Determination method for evaluating equivalent view field domain of high-temperature gas radiation environment

Abstract

The invention discloses a method for determining an equivalent view field domain for evaluating a high-temperature gas radiation environment. The method comprises the following steps: S1, acquiring a density rho database of a high-temperature flow field domain in which a star sensor works; s2, according to the density rho database of the high-temperature flow field domain, the high-temperature flow field domain is discretely divided into n layers, and n is larger than 1; the n layers are sequentially defined as the first layer, the second layer,... and the nth layer according to the direction from near to far away from the shading cylinder of the star sensor; s3, determining an incident angle of high-temperature flow field radiation visible light entering a shading cylinder based on a taper angle of the shading cylinder of the star sensor; s4, obtaining an incident angle of the ith layer of light according to the refraction angle of the ith layer of light; s5, when i is smaller than or equal to n-2, the incidence angle of the ith layer of light serves as the refraction angle of the (i + 1) th layer of light, i + 1 is made to be equal to i, and the step S4 is executed again; and when i is greater than n-2, obtaining incident angles of light of the first, second,... and nth layers, namely an equivalent view field domain. The method provided by the invention can improve the prediction precision of the star sensitive light environment, and has important guiding significance for the research and design of the star sensor.

Description

Technical Field

[0001] The present invention relates to a method for determining an equivalent field of view for evaluating a high-temperature gas radiation environment, and belongs to the technical field of equivalent field of view. Background Art

[0002] As the range of inertial navigation increases, its positioning error accumulates over time. Combining star sensors with inertial systems can significantly improve positioning accuracy. However, for near-space vehicles, the gas surrounding the vehicle is subjected to intense compression and a sharp increase in temperature, forming a complex polymorphic particle state. Under these high-temperature conditions, a large number of high-energy states of the polymorphic particles are successively excited, causing spontaneous emission from the surrounding flow field gas, creating background interference with starlight detection. Therefore, accurate prediction of the flow field light environment is a prerequisite for star sensor design.

[0003] Light environment prediction requires accurate solution of the thermochemical non-equilibrium flow field, and further calculation and solution of the radiation characteristics and spatial transmission of each gas component within the field of view. However, for three-dimensional complex flow fields, the temperature and component concentration of the gas within different fields of view of the star sensor will vary greatly. Therefore, the actual field of view detection range of the star sensor in the flow field must be determined first to obtain a more accurate light environment.

[0004] Current light environment calculations generally don't consider the effects of refraction from high-temperature gases. Instead, they use the physical angle of the star sensor's light shield as the field of view detection range, performing radiation calculations for the high-temperature gases within the detection range as input to the star sensor design. This method is suitable for low-density areas of the flow field, but when the star sensor's detection range is located in high-density areas of the flow field, where the density gradient is large and the scattering and refraction effects of the high-temperature gases are significant, the results obtained using this method can be subject to significant errors. Summary of the Invention

[0005] The present invention aims to overcome these shortcomings by providing a method for determining the equivalent field of view for assessing the high-temperature gas radiation environment. This method addresses the technical issue of large errors in calculating the high-temperature gas radiation environment using the physical angle of the star sensor light shield as the detection angle in high-temperature flow fields and high-density areas. This invention improves the accuracy of star sensor light environment prediction and has important guiding significance for the research and design of star sensors.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] A method for determining an equivalent field of view for evaluating a high-temperature gas radiation environment comprises:

[0008] S1 obtains the density ρ database of the high-temperature flow field in the working field of the star sensor;

[0009] S2 divides the high-temperature flow field into n layers according to the density ρ database of the high-temperature flow field, where n>1; the n layers are defined as the 1st, 2nd, ...nth layers in order from the direction of the star sensor shielding tube from near to far;

[0010] S3 determines the incident angle of the visible light radiated by the high-temperature flow field into the light-shielding tube based on the cone angle of the star sensor light-shielding tube, that is, the refraction angle of the first layer of light;

[0011] S4 obtains the incident angle of the i-th layer of light according to the refraction angle of the i-th layer of light; i=1, 2...n-1;

[0012] S5: when i≤n-2, the incident angle of the i-th layer of light is used as the refraction angle of the i+1-th layer of light, and i+1=i, and return to step S4;

[0013] When i>n-2, the incident angles of the 1st, 2nd…nth layers of light are obtained, that is, the equivalent field of view.

[0014] Furthermore, in step S1, the method for obtaining a density ρ database of the high-temperature flow field in the working field of the star sensor includes:

[0015] According to the flight state parameters, the high enthalpy flow is simulated by the three-dimensional Navier-Stokes equations considering the thermochemical non-equilibrium model, and the density ρ database of the high-temperature flow field where the star sensor operates is obtained.

[0016] Furthermore, the flight state parameters include altitude, Mach number, angle of attack, and rudder deflection angle;

[0017] When simulating high enthalpy flows using the three-dimensional Navier-Stokes equations considering the thermochemical nonequilibrium model, it is assumed that the translational and rotational temperature balance and the vibrational electronic temperature balance are balanced, and the thermodynamic nonequilibrium is described by a two-temperature model.

[0018] Furthermore, in step S2, the method of discretely dividing the high-temperature flow field into n layers according to the density ρ database of the high-temperature flow field includes:

[0019] The density variation between two adjacent gas layers does not exceed 10%.

[0020] Furthermore, in step S4, the method of obtaining the incident angle of the i-th layer of light according to the refraction angle of the i-th layer of light includes:

[0021]

[0022] Among them, k GD is the conversion coefficient from gas density to refractive index; β i is the refraction angle of the light in the i-th layer; β i+1 is the incident angle of the i-th layer of light, that is, the refraction angle of the i+1-th layer of light; ρi , ρ i+1 are the densities of the gas in the i-th layer and the i+1-th layer respectively.

[0023] Further,

[0024] Among them, k GD m is the conversion coefficient from gas density to refractive index 3 / kg, λ is the wavelength of visible light, unit is um.

[0025] Furthermore, the density ρ database is used to characterize the relationship between density ρ and position coordinates.

[0026] Furthermore, in the high-temperature flow field, the density of the i-th layer of gas ρ i According to the flow field density ρ data, it is obtained by using the distance reverse interpolation method.

[0027] Furthermore, after obtaining the refraction angles of the 1st, 2nd, ... nth layers of light, the coordinates of the incident point of the nth layer of light are obtained, and the equivalent field of view is calculated based on the coordinates of the incident point of the nth layer of light.

[0028] Furthermore, when calculating the equivalent field of view, The calculation deviation of the tail flow field is considered based on the angle θ2 of the vector, and the deviation is not less than 30%;

[0029] Among them, point b and point e are the coordinates of the incident point of the nth layer of light, point b and point e are symmetrical about the axis of the light-shielding tube, point A and point B are the coordinates of the incident point of visible light entering the light-shielding tube, point A and point B are symmetrical about the axis of the light-shielding tube, and point b, point e, point A, and point B are coplanar.

[0030] Compared with the prior art, the present invention has at least one of the following beneficial effects:

[0031] (1) The present invention creatively provides a method for determining the equivalent field of view for evaluating a high-temperature gas radiation environment. Based on flow field characteristics, the equivalent field of view is determined by taking into account the effect of gas on the propagation path of visible light, effectively improving the prediction accuracy of the star-sensitive light environment.

[0032] (2) The present invention provides a layering method and a calculation formula for the refractive index of each layer, which has high reliability and strong applicability;

[0033] (3) The present invention can effectively improve the calculation efficiency of the equivalent field of view in a high-temperature gas radiation environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a schematic diagram of the field of view angle of the star sensor;

[0035] Figure 2Schematic diagram of the effect of high-temperature gas refraction on light transmission;

[0036] Figure 3 Schematic diagram of the equivalent field of view calculation principle of the present invention. DETAILED DESCRIPTION

[0037] The following detailed description of the present invention will make the features and advantages of the present invention more clear and explicit.

[0038] The word "exemplary" is used exclusively herein to mean "serving as an example, example, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. Although various aspects of the embodiments are shown in the drawings, the drawings are not necessarily drawn to scale unless otherwise indicated.

[0039] like Figure 1 The present invention defines two angles θ1 based on the geometric shape of the star sensor's light-shielding tube. θ1 is the cone angle of the light-shielding tube, and the area within this angle is the detection range currently used for the star sensor; θ2 is the equivalent field of view determined by the present invention for evaluating the high-temperature gas radiation environment. This angle is determined based on the flow field characteristics, taking into account the influence of gas on the propagation path of visible light.

[0040] like Figure 2 and Figure 3 The present invention provides a method for determining an equivalent field of view for evaluating a high-temperature gas radiation environment, comprising the following steps:

[0041] (1) Based on the flight state parameters (altitude, Mach number, angle of attack, and rudder deflection angle), the high enthalpy flow is simulated using the three-dimensional Navier-Stokes equations taking into account the thermochemical non-equilibrium model. The thermodynamic non-equilibrium effect is described by a two-temperature model. The flow field density ρ data of the star sensor working field is obtained using the CFD method (computational fluid dynamics method);

[0042] (2) Based on the flow field density data in step (1), starting from the light shielding tube outlet, the high temperature flow field is discretely divided into n thin layers, requiring that the density change between two adjacent layers of gas does not exceed 10%, and the density of each layer ρ i Obtained by reverse interpolation of distance;

[0043] (3) According to the geometrical parameters of the star sensor light shielding tube, The vector is used as the incident angle of the visible light radiated by the high temperature flow field into the star sensor shielding tube, from Figure 1 Starting from points A and B, reversely solve and calculate the transmission path of visible light to obtain the incident point b of the outermost light;

[0044] The specific method is: According to Snell's law and Lorenz's law, the high-temperature gas density refraction effect can be expressed as:

[0045]

[0046] Where: k GD m is the conversion coefficient from gas density to refractive index 3 / kg; λ is the wavelength of visible light, unit is um; β1 is the refraction angle of light; β2 is the incident angle of light; ρ1 and ρ2 are the densities of the two layers of gas respectively.

[0047]

[0048] (4) The equivalent field of view angle in the calculation of the star sensor light environment is The calculation deviation of the tail flow field is considered based on the angle θ2 of the vector, and the deviation is not less than 30%.

[0049] Specifically, the refraction angle of the light in the first layer is the cone angle θ1 of the light-shielding tube. According to the refraction angle of the light in the first layer, the incident angle of the light in the first layer can be obtained, that is, the refraction angle of the light in the second layer. The calculation is carried out in sequence to finally obtain the refraction angle of the light in the nth layer, and the coordinates of the incident point of the outermost layer of light are obtained for the calculation of the equivalent field of view.

[0050] In summary, the present invention provides a method for determining the equivalent field of view angle for evaluating high-temperature gas radiation environments. By accounting for the influence of high-temperature gas on the transmission characteristics of visible light, a more accurate calculation of the effective detection range of a starlight sensor in a real-world flow field environment is obtained. Compared with experimental results, using the currently widely used θ1 as the light environment calculation domain results in an underestimation and fails to reflect the changing patterns of the light environment. However, using the equivalent field of view angle θ2 proposed in this invention to calculate the high-temperature gas radiation environment within this detection range produces results that better reflect the patterns of the light radiation environment.

[0051] The present invention has been described in detail above with reference to specific embodiments and exemplary examples. However, these descriptions should not be construed as limiting the present invention. Those skilled in the art will appreciate that various equivalent substitutions, modifications, or improvements may be made to the technical solutions and implementations of the present invention without departing from the spirit and scope of the present invention, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be determined by the appended claims.

[0052] The contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.

Claims

1. A method for determining an equivalent field of view for evaluating a high-temperature gas radiation environment, characterized in that: include: S1 obtains the flow field density ρ data of the star sensor working field; S2 divides the high-temperature flow field into n layers according to the flow field density ρ data, where n>1; the n layers are defined as the 1st, 2nd, ...nth layers in order from the direction of the star sensor light shielding tube from near to far; S3 determines the incident angle of the visible light radiated by the flow field into the light shielding tube based on the cone angle of the star sensor light shielding tube, that is, the refraction angle of the first layer of light; S4 obtains the incident angle of the i-th layer of light according to the refraction angle of the i-th layer of light; i=1, 2...n-1; S5: when i≤n-2, the incident angle of the i-th layer of light is used as the refraction angle of the i+1-th layer of light, and i+1=i, and return to step S4; When i>n-2, the refraction angles of the 1st, 2nd, ...nth layers of light are obtained and used to calculate the equivalent field of view.

2. The method for determining the equivalent field of view for evaluating a high-temperature gas radiation environment according to claim 1, characterized in that: In step S1, the method for obtaining the flow field density ρ data of the working field of the star sensor includes: According to the flight state parameters, the high enthalpy flow is simulated by the three-dimensional Navier-Stokes equation considering the thermochemical non-equilibrium model, and the flow field density ρ data of the star sensor working field is obtained.

3. The method for determining the equivalent field of view for evaluating a high-temperature gas radiation environment according to claim 2, characterized in that: Flight status parameters include altitude, Mach number, angle of attack and rudder deflection angle; When simulating high enthalpy flows using the three-dimensional Navier-Stokes equations considering the thermochemical nonequilibrium model, the thermodynamic nonequilibrium is described by a two-temperature model. The flow field density ρ data of the star sensor working field is obtained using the CFD method.

4. The method for determining the equivalent field of view for evaluating a high-temperature gas radiation environment according to claim 1, characterized in that: In step S2, the method of discretely dividing the high-temperature flow field into n layers according to the flow field density ρ data includes: The density variation between two adjacent gas layers does not exceed 10%.

5. The method for determining the equivalent field of view for evaluating a high-temperature gas radiation environment according to claim 1, characterized in that: In step S4, the method for obtaining the incident angle of the i-th layer of light according to the refraction angle of the i-th layer of light includes: Among them, k GD is the conversion coefficient from gas density to refractive index; β i is the refraction angle of the light in the i-th layer; β i+1 is the incident angle of the i-th layer of light, that is, the refraction angle of the i+1-th layer of light; ρ i , ρ i+1 are the densities of the gas in the i-th layer and the i+1-th layer respectively.

6. The method for determining the equivalent field of view for evaluating a high-temperature gas radiation environment according to claim 5, characterized in that: Among them, k GD m is the conversion coefficient from gas density to refractive index 3 / kg, λ is the wavelength of visible light, unit is um.

7. The method for determining the equivalent field of view for evaluating a high-temperature gas radiation environment according to claim 5, characterized in that: The flow field density ρ data is used to characterize the relationship between density ρ and position coordinates.

8. The method for determining the equivalent field of view for evaluating a high-temperature gas radiation environment according to claim 7, characterized in that: In the high-temperature flow field, the density of the i-th layer of gas ρ i According to the flow field density ρ data, it is obtained by using the distance reverse interpolation method.

9. The method for determining the equivalent field of view for evaluating a high-temperature gas radiation environment according to claim 1, characterized in that: After obtaining the refraction angles of the 1st, 2nd, ... nth layers of light, the coordinates of the incident point of the nth layer of light are obtained, and the equivalent field of view is calculated based on the coordinates of the incident point of the nth layer of light.

10. The method for determining the equivalent field of view for evaluating a high-temperature gas radiation environment according to claim 1, characterized in that: When calculating the equivalent field of view, The calculation deviation of the tail flow field is considered based on the angle θ2 of the vector, and the deviation is not less than 30%; Among them, point b and point e are the coordinates of the incident point of the nth layer of light, point b and point e are symmetrical about the axis of the light-shielding tube, point A and point B are the coordinates of the incident point of visible light entering the light-shielding tube, point A and point B are symmetrical about the axis of the light-shielding tube, and point b, point e, point A, and point B are coplanar.

Images