A method for measuring the remaining propellant in a GEO orbital fuel station throughout its life cycle

Abstract

A method for measuring the remaining propellant in a GEO orbital fuel station over its entire life cycle is proposed. By analyzing the operating characteristics of different mission segments in the GEO orbital fuel station mission profile and configuring the necessary hardware on the system, it is proposed to use the engine small deviation equation to indirectly calculate the total remaining oxidizer and the total remaining fuel in the GTO transfer segment. In the GEO steady-state operation segment, it is proposed to use the gas volume excitation method to measure the remaining propellant in a single tank. In the propellant replenishment mission segment, it is proposed to use the ultrasonic flow meter method to indirectly measure the remaining propellant. This forms a propellant remaining measurement system solution for the entire life cycle of the fuel station, solves the propellant remaining system measurement problem in the GEO orbit on-orbit refueling technology, provides a monitoring means for the mission safety of the GTO transfer segment and the on-orbit propellant replenishment segment of the fuel station, and provides design input for the design of the on-orbit refueling mission. The development and application of on-orbit refueling technology can effectively improve the maneuverability of satellites.

Description

Technical Field

[0001] The present invention relates to a full life cycle propellant remaining quantity measurement system solution for a GEO orbit fuel station, belonging to the technical field of on-orbit services. Background Art

[0002] In the future, there will be two types of high-value targets in GEO orbit: high-value satellites that maintain three-axis stability in a fixed orbital position, and high-value satellites capable of maneuverable operations. Both types of high-value targets require on-orbit propellant replenishment to enhance their application value, making the application of on-orbit refueling technology in GEO orbit extremely urgent.

[0003] The application of on-orbit refueling technology must first address the deployment of two types of spacecraft. One is the service spacecraft, which actively approaches and docks with high-value targets and refuels its own fuel into the high-value target's tank. This type of spacecraft has strong maneuverability. The other type of spacecraft is the GEO orbital fuel station. After entering orbit through multiple GTO transfers, this type of spacecraft operates steadily in the GEO orbit and waits for the service spacecraft to dock. After docking, it refuels the service spacecraft. Measuring the remaining propellant amount at the GEO orbital fuel station not only provides a guarantee for mission safety monitoring of the fuel station, but also is one of the key parameters affecting the design of the refueling mission. Therefore, it is particularly important to measure the remaining propellant amount in the fuel station tank by combining the operating characteristics of each mission segment of the fuel station. It is one of the key technologies in on-orbit refueling technology.

[0004] In order to save weight costs, the tanks of GEO orbital fuel stations are generally surface tension tanks. The tanks contain a mixture of gas and liquid. There is no direct sensor to measure the remaining amount of propellant in the tanks. The configuration of the entire propulsion system is needed to coordinate the measurement of the remaining amount of propellant in the tanks. Summary of the Invention

[0005] The technical problem solved by the present invention is: in view of the lack of a systematic measurement method for the remaining propellant in the tank of a GEO orbital fuel station throughout its life cycle in the current existing technology, a method for measuring the remaining propellant in a GEO orbital fuel station throughout its life cycle is proposed.

[0006] The present invention solves the above technical problems by the following technical solutions:

[0007] A method for measuring the remaining amount of propellant in a GEO orbital fuel station throughout its life cycle, comprising the following steps:

[0008] (1) After the GEO orbit fuel station separates from the rocket, it enters the GTO transfer orbit and uses the orbit control engine to make multiple apogee changes to enter the GEO orbit. During the GTO transfer phase, the propellant consumption is calculated using the engine small deviation equation, and the total remaining amount of oxidizer and the total remaining amount of propellant are indirectly obtained;

[0009] (2) During the steady-state flight phase of the GEO orbital fuel station, the boost gas is replenished to each tank of the fuel station through the small gas cylinders configured in the propulsion system. Based on the data from the high-precision pressure and temperature sensors configured on the system, the remaining propellant amount of each oxidizer tank and fuel tank is obtained through the gas volume excitation method;

[0010] (3) During the propellant replenishment phase for the service aircraft, the fuel station installs ultrasonic flowmeters on the oxidizer replenishment pipeline and the fuel replenishment pipeline respectively, and measures the amount of propellant replenished by the ultrasonic flowmeter method based on the principle of forward and reverse flow phase difference, thereby indirectly obtaining the remaining amount of a single tank.

[0011] In step (1), the propellant replenishment module is not working during the GTO transfer phase, and the system cannot use the gas volume excitation method to measure the remaining propellant. The gas volume excitation method will affect the operating characteristics of the main engine. During the operation of the main engine, the propellant flow is large and the flow parameters are relatively stable. The remaining propellant can be calculated using the small deviation equation of the orbit control engine, including the following steps:

[0012] 1-1) Obtain the oxidizer and fuel consumption per second of the orbit control engine using the small deviation equation;

[0013]

[0014]

[0015] The seconds consumed for each orbit change are different, and the precise seconds consumed for the oxidizer and fuel of the orbit change can be fitted by the main engine inlet pressure and propellant temperature parameters at the orbit change fuel station. is the oxidant consumption per second, is the fuel consumption per second, both in kg / s, a1 is the sensitivity of the oxidizer consumption per second to the oxidizer tank pressure, a2 is the sensitivity of the oxidizer consumption per second to the oxidizer tank temperature, a3 is the sensitivity of the oxidizer consumption per second to the fuel tank pressure, a4 is the sensitivity of the oxidizer consumption per second to the fuel tank temperature, b1 is the sensitivity of the fuel consumption per second to the fuel tank pressure, b2 is the sensitivity of the fuel consumption per second to the fuel tank temperature, b3 is the sensitivity of the fuel consumption per second to the oxidizer tank pressure, b4 is the sensitivity of the fuel consumption per second to the oxidizer tank temperature, P eo 、P er 、T eo 、Ter are the main engine rated operating condition inlet oxidant pressure, fuel pressure, oxidant temperature, fuel temperature, P to 、P tr 、T to 、T tr are the oxidant pressure, fuel pressure, oxidant temperature, and fuel temperature at the inlet of the main engine under actual working conditions, respectively. a0 and b0 are fitting constants, respectively.

[0016] 1-2) Calculate propellant consumption;

[0017]

[0018]

[0019] The unit is kg, where t1 is the start-up time of the orbit control engine. For multiple orbit changes, the total oxidizer consumption m can be calculated by accumulating the seconds consumed for each orbit change and the orbit change time. o1 and fuel consumption m r1 .

[0020] 1-3) Calculate the remaining amount of propellant, including the total remaining amount of oxidizer and the total remaining amount of fuel

[0021] Δm o1 =m o -m o1

[0022] Δm r1 =m r -m r1

[0023] where m o is the total amount of oxidant added, m r is the total amount of fuel filled. During the GTO transfer phase, two oxidizer tanks are discharged in parallel, and two fuel tanks are discharged in parallel. The calculated remaining amount of oxidizer Δm o1 and the remaining fuel volume Δm r1 are the total remaining amount of oxidant and the total remaining amount of combustion agent respectively.

[0024] In the step (2), the system volume excitation method requires the system to have a certain hardware configuration. A small gas cylinder needs to be added to the upstream of each tank gas supply. The small gas cylinder is isolated from the tank by a self-locking valve, and is also isolated from the booster main gas cylinder of the propulsion system by a self-locking valve. The small gas cylinder is inflated on demand through the booster main gas cylinder. The small gas cylinder is equipped with a pressure and temperature sensor, and the tank is also equipped with a pressure and temperature sensor. Before measurement, the small gas cylinder is filled with gas of a certain pressure range through the booster main gas cylinder, and then the valve between the small gas cylinder and the tank is opened to discharge part of the gas in the small gas cylinder into the measured tank, and the remaining amount of a single tank is measured; assuming that the pressure p of the small gas cylinder set before measurement is g0 MPa, temperature is T g0 K, volume V g0 L, the compression factor is Z g0 , after measuring the pressure of the small gas cylinder p g1 MPa, temperature is T g1 K, the compression factor is Z g1 , measure the front tank pressure p z0 MPa, temperature is T z0 K, the volume of the tank air cavity is V z0 L, the compression factor is Z z0 , measure the rear tank pressure p z1 MPa, temperature is T z1 K, the compression factor is Z z1 The measurement of the remaining propellant at this stage includes the following steps:

[0025] 2-1) The small gas cylinder is inflated through the main gas cylinder of the booster circuit. The inflation pressure of the small gas cylinder is determined by the storage tank volume, the small gas cylinder volume, and the accuracy of the pressure sensor, and is designed to be within 5MPa;

[0026] 2-2) Open the valve between the small gas cylinder and the storage tank to stimulate the gas in the small gas cylinder into the storage tank, changing the tank pressure;

[0027] 2-3) Calculate the volume V of the gas cavity of a single tank after gas volume excitation z0 ;

[0028]

[0029] 2-4) Calculate the remaining volume Δm2 of a single tank;

[0030] Δm2=(VV z0 )×ρ

[0031] Where V is the total volume of a single tank in L, and ρ is the propellant density in the tank. The remaining volume of different tanks is obtained by repeating steps 2-1) to 2-4).

[0032] The gas volume excitation method depends on the accuracy of pressure and temperature sensors. In order to improve the accuracy of residual measurement, high-precision pressure sensors and temperature sensors are required.

[0033] In step (3), during the propellant replenishment mission, one fuel station tank is typically replenished with one service vehicle tank. During the on-orbit refueling process, the remaining propellant in the fuel station tank changes dynamically, requiring real-time measurement of the remaining propellant in the fuel station tank. During this process, the engine is almost inoperative, making the engine small deviation equation method ineffective. Furthermore, the gas volume excitation method is also inappropriate during the refueling process. Instead, an ultrasonic flowmeter can be used to dynamically measure the real-time and cumulative refueling amounts.

[0034] The ultrasonic flowmeter method uses the phase difference of ultrasonic waves flowing in the feed pipe to obtain the real-time feed amount. The ultrasonic flowmeter is interspersed in the feed pipe, one for the chemical feed pipe and one for the combustion agent feed pipe. Unlike the clamp-on flowmeter used in industrial applications, it includes the following steps:

[0035] 3-1) Using ultrasonic flowmeters to obtain real-time forward and reverse flow phase difference data during the refilling process of each tank;

[0036] 3-2) Real-time calculation of the amount of fuel to be added to each tank at the fuel station;

[0037]

[0038] Unit is m 3 / s, where q is the volume flow rate of the propellant, c is the velocity of the ultrasonic wave in the static propellant, D is the diameter of the pipe, L is the length of the pipe for ultrasonic measurement, and f is the ultrasonic frequency. k is the ultrasonic forward and reverse flow phase difference, h is the flow correction factor.

[0039] 3-3) Calculation of cumulative supplementary amount;

[0040] m bujia =∫qdt

[0041] The unit is Kg, and the cumulative amount of replenishment is obtained by adding up the real-time replenishment amounts.

[0042] 3-4) Calculation of remaining propellant in a single tank;

[0043] Δm3=Δm2-m bujia

[0044] The unit is Kg. For different tank remaining amounts, repeat steps 3-1) to 3-4).

[0045] The advantages of the present invention compared with the prior art are:

[0046] The GEO orbital fuel station is currently in the ground planning and development phase and has not yet been put into operation. The technology for measuring the remaining propellant in the tanks of the GEO orbital fuel station will be one of the key technologies for on-orbit refueling. Currently, there are no research results on the technical solutions for measuring the remaining propellant in the GEO orbital fuel station. This patent designs a systematic, full-lifecycle propellant remaining measurement solution using a segmented relay mechanism based on the characteristics of each mission segment of a GEO orbital fuel station under development. In addition, the ultrasonic flowmeter method proposed in this patent is currently mainly used in industrial fields such as natural gas. Due to the different propagation characteristics of ultrasonic waves in different media and the different flow characteristics of fluids on the ground and in microgravity environments, special propellant media are used in aerospace, and engineering applications in aerospace have not yet been realized. Currently, only a few papers have mentioned the measurement of refueling volume based on the ultrasonic time difference method. This patent proposes using ultrasonic phase difference to solve the propellant remaining measurement solution for the on-orbit refueling segment of the GEO orbit, which is simpler and more direct to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 A flow chart of the GEO orbital fuel life cycle propellant remaining measurement system solution provided for the invention;

[0048] Figure 2 A GEO orbital fuel station mission flow chart provided for the invention;

[0049] Figure 3 A GEO orbital fuel station tank layout diagram provided for the invention;

[0050] Figure 4 Schematic diagram of the gas volume excitation method system for the GEO orbital fuel station provided for the invention;

[0051] Figure 5 Schematic diagram of the ultrasonic flowmeter measurement system for the GEO rail fuel station provided for the invention; DETAILED DESCRIPTION

[0052] A method for measuring the remaining propellant in a GEO orbital fuel station throughout its life cycle is proposed. This method combines the operating characteristics of different mission segments of the GEO orbital fuel station and selects a propellant remaining measurement method suitable for the mission characteristics of that segment. This method monitors and measures the remaining propellant in the tanks throughout the fuel station's life cycle, providing support and assurance for the fuel station's mission design and mission safety monitoring. The flow chart of the GEO orbital fuel station's full life cycle propellant remaining measurement system is shown below. Figure 1 As shown, the specific process is as follows:

[0053] (1) After the GEO orbit fuel station separates from the rocket, it enters the GTO transfer orbit and uses the orbit control engine to make multiple apogee changes to enter the GEO orbit. During the GTO transfer phase, the propellant consumption is calculated using the engine small deviation equation, and the total remaining amount of oxidizer and the total remaining amount of propellant are indirectly obtained;

[0054] During the GTO transfer phase, the propellant replenishment module is inoperative, and the system cannot measure the remaining propellant using the gas volume excitation method, which would affect the main engine operating point. During the main engine operation, the propellant flow is high and the flow parameters are relatively stable. The remaining propellant can be calculated using the orbit control engine's small deviation equation, which includes the following steps:

[0055] 1-1) Obtain the oxidizer and fuel consumption per second of the orbit control engine using the small deviation equation;

[0056]

[0057]

[0058] The seconds consumed for each orbit change are different, and the precise seconds consumed for the oxidizer and fuel of the orbit change can be fitted by the main engine inlet pressure and propellant temperature parameters at the orbit change fuel station. is the oxidant consumption per second, is the fuel consumption per second, both in kg / s, a1 is the sensitivity of the oxidizer consumption per second to the oxidizer tank pressure, a2 is the sensitivity of the oxidizer consumption per second to the oxidizer tank temperature, a3 is the sensitivity of the oxidizer consumption per second to the fuel tank pressure, a4 is the sensitivity of the oxidizer consumption per second to the fuel tank temperature, b1 is the sensitivity of the fuel consumption per second to the fuel tank pressure, b2 is the sensitivity of the fuel consumption per second to the fuel tank temperature, b3 is the sensitivity of the fuel consumption per second to the oxidizer tank pressure, b4 is the sensitivity of the fuel consumption per second to the oxidizer tank temperature, P eo 、P er 、T eo 、T er are the main engine rated operating condition inlet oxidant pressure, fuel pressure, oxidant temperature, fuel temperature, P to 、P tr 、T to 、T tr are the oxidant pressure, fuel pressure, oxidant temperature, and fuel temperature at the inlet of the main engine under actual working conditions, respectively. a0 and b0 are fitting constants, respectively.

[0059] 1-2) Calculate propellant consumption;

[0060]

[0061]

[0062] The unit is kg, where t1 is the start-up time of the orbit control engine. For multiple orbit changes, the total oxidizer consumption m can be calculated by accumulating the seconds consumed for each orbit change and the orbit change time. o1 and fuel consumption m r1 .

[0063] 1-3) Calculate the remaining amount of propellant, including the total remaining amount of oxidizer and the total remaining amount of fuel

[0064] Δm o1 =m o -m o1

[0065] Δm r1 =m r -m r1

[0066] where m o is the total amount of oxidant added, m r is the total amount of fuel filled. During the GTO transfer phase, two oxidizer tanks are discharged in parallel, and two fuel tanks are discharged in parallel. The calculated remaining amount of oxidizer Δm o1 and the remaining fuel volume Δm r1 They are the total remaining amount of oxidizer and the total remaining amount of fuel, respectively. The remaining amount of each tank cannot be accurately given.

[0067] (2) During the steady-state flight phase of the GEO orbital fuel station, the boost gas is replenished to each tank of the fuel station through the small gas cylinders configured in the propulsion system. Based on the data from the high-precision pressure and temperature sensors configured on the system, the remaining propellant amount of each oxidizer tank and fuel tank is obtained through the gas volume excitation method;

[0068] The specific gas volume excitation system composition is as shown in the attached Figure 4 As shown, each tank is connected to a small gas cylinder upstream. The gas cylinder and the tank are isolated by a valve. The gas cylinder is equipped with pressure, temperature and other sensors. Similarly, the tank is also equipped with pressure, temperature and other sensors. Before measurement, the small gas cylinder is filled with gas within a certain pressure range through the main gas cylinder of the booster circuit. Then, the valve between the small gas cylinder and the tank is opened to discharge part of the gas in the small gas cylinder into the measured tank. This measurement method can measure the remaining amount of a single tank. Assuming that the gas cylinder pressure p set before measurement is g0 MPa, temperature is T g0 K, the volume of the gas cylinder is V g0 L, the compression factor is Z g0 , after measuring the cylinder pressure p g1 MPa, temperature is T g1 K, the compression factor is Zg1 , measure the front tank pressure p z0 MPa, temperature is T z0 K, the volume of the tank air cavity is V z0 L, the compression factor is Z z0 , measure the rear tank pressure p z1 MPa, temperature is T z1 K, the compression factor is Z z1 The measurement of the remaining propellant at this stage includes the following steps:

[0069] 2-1) The small gas cylinder is inflated through the main gas cylinder of the booster circuit. The inflation pressure of the small gas cylinder is determined by the storage tank volume, the small gas cylinder volume, and the accuracy of the pressure sensor, and is designed to be within 5MPa;

[0070] 2-2) Open the valve between the small gas cylinder and the storage tank to stimulate the gas in the small gas cylinder into the storage tank, changing the tank pressure;

[0071] 2-3) Calculate the volume V of the gas cavity of a single tank after gas volume excitation z0 ;

[0072]

[0073] 2-4) Calculate the remaining volume Δm2 of a single tank;

[0074] Δm2=(VV z0 )×ρ

[0075] Where V is the total volume of a single tank, in L, and ρ is the propellant density in the tank, in kg / L. For different tank remaining capacities, steps 2-1) to 2-4) are repeated.

[0076] The gas volume excitation method depends on the accuracy of the pressure and temperature sensors. In order to improve the accuracy of the residual quantity measurement, it is necessary to select high-precision pressure sensors and temperature sensors.

[0077] (3) During the propellant replenishment phase for the service aircraft, the fuel station installs ultrasonic flowmeters on the oxidizer replenishment pipeline and the fuel replenishment pipeline respectively, and measures the amount of propellant replenished by the ultrasonic flowmeter method based on the principle of forward and reverse flow phase difference, thereby indirectly obtaining the remaining amount of a single tank;

[0078] During the propellant refueling phase, typically one fuel station tank is refueled with one service vehicle tank. The remaining propellant in the fuel station tank changes dynamically during the on-orbit refueling process, necessitating real-time measurement of the remaining propellant. During this process, the engine is virtually inoperative, making the engine's small deviation equation method ineffective. Furthermore, the gas volume excitation method is also inadequate during the refueling process. Therefore, an ultrasonic flow meter can be used to dynamically measure both the real-time and cumulative refueling amounts.

[0079] The ultrasonic flow meter method obtains the real-time replenishment amount through the phase difference of the ultrasonic wave flowing forward and backward on the replenishment pipeline. The ultrasonic flow meter is integrated in the replenishment pipeline, one for oxidant and one for fuel. The specific principle diagram is attached. Figure 5 , the method comprises the following steps:

[0080] 3-1) Using ultrasonic flowmeters to obtain real-time forward and reverse flow phase difference data during the refilling process of each tank;

[0081] 3-2) Real-time calculation of the amount of fuel to be added to each tank at the fuel station;

[0082]

[0083] Unit is m 3 / s, where q is the volume flow rate of the propellant, c is the velocity of the ultrasonic wave in the static propellant, D is the diameter of the pipe, L is the length of the pipe for ultrasonic measurement, and f is the ultrasonic frequency. k is the ultrasonic forward and reverse flow phase difference, h is the flow correction factor.

[0084] 3-3) Calculation of cumulative supplementary amount;

[0085] m bujia =∫qdt

[0086] The unit is Kg, and the cumulative amount of replenishment is obtained by adding up the real-time replenishment amounts.

[0087] 3-4) Calculation of remaining propellant in a single tank;

[0088] Δm3=Δm2-m bujia

[0089] The unit is Kg. For different tank remaining amounts, repeat steps 3-1) to 3-4).

[0090] The following is further described in conjunction with specific embodiments:

[0091] In this embodiment, a high-speed rail fuel station is taken as an example to further illustrate the present invention.

[0092] The specific task process of the fuel station throughout its life cycle is shown in the attached Figure 1 After separating from the rocket, the high-orbit fuel station enters the GTO transfer orbit and enters the GEO orbit through multiple apogee changes in the GTO transfer orbit; during the non-mission period in the GEO orbit, the fuel station is in a steady-state flight state, maintaining a three-axis stable attitude relative to the earth, and the orbit is maintained as needed; during the GEO orbit mission period, the service spacecraft approaches and docks at the fuel station, and then the fuel station replenishes bipropellant to the service spacecraft.

[0093] The fuel station has a bipropellant high-thrust orbit control engine and a low-thrust attitude control engine. The propellant tank is as shown in the attached Figure 3 As shown, the two oxidizer tanks and the two fuel tanks are symmetrically distributed in parallel.

[0094] The following is a detailed description of the measurement scheme for the remaining propellant at different mission stages of the fuel station. Figure 1

[0095] Step 1: After the GEO orbital fuel station separates from the rocket, the orbital control engine performs multiple apogee maneuvers to enter the GEO orbit. During this stage, the propellant consumption is calculated using the orbital control engine's small deviation equation, indirectly obtaining the total remaining amount of oxidizer and the total remaining amount of fuel.

[0096] The propellant of the fuel station in the GTO transfer phase flows out through the pipeline with propulsion function. The flow rate is large and the remaining propellant can be calculated by the small deviation equation of the orbital control engine, including the following steps

[0097] 1-1) Obtain the oxidizer and fuel consumption per second of the orbit control engine using the small deviation equation;

[0098]

[0099]

[0100] The seconds consumed for each orbit change are different, and the precise seconds consumed for the oxidizer and fuel of the orbit change can be fitted by the main engine inlet pressure and propellant temperature parameters at the orbit change fuel station. is the oxidant consumption per second, is the fuel consumption per second, both in kg / s, a1 is the sensitivity of the oxidizer consumption per second to the oxidizer tank pressure, a2 is the sensitivity of the oxidizer consumption per second to the oxidizer tank temperature, a3 is the sensitivity of the oxidizer consumption per second to the fuel tank pressure, a4 is the sensitivity of the oxidizer consumption per second to the fuel tank temperature, b1 is the sensitivity of the fuel consumption per second to the fuel tank pressure, b2 is the sensitivity of the fuel consumption per second to the fuel tank temperature, b3 is the sensitivity of the fuel consumption per second to the oxidizer tank pressure, b4 is the sensitivity of the fuel consumption per second to the oxidizer tank temperature, P eo 、P er 、T eo 、T er are the main engine rated operating condition inlet oxidant pressure, fuel pressure, oxidant temperature, fuel temperature, P to 、P tr 、T to 、T trare the oxidant pressure, fuel pressure, oxidant temperature, and fuel temperature at the inlet of the main engine under actual working conditions, respectively. a0 and b0 are fitting constants, respectively.

[0101] 1-2) Calculate propellant consumption;

[0102]

[0103]

[0104] The unit is kg, where t1 is the start-up time of the orbit control engine. For multiple orbit changes, the total oxidizer consumption m can be calculated by accumulating the seconds consumed for each orbit change and the orbit change time. o1 and fuel consumption m r1 .

[0105] 1-3) Calculate the remaining amount of propellant, including the total remaining amount of oxidizer and the total remaining amount of fuel

[0106] Δm o1 =m o -m o1

[0107] Δm r1 =m r -m r1

[0108] where m o is the total amount of oxidant added, m r is the total amount of fuel filled. During the GTO transfer phase, two oxidizer tanks are discharged in parallel, and two fuel tanks are discharged in parallel. The calculated remaining amount of oxidizer Δm o1 and the remaining fuel volume Δm r1 are the total remaining amount of oxidant and the total remaining amount of combustion agent respectively.

[0109] The GTO transfer section supplementary module is not working, so it cannot be measured by the ultrasonic flow meter method or the gas volume excitation method, because this method will affect the engine inlet pressure and cause the engine to deviate from the operating point.

[0110] Step 2: During the steady-state flight phase of the GEO orbital fuel station, the remaining amount of each oxidizer tank and fuel tank is obtained by the gas volume excitation method;

[0111] During the steady-state GEO orbit phase, the fuel station doesn't need to perform a refueling mission; it only needs to maintain three-axis attitude stability and maintain orbit. During this phase, propellant consumption is minimal, so real-time monitoring of remaining propellant in the tanks is unnecessary. Prior to the refueling mission, the remaining propellant in each oxidizer and fuel tank can be determined using the gas volume excitation method to prepare for the mission.

[0112] The specific gas volume excitation system composition is as shown in the attached Figure 4 As shown, each tank is connected to a small gas cylinder upstream. The gas cylinder and the tank are isolated by a valve. The gas cylinder is equipped with pressure, temperature and other sensors. Similarly, the tank is also equipped with pressure, temperature and other sensors. Before measurement, the small gas cylinder is filled with gas within a certain pressure range through the main gas cylinder of the booster circuit. Then, the valve between the small gas cylinder and the tank is opened to discharge part of the gas in the small gas cylinder into the measured tank. This measurement method can measure the remaining amount of a single tank. Assuming that the gas cylinder pressure p set before measurement is g0 MPa, temperature is T g0 K, the volume of the gas cylinder is V g0 L, the compression factor is Z g0 , after measuring the cylinder pressure p g1 MPa, temperature is T g1 K, the compression factor is Z g1 , measure the front tank pressure p z0 MPa, temperature is T z0 K, the volume of the tank air cavity is V z0 L, the compression factor is Z z0 , measure the rear tank pressure p z1 MPa, temperature is T z1 K, the compression factor is Z z1 The measurement of the remaining propellant at this stage includes the following steps:

[0113] 2-1) The small gas cylinder is inflated through the main gas cylinder of the booster circuit. The inflation pressure of the small gas cylinder is determined by the storage tank volume, the small gas cylinder volume, and the accuracy of the pressure sensor, and is designed to be within 5MPa;

[0114] 2-2) Open the valve between the small gas cylinder and the storage tank to stimulate the gas in the small gas cylinder into the storage tank, changing the tank pressure;

[0115] 2-3) Calculation of the gas cavity volume of a single tank after gas volume excitation;

[0116]

[0117] 2-4) Calculation of remaining quantity in a single tank;

[0118] Δm2=(VV z0 )×ρ

[0119] The unit is kg, where V is the total volume of the tank, in L, and ρ is the density of the propellant in the tank, in kg / L. For different tank remaining capacities, steps 2-1) to 2-4) are repeated.

[0120] The gas volume excitation method depends on the accuracy of the pressure and temperature sensors. In order to improve the accuracy of the residual quantity measurement, it is necessary to select high-precision pressure sensors and temperature sensors.

[0121] As attached Figure 3 The fuel station has two oxidizer tanks and two fuel tanks, so steps 2-1) to 2-4) need to be performed four times so that the remaining propellant in each oxidizer tank and each fuel tank can be calculated separately.

[0122] Step 3: During the propellant replenishment phase for the service aircraft at the fuel station, the amount of propellant replenished is measured using an ultrasonic flow meter, thereby indirectly obtaining the remaining amount in a single tank;

[0123] During the propellant refueling phase, typically one fuel station tank is refueled with one service vehicle tank. The remaining propellant in the fuel station tank changes dynamically during the on-orbit refueling process, necessitating real-time measurement of the remaining propellant. During this process, the engine is virtually inoperative, making the engine's small deviation equation method ineffective. Furthermore, the gas volume excitation method is also inadequate during the refueling process. Therefore, an ultrasonic flow meter can be used to dynamically measure both the real-time and cumulative refueling amounts.

[0124] The ultrasonic flowmeter method uses the phase difference of the ultrasonic waves in the forward and reverse flow on the replenishment pipeline to obtain the real-time replenishment amount. The ultrasonic flowmeter is interspersed in the replenishment pipeline, one for the oxidizer replenishment pipeline and one for the fuel replenishment pipeline. Unlike industrial applications, the clamp-type flowmeter used in industry is independent of the pipeline. The flowmeter proposed in this paper must participate in the propellant transmission as part of the pipeline. The specific single-channel schematic diagram is attached. Figure 5 , the method comprises the following steps:

[0125] 3-1) Using ultrasonic flowmeters to obtain real-time forward and reverse flow phase difference data during the refilling process of each tank;

[0126] 3-2) Real-time calculation of the amount of fuel to be added to each tank at the fuel station;

[0127]

[0128] Unit is m 3 / s, where q is the volume flow rate of the propellant, c is the velocity of the ultrasonic wave in the static propellant, D is the diameter of the pipe, L is the length of the pipe for ultrasonic measurement, and f is the ultrasonic frequency. k is the ultrasonic forward and reverse flow phase difference, h is the flow correction factor.

[0129] 3-3) Calculation of cumulative supplementary amount;

[0130] m bujia =∫qdt

[0131] The unit is Kg, and the cumulative amount of replenishment is obtained by adding up the real-time replenishment amounts.

[0132] 3-4) Calculation of remaining propellant in a single tank;

[0133] Δm3=Δm2-m bujia

[0134] The unit is Kg. For different tank remaining amounts, repeat steps 3-1) to 3-4).

[0135] Similarly, the fuel station has two oxidizer tanks and two fuel tanks, so steps 3-1) to 3-4) need to be performed four times, so that the remaining propellant in each oxidizer tank and each fuel tank of the fuel station during the refueling mission can be calculated separately.

[0136] 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 measuring the remaining propellant in a GEO orbital fuel station during its entire life cycle, characterized in that: include: After the GEO orbit fuel station separates from the rocket, it enters the GTO transfer orbit and uses the orbit control engine to make multiple apogee changes to enter the GEO orbit. During the GTO transfer phase, the propellant consumption is calculated using the engine small deviation equation, indirectly obtaining the total remaining amount of oxidizer and the total remaining amount of fuel. During the steady-state flight phase of the GEO orbital fuel station, pressurized gas is replenished into each tank of the fuel station through small gas cylinders configured in the propulsion system. Based on the data from the high-precision pressure and temperature sensors configured on the system, the remaining propellant amount in each oxidizer tank and fuel tank is obtained through the gas volume excitation method; During the propellant replenishment stage at the fuel station, ultrasonic flow meters are respectively installed on the oxidizer replenishment pipeline and the fuel replenishment pipeline. The amount of propellant replenished is measured by the ultrasonic flow meter method based on the principle of forward and reverse flow phase difference, thereby indirectly obtaining the remaining amount of a single tank.

2. The method for measuring the remaining propellant in a GEO orbital fuel station during its entire life cycle according to claim 1, wherein: During the GTO transfer mission at the fuel station, the total remaining amount of oxidizer and the total remaining amount of fuel are indirectly obtained by calculating the propellant consumption, including: The oxidizer consumption per second and the combustible consumption per second of the orbit control engine are obtained through the small deviation equation; the propellant consumption is calculated based on the oxidizer consumption per second and the combustible consumption per second, and then the propellant remaining amount is obtained, including the total remaining amount of oxidizer and the total remaining amount of combustible.

3. The method for measuring the remaining propellant in a GEO orbital fuel station during its entire life cycle according to claim 2, wherein: The method of obtaining the oxidizer consumption per second and the combustion agent consumption per second of the orbit control engine by using the small deviation equation includes: The second consumption of each orbit change is different. The precise second consumption of the oxidizer and fuel of the orbit change is fitted by the main engine inlet pressure and propellant temperature parameters at the orbit change fuel station. is the oxidant consumption per second, is the fuel consumption per second, a1 is the sensitivity of the oxidizer consumption per second to the oxidizer tank pressure, a2 is the sensitivity of the oxidizer consumption per second to the oxidizer tank temperature, a3 is the sensitivity of the oxidizer consumption per second to the fuel tank pressure, a4 is the sensitivity of the oxidizer consumption per second to the fuel tank temperature, b1 is the sensitivity of the fuel consumption per second to the fuel tank pressure, b2 is the sensitivity of the fuel consumption per second to the fuel tank temperature, b3 is the sensitivity of the fuel consumption per second to the oxidizer tank pressure, b4 is the sensitivity of the fuel consumption per second to the oxidizer tank temperature, P eo 、P er 、T eo 、T er are the main engine rated operating condition inlet oxidant pressure, fuel pressure, oxidant temperature, fuel temperature, P to 、P tr 、T to 、T tr are the oxidant pressure, fuel pressure, oxidant temperature, and fuel temperature at the inlet of the main engine under actual working conditions, respectively. a0 and b0 are the fitting constants, respectively.

4. The method for measuring the remaining propellant in a GEO orbital fuel station during its entire life cycle according to claim 3, wherein: The propellant consumption is calculated as follows: Where t1 is the start-up time of the orbit control engine. For multiple orbit changes, the total oxidizer consumption m can be calculated by accumulating the seconds consumed for each orbit change and the orbit change time. o1 and fuel consumption m r1。 5. The method for measuring the remaining propellant in a GEO orbital fuel station during its entire life cycle according to claim 4, characterized in that: The remaining amount of propellant is calculated as follows: Δm o1 =m o -m o1 Δm r1 =m r -m r1 where m o is the total amount of oxidant added, m r is the total amount of fuel filled. During the GTO transfer phase, two oxidizer tanks are discharged in parallel, and two fuel tanks are discharged in parallel. The calculated remaining amount of oxidizer Δm o1 and the remaining fuel volume Δm r1 are the total remaining amount of oxidant and the total remaining amount of combustion agent respectively.

6. The method for measuring the remaining propellant in a GEO orbital fuel station during its entire life cycle according to claim 1, characterized in that: During the steady-state flight phase of the GEO orbit at the fuel station, the remaining propellant in each oxidizer tank and fuel tank is obtained using the gas volume excitation method, including: First, hardware configuration is added to the propulsion system configuration. A separate gas cylinder is required upstream of the gas supply of each tank. This gas cylinder is isolated from the tank by a self-locking valve, and is also isolated from the propulsion system's main booster gas cylinder by a self-locking valve. The gas cylinder is inflated on demand through the booster main gas cylinder. This gas cylinder is equipped with pressure and temperature sensors, and the tank is also equipped with pressure and temperature sensors. Before measurement, the gas cylinder is filled with gas within a certain pressure range through the booster main gas cylinder. Then, the valve between the gas cylinder and the tank is opened to discharge part of the gas in the gas cylinder into the measured tank, and the remaining amount in the single tank is measured. Assume that the cylinder pressure p set before measurement g0 MPa, temperature is T g0 , volume is V g0 , the compression factor is Z g0 , after measuring the cylinder pressure p g1 , temperature is T g1 , the compression factor is Z g1 , measure the front tank pressure p z0 , temperature is T z0 , the volume of the tank air cavity is V z0 , the compression factor is Z z0 , measure the rear tank pressure p z1 , temperature is T z1 , the compression factor is Z z1 The measurement of the remaining propellant at this stage includes the following steps: Inflate the gas cylinder through the main gas cylinder of the booster circuit; Open the valve between the gas cylinder and the storage tank to stimulate the gas in the small gas cylinder into the storage tank and change the tank pressure; Calculate the volume V of the gas cavity of a single tank after gas volume excitation z0 ; Then get the remaining amount of a single tank Δm2; Δm2=(VV z0 )×ρ Where V is the total volume of a single tank and ρ is the propellant density in the tank.

7. The method for measuring the remaining propellant in a GEO orbital fuel station during its entire life cycle according to claim 6, wherein: Calculate the volume V of the gas cavity of a single tank after gas volume excitation z0 8. The method for measuring the remaining propellant in a GEO orbital fuel station during its entire life cycle according to claim 6, wherein: The filling pressure of the gas cylinder is determined by the tank volume, the cylinder volume and the accuracy of the pressure sensor, and is designed to be within 5MPa.

9. The method for measuring the remaining propellant in a GEO orbital fuel station during its entire life cycle according to claim 8, characterized in that: During the GEO orbital propellant replenishment mission at the fuel station, the amount of propellant replenished is measured using an ultrasonic flowmeter based on the principle of forward and reverse flow phase difference, indirectly obtaining the remaining amount in a single tank, including: The ultrasonic flow meter method uses the phase difference of the forward and reverse ultrasonic waves in the feeding pipeline to obtain the real-time feeding amount. The ultrasonic flow meter is integrated in the feeding pipeline, one for the oxidant feeding pipeline and one for the fuel feeding pipeline, as part of the feeding pipeline, and includes the following steps: The ultrasonic flow meter is used to obtain the forward and reverse flow phase difference data of a single tank during the replenishment process in real time; Calculate the real-time replenishment quantity q of a single tank at a fuel station; Calculate the cumulative replenishment volume of a single tank m bujia ; m bujia =∫qdt The unit is kg, and the cumulative amount of supplementation is obtained by adding up the real-time amount of supplementation; Calculate the remaining amount of propellant in a single tank Δm3; Δm3=Δm2-m bujia Where Δm2 is the remaining amount of propellant in a single tank calculated for the GEO orbit steady-state flight mission segment.

10. The method for measuring the remaining propellant in a GEO orbital fuel station during its entire life cycle according to claim 9, characterized in that: The specific calculation of the real-time replenishment amount of a single tank at a fuel station is: Where q is the instantaneous volume flow rate of the propellant, c is the flow rate of the ultrasonic wave in the static propellant, D is the pipe diameter, L is the length of the pipe for ultrasonic measurement, and f is the ultrasonic frequency. k is the ultrasonic forward and reverse flow phase difference, h is the flow correction factor.

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