Gas injection excitation propellant remaining quantity measurement system and method based on differential pressure

Abstract

The present invention discloses a differential pressure-based gas injection-stimulated propellant remaining quantity measurement system and method, comprising: a high-pressure gas cylinder; an inflation gas container, connected in sequence to a first latching valve and the high-pressure gas cylinder via a pipeline, and in sequence to a second latching valve and a storage tank via another pipeline; a first pressure-stabilizing gas container, connected to one end of a third latching valve via a pipeline, the other end of which is connected to a pipeline between the second latching valve and the storage tank via a pipeline; a second pressure-stabilizing gas container, connected to one end of a fourth latching valve via a pipeline, the other end of which is connected to a pipeline between the second latching valve and the storage tank via a pipeline, a differential pressure sensor being connected between the first and second pressure-stabilizing gas containers; and a storage tank, a second pressure sensor being provided on a pipeline outside the storage tank. The present invention can accurately measure the gas pressure difference within the storage tank before and after gas injection, thereby improving the measurement accuracy of the remaining propellant quantity by at least one order of magnitude.

Description

Technical Field

[0001] The present invention relates to the field of on-orbit measurement technology for spacecraft propulsion systems, and in particular to a system and method for measuring the remaining amount of a propellant excited by gas injection based on differential pressure. Background Art

[0002] While operating in orbit, spacecraft sometimes need to maintain their orbit. This operation consumes the spacecraft's own propellant, and the spacecraft's on-orbit lifespan is largely determined by its ability to maintain its orbit. Therefore, the consumption of a spacecraft's own propellant plays a crucial role in predicting its on-orbit lifespan and is a crucial component of its on-orbit management. To accurately measure the amount of propellant remaining in spacecraft under microgravity conditions on-orbit and thus accurately predict its on-orbit lifespan, numerous technologies have been developed, including flow meters, pressure-volume-temperature (PVT), radioactive tracers, radioactive absorption, bookkeeping (BK), radiofrequency, ultrasonic, gas injection pressure stimulation (PGS), volumetric stimulation, and propellant sloshing amplitude, frequency, and phase. The PGS method, due to its high accuracy, simple equipment, and ease of implementation, holds great potential as a future method for measuring propellant remaining, providing more accurate predictions of future spacecraft orbital lifespans.

[0003] The existing gas injection pressure excitation method uses a gas cylinder to inject a certain amount of gas into the propellant tank. An absolute pressure sensor is used to measure the change in gas pressure before and after injection. The amount of gas inside the tank is then calculated using the laws of thermodynamics to inversely infer the amount of gas inside the tank, thereby calculating the volume of propellant inside the tank. However, due to the high operating pressure of propellant tanks, ranging from 0.1 to 3 MPa, the tank pressure change caused by the gas injection pressure excitation method is currently typically in the range of tens of kilopascals or even several kilopascals. Therefore, using an absolute pressure sensor to measure the pressure difference before and after gas injection places extremely high demands on the absolute pressure sensor's accuracy, range, and operating pressure. Furthermore, even if the absolute pressure sensor's accuracy, range, and operating pressure meet the measurement requirements, the absolute error in the measurement of the gas pressure inside the tank before and after gas injection is still large, resulting in significant limitations for the existing gas injection pressure excitation method in measuring the remaining propellant in spacecraft. Summary of the Invention

[0004] In order to solve some or all of the technical problems existing in the above-mentioned prior art, the present invention provides a gas injection excitation propellant remaining amount measurement system and method based on differential pressure.

[0005] The technical solutions of the present invention are as follows:

[0006] In a first aspect, a differential pressure-based gas injection excitation propellant remaining amount measurement system is provided, the system comprising:

[0007] A high-pressure gas cylinder, which is used as a gas source;

[0008] an inflatable gas container, the inflatable gas container being sequentially connected to a first self-locking valve and the high-pressure gas cylinder via a pipeline, and sequentially connected to a second self-locking valve and a storage tank via another pipeline, the inflatable gas container being provided with a first pressure sensor and a first temperature sensor;

[0009] a first pressure-stabilizing gas container, the first pressure-stabilizing gas container being connected to one end of a third self-latching valve via a pipeline, and the other end of the third self-latching valve being connected to a pipeline between the second self-latching valve and the tank via a pipeline;

[0010] a second pressure-stabilized gas container, the second pressure-stabilized gas container being connected to one end of a fourth self-latching valve via a pipeline, the other end of the fourth self-latching valve being connected to a pipeline between the second self-latching valve and the tank via a pipeline, and a differential pressure sensor being connected between the first pressure-stabilized gas container and the second pressure-stabilized gas container for measuring a pressure difference between the first pressure-stabilized gas container and the second pressure-stabilized gas container;

[0011] The storage tank and the pipeline outside the storage tank are provided with a second pressure sensor.

[0012] In some possible implementations, the system further includes: a fifth self-locking valve connected to the pipeline between the high-pressure gas cylinder and the first self-locking valve, and a filter connected between the fifth self-locking valve and the first self-locking valve for filtering impurities in the gas.

[0013] In some possible implementations, the system further includes a sixth self-latching valve, one end of which is connected to the pipeline between the filter and the first self-latching valve through a pipeline, and the other end of which is connected to the pipeline between the tank and the second self-latching valve through a pipeline.

[0014] In some possible implementations, the sixth self-locking valve is a pressure reducing valve.

[0015] In some possible implementations, the first self-latching valve, the second self-latching valve, the third self-latching valve, the fourth self-latching valve, and the fifth self-latching valve are all solenoid valves.

[0016] In a second aspect, a method for measuring the remaining amount of a propellant using a gas injection excitation system based on differential pressure is provided. The method comprises:

[0017] Control the second self-locking valve, the third self-locking valve and the fourth self-locking valve to be in a closed state, and control the first self-locking valve to be in an open state;

[0018] After the temperature and pressure of the high-pressure gas cylinder and the inflation gas container reach equilibrium, closing the first self-locking valve and recording the gas pressure in the inflation gas container;

[0019] opening one of the third self-locking valve and the fourth self-locking valve, and closing the third self-locking valve or the fourth self-locking valve in the open state after the pressure of the first pressure-stabilizing gas container or the second pressure-stabilizing gas container and the tank reaches equilibrium;

[0020] opening the second self-locking valve, and after the temperature and pressure of the inflation gas container and the storage tank reach equilibrium, closing the second self-locking valve and recording the gas pressure in the inflation gas container;

[0021] opening the other of the third self-latching valve and the fourth self-latching valve, and closing the third self-latching valve or the fourth self-latching valve that is in the open state after the pressure of the first pressure-stabilizing gas container or the second pressure-stabilizing gas container reaches equilibrium with the storage tank;

[0022] Recording the pressure difference between the first pressure-stabilized gas container and the second pressure-stabilized gas container;

[0023] The remaining amount of propellant in the tank is calculated based on the gas pressure in the inflation gas container, the pressure difference between the first and second pressure-stabilizing gas containers, and the pre-measured volumes of the inflation gas container and the tank.

[0024] In some possible implementations, the remaining amount of propellant in the tank is calculated using the following formula:

[0025]

[0026] Among them, V L represents the volume of propellant in the tank, V T Denotes the volume of the tank, V p represents the volume of the inflatable gas container, P' represents the gas pressure in the inflatable gas container after gas injection, P1 represents the gas pressure in the inflatable gas container before gas injection, and ΔP represents the pressure difference between the first pressure-stabilizing gas container and the second pressure-stabilizing gas container.

[0027] The main advantages of the technical solution of the present invention are as follows:

[0028] The differential pressure-based gas injection excitation propellant remaining amount measurement system and method of the present invention achieves pressure balance between the tank before and after gas injection by setting a first pressure-stabilized gas container and a second pressure-stabilized gas container, and uses a differential pressure sensor to measure the pressure difference data between the first pressure-stabilized gas container and the second pressure-stabilized gas container. It can accurately measure the gas pressure difference inside the tank before and after gas injection. Compared with the existing gas injection pressure excitation method that directly uses an absolute pressure sensor to measure the gas pressure difference inside the tank before and after gas injection, the corresponding pressure difference measurement accuracy can be improved by 50 to 100 times, thereby improving the measurement accuracy of the propellant remaining amount by at least one order of magnitude, thereby significantly improving the prediction accuracy of the spacecraft's on-orbit life, and reducing the measurement accuracy performance requirements of the pressure sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The drawings described herein are used to provide a further understanding of the embodiments of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0030] Figure 1 This is a schematic structural diagram of a system for measuring the remaining amount of propellant using a gas injection excitation system based on differential pressure according to an embodiment of the present invention;

[0031] Figure 2 This is a schematic structural diagram of another differential pressure-based gas injection excitation propellant remaining quantity measurement system according to an embodiment of the present invention;

[0032] Figure 3 This is a schematic structural diagram of another differential pressure-based gas injection excitation propellant remaining quantity measurement system according to an embodiment of the present invention;

[0033] Figure 4 This is a flow chart of a method for measuring the remaining amount of propellant using gas injection stimulation based on differential pressure according to an embodiment of the present invention.

[0034] Description of reference numerals:

[0035] 1-high-pressure gas cylinder, 21-inflatable gas container, 22-first pressure sensor, 23-first temperature sensor, 31-first pressure-stabilizing gas container, 32-second pressure-stabilizing gas container, 33-differential pressure sensor, 41-storage tank, 42-second pressure sensor, 51-first self-locking valve, 52-second self-locking valve, 53-third self-locking valve, 54-fourth self-locking valve, 55-fifth self-locking valve, 56-sixth self-locking valve, 6-filter. DETAILED DESCRIPTION

[0036] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments of the present invention and corresponding drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0037] The technical solutions provided by the embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0038] See also Figure 1 In a first aspect, an embodiment of the present invention provides a system for measuring the remaining amount of propellant using a gas injection excitation system based on differential pressure, the system comprising:

[0039] High-pressure gas cylinder 1, which is used as a gas source;

[0040] The inflation gas container 21 is connected to the first self-locking valve 51 and the high-pressure gas cylinder 1 in sequence through a pipeline, and is connected to the second self-locking valve 52 and the storage tank 41 in sequence through another pipeline. The inflation gas container 21 is provided with a first pressure sensor 22 and a first temperature sensor 23;

[0041] A first pressure-stabilizing gas container 31 is connected to one end of a third self-locking valve 53 via a pipeline, and the other end of the third self-locking valve 53 is connected to the pipeline between the second self-locking valve 52 and the tank 41 via a pipeline;

[0042] A second pressure-stabilizing gas container 32 is connected to one end of a fourth self-locking valve 54 via a pipeline. The other end of the fourth self-locking valve 54 is connected to a pipeline between the second self-locking valve 52 and the storage tank 41 via a pipeline. A differential pressure sensor 33 is connected between the first pressure-stabilizing gas container 31 and the second pressure-stabilizing gas container 32 for measuring the pressure difference between the first pressure-stabilizing gas container 31 and the second pressure-stabilizing gas container 32;

[0043] The storage tank 41 and the second pressure sensor 42 are arranged on the pipeline outside the storage tank 41 .

[0044] Specifically, when the differential pressure-based gas injection excitation propellant remaining quantity measurement system provided by an embodiment of the present invention is in use, if it is not necessary to measure the propellant remaining quantity in the tank 41, the first self-locking valve 51, the second self-locking valve 52, the third self-locking valve 53 and the fourth self-locking valve 54 are all controlled to be in a closed state. If it is necessary to measure the propellant remaining quantity in the tank 41, the second self-locking valve 52, the third self-locking valve 53 and the fourth self-locking valve 54 are kept in a closed state, and the first self-locking valve 51 is opened; after the temperature and pressure of the high-pressure gas cylinder 1 and the inflation gas container 21 reach equilibrium, the first self-locking valve 51 is closed, and the gas pressure in the inflation gas container 21 is recorded; one of the third self-locking valve 53 and the fourth self-locking valve 54 is opened, and after the pressure of the first pressure-stabilizing gas container 31 or the second pressure-stabilizing gas container 32 reaches equilibrium with the tank 41, the valve is closed. The third self-locking valve 53 or the fourth self-locking valve 54 is in the open state. Specifically, if the third self-locking valve 53 is currently opened, the third self-locking valve 53 is closed after the pressure of the first pressure-stabilizing gas container 31 and the storage tank 41 are balanced. If the fourth self-locking valve 54 is currently opened, the fourth self-locking valve 54 is closed after the pressure of the second pressure-stabilizing gas container 32 and the storage tank 41 are balanced. The second self-locking valve 52 is opened, and the temperature and pressure of the inflation gas container 21 and the storage tank 41 are balanced, and then the second self-locking valve 52 is closed, and the inflation is recorded. The gas pressure in the gas container 21; open the other of the third self-locking valve 53 and the fourth self-locking valve 54, and after the pressure of the first pressure-stabilizing gas container 31 or the second pressure-stabilizing gas container 32 reaches equilibrium with the storage tank 41, close the third self-locking valve 53 or the fourth self-locking valve 54 in the open state. Specifically, if the third self-locking valve 53 is opened in the previous step, open the fourth self-locking valve 54 at this time, and after the pressure of the second pressure-stabilizing gas container 32 reaches equilibrium with the storage tank 41, close the fourth self-locking valve 54. If the third self-locking valve 53 is opened in the previous step, open the fourth self-locking valve 54 at this time, and after the pressure of the second pressure-stabilizing gas container 32 reaches equilibrium with the storage tank 41, close the fourth self-locking valve 54. The fourth self-locking valve 54 is opened, and the third self-locking valve 53 is opened at this time. After the pressure of the first pressure-stabilizing gas container 31 and the storage tank 41 reach equilibrium, the third self-locking valve 53 is closed, and the pressure difference data between the first pressure-stabilizing gas container 31 and the second pressure-stabilizing gas container 32 is recorded. The remaining amount of propellant in the storage tank 41 is calculated based on the recorded pressure data of the inflation gas container 21 before and after gas injection, the pressure difference data between the first pressure-stabilizing gas container 31 and the second pressure-stabilizing gas container 32, and the pre-measured volume data of the inflation gas container 21 and the storage tank 41.

[0045] It can be seen that the differential pressure-based gas injection excitation propellant remaining amount measurement system provided by an embodiment of the present invention provides a first pressure-stabilized gas container 31 and a second pressure-stabilized gas container 32 to balance the pressure with the tank 41 before and after gas injection, and uses a differential pressure sensor 33 to measure the pressure difference data between the first pressure-stabilized gas container 31 and the second pressure-stabilized gas container 32. It can accurately measure the gas pressure difference inside the tank 41 before and after gas injection. Compared with the existing gas injection pressure excitation method that directly uses an absolute pressure sensor to measure the gas pressure difference inside the tank 41 before and after gas injection, the corresponding pressure difference measurement accuracy can be improved by 50 to 100 times, so that the measurement accuracy of the propellant remaining amount is improved by at least one order of magnitude, thereby significantly improving the prediction accuracy of the spacecraft's on-orbit life and reducing the measurement accuracy requirements of the pressure sensor.

[0046] Further, see Figure 2 In one embodiment of the present invention, the measurement system may further include: a fifth self-locking valve 55 connected to the pipeline between the high-pressure gas cylinder 1 and the first self-locking valve 51, and a filter 6 connected between the fifth self-locking valve 55 and the first self-locking valve 51 for filtering impurities in the gas.

[0047] Specifically, by providing the fifth self-locking valve 55 and the filter 6 , the gas discharged from the high-pressure gas cylinder 1 can be filtered to prevent impurities contained in the gas from entering the tank 41 and causing damage to the spacecraft propulsion system.

[0048] Among them, when the measurement system includes the fifth self-locking valve 55, if it is necessary to use the high-pressure gas cylinder 1 to inflate the inflation gas container 21, the first self-locking valve 51 and the fifth self-locking valve 55 are controlled to be in the open state. After the temperature and pressure of the high-pressure gas cylinder 1 and the inflation gas container 21 reach equilibrium, the fifth self-locking valve 55 and the first self-locking valve 51 are closed.

[0049] The gas stored in the high-pressure gas cylinder 1 may be helium with a pressure higher than a preset value, and the preset value may be set according to the working pressure of the storage tank 41 .

[0050] Further, see Figure 3 In one embodiment of the present invention, the measuring system may further include a sixth self-locking valve 56, one end of the sixth self-locking valve 56 is connected to the pipeline between the filter 6 and the first self-locking valve 51 through a pipeline, and the other end is connected to the pipeline between the tank 41 and the second self-locking valve 52 through a pipeline.

[0051] Specifically, by providing the sixth self-locking valve 56, the high-pressure gas cylinder 1 can be connected to the tank 41 through the fifth self-locking valve 55, the filter 6 and the sixth self-locking valve 56. This allows the high-pressure gas stored in the high-pressure gas cylinder 1 to be used to accurately measure the remaining amount of propellant in the tank 41, and the high-pressure gas stored in the high-pressure gas cylinder 1 can be used as the squeezing gas of the tank 41 during operation to discharge the propellant.

[0052] Optionally, the sixth self-locking valve 56 may be a pressure reducing valve. By adopting the pressure reducing valve, it is possible to control the on-off of the pipeline between the high-pressure gas cylinder 1 and the storage tank 41 and to regulate the pressure of the gas entering the storage tank 41.

[0053] Optionally, the first self-latching valve 51, the second self-latching valve 52, the third self-latching valve 53, the fourth self-latching valve 54 and the fifth self-latching valve 55 are all solenoid valves. By adopting solenoid valves, automatic control of the self-latching valves can be achieved, making it easy to open and close the self-latching valves.

[0054] See also Figure 4 In a second aspect, an embodiment of the present invention further provides a method for measuring the remaining amount of propellant using a gas injection excitation system based on differential pressure, the method comprising the following steps:

[0055] S1, control the second self-latching valve 52, the third self-latching valve 53 and the fourth self-latching valve 54 to be in the closed state, and control the first self-latching valve 51 to be in the open state;

[0056] S2, after the temperature and pressure of the high-pressure gas cylinder 1 and the inflation gas container 21 reach equilibrium, close the first self-locking valve 51 and record the gas pressure in the inflation gas container 21;

[0057] S3, open one of the third self-locking valve 53 and the fourth self-locking valve 54, and after the pressure of the first pressure-stabilizing gas container 31 or the second pressure-stabilizing gas container 32 reaches equilibrium with the storage tank 41, close the third self-locking valve 53 or the fourth self-locking valve 54 in the open state;

[0058] S4, open the second self-locking valve 52, wait until the temperature and pressure of the inflation gas container 21 and the storage tank 41 reach equilibrium, then close the second self-locking valve 52 and record the gas pressure in the inflation gas container 21;

[0059] S5: Open the other of the third self-locking valve 53 and the fourth self-locking valve 54. After the pressure of the first pressure-stabilizing gas container 31 or the second pressure-stabilizing gas container 32 reaches equilibrium with the storage tank 41, close the third self-locking valve 53 or the fourth self-locking valve 54 in the open state.

[0060] S6, recording the pressure difference between the first pressure-stabilizing gas container 31 and the second pressure-stabilizing gas container 32;

[0061] S7 , calculating the remaining amount of propellant in the tank 41 based on the gas pressure in the inflation gas container 21 , the pressure difference between the first and second pressure-stabilizing gas containers 31 and 32 , and the pre-measured volumes of the inflation gas container 21 and the tank 41 .

[0062] The gas pressure in the inflation gas container 21 is directly measured by the first pressure sensor 22 , and the pressure difference between the first pressure-stabilizing gas container 31 and the second pressure-stabilizing gas container 32 is directly measured by the differential pressure sensor 33 .

[0063] In step S2, when the pressure value detected by the first pressure sensor 22 remains unchanged or the pressure value fluctuates only within a preset pressure range, it indicates that the pressures of the high-pressure gas cylinder 1 and the inflation gas container 21 have reached equilibrium; when the temperature value detected by the first temperature sensor 23 remains unchanged or the temperature value fluctuates only within a preset temperature range, it indicates that the temperatures of the high-pressure gas cylinder 1 and the inflation gas container 21 have reached equilibrium.

[0064] In step S3 and step S5, when the pressure value detected by the second pressure sensor 42 remains unchanged or fluctuates only within the preset pressure range, it means that the pressure of the first stabilizing gas container 31 or the second stabilizing gas container 32 and the tank 41 is balanced.

[0065] In step S4, when the pressure values ​​detected by the first pressure sensor 22 and the second pressure sensor 42 remain unchanged or fluctuate only within a preset pressure range, it indicates that the pressures of the inflation gas container 21 and the storage tank 41 have reached equilibrium; and when the temperature value detected by the first temperature sensor 23 remains unchanged or fluctuates only within a preset temperature range, it indicates that the temperatures of the inflation gas container 21 and the storage tank 41 have reached equilibrium.

[0066] Assuming that the liquid in the tank 41 is in an incompressible state, the remaining amount of propellant in the tank 41 can be calculated using the following formula:

[0067]

[0068] Among them, V L represents the volume of propellant in the tank 41, V T represents the volume of the tank 41, V p represents the volume of the inflation gas container 21, P' represents the gas pressure in the inflation gas container 21 after gas injection, P1 represents the gas pressure in the inflation gas container 21 before gas injection, and ΔP represents the pressure difference between the first pressure-stabilizing gas container 31 and the second pressure-stabilizing gas container 32.

[0069] The following is a detailed description of the derivation process of the above-mentioned calculation formula for the remaining propellant:

[0070] Assumption: Before gas injection, the first gas in the gas container 21 satisfies the following ideal gas state equation:

[0071] P1V1=n1RT1

[0072] The second gas in the tank 41 satisfies the following ideal gas state equation:

[0073] P2V2=n2RT2

[0074] Among them, P1 represents the gas pressure in the inflation gas container 21 before gas injection, V1 represents the gas volume in the inflation gas container 21, n1 represents the amount of substance of the first gas, R represents the ideal gas constant, T1 represents the gas temperature in the inflation gas container 21 before gas injection, P2 represents the gas pressure in the storage tank 41 before gas injection, V2 represents the gas volume in the storage tank 41, n2 represents the amount of substance of the second gas, and T2 represents the gas temperature in the storage tank 41 before gas injection.

[0075] When the inflation gas container 21 is used to inject gas into the storage tank 41 , part of the first gas in the inflation gas container 21 will enter the storage tank 41 and mix with the second gas in the storage tank 41 .

[0076] Assumption: After gas injection, the first gas satisfies the following ideal gas state equation:

[0077] P1'V1'=n1RT1'

[0078] The second gas satisfies the following ideal gas state equation:

[0079] P2'V2'=n2RT2'

[0080] Wherein, P1' represents the pressure of the first gas after gas injection, V1' represents the volume of the first gas after gas injection, T1' represents the temperature of the first gas after gas injection, P2' represents the pressure of the second gas after gas injection, V2' represents the volume of the second gas after gas injection, and T2' represents the temperature of the second gas after gas injection.

[0081] Wherein, V1′=V1+ΔV, V2′=V2−ΔV, and ΔV represents the volume of the first gas in the tank 41 after gas injection.

[0082] Since the gas temperature and gas pressure in the inflation gas container 21 and the storage tank 41 are equal when the inflation gas container 21 and the storage tank 41 reach the final equilibrium state, we have:

[0083] P1'=P2'

[0084] T1'=T2'

[0085] Furthermore, from the perspective of gas energy change, since the first gas and the second gas do not exchange heat with the outside world, and the mutual compression of the gases is internal work, the entire gas system maintains energy conservation during the gas injection process.

[0086] Furthermore, the energy changes of the gas in the inflation gas container 21 and the storage tank 41 are analyzed respectively.

[0087] Specifically, the gas energy in the inflation gas container 21 can be expressed as:

[0088] E1=n1(u1+KE1+PE1)

[0089] u1=h1-p1V1

[0090]

[0091] PE1=gz1

[0092] Among them, E1 represents the gas energy in the gas-filled gas container 21, u1 represents the specific internal energy of the gas in the gas-filled gas container 21, h1 represents the specific enthalpy of the gas in the gas-filled gas container 21, p1 represents the specific pressure of the gas in the gas-filled gas container 21, KE1 represents the specific kinetic energy of the gas in the gas-filled gas container 21, v1 represents the velocity of the gas in the gas-filled gas container 21, PE1 represents the specific potential energy of the gas in the gas-filled gas container 21, g represents the acceleration due to gravity, and z1 represents the height change of the gas in the gas-filled gas container 21.

[0093] Because the gas in the gas container 21 does not exchange heat with the outside world before and after gas injection, the gas velocity is 0, no gravity work occurs, and the specific kinetic energy and specific potential energy inside the system do not change. Therefore, the energy change of the gas in the gas container 21 after gas injection is expressed as:

[0094] ΔE1=n1Δu1

[0095] Here, ΔE1 represents the change in the gas energy in the gas container 21 , and Δu1 represents the change in the specific internal energy of the gas in the gas container 21 .

[0096] Since h=C p T, pV = RT, then the energy change of the gas in the gas container 21 can be expressed as:

[0097] ΔE1=n1Δu1=n1[Δh1-Δ(p1V1)]=n1C p1 (T1′-T1)-n1R(T1′-T1)=n1C V1 (T1'-T1)

[0098] Where h represents the specific enthalpy of the gas, C prepresents the constant pressure specific heat capacity of the gas, T represents the gas temperature, p represents the gas specific pressure, V represents the gas volume, Δh1 represents the change in the specific enthalpy of the gas in the gas container 21, Δ(p1V1) represents the change in p1V1, C p1 represents the constant pressure specific heat capacity of the gas in the gas container 21, C V1 represents the constant volume specific heat capacity of the gas in the inflation gas container 21.

[0099] Referring to the above analysis process for the change in gas energy in the inflation gas container 21, similarly, the change in gas energy in the storage tank 41 can be expressed as:

[0100] ΔE2=n2C V2 (T2'-T2)

[0101] Wherein, ΔE2 represents the energy change of the gas in the tank 41, C V2 represents the constant volume specific heat capacity of the gas in the tank 41.

[0102] Since the energy change of the entire gas system ΔE=0, we can get:

[0103] n1C V1 (T1'-T1)=-n2C V2 (T2'-T2)

[0104]

[0105] Among them, T'=T1'=T2'.

[0106] set up Then T' can be expressed as:

[0107]

[0108] Combining the above expressions, we can get:

[0109]

[0110]

[0111] Where P'=P1'=P2'

[0112] When the pressure of a gas does not change greatly, the change range of its constant volume specific heat capacity is extremely small. For example, the C of helium He (4.004) at 1.55MPa to 6MPa and 200K to 350K is V The value range is: 3119.1 (1.55MPa, 350K)-3138.3 (6.0MPa, 200K) kJ / (kg·K), and the variation range is only ±0.6%. Therefore, in one embodiment of the present invention, the CV The value remains unchanged, that is, C V1 =C V2 , then T' and P' can be expressed as:

[0113]

[0114]

[0115] Furthermore, when only propellant and gas exist inside the tank 41, the volume of the propellant inside the tank 41 satisfies the formula V L =V T -V2, when there is only gas inside the inflatable gas container 21, there is V p = V1, and the pressure difference ΔP between the first and second pressure-stabilizing gas containers 31, 32 = P'-P2. Therefore, combined with the above expression for P', the calculation formula for the remaining amount of propellant in the tank 41 can be obtained:

[0116] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In addition, "front", "back", "left", "right", "upper" and "lower" in this document are all referenced to the placement states shown in the accompanying drawings.

[0117] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for measuring the remaining amount of a propellant using a differential pressure gas injection excitation system, the method comprising: A high-pressure gas cylinder used as a gas source; an inflation gas container, the inflation gas container being connected in sequence to a first self-locking valve and the high-pressure gas cylinder via a pipeline, and to a second self-locking valve and a tank via another pipeline, the inflation gas container being provided with a first pressure sensor and a first temperature sensor; a first pressure-stabilizing gas container, the first pressure-stabilizing gas container being connected to one end of a third self-locking valve via a pipeline, the other end of the third self-locking valve being connected to a pipeline between the second self-locking valve and the tank via a pipeline; a second pressure-stabilizing gas container, the second pressure-stabilizing gas container being connected to one end of a fourth self-locking valve via a pipeline, the other end of the fourth self-locking valve being connected to a pipeline between the second self-locking valve and the tank via a pipeline, a differential pressure sensor being connected between the first and second pressure-stabilizing gas containers for measuring the pressure difference between the first and second pressure-stabilizing gas containers; and a second pressure sensor being provided on a pipeline outside the tank, wherein the method for measuring the remaining amount of propellant for gas injection excitation based on differential pressure comprises: Control the second self-locking valve, the third self-locking valve and the fourth self-locking valve to be in a closed state, and control the first self-locking valve to be in an open state; After the temperature and pressure of the high-pressure gas cylinder and the inflation gas container reach equilibrium, closing the first self-locking valve and recording the gas pressure in the inflation gas container; opening one of the third self-locking valve and the fourth self-locking valve, and closing the third self-locking valve or the fourth self-locking valve in the open state after the pressure of the first pressure-stabilizing gas container or the second pressure-stabilizing gas container and the tank reaches equilibrium; opening the second self-locking valve, and after the temperature and pressure of the inflation gas container and the storage tank reach equilibrium, closing the second self-locking valve and recording the gas pressure in the inflation gas container; opening the other of the third self-latching valve and the fourth self-latching valve, and closing the third self-latching valve or the fourth self-latching valve that is in the open state after the pressure of the first pressure-stabilizing gas container or the second pressure-stabilizing gas container reaches equilibrium with the storage tank; Recording the pressure difference between the first pressure-stabilized gas container and the second pressure-stabilized gas container; The remaining amount of propellant in the tank is calculated based on the gas pressure in the inflation gas container, the pressure difference between the first and second pressure-stabilizing gas containers, and the pre-measured volumes of the inflation gas container and the tank.

2. The method for measuring the remaining amount of propellant using gas injection excitation based on differential pressure according to claim 1, characterized in that: The remaining amount of propellant in the tank is calculated using the following formula: Among them, V L represents the volume of propellant in the tank, V T Denotes the volume of the tank, V p represents the volume of the inflatable gas container, P' represents the gas pressure in the inflatable gas container after gas injection, P1 represents the gas pressure in the inflatable gas container before gas injection, and ΔP represents the pressure difference between the first pressure-stabilizing gas container and the second pressure-stabilizing gas container.

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