middle and closest height is used as a basic template, and the maximum equivalent radius R of the jet flame of the basic template is calculated according to the jet flame flow field characteristic parameters of the basic template_templateLength equivalent to that of the jet flame L_template。

The jet flame flow field is determined by the jet nozzle outlet flow parameters and the incident flow (i.e., the ambient atmospheric incident flow), which can be attributed to the expansion ratio N_PR(ratio of nozzle outlet pressure to ambient pressure),Specific heat ratio gamma of spray pipe outlet_exitAnd accompanying flow velocity U_∞。

When the height to be estimated is H, the corresponding ambient pressure is P_∞Ambient temperature T_∞And the incoming flow velocity U_∞At this time, the expansion ratio N corresponding to the height H to be estimated_PR＝P_exit/P_∞Since the height H to be estimated is between the first height H₁And a second height H₂In between, i.e. N_PRBetween N_PR1And N_PR2In which N is_PRThe closest height is the base template, assuming | N_PR-N_PR1|＜|N_PR-N_PR2Taking the basic template as the first height H₁Otherwise, the basic template is taken as the second height H₂。

The parameter R is determined in the template by the following relationship_templateAnd L_templateThe generation method comprises the following steps: taking the temperature of the jet flame boundary and reducing it to the ambient incoming flow temperature T_{∞_template}1.05 times of the jet flame, namely the maximum equivalent radius R of the jet flame_templateFrom the nozzle outlet to the oxygen x in the ambient gas_{o2∞_template}The distance when the mass fraction is reduced to 0.1 is the equivalent length L of the flame_template。

The invention determines the maximum equivalent radius R of the jet flame from the basic template according to the distribution characteristics of the low-altitude jet flame flow field characteristics and the following relation_templateLength equivalent to that of the jet flame L_template: taking the temperature T of the jet flame boundary and reducing to the ambient incoming flow temperature T_{∞_template}Radius 1.05 times that of the jet flame, namely the maximum equivalent radius R of the jet flame_template(ii) a Oxygen x from the nozzle outlet to the ambient gas_{o2∞_template}Mass fraction Y_aThe distance reduced to 0.1 is the equivalent length L of the flame_template. As shown in fig. 2, a schematic view of a low-altitude flame flow field is shown. Thus, the parameter R_templateAnd L_templateCan be obtained by processing the template according to the method.

B2, maximum equivalent radius R of flame according to the basic template_templateLength equivalent to that of the jet flame L_templateIs calculated by the following formulaThe jet flame flow field dimension of the height H change to be estimated:

wherein R is_newMaximum equivalent radius of the flame for the height H variation to be estimated, L_newFor equivalent length of the jet, N, as a function of the height H to be estimated_PRAnd N_{PR_template}For the expansion ratio of the height to be estimated and the expansion ratio of the base form, f (U)_∞template) And g (U)_∞template) And the accompanying flow velocity U of the basic template_∞templateAs the accompanying flow velocity U_∞Substituting into the high-speed accompanying flow influence function f (U)_∞) And g (U)_∞) To obtain k_LAnd k_RIs the fitting constant. For liquid rocket engines, preferably k_L＝1.54，k_R1.2; for solid rocket engines, preferably k_L＝1.32，k_R＝1.1。

The invention analyzes the statistical characteristics of the jet flame flow field through a large amount of experimental data, and finds that the specific heat ratio gamma is given_exi_tAnd U_∞＜U^*/2, velocity U with accompanying flow_∞The corresponding equivalent length of the jet flame is increased, and the accompanying flow velocity approaches the limit expansion velocity U of the jet flame^*The jet equivalent length reaches its maximum value when it is time, and then decreases as the incident flow increases. As shown in fig. 3a and 3b, fitting graphs are fitted to the infrared radiation characteristics of the low-air flame according to the present invention. The curve is based on L of statistics in 100 groups of flow fields corresponding to different incoming flow velocities of numerical simulation_templateFitting on the basis of data, wherein gamma_exit＝1.2。

FIG. 3a shows the equivalent length L of the flame_templateExpansion ratio N_PRFIG. 3b is the equivalent length L of the flame_templateVelocity U with accompanying flow_∞The fitted curve of (1).

From the fitted curve, a high-speed adjoint flow influence function f (U) can be obtained_∞) And g (U)_∞) Respectively as follows:

Obtaining the maximum equivalent radius R of the flame of the calculated basic template_templateLength equivalent to that of the jet flame L_templateAnd a high speed companion flow influence function f (U)_∞) And g (U)_∞) Then, the jet flame flow field dimension R of the height H change to be estimated can be obtained through the formulas (2) and (3)_newAnd L_new。

The invention constructs a jet flame flow field scale correction formula, and can calculate the jet flame flow field scale which changes along with the height H to be estimated according to the jet flame flow field scale of the basic template, thereby converting the simulation result under the fixed height into different altitudes H, and being convenient for solving the infrared radiation characteristics of different altitudes.

Furthermore, the invention also fits a high-speed adjoint flow influence function f (U) by analyzing the statistical characteristics of the jet flame flow field_∞) And g (U)_∞) The jet flow field size of the low-altitude jet flow field along with the velocity U of the accompanying flow is obtained by the formula_∞The change rule of (2).

Example four

Low altitude flame IR as provided in example IIIBased on the radiation characteristic estimation method, in step S102, an infrared radiation intensity function I changing with the height H to be estimated is obtained according to the jet flame flow field scale changing with the height to be estimated and the spectral absorption coefficient of each subarea_new(H) The process can be specifically realized by the following steps:

c1, calculating the spectral absorption coefficient k of each jet flow field subarea according to the jet flow field scale changing along with the height H to be estimated_m,ηWhere m is the partition number and η is the wavelength. The jet flame flow field subarea comprises a reburning area, an incoming flow influence area and a flow field outlet area, and the corresponding spectral absorption coefficients are respectively k_1,η、k_2,ηAnd k_3,η。

C2, obtaining an infrared radiation intensity function I changing with the height to be estimated according to the spectral absorption coefficient of each jet flame flow field subarea_new(H)。

Fig. 4 is a diagram of the predicted distribution characteristics of the low-pressure flame flow field according to the present invention. As shown in fig. 4, the flame flow field of the present invention is divided into 3 flame flow field zones, and the area and corresponding characteristic parameters of each zone are respectively:

1. and (3) a flow field outlet area: l is more than or equal to 0 and less than or equal to k₁*L_new，0≤R≤R_{exit_template}；

The parameter of the outlet region of the flow field has an outlet temperature T_{exit_template}Outlet pressure P_{exit_template}Outlet density ρ_{exit_template}、co₂Mass fraction

h₂o mass fraction

co mass fraction x_{coexit_template}The parameters of the nozzle engine outlet are input parameters in the basic template. In FIG. 4, the above parameters are abbreviated as T_e、P_e、ρ_e、X_CO、X_H2O、X_CO2。

2. The incoming flow influence area: l is more than or equal to 0 and less than or equal to k₁*L_new，R_{exit_template}≤R≤R_new；

Parameters of the inflow influencing zone the temperature, pressure, density, co mass fraction, h of the influencing zone₂o mass fraction and co₂Mass fraction, i.e. T_i、P_i、ρ_i、X_{CO_i}、X_{H2O_i}、X_{CO2_i}. The parameters are the variation parameters of the environment from the outlet of the spray pipe to the incoming flow, and are linearly changed along with the radial distance R,

for example: when the radial distance R is equal to R_{exit_template}At this time T_i＝T_{exit_template}When the radial distance R is equal to R_newAt this time T_i＝1.05T_{∞_template}；

When the distance R is between R_{exit_template}And R_newIn the meantime:

T_i＝T_{exit_template}+(R-R_{exit_template})*(1.05T_{∞_template}-T_{exit_template})/(R_new-R_{exit_template}) (6)

the remaining parameters are solved in the same way.

3. A reburning area: k is a radical of₁*L_new≤l≤L_new，0≤R≤R_new。

Temperature, pressure, density, co mass fraction, h of reburning zone₂o mass fraction and co₂Mass fraction T_afterburning、P_afterburning、ρ_afterburning、X_{CO_afterburning}、X_{H2O_afterburning}、X_{CO2_afterburning}To take into account the flow field parameters of the afterburning effect.

I in the above subdivision is the length across the flow field, i.e. in the direction of flight of the aircraft, and R is the radial distance (i.e. radius). R_{exit_template}Is the nozzle exit radius in the known engine nozzle exit parameters. k is a radical of₁The calculation method of (2) is as follows: the expansion ratio N at the first height and the second height selected in step S101_PR1And N_PR2Taking X from the nearest template_oh(X, y) representing the mass concentration of the hydroxide (oh) component as a function of the coordinates (X, y), and making y 0, when X is_oh(x,0)>When 0 appears, x at this position is obtained from the template, then k₁＝x/R_template。

The invention is based on a first height H₁And a second height H₂The method for calculating the flow field parameters of the reburning area of the height H to be estimated comprises the following steps:

1) the temperature T of the reheat zone is calculated by the following formula_afterburning：

T_afterburning＝T_{1_max}+(T_{2_max}-T_{1_max})(H-H₁)/(H₂-H₁) (7)

at a first height H₁Known jet flame flow field temperature distribution T in template₁(X, y) and OH component mass concentration distribution X_{1_OH}(x, y) with y equal to 0, there is a temperature distribution function T of temperature along the axis (i.e., L direction)₁(X,0) and OH component Mass concentration distribution function X_{1_OH}(X,0) when X_{1_OH}When (x ', 0) is more than or equal to 0, the position x ' is obtained, and x ' is more than or equal to x and less than or equal to L_templateWithin the interval, obtaining the maximum value T₁(x', 0) (denoted T_{1_max}) Obtaining the second height H in the same way₂Maximum value of intermediate temperature T₂(x' ", 0) (denoted T_{2_max}). Since the expansion ratio (outlet pressure to ambient pressure) is greater with increasing altitude, the losses after passing through the mach disk are greater, and the recovery temperature after expansion is reduced, the oxygen concentration decreases with altitude, on the other hand, the jet flame outlet velocity (about 2000m/s to 3000m/s), the velocity difference is smaller with increasing rocket velocity, the mixing is weaker, and the afterburning effect becomes weaker with increasing altitude under the assumed conditions, characterized by a reduction in the maximum temperature. Therefore, the altitude H is between H₁And H₂So that T is_afterburningBetween T_{1_max}And T_{2_max}In between, linear interpolation is performed on the height to obtain the T calculated by the above formula (7)_afterburning：

2) By passingThe pressure P of the reburning zone is calculated by the following formula_afterburning：

P_afterburning＝0.5*(P₁(x″,0)+P₂(x″′,0)) (8)

3) the density ρ of the reburning zone is calculated by the following formula_afterburning：

ρ_afterburning＝0.5*(ρ₁(x″,0)+ρ₂(x″′,0)) (9)

since the pressure and density do not change much, the pressure and density in the reburning zone can be calculated by using the above (8) and (9).

U_afterburning＝0.5*(U₁(x″,0)+U₂(x″′,0)) (10)

X_{CO2_afterburning}＝(X_{1_co2}(x″,0)-X_{1_co2}(x′,0))*α_afterburning/α₁+X_{1_co2}(x′,0) (11)

Wherein, X_{1_co2}(x', 0) is a first height H₁At a position CO in the template₂Mass concentration of component X_{1_co2}(x', 0) is the first heightDegree H₁At the (x', 0) position CO in the template₂Mass concentration of the components, wherein (x', 0) is a first height H₁The mass concentration X of OH component in the template_{1_OH}Position where (x,0) is not less than 0, alpha_afterburningAccording to the velocity U of the reburning zone_afterburningAnd temperature T of the reheat zone_afterburningCalculated entrainment coefficient, α₁According to a first height H₁Speed U of the position corresponding to the maximum temperature value in the template₁(x', 0) and temperature T_{1_max}Calculated entrainment coefficient.

In order to characterize the afterburning effect, the empirical coefficient of the entrainment of gas mixture from the ambient atmosphere by the jet flame is described by the entrainment coefficient α, which is a parameter that varies with mach number. The entrainment coefficient can be calculated by the following equation (12):

in the formula M_exitMach number, p, at the nozzle outlet_exitI.e., the density at the nozzle exit, u is the velocity at the entrainment location, and T is the temperature at the entrainment location.

Thus, changing U to U₁(x″,0)，T＝T_{1_max}Substituting into formula (12) to obtain entrainment coefficient alpha₁(ii) a Changing U to U_afterburning，T＝T_afterburningSubstituting into formula (12) to obtain entrainment coefficient alpha_afterburning。

Mass concentration X of CO component in reburning zone_{CO_afterburning}And H₂Mass concentration X of O component_{H2O_afterburning}The process is similar to the above-described CO₂The solving method of the mass concentration of the components is the same, and the details are not repeated herein.

Preferably, said function is dependent on the accompanying flow velocity U_∞The method comprises the following steps of calculating the spectral absorption coefficient of each jet flow field subarea by the changed jet flow field scale, wherein the method comprises the following steps:

(1) calculating the spectral absorption coefficient of the area according to the outlet parameters of the jet pipe engine in the outlet area of the flow field;

(2) calculating the spectral absorption coefficient of the region according to the flow field parameters of the incoming flow influence region;

(3) according to a first height H₁And a second height H₂The flow field parameters of the reburning area with the height H to be estimated are calculated, and the spectral absorption coefficient of the reburning area is calculated according to the flow field parameters of the reburning area.

After 3 jet flow field partitions are divided, a HITRAN/HITEMP spectral database can be adopted to calculate the gas absorption coefficient k of each jet flow field partition_m,η. The specific calculation method is as follows:

for the same gas, its spectral absorption coefficient k at wave number eta_ηIs equal to the linear absorption coefficient k of the mutually overlapped spectral lines at the wave number eta_η,iAnd (c) the sum, i.e.:

in the formula, k_ηIs the absorption coefficient, F (. eta. -eta.)_0,i) Is a linear function of the spectral line, η_0,iTo calculate the wavenumber at the center of the ith line in the domain, S_iN is the number density of molecules of a single component, normalized to the integrated intensity of the line of a single molecule.

The standard state (P) is given in the HITRAN/HITEMP spectral database₀＝1.01325×10⁵pa、T₀296K) of the components in the atmosphere^*(T₀) (normalized to 296K single molecules). Single molecule spectral line intensity expression at other temperatures:

in the formula: eta₀At the center of the spectral line, E' is a low-state spectral term, Q_V(T) is a vibration distribution function, Q_R(T) is a rotational distribution function, S^*(T) is the integral intensity of the spectral line of a single molecule at the temperature T, c is the speed of light, h is the Planckian constant, and k is the Boltzmann constant.

Wherein the line linear function has Lorentz line type (Lorentz) and Doppler line type (Doppler), the invention uses Foott (Viogt) line type, and the calculation formula is as follows:

in the formula, W_LIs the full linewidth of the Lorentzian line, W_DIs the full line width, W, of the Doppler line_VIs the full line width of the Foott line, I_V,maxThe value of the Foott line function at the center of the line.

Wherein

Obtaining the temperature, pressure, density, co mass fraction, h of each jet flame flow field subarea₂o mass fraction and co₂After the mass fractions, the integrated intensity of the spectral line S of a single molecule can be calculated by substituting the respective temperatures as the temperatures T into equation (14)^*(T) is S in the formula (13)_i. Will S_i、F(η-η_0,i) Substituting N into formula (13) to obtain the spectral absorption coefficient k of a single gas_η. Wherein the molecular number density N is obtained by density conversion of a flame flow field partition.

Total absorption coefficient for a mixture of n' components (i.e., gas absorption coefficient for a burner flow field zone)

Wherein k is_η,jThe spectral absorption coefficient of the j-th gas in this division is expressed by the above formula (13). Preferably, the gas component of primary concern in the present invention is co₂、co、h₂o three components, wherein n' is 3.

Since the spectral radiation is different when observed along different directions, a person skilled in the art can calculate the infrared radiation intensity function I which changes along with the height H to be estimated by using the spectral absorption coefficient of each jet flow field subarea according to different observation angles_new(H) In that respect For example, in a radial direction (upwards)The above R direction) is taken as an example, then it is:

in the formula k_1,ηIs the spectral absorption coefficient, k, of the reburning zone_2,ηIs the spectral absorption coefficient, k, of the region of influence of the incoming flow_3,ηIs the spectral absorption coefficient of the outlet region of the flow field, where k_4,η＝k_2,η。c₁Is a first radiation constant, c₂And λ is the second radiation constant, and λ is the radiation wavelength λ 10000/η.

According to the above method, I can be calculated_new(H) For a first height H₁，H＝H₁Can obtain I_new(H₁) For the second height H₂，H＝H₂Then, I can also be calculated_new(H₂) In order to obtain higher precision spectral radiation intensity, the value of I obtained in step S101 is used_template(H₁) And I_template(H₂) And correcting to calculate the spectral radiation intensity at different heights with higher precision, wherein the method comprises the following steps:

from a first height H₁Template I_template(H₁) Corrected to obtain_new(H)*I_template(H₁)/I_new(H₁) (ii) a From the second height H₂Template I_template(H₂) Corrected to obtain_new(H)*I_template(H₂)/I_new(H₂)。

The jet flame infrared radiation intensity I in the interval along with the height can be obtained by taking the mean value:

wherein I is the spectral radiation intensity of height H estimated and obtained by the method, and I is_template(H₁) And I_template(H₂) First height H generated based on fine simulation for first step₁And the second highestDegree H₂Intensity of jet flame infrared radiation, I_new(H₁) And I_new(H₂) Respectively is the first height H₁And a second height H₂Substituting the estimated infrared radiation intensity function I_new(H) The infrared radiation intensity obtained is then determined.

In order to verify the efficiency of the low-altitude flame infrared radiation characteristic estimation method along with the change of height under the influence of the accompanying flow, the invention calculates the flame flow field and the infrared radiation characteristic of 40 typical heights at the interval of 1km to 40km based on simulation platform simulation configured by Dell Optiplex 780 software and hardware, the CFD method (CFD + + software) is adopted to simulate and generate the flame flow field and the infrared radiation characteristic of about 11 hours under each height state, and the total consumed time is about 40 multiplied by 11 hours under the condition of not adopting a parallel algorithm. By adopting the estimation method, about 2 multiplied by 11hour preparation templates in the total time consumption of typical states (1km and 40km) are calculated, 15 minutes are consumed for generating the flame infrared radiation characteristics of other heights, and the time cost is greatly reduced, so that the low-altitude flame infrared radiation characteristic estimation method can realize the rapid calculation of the low-altitude flame flow field and the infrared radiation characteristics along with the height change.

EXAMPLE five

As shown in fig. 5, the device for estimating the infrared radiation characteristic of the low-altitude flame according to the embodiment of the invention may include: a simulation unit 501, a change estimation unit 502 and an intensity correction unit 503;

a simulation unit 501, configured to obtain flow field characteristic parameters of the jet flame at the first height and the second height based on simulation, and calculate an infrared radiation intensity I of the jet flame at the first height and the second height_template(H₁) And I_template(H₂). The simulation unit 501 performs the same operation as step S101 in the foregoing method.

A change estimation unit 502, configured to calculate a jet flame flow field dimension that changes with the height to be estimated according to the jet flame flow field characteristic parameters at the first height and the second height obtained through simulation, and obtain an infrared radiation intensity function I that changes with the height H to be estimated according to the jet flame flow field dimension that changes with the height to be estimated and the spectral absorption coefficient of each partition_new(H) In that respect The changeThe operation performed by the prediction unit 502 is the same as step S102 in the method described above.

An intensity correction unit 503, configured to correct the flame infrared radiation intensity I according to the following formula:

wherein, I_new(H₁) And I_new(H₂) Respectively is the first height H₁And a second height H₂Substitution into an infrared radiation intensity function I_new(H) The infrared radiation intensity obtained is then determined. The intensity correction unit 503 performs the same operation as step S103 in the foregoing method.

Optionally, the variation estimation unit 502 is configured to perform the following operations to calculate the flow field dimension of the flame as a function of the height to be estimated:

wherein R is_newMaximum equivalent radius of the flame for the height H variation to be estimated, L_newFor equivalent length of the jet, N, as a function of the height H to be estimated_PRAnd N_PR__templateFor the expansion ratio of the height to be estimated and the expansion ratio of the base form, f (U)_∞template) And g (U)_∞template) And the accompanying flow velocity U of the basic template_∞templateAs the accompanying flow velocity U_∞Substituting the high-speed adjoint flow influence functions f (U infinity) and g (U infinity) to obtain kL and k_RIs the fitting constant.

wherein, U_∞For accompanying flow velocity, U is the flame limit expansion velocity, and

gamma exit is specific heat ratio of engine outlet, R is gas constant, T_exitIs the engine nozzle exit temperature.

Optionally, the variation estimation unit 502 is configured to perform the following operations to obtain an infrared radiation intensity function I varying with the height H to be estimated_new(H)：

It should be noted that, because the embodiments of the method of the present invention are based on the same concept, specific contents may be referred to the description of the embodiments of the method of the present invention, and details thereof are not repeated herein.

In addition, the low-altitude flame infrared radiation characteristic estimation device provided by the embodiment of the invention can be realized by software, or by hardware or a combination of hardware and software. From a hardware aspect, the device for estimating the infrared radiation characteristic of the low-altitude flame spraying according to the embodiment of the present invention may further include other hardware, such as a forwarding chip responsible for processing a message, in addition to the processor, the memory, the network interface, and the nonvolatile memory. Taking a software implementation as an example, as shown in fig. 5, as a logical apparatus, the apparatus is formed by reading a corresponding computer program instruction in a non-volatile memory into a memory by a CPU of a device in which the apparatus is located and running the computer program instruction.

In summary, the method and the device for estimating the low-altitude flame infrared radiation characteristic along with the height change provided by the embodiment of the invention establish a quick and effective estimation method for the low-altitude flame infrared radiation characteristic along with the height change based on the low-altitude flame flow field characteristic of the liquid rocket engine, and are mainly applied to a real-time/quasi-real-time generation system of a target infrared scene.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims

1. A low-altitude flame infrared radiation characteristic estimation method along with height change is characterized by comprising the following steps:

Is obtained according to simulationThe jet flame flow field characteristic parameters under the first height and the second height are calculated to obtain the jet flame flow field scale changing along with the height to be estimated, and an infrared radiation intensity function I changing along with the height H to be estimated is obtained according to the jet flame flow field scale changing along with the height to be estimated and the spectral absorption coefficient of each subarea_new(H)；

wherein, I_new(H₁) And I_new(H₂) Respectively is the first height H₁And a second height H₂Substitution into an infrared radiation intensity function I_new(H) The obtained infrared radiation intensity;

wherein, the calculating the jet flame flow field scale changing with the height to be estimated according to the jet flame flow field characteristic parameters under the first height and the second height obtained by simulation comprises the following steps:

wherein R is_newMaximum equivalent radius of the flame for the height H variation to be estimated, L_newFor equivalent length of the jet, N, as a function of the height H to be estimated_PRAnd N_{PR_template}For the expansion ratio of the height to be estimated and the expansion ratio of the base form, f (U)_∞template) And g (U)_∞template) For accompanying flow rate U of basic template_∞templateAs the accompanying flow velocity U_∞Substituting into the high-speed accompanying flow influence function f (U)_∞) And g (U)_∞) To obtain k_LAnd k_RIs the fitting constant.

2. The method of claim 1, wherein the high-speed companion stream impact function f (U)_∞) And g (U)_∞) Respectively as follows:

3. The method according to any one of claims 1-2, wherein the infrared radiation intensity function I varying with the height H to be estimated is obtained according to the jet flame flow field dimension varying with the height to be estimated and the spectral absorption coefficient of each subarea_new(H) The method comprises the following steps:

4. The method of claim 3, wherein the function is based on accompanying flow velocity U_∞Calculating the spectral absorption coefficient of each jet flow field partition by the changed jet flow field scale, wherein the calculation comprises the following steps:

5. Method according to claim 4, characterized in that said first height H is defined by a first height H₁And a second height H₂The flow field parameter calculation of the reburning zone of the height H to be estimated comprises the following steps:

(1) the temperature T of the reheat zone is calculated by the following formula_afterburning：

T_afterburning＝T_{1_max}+(T_{2_max}-T_{1_max})(H-H₁)/(H₂-H₁)；

P_afterburning＝0.5*(P₁(x″,0)+P₂(x″′,0))；

ρ_afterburning＝0.5*(ρ₁(x″,0)+ρ₂(x″′,0))；

U_afterburning＝0.5*(U₁(x″,0)+U₂(x″′,0))；

X_{CO2_afterburning}＝(X_{1_co2}(x″,0)-X_{1_co2}(x′,0))*α_afterburning/α₁+X_{1_co2}(x′,0)

Wherein, X_{1_co2}(x', 0) is a first height H₁At the (x', 0) position of the template of (A)₂Mass concentration of component X_{1_co2}(x', 0) is a first height H₁At the (x', 0) position CO in the template₂Mass concentration of the components, wherein (x', 0) is a first height H₁The mass concentration X of OH component in the template_{1_OH}Position where (x,0) is not less than 0, alpha_afterburningAccording to the velocity U of the reburning zone_afterburningAnd temperature T of the reheat zone_afterburningCalculated entrainment coefficient, α₁According to a first height H₁Speed U of the position corresponding to the maximum temperature value in the template₁(x', 0) and temperature T_{1_max}(ii) a calculated entrainment coefficient; calculating the reburning zone by the same methodMass concentration X of CO component(s)_{CO_afterburning}And H₂Mass concentration X of O component_{H2O_afterburning}。

6. A low-altitude flame infrared radiation characteristic estimation device along with height change is characterized by comprising the following components: the device comprises a simulation unit, a change estimation unit and an intensity correction unit;

the simulation unit obtains jet flame flow field characteristic parameters under a first height and a second height based on simulation, and calculates the infrared radiation intensity I of jet flames under the first height and the second height_template(H₁) And I_template(H₂)；

The intensity correction unit is used for correcting the jet flame infrared radiation intensity I according to the following formula:

wherein the change estimation unit is used for executing the following operations to calculate the flow field scale of the jet flame along with the height to be estimated:

7. The apparatus of claim 6, wherein the high-speed companion flow influence function f (U)_∞) And g (U)_∞) Respectively as follows:

8. The apparatus according to any one of claims 6 to 7, wherein the variation estimation unit is configured to perform the following operation to obtain the IR radiation intensity function I as a function of the height H to be estimated_new(H)：