CN111723537A - Method, device, equipment and storage medium for measuring molecular flow thermal adaptive coefficient - Google Patents

Method, device, equipment and storage medium for measuring molecular flow thermal adaptive coefficient Download PDF

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CN111723537A
CN111723537A CN202010558870.6A CN202010558870A CN111723537A CN 111723537 A CN111723537 A CN 111723537A CN 202010558870 A CN202010558870 A CN 202010558870A CN 111723537 A CN111723537 A CN 111723537A
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incident angle
measuring
preset
thrust
molecular flow
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CN111723537B (en
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姜利祥
李涛
商圣飞
焦子龙
郑慧奇
唐振宇
向树红
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Beijing Institute of Spacecraft Environment Engineering
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    • G06—COMPUTING; CALCULATING OR COUNTING
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    • G06F30/00—Computer-aided design [CAD]
    • G06F30/20—Design optimisation, verification or simulation
    • G06F30/28—Design optimisation, verification or simulation using fluid dynamics, e.g. using Navier-Stokes equations or computational fluid dynamics [CFD]
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/20—Design optimisation, verification or simulation
    • G06F30/25—Design optimisation, verification or simulation using particle-based methods
    • G—PHYSICS
    • G16—INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR SPECIFIC APPLICATION FIELDS
    • G16C—COMPUTATIONAL CHEMISTRY; CHEMOINFORMATICS; COMPUTATIONAL MATERIALS SCIENCE
    • G16C10/00—Computational theoretical chemistry, i.e. ICT specially adapted for theoretical aspects of quantum chemistry, molecular mechanics, molecular dynamics or the like
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2113/00—Details relating to the application field
    • G06F2113/08—Fluids
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2119/00—Details relating to the type or aim of the analysis or the optimisation
    • G06F2119/08—Thermal analysis or thermal optimisation
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2119/00—Details relating to the type or aim of the analysis or the optimisation
    • G06F2119/14—Force analysis or force optimisation, e.g. static or dynamic forces
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T90/00—Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation

Abstract

The application discloses a molecular flow thermal adaptation coefficient determination method, a device, equipment and a storage medium, firstly a pressure value of incoming flow atmosphere at a preset incident angle to a measurement plane is measured based on a three-wire torsion pendulum micro-thrust measurement system, secondly a molecular flow thermal adaptation coefficient corresponding to the preset incident angle is calculated by utilizing a Maxwell reflection model based on the pressure value, then a reference curve between the preset incident angle and the thermal adaptation coefficient is constructed, and in the flight process of an aircraft, the molecular flow thermal adaptation coefficient corresponding to the incident angle is determined based on the incident angle formed by the incoming flow atmosphere relative to a structural surface element of the aircraft and the reference curve. The aerodynamic force calculation accuracy of the aircraft with the complex appearance is effectively improved.

Description

Method, device, equipment and storage medium for measuring molecular flow thermal adaptive coefficient
Technical Field
The invention relates to the technical field of aerodynamic force and heat of ultra-low rail rarefied gas and aircraft action, in particular to a method, a device, equipment and a storage medium for measuring a molecular flow thermal adaptation coefficient.
Background
Lean gas dynamics have an important background of application in the aerospace field. The atmosphere in the LEO orbit and the adjacent space is very thin and cannot support the normal life activities of human beings, but the atmosphere can cause great influence on the spacecraft flying at high speed in the orbit. The impact of the high-speed moving atoms on the spacecraft can increase the aerodynamic resistance of the spacecraft, so that the orbit of the aircraft descends and even crashes, and the service life of the aircraft is shortened.
Due to the rarefaction effect, the conventional continuous medium assumption is not established, so that the N-S equation for processing continuous flow is not applicable any more, and the aerodynamic force and the thermal effect of rarefaction gas on the wall surface cannot be calculated by using the N-S equation. Early scholars used drag coefficients to calculate the aerodynamic drag experienced by an aircraft. However, the drag coefficient is a macroscopic parameter, and at present, the reference value of the drag coefficient only exists for regular standard shapes such as planes, spheres, cylinders and the like, and the drag coefficient obviously cannot meet the requirement for complex aircraft shapes.
The direct monte carlo (DSMC) method of calculating lean gas was later proposed to describe the motion of lean gas at the molecular level, making it possible to calculate lean gas flows of complex shape. The reflection model of the rarefied gas and the wall action comprises a specular reflection model, a diffuse reflection model (DRIA) with incomplete energy adaptation, an object plane reflection model (CLL), a Maxwell wall reflection model (Maxwell) and the like. The mirror reflection means that the particles are directly reflected out of the mirror without energy exchange with the wall surface. Diffuse reflection means that incident molecules are in complete thermal adaptation with the surface of the material, and the probability of the direction of the molecular velocity is the same in all directions. The incomplete energy adaptation diffuse reflection model (DRIA) means that the random distribution probability of the velocity direction of the reflecting molecules is the same, but the thermal adaptation degree of the reflecting molecules to the surface of a material is variable. The object plane reflection model (CLL) provides distribution functions for normal and tangential components of the reflected molecule velocity, and the main parameters of the distribution functions are normal energy adaptive coefficients and tangential energy adaptive coefficients. The Maxwell wall reflection model (Maxwell) is the superposition of specular reflection and diffuse reflection, and assumes that alpha particles adapt to the wall temperature and diffuse reflection, and 1-alpha particles are specular reflection.
It is easy to see that specular reflection and diffuse reflection are extreme reflection models and do not describe well the action reflection behavior of molecules and walls. The object plane reflection model (CLL) is physically more realistic, but it contains two adaptive parameters, namely tangential and normal, and the two parameters have certain coupling, so that the parameters are difficult to measure, and therefore, the object plane reflection model (CLL) is difficult to be practically applied. The Maxwell wall reflection model (Maxwell) is the most widely applied model and has a better effect at present, but the parameter α in the Maxwell wall reflection model (Maxwell) becomes a key parameter which restricts the calculation accuracy of the Maxwell wall reflection model.
The adaptive coefficient in the Maxwell wall reflection model (Maxwell) is influenced by various aspects such as material characteristics, roughness, incoming flow gas properties, speed and the like, and no data reference is available. Researchers either take empirical parameters such as 0.5, 0.9 to do the research, or directly take two extreme conditions, directly take 0 and 1 to give an envelope. It can be seen that, due to the limitation of the parameter α, it is difficult to measure the aerodynamic resistance of a Maxwell wall reflection model (Maxwell) when flowing a lean gas with a complicated shape by using a direct monte carlo simulation method.
Disclosure of Invention
In view of the above-mentioned drawbacks and deficiencies of the prior art, it is desirable to provide a method, an apparatus, a device and a storage medium for measuring a thermal adaptive coefficient of a molecular stream. By constructing a curve between the incident angle and the thermal adaptation coefficient of the molecular flow, the corresponding thermal adaptation coefficient of the aircraft subjected to the incoming flow of the atmosphere is effectively obtained.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the present invention provides a method for measuring a thermal adaptive coefficient of a molecular stream, comprising:
measuring the pressure value of the atmospheric incoming flow at a preset incident angle to a measuring plane based on a three-line torsional pendulum micro-thrust measuring system;
calculating a molecular flow thermal adaptation coefficient corresponding to the preset incident angle by using a Maxwell reflection model based on the pressure value;
constructing a reference curve between the preset incident angle and the thermal adaptive coefficient;
and during the flight of the aircraft, determining a molecular flow thermal adaptation coefficient corresponding to the incident angle based on the incident angle formed by the incoming atmospheric flow relative to the structural surface element of the aircraft and the reference curve.
In one embodiment, determining a molecular flow thermal accommodation coefficient corresponding to an incident angle of an incoming atmospheric flow relative to a structural bin of the aircraft based on the reference curve and the incident angle includes:
obtaining a plurality of structural bins into which an exterior of the aircraft is divided,
determining an angle of incidence of the incoming flow of atmosphere with respect to each of the structural bins;
and searching a molecular flow thermal adaptation coefficient corresponding to the incident angle in the reference curve by using the incident angle, wherein the first axial direction of the reference curve represents the angle value of the incident angle, and the second axial direction represents the molecular flow thermal adaptation coefficient.
In one embodiment, the step of calculating a molecular flow thermal adaptation coefficient corresponding to the preset incident angle by using a maxwell reflection model based on the pressure value comprises:
obtaining a pressure statistical calculation formula of the rarefied gas to the wall surface based on a Maxwell reflection model;
and calculating the molecular flow thermal adaptation coefficient corresponding to the preset incident angle based on the pressure value and the pressure statistical calculation formula.
In one embodiment, the step of calculating a pressure value on the measurement plane based on the aerodynamic force of the incoming atmosphere comprises:
the step of measuring the pressure value of the incoming flow atmosphere at a preset incidence angle to a measuring plane based on the three-wire torsional pendulum micro-thrust measuring system comprises the following steps:
measuring aerodynamic force of incoming flow atmosphere at a preset incident angle to a measuring plane by using a three-line torsional pendulum micro-thrust measuring system;
calculating a pressure value on the measurement plane based on the aerodynamic force of the measurement plane.
In one embodiment, the three-wire torsional pendulum micro-thrust measuring system comprises a thrust measuring plate, a thrust transmission rod, a laser and a reflecting mirror;
the method for measuring the aerodynamic force of the incoming flow atmosphere at the preset incidence angle on the measuring plane by using the three-line torsional pendulum micro-thrust measuring system comprises the following steps:
emitting inflow atmosphere onto the measuring plane along a preset angle, pushing the thrust measuring plate to rotate so as to drive the reflecting mirror to rotate, and enabling the position of reflected light of the laser to move due to the rotation of the reflecting mirror;
and estimating the aerodynamic force provided by the incoming air to the thrust plate based on the displacement of the reflected light.
In one embodiment, the step of measuring the aerodynamic force of the incoming flow atmosphere at the preset incidence angle to the measuring plane by using the three-line torsional pendulum micro-thrust measuring system further comprises:
and adjusting the angle between the thrust measuring plate and the thrust transmission rod to measure aerodynamic force under different preset incidence angles.
The invention provides a device for measuring the molecular flow thermal adaptive coefficient, which is characterized by comprising a pressure measuring module of a measuring plane, a pressure calculation expression obtaining module, a reference curve constructing module, a processing module and a thermal adaptive coefficient obtaining module;
the pressure measurement module of the measurement plane is used for measuring the pressure value of the incoming flow atmosphere at a preset incident angle to the measurement plane based on the three-wire torsional pendulum micro-thrust measurement system;
the molecular flow thermal adaptation coefficient calculation module is used for calculating a molecular flow thermal adaptation coefficient corresponding to the preset incident angle by utilizing a Maxwell reflection model based on the pressure value;
the reference curve building module is used for building a reference curve between the preset incidence angle and the thermal adaptive coefficient;
and the thermal adaptation coefficient acquisition module is used for determining a molecular flow thermal adaptation coefficient corresponding to an incident angle based on the incident angle formed by the incoming flow of the atmosphere relative to the structural surface element of the aircraft and the reference curve in the flying process of the aircraft.
In one embodiment, the thermal adaptive coefficient obtaining module includes:
a structural bin acquisition subunit for acquiring a plurality of structural bins into which the exterior of the aircraft is divided,
an incident angle determining subunit, configured to determine an incident angle formed by the incoming flow of the atmosphere with respect to each of the structural bins;
and the searching subunit is configured to search, in the reference curve, a molecular flow thermal adaptation coefficient corresponding to the incident angle by using the incident angle, where a first axial direction of the reference curve represents an angle value of the incident angle, and a second axial direction of the reference curve represents the molecular flow thermal adaptation coefficient.
In one embodiment, the molecular flow thermal adaptation coefficient calculation module comprises a pressure statistical calculation formula obtaining unit and a molecular flow thermal adaptation coefficient calculation unit;
the pressure statistical calculation formula obtaining unit is used for obtaining a pressure statistical calculation formula of the rarefied gas to the wall surface based on the Maxwell reflection model;
and the pressure calculation expression obtaining unit is used for calculating the molecular flow thermal adaptation coefficient corresponding to the preset incidence angle based on the pressure value and the pressure statistical calculation formula.
In one embodiment, the pressure measurement module of the measurement plane comprises an aerodynamic force measurement unit of the measurement plane and a pressure calculation unit of the measurement plane;
the aerodynamic force measuring unit is used for measuring the aerodynamic force of the incoming flow atmosphere at a preset incident angle to the measuring plane by applying a three-line torsional pendulum micro-thrust measuring system;
a pressure calculation unit of the measurement plane for calculating a pressure value on the measurement plane based on the aerodynamic force of the measurement plane.
In a third aspect, the invention provides a computer device comprising a memory and a processor, the memory storing a computer program, characterized in that the processor implements the method described above when executing the computer program.
In a fourth aspect, the invention provides a computer-readable storage medium, on which a computer program is stored, which is characterized in that the computer program realizes the above-mentioned method when being executed by a processor.
Compared with the prior art, the invention has the beneficial effects that:
according to the technical scheme, the pressure value of incoming flow atmosphere at a preset incidence angle to a measuring plane is measured based on a three-wire torsion pendulum micro-thrust measuring system, the molecular flow thermal adaptation coefficient corresponding to the preset incidence angle is calculated by utilizing a Maxwell reflection model based on the pressure value, a reference curve between the preset incidence angle and the thermal adaptation coefficient is established, and the molecular flow thermal adaptation coefficient corresponding to the incidence angle is determined based on the incidence angle formed by the atmospheric incoming flow relative to a structural surface element of an aircraft and the reference curve in the flight process of the aircraft. According to the method and the device, the molecular flow thermal adaptation coefficient of the incoming air flow to the aircraft is determined through the pre-constructed reference curve, the aerodynamic resistance of the incoming air flow to the aircraft is calculated, and the calculation efficiency of the aerodynamic resistance of the incoming air flow to the aircraft is effectively improved. In the process of calculating the molecular flow thermal adaptation coefficient corresponding to the set incident angle, the atmospheric resistance of the ultra-low rail is very small, how to measure the micro thrust is a technical difficulty, and the three-wire torsion pendulum micro thrust measuring system can measure the micro thrust very accurately, so that the technical difficulty is well solved.
Drawings
Other features, objects and advantages of the present application will become more apparent upon reading of the following detailed description of non-limiting embodiments thereof, made with reference to the accompanying drawings in which:
FIG. 1 is a schematic flow chart of a method for measuring the adaptive coefficient of molecular flow according to an embodiment of the present invention;
FIG. 2 is a schematic flow chart illustrating the steps of measuring the pressure value on the measurement plane according to the embodiment of the present invention;
FIG. 3 is a schematic flow chart illustrating a step of calculating a thermal adaptive coefficient of a molecular flow according to a predetermined incident angle according to an embodiment of the present invention;
FIG. 4 is a schematic flow chart of the step of obtaining the adaptive coefficient of molecular flow at different incident angles according to the embodiment of the present invention;
FIG. 5 is a block diagram illustrating an exemplary configuration of an apparatus for determining a thermal adaptive coefficient of a molecular flow according to an embodiment of the present invention;
FIG. 6 is a schematic block diagram of a computer device suitable for implementing embodiments of the present invention;
fig. 7 is a schematic structural diagram of a three-wire torsional pendulum micro-thrust measurement system according to an embodiment of the present invention.
In the figure: the method comprises the following steps of 1-thrust measuring plate, 2-thrust transfer rod, 3-laser, 4-reflector and 5-scale.
Detailed Description
The present application will be described in further detail with reference to the following drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the relevant invention and not restrictive of the invention. It should be noted that, for convenience of description, only the portions related to the present invention are shown in the drawings.
It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present application will be described in detail below with reference to the embodiments with reference to the attached drawings.
As mentioned in the background art, the Maxwell wall reflection model (Maxwell) is the most widely used model and has a relatively good effect at present, but the parameter α in the Maxwell wall reflection model (Maxwell) becomes a key parameter that restricts the calculation accuracy. The adaptive coefficient in the Maxwell wall reflection model (Maxwell) is influenced by various aspects such as material characteristics, roughness, incoming flow gas properties, speed and the like, and no data reference is available. Researchers either take empirical parameters such as 0.5, 0.9 to do the research, or directly take two extreme conditions, directly take 0 and 1 to give an envelope. It can be seen that, due to the limitation of the parameter α, the determination of the aerodynamic resistance of the Maxwell wall reflection model (Maxwell) in the flow of the lean gas with a complicated shape by using a direct monte carlo simulation method is difficult and has low accuracy.
Therefore, how to provide a method for obtaining a proper thermal adaptation coefficient so that the accuracy of the calculation of the resistance of the ultra-low rail aircraft with a complex appearance to the thin gas by adopting the direct Monte Carlo simulation method is higher becomes an improvement direction of the application.
The basic concept of the invention is to construct a reference curve of angle-thermal adaptive coefficients based on a pressure value measured by a three-line torsional pendulum micro-thrust measurement system and a pressure calculation expression obtained based on a Maxwell reflection model, and obtain the thermal adaptive coefficients of different angles from the reference curves of the angle-thermal adaptive coefficients under different incidence angles. Based on the above concept, the invention provides a method, a device, equipment and a storage medium for measuring the thermal adaptive coefficient of a molecular flow, in particular to a technical scheme for measuring the thermal adaptive coefficient parameter in a Maxwell wall reflection model (Maxwell) in a Monte Carlo (MC) or direct Monte Carlo (DSMC) calculation method for the effect of a molecular layer on a thin gas and a wall surface.
Referring to fig. 1, fig. 1 shows a schematic flow chart of a method for determining a thermal adaptive coefficient of a molecular flow provided in an embodiment of the present application. As shown in fig. 1, the method includes:
step 10, measuring a pressure value of an incoming flow of atmosphere at a preset incident angle to a measuring plane based on a three-line torsional pendulum micro-thrust measuring system;
in step 20, calculating a molecular flow thermal adaptation coefficient corresponding to the preset incident angle by using a Maxwell reflection model based on the pressure value;
in step 30, constructing a reference curve between the preset incident angle and the thermal adaptive coefficient;
in step 40, during the flight of the aircraft, based on the incident angle formed by the incoming atmospheric flow relative to the structural surface element of the aircraft and the reference curve, determining a molecular flow thermal adaptation coefficient corresponding to the incident angle.
In the above steps, it is necessary to know that the measuring plane is disposed in a laboratory, and the inflow atmosphere is generated by a high-speed jet device, such as a rocket motor, a nozzle, and the like. The preset incident angle refers to an included angle between the incoming flow atmosphere and the normal of the measuring plane.
The macro-aerodynamic integral equation is directed to a Maxwell wall reflection model (Maxwell), which is a superposition of specular reflection and diffuse reflection, and assumes that alpha particles are diffuse reflection while adapting to the wall temperature, and 1-alpha particles are specular reflection.
A measured pressure value is obtained firstly based on a laboratory, then an expression of the pressure in a wall reflection model (Maxwell) is obtained through a macroscopic aerodynamic integral equation, and a parameter alpha, namely a thermal adaptive coefficient, is obtained according to the equivalent relation of the pressure value and the expression.
Referring to fig. 2, fig. 2 shows a schematic flow diagram of step 10, said step 10 comprising:
step 101, measuring aerodynamic force of incoming flow atmosphere at a preset incident angle to a measuring plane by using a three-line torsional pendulum micro-thrust measuring system;
and 102, calculating a pressure value on the measuring plane based on the aerodynamic force of the measuring plane.
Fig. 6 shows a specific structure of the three-line torsional pendulum micro-thrust measurement system. As shown in fig. 6, the three-wire torsional pendulum micro-thrust measuring system comprises a thrust measuring plate 1, a thrust transmission rod 2, a laser 3 and a reflecting mirror 4. The measuring plane constitutes on three-way torsional pendulum small thrust measurement system's thrust survey board 1, and thrust survey board 1 is used for receiving the aerodynamic force of coming the flow, and the thrust dowel steel is used for connecting 1 and the torsional pendulum main part with certain installation angle, laser instrument 3 is used for providing the incident light, and speculum 4 is used for reflecting the incident light.
The following describes a process of measuring aerodynamic force of an incoming flow atmosphere at a preset incident angle on a measurement plane at a preset speed, with reference to a specific structure of a three-line torsional pendulum micro-thrust measurement system.
Emitting inflow atmosphere onto the thrust measuring plate 1 along a preset angle, pushing the thrust measuring plate 1 to rotate so as to drive the reflecting mirror 4 to rotate through the thrust transmission rod 2, wherein the reflecting mirror rotates to enable the position of reflected light of the laser 3 to move;
the magnitude of aerodynamic force provided by the incoming air to the thrust plate 1 is estimated based on the displacement amount of the reflected light. The displacement of the reflected light can be measured by the scale 5, the reflected light is reflected to the scale 5, and the displacement is obtained by the reading change of the scale 5.
Specifically, firstly, the inflow atmosphere at a preset speed is measured by a three-wire torsional pendulum micro-thrust measurement system, and aerodynamic force F borne by a measurement plane is measured when the inflow atmosphere is sprayed to the measurement plane at a preset incidence angle theta.
Obtaining the pressure p of the measuring plane on the thrust measuring plate according to the formula (1):
Figure BDA0002545541640000081
wherein A is the area of the thrust plate.
The preset incidence angle theta is set, and the area A of the thrust measuring plate is measured in advance, so that the pressure p of the atmosphere flowing at the preset speed to the measuring plane can be obtained.
Preferably, the step of measuring the aerodynamic force of the incoming flow atmosphere at the preset incident angle to the measuring plane by using the three-line torsional pendulum micro-thrust measuring system further comprises: and adjusting an angle beta between the thrust measuring plate and the thrust transmission rod to measure aerodynamic force under different preset incidence angles.
Referring to fig. 3, fig. 3 shows a schematic flow chart of step 20. The step 20 comprises:
step 201, obtaining a pressure statistical calculation formula of the rarefied gas to the wall surface based on a Maxwell reflection model;
and 202, calculating a molecular flow thermal adaptation coefficient corresponding to the preset incident angle based on the pressure value and the pressure statistical calculation formula.
In the above steps, pressure statistical calculation formulas of pressures generated by direct collision gas, diffuse reflection gas and specular reflection gas to the wall surface are respectively deduced based on the Maxwell reflection model; and obtaining the pressure calculation expression based on a pressure statistical calculation formula of the pressure generated by the direct collision gas, the diffuse reflection gas and the specular reflection gas on the wall surface.
For the high-speed incoming flow of the thin atmosphere, because the incoming flow is very thin, the gas does not generate a viscous effect under the condition of continuous flow, and a Monte Carlo (MC) method is often adopted for simulating the gas, namely, the gas is regarded as mutually independent small particles. In addition, the gas temperature is far higher than the condensation temperature of the gas, and the cold adsorption effect on the wall surface can not be generated. Therefore, in the current theoretical process, the statistical calculation formula of the pressure of the direct collision of the lean gas against the wall surface is as follows:
Figure BDA0002545541640000091
wherein U, v and w respectively correspond to the component velocities in the three directions of X, Y, Z, ρ is the density of the incoming flow gas, U is the normal velocity,
Figure BDA0002545541640000092
α is the adaptation coefficient in Maxwell model (Maxwell) for molecular velocity ratio, with values between 0-1, erf () is the error function, and R is the gas constant.
erf () is an error function whose expression is:
Figure BDA0002545541640000093
according to the definition of Maxwell model, α particles are diffusely reflected according to the wall temperature, and 1- α particles are specularly reflected. The speed of the diffuse reflection part due to the reflection of the incoming flow particles is Maxwell distribution, the speed is the thermal motion speed, and the size of the diffuse reflection part is adapted to the wall temperature TwThen its average velocity vrCan be expressed as:
Figure BDA0002545541640000101
where v is the component velocity in any direction.
Wherein the distribution function f (v) is:
Figure BDA0002545541640000102
the diffuse reflection pressure p can be obtained according to the pressure integral in the same wayre1Comprises the following steps:
Figure BDA0002545541640000103
where T is the local gas molecular temperature, the specularly reflected fraction pre2The positive pressure expression is the same as the incoming flow, since its incoming flow is opposite in the normal direction to the incoming flow.
The pressure p of the resulting plate is:
p＝pin+αpre1+(1-α)pre2(7)
from the formula (1) to the formula (7), it can be obtained
Figure BDA0002545541640000104
Combining equation (8) and equation (1) in step 20, we can obtain:
Figure BDA0002545541640000105
the adaptive coefficient α can be obtained from the formula (9).
The aerodynamic force of the incoming flow atmosphere at each preset incidence angle to the measuring plane is measured by the three-line torsional pendulum micro-thrust measuring system, different relation curves of the preset angle and the thermal adaptation coefficient can be established, and the thermal adaptation coefficients corresponding to different incidence angles can be measured.
Specifically, the step 30 of constructing a reference curve between the preset incident angle and the thermal adaptation coefficient includes:
measuring aerodynamic force of incoming flow atmosphere at a preset incident angle on a thrust measuring plate based on a three-line torsional pendulum micro-thrust measuring system;
calculating a pressure value on the thrust plate based on the aerodynamic force of the measurement plane;
calculating a molecular flow thermal adaptation coefficient corresponding to the preset incident angle by using a Maxwell reflection model based on the pressure value;
changing the preset incidence angle, and returning to the step of measuring the aerodynamic force of the incoming flow atmosphere at the preset incidence angle on the thrust measuring plate based on the three-line torsional pendulum micro thrust measuring system;
and obtaining a molecular flow thermal adaptation coefficient corresponding to each preset incidence angle.
Referring to fig. 4, fig. 4 shows a schematic flow chart of step 40. Determining a molecular flow thermal accommodation coefficient corresponding to an incident angle of an incoming atmospheric flow relative to a structural surface element of the aircraft based on the reference curve and the incident angle, includes:
step 401, obtaining a plurality of structural bins divided by the exterior of the aircraft,
step 402, determining an incident angle formed by the incoming atmospheric air flow relative to each structural bin;
and step 403, searching a molecular flow thermal adaptation coefficient corresponding to the incident angle in the reference curve by using the incident angle, wherein a first axis direction of the reference curve represents an angle value of the incident angle, and a second axis direction represents the molecular flow thermal adaptation coefficient.
It should be noted that the first axis direction and the second axis direction refer to coordinate axis directions in which the curves are located, and may specifically include, but are not limited to, an X axis and a Y axis.
In the application link, in the flying process of the aircraft, the included angle between the front part of the aircraft and the incoming flow of the atmosphere can be determined according to the shape of the aircraft. For example, the nose of an aircraft is bullet-shaped, the bullet surface of which may be divided into a plurality of structural bins, also referred to as grid bins, and the angle of incidence of the incoming atmospheric air flow with respect to each structural bin is referred to as the angle of incidence. Through a plurality of structural surface elements of the outer surface of the determined aircraft, the included angle corresponding to each structural surface element is respectively determined, and the corresponding incident angles of the aircrafts with different shapes can be obtained. The pre-constructed curve is then used to determine the thermal adaptation coefficient corresponding to the angle of incidence.
Assuming that the incidence angle corresponding to the vertex of the aircraft is 0 DEG and the incidence angle at a certain point on the side surface is 80 deg, the thermal adaptation coefficient corresponding to 0 deg and the thermal adaptation coefficient corresponding to 80 deg can be obtained according to the pre-established reference curve of the preset incidence angle and the thermal adaptation coefficient.
The thermal adaptation coefficient values of different angles can be obtained through the method, so that the thermal adaptation coefficients of different positions of the aircraft blown by the incoming flow are known, the aerodynamic force of the aircraft at different positions can be calculated, and then the aerodynamic force on the small surface elements corresponding to all the positions is added to be the aerodynamic force of the aircraft.
Referring to fig. 5, fig. 5 shows a device for determining a thermal adaptive coefficient of a molecular flow according to an embodiment of the present application. The device comprises a pressure measuring module 501 for measuring a plane, a molecular flow thermal adaptation coefficient calculating module 502, a reference curve constructing module 503 and a thermal adaptation coefficient obtaining module 504;
the pressure measurement module 501 of the measurement plane is used for measuring the pressure value of the incoming flow atmosphere at a preset incident angle to the measurement plane based on the three-wire torsional pendulum micro-thrust measurement system;
a molecular flow thermal adaptation coefficient calculation module 502, configured to calculate a molecular flow thermal adaptation coefficient corresponding to the preset incident angle by using a maxwell reflection model based on the pressure value;
a reference curve constructing module 503, configured to construct a reference curve between the preset incident angle and the thermal adaptive coefficient;
the thermal adaptive coefficient obtaining module 504 determines a molecular flow thermal adaptive coefficient corresponding to an incident angle of an incoming atmospheric flow relative to a structural surface element of the aircraft during flight of the aircraft based on the incident angle and the reference curve.
Optionally, the thermal adaptive coefficient obtaining module 504 includes a structural bin obtaining subunit, an incident angle determining subunit, and a searching subunit;
a structural surface element acquisition subunit, configured to acquire a plurality of structural surface elements into which the exterior of the aircraft is divided;
an incident angle determining subunit, configured to determine an incident angle formed by the incoming flow of the atmosphere with respect to each of the structural bins;
and the searching subunit is configured to search, in the reference curve, a molecular flow thermal adaptation coefficient corresponding to the incident angle by using the incident angle, where a first axial direction of the reference curve represents an angle value of the incident angle, and a second axial direction of the reference curve represents the molecular flow thermal adaptation coefficient.
Optionally, the molecular flow thermal adaptation coefficient calculation module 502 includes a pressure statistical calculation formula obtaining unit and a molecular flow thermal adaptation coefficient calculation unit;
the pressure statistical calculation formula obtaining unit is used for obtaining a pressure statistical calculation formula of the rarefied gas to the wall surface based on the Maxwell reflection model;
and the pressure calculation expression obtaining unit is used for calculating the molecular flow thermal adaptation coefficient corresponding to the preset incidence angle based on the pressure value and the pressure statistical calculation formula.
Optionally, the reference curve construction module 503 comprises an aerodynamic force measurement unit, a pressure value calculation unit, a repetitive processing unit and a molecular flow thermal adaptation coefficient;
the aerodynamic force measuring unit is used for measuring the aerodynamic force of the incoming flow atmosphere at a preset incident angle to the thrust measuring plate based on the three-line torsional pendulum micro-thrust measuring system;
a pressure value calculation unit for calculating a pressure value on the thrust plate based on the aerodynamic force of the measurement plane;
the molecular flow thermal adaptation coefficient calculation unit is used for calculating a molecular flow thermal adaptation coefficient corresponding to the preset incident angle by utilizing a Maxwell reflection model based on the pressure value;
the repeated processing unit is used for changing the preset incidence angle and returning to the step of measuring the aerodynamic force of the incoming flow atmosphere at the preset incidence angle on the thrust measuring plate based on the three-line torsional pendulum micro thrust measuring system;
and the molecular flow thermal adaptation coefficient acquisition unit is used for acquiring a molecular flow thermal adaptation coefficient corresponding to each preset incidence angle.
Optionally, the three-line torsional pendulum micro-thrust measurement system comprises a thrust measurement plate, a thrust transmission rod, a laser and a reflector;
an aerodynamic force measurement unit for measuring a plane includes:
the aerodynamic force measuring subunit is used for emitting inflow atmosphere onto the measuring plane along a preset angle, pushing the thrust measuring plate to rotate so as to drive the reflecting mirror to rotate, and enabling the reflecting light position of the laser to move due to the rotation of the reflecting mirror;
and the aerodynamic force calculation subunit is used for estimating the aerodynamic force provided by the incoming flow air to the thrust plate based on the displacement of the reflected light.
Optionally, the aerodynamic force measurement unit of the measurement plane further comprises:
and the angle adjusting subunit is used for adjusting the angle between the thrust measuring plate and the thrust transmission rod so as to measure aerodynamic force under different preset incidence angles.
Fig. 5 is a schematic structural diagram of a computer device according to an embodiment of the present invention. As shown in fig. 5, a schematic structural diagram of a computer system 600 suitable for implementing the terminal device or the server of the embodiment of the present application is shown.
As shown in fig. 5, the computer system 600 includes a Central Processing Unit (CPU)601 that can perform various appropriate actions and processes according to a program stored in a Read Only Memory (ROM)602 or a program loaded from a storage section 608 into a Random Access Memory (RAM) 603. In the RAM 603, various programs and data necessary for the operation of the system 600 are also stored. The CPU 601, ROM 602, and RAM 603 are connected to each other via a bus 604. An input/output (I/O) interface 606 is also connected to bus 604.
The following components are connected to the I/O interface 605: an input portion 606 including a keyboard, a mouse, and the like; an output portion 607 including a display such as a Cathode Ray Tube (CRT), a Liquid Crystal Display (LCD), and the like, and a speaker; a storage section 608 including a hard disk and the like; and a communication section 609 including a network interface card such as a LAN card, a modem, or the like. The communication section 609 performs communication processing via a network such as the internet. The driver 610 is also connected to the I/O interface 606 as needed. A removable medium 611 such as a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory, or the like is mounted on the drive 610 as necessary, so that a computer program read out therefrom is mounted in the storage section 608 as necessary.
In particular, the process described above with reference to fig. 5 may be implemented as a computer software program, according to an embodiment of the present disclosure. For example, embodiments of the present disclosure include a computer program product comprising a computer program tangibly embodied on a machine-readable medium, the computer program comprising program code for performing the above-described method of stand allocation for a plurality of aircraft. In such an embodiment, the computer program may be downloaded and installed from a network through the communication section 609, and/or installed from the removable medium 611.
The flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.
The units or modules described in the embodiments of the present application may be implemented by software or hardware. The described units or modules may also be provided in a processor. The names of these units or modules do not in some cases constitute a limitation of the unit or module itself.
As another aspect, the present application also provides a computer-readable storage medium, which may be the computer-readable storage medium included in the foregoing device in the foregoing embodiment; or it may be a separate computer readable storage medium not incorporated into the device. The computer readable storage medium stores one or more programs for use by one or more processors in performing the method for stand allocation for a plurality of aircraft described herein.
The above description is only a preferred embodiment of the application and is illustrative of the principles of the technology employed. It will be appreciated by a person skilled in the art that the scope of the invention as referred to in the present application is not limited to the embodiments with a specific combination of the above-mentioned features, but also covers other embodiments with any combination of the above-mentioned features or their equivalents without departing from the inventive concept. For example, the above features may be replaced with (but not limited to) features having similar functions disclosed in the present application.

Claims (10)

1. A method for measuring a molecular stream thermal adaptive coefficient, comprising:
measuring the pressure value of the atmospheric incoming flow at a preset incident angle to a measuring plane based on a three-line torsional pendulum micro-thrust measuring system;
calculating a molecular flow thermal adaptation coefficient corresponding to the preset incident angle by using a Maxwell reflection model based on the pressure value;
constructing a reference curve between the preset incident angle and the thermal adaptive coefficient;
and during the flight of the aircraft, determining a molecular flow thermal adaptation coefficient corresponding to the incident angle based on the incident angle formed by the incoming atmospheric flow relative to the structural surface element of the aircraft and the reference curve.
2. The method of claim 1, wherein determining the molecular flow thermal adaptation coefficient corresponding to the incident angle based on the reference curve and the incident angle formed by the incoming flow of the atmosphere relative to the structural surface element of the aircraft comprises:
obtaining a plurality of structural bins into which an exterior of the aircraft is divided,
determining an angle of incidence of the incoming flow of atmosphere with respect to each of the structural bins;
and searching a molecular flow thermal adaptation coefficient corresponding to the incident angle in the reference curve by using the incident angle, wherein the first axial direction of the reference curve represents the angle value of the incident angle, and the second axial direction represents the molecular flow thermal adaptation coefficient.
3. The method for determining the thermal adaptive coefficient for molecular flow according to claim 1, wherein the calculating the thermal adaptive coefficient for molecular flow corresponding to the preset incident angle by using a maxwell reflection model based on the pressure value comprises:
obtaining a pressure statistical calculation formula of the rarefied gas to the wall surface based on a Maxwell reflection model;
and calculating the molecular flow thermal adaptation coefficient corresponding to the preset incident angle based on the pressure value and the pressure statistical calculation formula.
4. The method for determining the thermal adaptive coefficient for molecular flow according to claim 1, wherein constructing the reference curve between the preset incident angle and the thermal adaptive coefficient comprises:
measuring aerodynamic force of incoming flow atmosphere at a preset incident angle on a thrust measuring plate based on a three-line torsional pendulum micro-thrust measuring system;
calculating a pressure value on the thrust plate based on the aerodynamic force of the measurement plane;
calculating a molecular flow thermal adaptation coefficient corresponding to the preset incident angle by using a Maxwell reflection model based on the pressure value;
changing the preset incidence angle, and returning to the step of measuring the aerodynamic force of the incoming flow atmosphere at the preset incidence angle on the thrust measuring plate based on the three-line torsional pendulum micro thrust measuring system;
and obtaining a molecular flow thermal adaptation coefficient corresponding to each preset incidence angle.
5. The method for determining the thermal adaptive coefficient of molecular flow according to claim 4, wherein the three-wire torsional pendulum micro-thrust measurement system comprises a thrust measurement plate, a thrust transmission rod, a laser and a reflector, and the measuring of the aerodynamic force of the incoming flow atmosphere at the preset incident angle on the thrust measurement plate based on the three-wire torsional pendulum micro-thrust measurement system comprises:
emitting inflow atmosphere onto the measuring plane along a preset angle, pushing the thrust measuring plate to rotate so as to drive the reflecting mirror to rotate, and enabling the position of reflected light of the laser to move due to the rotation of the reflecting mirror;
and estimating the aerodynamic force provided by the incoming air to the thrust plate based on the displacement of the reflected light.
6. The method of claim 4, wherein the changing the predetermined incident angle comprises:
and adjusting the angle between the thrust measuring plate and the thrust transmission rod to measure aerodynamic force under different preset incidence angles.
7. The device for determining the molecular flow thermal adaptive coefficient is characterized by comprising a pressure measuring module for measuring a plane, a molecular flow thermal adaptive coefficient calculating module, a reference curve constructing module and a thermal adaptive coefficient acquiring module;
the pressure measurement module of the measurement plane is used for measuring the pressure value of the incoming flow atmosphere at a preset incident angle to the measurement plane based on the three-wire torsional pendulum micro-thrust measurement system;
the molecular flow thermal adaptation coefficient calculation module is used for calculating a molecular flow thermal adaptation coefficient corresponding to the preset incident angle by utilizing a Maxwell reflection model based on the pressure value;
the reference curve building module is used for building a reference curve between the preset incidence angle and the thermal adaptive coefficient;
and the thermal adaptation coefficient acquisition module is used for determining a molecular flow thermal adaptation coefficient corresponding to an incident angle based on the incident angle formed by the incoming flow of the atmosphere relative to the structural surface element of the aircraft and the reference curve in the flying process of the aircraft.
8. The apparatus for determining the thermal adaptive coefficient of molecular flow according to claim 7, wherein the thermal adaptive coefficient obtaining module comprises:
a structural bin acquisition subunit for acquiring a plurality of structural bins into which the exterior of the aircraft is divided,
an incident angle determining subunit, configured to determine an incident angle formed by the incoming flow of the atmosphere with respect to each of the structural bins;
and the searching subunit is configured to search, in the reference curve, a molecular flow thermal adaptation coefficient corresponding to the incident angle by using the incident angle, where a first axial direction of the reference curve represents an angle value of the incident angle, and a second axial direction of the reference curve represents the molecular flow thermal adaptation coefficient.
9. A computer device comprising a memory and a processor, the memory storing a computer program, wherein the processor when executing the computer program implements the method of any of claims 1-6.
10. A computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, carries out the method of any one of claims 1 to 6.
CN202010558870.6A 2020-06-18 2020-06-18 Method, device, equipment and storage medium for measuring molecular flow thermal adaptation coefficient Active CN111723537B (en)

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