Near space atmospheric pressure in-situ inversion method

Abstract

The application provides a near space atmospheric pressure in-situ inversion method, and belongs to the technical field of near space environment detection. The method comprises the following steps: obtaining falling speed and acceleration information of a sounding instrument and a temperature change curve of the sounding instrument measured along with the falling of the sounding instrument; calculating an atmospheric density estimation value; calculating a static temperature estimation value; calculating an environmental pressure estimation value; calculating a cross-flow resistance coefficient, a cross-flow temperature recovery coefficient and a Mach number; and repeating iteration until the atmospheric pressure inversion calculation result converges. The application solves the problem of few means for obtaining near space full-altitude in-situ atmospheric pressure information.

Description

Technical Field

[0001] This invention belongs to the field of near-space environment detection technology, and in particular relates to an in-situ inversion method for near-space air pressure. Background Technology

[0002] High-precision near-space atmospheric environment detection is crucial for the design of near-space vehicles and, more importantly, for gaining control of the strategic near-space domain. Airborne detection systems can place payloads directly into the LJKJ environment, achieving high-precision in-situ detection and meeting the meteorological parameter detection requirements of the LJKJ environment.

[0003] Currently, mainstream near-space in-situ exploration methods fall into two categories. One approach involves using a sounding balloon to carry a sounding component to probe near space, primarily covering an area below 30 km. The other approach uses a sounding rocket to carry the sounding component, which is then dropped into the near-space environment for environmental detection during its descent. The second method, depending on the rocket's capabilities, can cover up to the entire near-space altitude. During the descent of the sounding component, the high speed, relative airflow, and aerodynamic heat generated by friction between the component's surface and the air cause detection errors in the internal pressure sensors.

[0004] Currently, near-space in-situ detection mainly utilizes sounding balloons or sounding rockets to carry radiosondes for in-situ detection. The radiosondes carry temperature sensors, pressure sensors, inertial measurement units (IMUs), and BeiDou satellite navigation modules. Using sounding rockets for drop-type detection can effectively improve the measurement altitude range of in-situ detection and achieve wide-area coverage, which can better meet the needs of establishing a spatiotemporal gridded dataset for near-space environment detection.

[0005] Currently, in-situ measurements of near-space pressure often employ piezoresistive pressure sensors, Pirani pressure sensors, or resonant pressure sensors. Piezoresistive pressure sensors have a limited range, their accuracy is significantly affected by temperature, and their long-term stability is poor. While Pirani pressure sensors are suitable for vacuum system monitoring, their response speed is slow and their power consumption is high. In-situ direct detection methods for near-space pressure across all elevations have significant limitations. Summary of the Invention

[0006] To address the aforementioned shortcomings in existing technologies, this invention provides an in-situ inversion method for near-space air pressure, which solves the problem of limited means of acquiring in-situ air pressure information at full elevation in near space.

[0007] To achieve the above objectives, the technical solution adopted by this invention is: a near-space air pressure in-situ inversion method, comprising the following steps: S1. Obtain the curves of the radiosonde's acceleration, velocity, and temperature as the radiosonde falls, and estimate the Mach number by measuring the temperature using the radiosonde. S2. Calculate the density estimate based on the radiosonde acceleration and velocity inversion. S3. Calculate the static temperature estimate by inverting the Mach number and density estimate based on the temperature estimate; S4. Calculate the estimated ambient air pressure based on the density estimate and the static temperature estimate. S5. Calculate the estimated values ​​of the transflow drag coefficient and the transflow temperature recovery coefficient based on the estimated values ​​of the ambient air pressure, and calculate the Mach number based on the estimated values ​​of the static temperature obtained by inversion; S6. Substitute the estimated values ​​of the transfluid drag coefficient, the transfluid temperature recovery coefficient, and the Mach number obtained in S4 and S5 back into the formulas in S2 and S3. Recalculate steps S2 to S6 using the new estimated values. Repeat S2 to S6 multiple times until the relative rate of change between the current pressure value iteration result and the previous pressure value iteration result is less than the preset accuracy value. Then, end the iteration and output the in-situ inversion result of the near-space pressure.

[0008] The beneficial effects of this invention are as follows: This invention uses data obtained from temperature sensors, IMUs, and BeiDou satellite navigation modules available at all altitudes during the descent of a rocket-type sounding instrument. Based on the theory of gas molecular dynamics, it performs inversion calculations on atmospheric pressure across the entire altitude range. Furthermore, this invention compensates for the direct temperature information obtained by the temperature sensors by using descent velocity and acceleration information, thereby improving the accuracy of the pressure inversion results and solving the problem of limited means of obtaining in-situ atmospheric pressure information at all altitudes in near space.

[0009] Further, S1 includes: A sounding rocket carries a radiosonde to the near-space region and drops it, obtaining curves showing the changes in the radiosonde's acceleration, velocity, and temperature as it falls. The Mach number is estimated by measuring the temperature using a radiosonde.

[0010] The beneficial effects of the above-mentioned further solutions are: the present invention uses acceleration, velocity and temperature data obtained by in-situ detection of a falling radiosonde, without relying on traditional barometric pressure sensors, and has the characteristics of high spatiotemporal accuracy and full-altitude measurement, and can obtain the barometric pressure change curve on the falling trajectory line of the radiosonde within the full altitude range.

[0011] Furthermore, the expression for the temperature estimation Mach number is as follows:

[0012] in, This indicates the estimated Mach number for temperature. This indicates the descent speed of the radiosonde. Indicates specific heat ratio. Represents the gas constant. Indicates temperature.

[0013] Furthermore, the expression for the density estimate is as follows:

[0014]

[0015] in, This represents the density estimate. Indicates the mass of the radiosonde. Indicates the acceleration of the radiosonde. This represents the drag coefficient under continuous flow conditions. This indicates the windward section of the radiosonde. This indicates the descent speed of the radiosonde. Indicates the radius of the radiosonde. Indicates angle of attack. This indicates the length of the radiosonde.

[0016] Furthermore, the expression for the static temperature estimate is as follows:

[0017] in, This represents the estimated static temperature value. This represents the temperature correction factor under continuous flow conditions. Indicates temperature. Indicates specific heat ratio. This indicates the Mach number for temperature estimation.

[0018] Furthermore, the expression for the estimated ambient air pressure is as follows:

[0019] in, This represents the estimated ambient air pressure. This represents the density estimate. This represents the estimated static temperature value. This represents the gas constant.

[0020] Furthermore, the expression for the estimated transflow drag coefficient is as follows:

[0021]

[0022] in, This represents the estimated value of the transflow drag coefficient. This represents the drag coefficient under continuous flow conditions. This represents the drag coefficient under molecular flow conditions. and All represent coefficients. Represents the Boltzmann constant. This represents the estimated static temperature value. This represents the average molecular diameter of air molecules. This represents the estimated ambient air pressure. Indicates the length of the radiosonde. This represents the Knudsen number.

[0023] Furthermore, the expression for the estimated transflow temperature restitution coefficient is as follows:

[0024] in, This represents the estimated value of the transflow temperature restitution coefficient. This represents the temperature correction factor under continuous flow conditions. Indicates the temperature recovery coefficient under molecular flow conditions. Represents the Knudsen number, and Both represent constants.

[0025] Furthermore, the expression for the Mach number is as follows:

[0026] in, Represents the Mach number. This indicates the descent speed of the radiosonde. Indicates specific heat ratio. This represents the estimated static temperature value. This represents the gas constant.

[0027] Furthermore, the expression for the relative rate of change is as follows:

[0028] in, Indicates the first The air pressure value in each iteration, Indicates the first The air pressure value in each iteration, Indicates the preset precision value. Indicates the number of iterations.

[0029] The beneficial effects of the above-mentioned further solutions are as follows: This invention establishes formulas for the drag coefficient and temperature recovery coefficient across different flow regimes through a bridging formula method, improving the accuracy of air pressure inversion under different flow regimes at all elevations in near-space. The calculation process uses curve data of the radiosonde's acceleration, velocity, and temperature as a function of the radiosonde's descent, encompassing the entire descent altitude range. The result obtained using this method is a curve of air pressure changing with descent altitude, rather than data from a single altitude point. Attached Figure Description

[0030] Figure 1 This is a flowchart of the method of the present invention. Detailed Implementation

[0031] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0032] Example like Figure 1 As shown, this invention provides a near-space pressure in-situ inversion method, the implementation of which is as follows: S1. Obtain the curves of the radiosonde's acceleration, velocity, and temperature as a function of the radiosonde's descent, and estimate the Mach number by measuring the temperature using the radiosonde. The implementation method is as follows: A sounding rocket carries a radiosonde to the near-space region and drops it, obtaining curves showing the changes in the radiosonde's acceleration, velocity, and temperature as it falls. The Mach number is estimated by measuring the temperature using a radiosonde.

[0033] In this invention, the calculation process uses curve data of the radiosonde's acceleration, velocity, and temperature as the radiosonde falls, including the entire falling height range of the radiosonde. The result obtained by this method is the curve of air pressure changing with the falling height, rather than data from a single altitude point.

[0034] In this embodiment, a sounding rocket carries a radiosonde to the near-space region and deploys it. Using the radiosonde's onboard IMU, BeiDou navigation module, and temperature sensor, curves showing the changes in acceleration, three-directional velocity, and temperature as measured by the sensors during the radiosonde's descent are obtained. The Mach number is estimated using the temperature measured by the radiosonde.

[0035] In this embodiment, the formula for calculating the temperature Mach number estimate is as follows:

[0036] Among them, M (1) This indicates the estimated Mach number for temperature. This indicates the descent speed of the radiosonde obtained through the BeiDou navigation module. Represents the specific heat ratio, which is taken as 1.4 based on engineering experience. air =287J / (kg·K) represents the gas constant. This indicates the temperature measured by the temperature sensor.

[0037] S2. Calculate the density estimate based on the radiosonde acceleration and velocity inversion:

[0038] In this embodiment, the calculation of the windward section requires calculating the radiosonde attitude information based on BeiDou navigation information and acceleration information obtained from the IMU, and then correcting the windward section area using the following correction formula:

[0039] in, This represents the density estimate. This indicates that the radiosonde weighs 994.24g. This indicates the radiosonde acceleration information obtained through the IMU. This represents the drag coefficient under continuous flow conditions, and is taken as 1.05 based on engineering experience. This indicates the windward section of the radiosonde. This indicates the descent speed of the radiosonde. This indicates that the radiosonde has a radius of 3cm. The angle of attack is calculated using attitude measurement. This indicates that the radiosonde is 33cm long.

[0040] S3. Calculate the static temperature estimate by inverting the Mach number and density estimate based on the temperature estimate:

[0041] in, This represents the estimated static temperature value. This represents the temperature correction factor under continuous flow conditions, and its value is taken as 0.845 based on engineering experience. Indicates temperature. Indicates specific heat ratio. This indicates the Mach number for temperature estimation.

[0042] S4. Calculate the estimated ambient pressure based on the density and static temperature estimates:

[0043] in, This represents the estimated ambient air pressure. This represents the density estimate. This represents the estimated static temperature value. This represents the gas constant.

[0044] S5. Calculate the estimated values ​​of the transflow drag coefficient and the transflow temperature recovery coefficient based on the estimated values ​​of the ambient air pressure, and calculate the Mach number based on the estimated values ​​of the static temperature obtained by inversion; In this embodiment, the formula for calculating the transflow drag coefficient is as follows:

[0045] In this embodiment, Knudsen number The calculation formula is as follows:

[0046] in, This represents the estimated value of the transflow drag coefficient. This represents the drag coefficient under continuous flow conditions. This represents the drag coefficient under molecular flow conditions, and is taken as 2.2 based on engineering experience. and Both represent coefficients, which are taken as 0.5 and -1 respectively based on engineering experience. This represents the estimated static temperature value. This represents the estimated ambient air pressure. Indicates the length of the radiosonde. Represents the Knudsen number, =3.65×10 -23 J / K represents the Boltzmann constant, and d represents the average molecular diameter of air molecules, which is taken as 3.65 × 10⁻⁶ based on engineering experience. -23 m.

[0047] In this embodiment, the formula for calculating the estimated value of the transflow temperature restitution coefficient is as follows:

[0048] in, This represents the estimated value of the transflow temperature restitution coefficient. This represents the temperature correction factor under continuous flow conditions. This represents the temperature recovery coefficient under molecular flow conditions, and based on engineering experience, it is taken as 1.0. Represents the Knudsen number, and Both represent constants, taking values ​​of -0.5 and 0.3 respectively.

[0049] S6. Substitute the estimated values ​​of the transfluid drag coefficient, the transfluid temperature recovery coefficient, and the Mach number obtained in S4 and S5 back into the formulas in S2 and S3. Recalculate steps S2 to S6 using the new estimated values. Repeat S2 to S6 multiple times until the relative rate of change between the current pressure value iteration result and the previous pressure value iteration result is less than the preset accuracy value. Then, end the iteration and output the in-situ inversion result of the near-space pressure.

[0050] In this embodiment, the Mach number is expressed as follows:

[0051] in, Represents the Mach number. This indicates the descent speed of the radiosonde. Indicates specific heat ratio. This represents the estimated static temperature value. This represents the gas constant.

[0052] The expression for the relative rate of change is as follows:

[0053] in, Indicates the first The air pressure value in each iteration, Indicates the first The air pressure value in each iteration, This indicates the preset precision value; a value of 0.1% meets the precision requirements. Indicates the number of iterations.

[0054] Through inversion calculations, continuous acceleration, velocity, and temperature information across the entire elevation range in near space can be obtained directly from the falling radiosonde. This inversion calculations can then yield air pressure information across the entire elevation range, effectively addressing the current limitation of air pressure sensors in detecting air pressure across the entire elevation range in near space. This technology can be applied to the construction of subsequent near space environmental air pressure models, solving engineering problems related to near space air pressure.

[0055] The above detailed description further illustrates the purpose, technical solution, and beneficial effects of the invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for in-situ inversion of near-space air pressure, characterized in that, Includes the following steps: S1. Obtain the curves of the radiosonde's acceleration, velocity, and temperature as the radiosonde falls, and estimate the Mach number by measuring the temperature using the radiosonde. S2. Calculate the density estimate based on the radiosonde acceleration and velocity inversion. S3. Calculate the static temperature estimate by inverting the Mach number and density estimate based on the temperature estimate; S4. Calculate the estimated ambient air pressure based on the density estimate and the static temperature estimate. S5. Calculate the estimated values ​​of the transflow drag coefficient and the transflow temperature recovery coefficient based on the estimated values ​​of the ambient air pressure, and calculate the Mach number based on the estimated values ​​of the static temperature obtained by inversion; S6. Substitute the estimated values ​​of the transfluid drag coefficient, the transfluid temperature recovery coefficient, and the Mach number back into the calculation formulas of S2 and S3, and recalculate steps S2 to S6 using the new estimates. Repeat S2 to S6 multiple times until the relative rate of change between the current pressure value iteration result and the previous pressure value iteration result is less than the preset accuracy value. Then, end the iteration and output the near-space pressure in-situ inversion result.

2. The near-space pressure in-situ inversion method according to claim 1, characterized in that, S1 includes: A sounding rocket carries a radiosonde to the near-space region and drops it, obtaining curves showing the changes in the radiosonde's acceleration, velocity, and temperature as it falls. The Mach number is estimated by measuring the temperature using a radiosonde.

3. The near-space pressure in-situ inversion method according to claim 1, characterized in that, The expression for the temperature estimation Mach number is as follows: in, This indicates the estimated Mach number for temperature. This indicates the descent speed of the radiosonde. Indicates specific heat ratio. Represents the gas constant. Indicates temperature.

4. The near-space pressure in-situ inversion method according to claim 1, characterized in that, The expression for the density estimate is as follows: in, This represents the density estimate. Indicates the mass of the radiosonde. Indicates the acceleration of the radiosonde. This represents the drag coefficient under continuous flow conditions. This indicates the windward section of the radiosonde. This indicates the descent speed of the radiosonde. Indicates the radius of the radiosonde. Indicates angle of attack. This indicates the length of the radiosonde.

5. The near-space pressure in-situ inversion method according to claim 1, characterized in that, The expression for the static temperature estimate is as follows: in, This represents the estimated static temperature value. This represents the temperature correction factor under continuous flow conditions. Indicates temperature. Indicates specific heat ratio. This indicates the Mach number for temperature estimation.

6. The near-space pressure in-situ inversion method according to claim 1, characterized in that, The expression for the estimated ambient air pressure is as follows: in, This represents the estimated ambient air pressure. This represents the density estimate. This represents the estimated static temperature value. This represents the gas constant.

7. The near-space pressure in-situ inversion method according to claim 1, characterized in that, The expression for the estimated transflow drag coefficient is as follows: in, This represents the estimated value of the transflow drag coefficient. This represents the drag coefficient under continuous flow conditions. This represents the drag coefficient under molecular flow conditions. and All represent coefficients. Represents the Boltzmann constant. This represents the estimated static temperature value. This represents the average molecular diameter of air molecules. This represents the estimated ambient air pressure. Indicates the length of the radiosonde. This represents the Knudsen number.

8. The near-space pressure in-situ inversion method according to claim 1, characterized in that, The expression for the estimated transfluid temperature restitution coefficient is as follows: in, This represents the estimated value of the transflow temperature restitution coefficient. This represents the temperature correction factor under continuous flow conditions. Indicates the temperature recovery coefficient under molecular flow conditions. Represents the Knudsen number, and Both represent constants.

9. The near-space pressure in-situ inversion method according to claim 1, characterized in that, The expression for the Mach number is as follows: in, Represents the Mach number. This indicates the descent speed of the radiosonde. Indicates specific heat ratio. This represents the estimated static temperature value. This represents the gas constant.

10. The near-space pressure in-situ inversion method according to claim 1, characterized in that, The expression for the relative rate of change is as follows: in, Indicates the first The air pressure value in each iteration, Indicates the first The air pressure value in each iteration, Indicates the preset precision value. Indicates the number of iterations.

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