Flow stability control method for on-orbit refueling of drop pressure propulsion system

Abstract

The application provides a flow stability control method for on-orbit refueling of a drop pressure type propulsion system, and has the characteristics that the total flow resistance of a supplement system under a desired stable flow is obtained; real-time pressure parameters of a storage tank are obtained, and a real-time desired head of an electric pump under a set desired stable flow is given; the supplement system is driven by a pressure difference between the storage tank of a service satellite and a receiver satellite to stably flow propellant; the speed requirement of the electric pump under the set desired stable flow is obtained; the electric pump is controlled to operate at the required speed, and the propellant is driven to stably transmit at the set desired flow interval; in the process of driving the supplement by the electric pump, the instantaneous supplement flow and the cumulative supplement total amount are measured by an ultrasonic flowmeter, and driving is continued until the cumulative supplement amount meets the requirement. The application combines the change characteristics of the storage tank pressure of the service satellite and the receiver satellite in the process of supplementing the propellant, and is an on-orbit flow stability control scheme completely designed for high-orbit conventional high-value targets.

Description

TECHNICAL FIELD

[0001] The present application relates to on-orbit servicing, in particular to a flow stability control method for on-orbit refueling of a drop pressure propulsion system. BACKGROUND

[0002] Since the propellant resource is a consumable product, it is a high-value resource on the orbit, and the carrying amount of the propellant directly determines the maneuverability of the spacecraft and the service life of the spacecraft. It can be said that the carrying amount of the propellant is an important factor to determine the service efficiency of the spacecraft. Therefore, in recent years, on-orbit refueling technology has attracted attention and recognition from many parties. At present, the domestic on-orbit small-flow refueling device with water medium has been verified, and the on-orbit refueling technology verification of real propellant is still in the ground development stage.

[0003] On-orbit refueling technology involves two types of satellites, one is a service satellite, which is the active supplement of propellant, and the other is a receiver satellite, which is the passive receiver of propellant. Especially for the GEO orbit receiver satellite currently in orbit, its propulsion system is mostly a drop pressure propulsion system, and its upstream high-pressure gas source has been cut off. As the propellant is consumed, the system pressure becomes smaller and smaller, and the system drop pressure range may be relatively large, which will affect the safety design of the supplement task. During the propellant supplement process, as the propellant is supplemented, the system pressure of the receiver satellite will become higher, and the pressure difference between the service satellite and the receiver satellite storage tank is a dynamic time-varying quantity, which causes certain difficulty in stable transmission of the propellant.

[0004] Research shows that the on-orbit refueling technology of GEO orbit satellite has a broad application prospect and high application value, so it is necessary to solve the on-orbit refueling problem of the drop pressure system, and the flow stability control technology is one of the key technologies of on-orbit refueling technology. The safe and stable supplement flow directly affects the safety of the supplement task, and in the face of this application background, it is necessary to carry out research on the flow stability control scheme in the on-orbit refueling process. SUMMARY

[0005] In order to solve the flow stability control problem of the drop pressure to drop pressure propulsion system, the present application provides a flow stability control method for on-orbit refueling of a drop pressure to drop pressure propulsion system.

[0006] The present application solves the above technical problems by the following technical scheme:

[0007] A flow stability control method for on-orbit refueling of a drop pressure to drop pressure propulsion system, characterized in that it comprises the following steps:

[0008] Step 1), obtaining the total flow resistance of the supplement system between the service satellite and the receiver satellite at the expected stable flow during the ground development stage;

[0009] Step 2), the real-time pressure parameters of the storage tanks of the service satellite and the receiver satellite are obtained by the on-orbit pressure sensor, and the real-time expected head of the electric pump at the set expected stable flow is given based on the total flow resistance of the replenishment system at the expected stable flow, and if the real-time expected head of the electric pump is not greater than zero, step 3) is entered, and if the real-time expected head of the electric pump is greater than zero, step 4) is entered;

[0010] Step 3), the replenishment system drives the stable flow of the propellant by the pressure difference between the storage tanks of the service satellite and the receiver satellite, and the cumulative replenishment amount is measured by the ultrasonic flow meter, and if the cumulative replenishment amount meets the requirement, the replenishment task is directly ended, and if the cumulative replenishment amount does not meet the requirement, step 2) is switched to;

[0011] Step 4), the speed requirement of the electric pump at the set expected stable flow is obtained by the flow-speed-head formula of the electric pump;

[0012] Step 5), the electric pump is controlled to operate at the required speed to drive the stable transmission of the propellant at the set expected flow interval;

[0013] Step 6), in the process of driving the replenishment by the electric pump, the instantaneous replenishment flow and the cumulative replenishment amount are measured by the ultrasonic flow meter, if the cumulative replenishment amount meets the requirement, the replenishment task is ended, and if the cumulative replenishment amount does not meet the requirement, the instantaneous replenishment amount is required to judge the replenishment process, if the instantaneous replenishment flow exceeds the set expected flow interval, step 2) is returned, and if the instantaneous replenishment flow does not exceed the set expected flow interval, the driving is continued at the current speed until the cumulative replenishment amount meets the requirement.

[0014] Further, in step 1), the total flow resistance of the replenishment system between the service satellite and the receiver satellite at the expected stable flow is obtained by means of cold flow test in the ground development stage.

[0015] Further, in step 1), the replenishment system involves the following components of the service satellite: storage tank, pipe valve assembly, electric pump, flow meter, floating disconnect, and involves the following components of the receiver satellite: storage tank, pipe valve assembly, floating disconnect, and the total flow resistance of the replenishment system at the set expected stable flow is tested by single machine development and ground system test, the set flow is the volume flow, and the total flow resistance of the replenishment system corresponding to different components of the propellant is different.

[0016] Further, in step 2), the service satellite and the receiver satellite are a falling pressure system in the process of replenishment, and the upstream high-pressure gas source cannot be supplied, and as the replenishment of the propellant, the pressure of the storage tank of the service satellite becomes lower and lower, and the pressure of the storage tank of the receiver satellite becomes higher and higher, the pressure difference between the storage tanks of the service satellite and the receiver satellite is a dynamic time-varying quantity, and the expected head requirement of the electric pump is also a dynamic time-varying quantity.

[0017] Further, in the step 2), the gas path between the service satellite and the recipient satellite is not connected, only the liquid path is connected to transmit the propellant.

[0018] Further, in the step 3), the supplement instantaneous flow driven by the pressure difference of the storage tank between the service satellite and the recipient satellite is monotonically reduced with the continuous reduction of the pressure difference, and the maximum pressure difference between the service satellite and the recipient satellite is considered in the design of the system, and the total flow resistance of the supplement system is designed to ensure that the instantaneous supplement flow is within the safe supplement flow range.

[0019] Further, in the step 4), the centrifugal pump scheme is adopted for the electric pump, and in the calculation formula of the flow, the rotational speed and the head, the head is a quadratic equation of the blade outlet linear speed under the condition of setting the expected flow, the electric pump blade outlet linear speed is inversely calculated through the formula, and the expected rotational speed of the electric pump under the expected flow is further obtained.

[0020] Further, in the step 5), the classic control method is adopted to control the electric pump motor to operate at the expected rotational speed, and to drive the propellant to be transmitted in the expected instantaneous flow range.

[0021] In the step 6), the ultrasonic flowmeter is adopted to measure the instantaneous supplement flow and the total supplement amount, and the number of times of adjusting the rotational speed of the electric pump is reduced through the setting of the expected flow range.

[0022] Further, the service satellite is the active supplement side of the propellant in the on-orbit refueling task, and the recipient satellite is the passive receiving side of the propellant.

[0023] Further, the step 4) comprises:

[0024] 4-1) obtaining the linear speed u2 corresponding to the electric pump blade outlet through the centrifugal pump flow rotational speed head formula;

[0025] 4-2) obtaining the rotational speed n of the electric pump through the electric pump outlet linear speed formula.

[0026] Compared with the prior art, the application has the following advantages:

[0027] The application provides a flow stability control method for on-orbit refueling of a drop pressure to drop pressure propelling system, which combines the change characteristics of the storage tank pressure of the service satellite and the recipient satellite in the propellant supplement process, is a kind of on-orbit flow stability control scheme specially designed for high-orbit conventional high-value targets, and the prior art is still blank in the on-orbit refueling application of the propellant. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 The application provides a flow stability control method for on-orbit refueling of a drop pressure to drop pressure propelling system.

[0029] Figure 2 The schematic diagram of the drop pressure to drop pressure propulsion system in the composition of the on-orbit refueling system provided by the application. DETAILED DESCRIPTION

[0030] The specific embodiments of the application are described in further detail below with reference to the accompanying drawings.

[0031] The application provides a drop pressure to drop pressure on-orbit refueling flow stability control scheme, which analyzes the system pressure parameter characteristics of a service satellite and a receptor satellite, combines the design flow resistance characteristics of a supplement system, calculates the required head of an electric pump at a desired stable flow, proposes that, in the case that the required head is not greater than zero, the stable transmission of propellant is driven by the safe pressure difference between the service satellite and the receptor satellite through the flow resistance design of the supplement system, and, in the case that the required head is greater than zero, the desired speed of the electric pump is obtained through the flow-speed-head equation of the electric pump, the motor of the electric pump is controlled to stably operate at the desired speed, the stable flow of propellant is driven, and it is ensured that the on-orbit refueling is performed at the desired set flow. The instantaneous supplement flow and the cumulative supplement total amount are measured through ultrasonic flow in the process, which are used as high-precision judgment means for the speed adjustment of the electric pump and whether the supplement task is terminated. The flow stability control technology in the on-orbit refueling process is one of the key technologies that need to be researched, and the safe and stable supplement flow directly affects the safety of the supplement task. The proposal of the scheme can greatly improve the safety of the on-orbit refueling task and provide strong technical support for the on-orbit application of the on-orbit refueling technology.

[0032] The drop pressure to drop pressure on-orbit refueling flow stability control method of the application is suitable for supplementing propellant from a drop pressure service satellite to a drop pressure receptor satellite. The scheme is also completely suitable for supplementing propellant from a constant pressure service satellite to a drop pressure receptor satellite. The proposal of the control scheme solves the stable supplement flow control problem of a conventional high-value target in a GEO orbit. In the supplement process, the gas circuit of the service satellite is not connected with the gas circuit of the receptor satellite, but only the liquid circuit between the two satellites is connected to transmit the propellant.

[0033] Figure 1 The flowchart of the drop pressure to drop pressure on-orbit refueling flow stability control method provided by the application is shown in FIG. 1. Figure 1 As shown in the figure, the specific process is as follows.

[0034] (1) In the ground development stage, the total flow resistance p of the supplement system between the service satellite and the receptor satellite at the desired stable flow Q is obtained through cold flow test and other means. f ;

[0035] The replenishment system involves components such as the storage tank, pipe valve assembly, electric pump, flow meter, and floating breakers of the service satellite, and the storage tank, pipe valve assembly, and floating breakers of the receptor satellite, and needs to test the total flow resistance of the replenishment system under a set expected stable flow rate through single machine development and ground system test, the set flow rate being a volume flow rate, and the total flow resistance of the system being different for different propellant components, p f The unit is MPa.

[0036] (2) In-orbit real-time pressure parameters of the storage tanks of the service satellite and the receptor satellite are obtained through on-board pressure sensors, and based on the total flow resistance of the replenishment system under the expected stable flow rate, the real-time expected head p h of the electric pump under the set expected stable flow rate is given. h If the real-time expected head p b of the electric pump is not greater than zero, step 3) is entered, and if it is greater than zero, step 4) is entered.

[0037] The service satellite and the receptor satellite are drop pressure systems during the replenishment process, and an upstream high-pressure gas source cannot be supplied. As the propellant is replenished, the pressure of the storage tank of the service satellite becomes lower and lower, and the pressure of the storage tank of the receptor satellite becomes higher and higher. The pressure difference between the storage tanks of the service satellite and the receptor satellite is a dynamic time-varying variable, so the expected head requirement of the electric pump is also a dynamic time-varying variable. The gas path between the service satellite and the receptor satellite is not connected, and only the liquid path is connected to transmit the propellant. The real-time pressure of the storage tank of the service satellite is p s , the unit being MPa, and the real-time pressure of the storage tank of the receptor satellite is p h , the unit being MPa. The head of the electric pump under the set expected stable flow rate Q is

[0038] p f = p b -p s

[0039] (3) If the real-time expected head p h of the electric pump is not greater than zero, the replenishment system drives the stable flow of the propellant through the pressure difference between the storage tanks of the service satellite and the receptor satellite, and measures the cumulative replenishment total through the ultrasonic flow meter. If the cumulative replenishment total under the driving of the pressure difference between the storage tanks meets the requirements, the replenishment task is directly ended, and if it does not meet the requirements, step 2) is switched to.

[0040] The instantaneous replenishment flow rate under the driving of the pressure difference between the storage tanks monotonically decreases as the pressure difference between the storage tanks of the service satellite and the receptor satellite continuously decreases. The maximum pressure difference between the storage tanks of the service satellite and the receptor satellite is considered at the beginning of the system design, and the instantaneous replenishment flow rate is ensured to be within the safe replenishment flow rate range through the total flow resistance design of the replenishment system.

[0041] (4) When the real-time expected head of the electric pump is greater than zero, the speed demand of the electric pump under the set expected stable flow is obtained through the flow-speed-head formula of the electric pump;

[0042] The centrifugal pump scheme is adopted by the electric pump. In the calculation formula of the flow, speed and head of the electric pump, under the condition of setting the expected flow, the head is a quadratic equation of the blade outlet linear speed. The electric pump blade outlet linear speed can be inversely calculated through the formula, and the expected speed of the electric pump under the expected flow can be further obtained.

[0043] The specific steps are as follows:

[0044] 4-1) The linear speed u2 corresponding to the electric pump blade outlet is obtained through the centrifugal pump flow-speed-head formula. The centrifugal pump flow-speed-head formula is as follows

[0045]

[0046] The linear speed u2 is in units of m / s, wherein β2 is the blade outlet angle of the electric pump, F2 is the flow area of the electric pump blade outlet, the blade outlet angle and the flow area of the electric pump blade outlet are known quantities, Q is the instantaneous flow of the electric pump, ρ is the density of the supplemented fluid, and k is the head loss coefficient of the electric pump. This equation is a quadratic equation about u2. It can be seen that the equation has two positive and negative roots, and the positive root is the required u2.

[0047]

[0048] 4-2) The speed n of the electric pump is obtained through the electric pump outlet linear speed formula;

[0049]

[0050] The unit is r / min, wherein D2 is the diameter of the blade outlet.

[0051] (5) The electric pump is controlled to operate at the required speed, and the propellant is driven to be stably transmitted at the set expected flow range.

[0052] The classic control method such as the PID method is used to control the electric pump motor to operate at the expected speed, and the propellant is driven to be transmitted in the expected instantaneous flow range.

[0053] (6) During the driving and supplementing process of the electric pump, the instantaneous supplementing flow and the cumulative supplementing total amount are measured through the ultrasonic flowmeter. If the cumulative supplementing total amount meets the requirement, the supplementing task is ended. If the cumulative supplementing total amount does not meet the requirement, the instantaneous supplementing flow is used to judge the supplementing process. If the instantaneous supplementing flow exceeds the set expected flow range, step 2) is returned. If it does not exceed, the driving is continued at the current speed until the cumulative supplementing amount meets the requirement.

[0054] The ultrasonic flowmeter is used to measure the instantaneous supplement flow and the cumulative supplement total amount, which is currently the only high-precision measurement method capable of directly measuring the instantaneous supplement flow, and the precision is higher than that of the conventional indirect measurement PVT method, and the number of electric pump speed adjustments is reduced through the setting of the expected flow interval Q±ΔQ.

[0055] The following will be further described in combination with specific embodiments:

[0056] In the embodiment, the on-orbit refueling task of two satellites in a high orbit is taken as an example to further illustrate the application.

[0057] In the on-orbit refueling task, two satellites are involved, one is a service satellite, which is the active supplement side of propellant in the on-orbit refueling task, and the other is a receptor satellite, which is the passive receiving side of propellant.

[0058] The service satellite propulsion system is a dual-component propulsion system, and the two components are methyl hydrazine and green nitrogen peroxide. The propulsion system is a drop pressure type propulsion system in the supplement process, and the high-pressure gas upstream of the tank is not supplied. The system tank pressure continuously decreases in the supplement process. The receptor satellite propulsion system is also a dual-component propulsion system, and the two components are methyl hydrazine and green nitrogen peroxide. The propulsion system is also a drop pressure type propulsion system in the supplement process, and the high-pressure gas upstream of the tank is not supplied. The system tank pressure continuously increases in the supplement process. In order to stably transmit the propellant of the service satellite to the receptor satellite, an electric pump and an ultrasonic flowmeter are configured on the supplement pipeline. Figure 2 The drop pressure type to drop pressure type propulsion system on-orbit refueling system provided by the application is shown in the schematic diagram, and the specific system configuration is shown in the attached Figure 2 .

[0059] The propellant flow stable control scheme of the on-orbit refueling task will be described in detail below, and the reference Figure 1 is made. The specific process is as follows:

[0060] Step 1: Obtain the total flow resistance p of the supplement system between the service satellite and the receptor satellite at the set expected stable flow Q through ground cold flow test and other means f ;

[0061] The supplement system involves the tank, pipe valve assembly, electric pump, flowmeter, floating disconnectors and other components of the service satellite, and also involves the tank, pipe valve assembly, floating disconnectors and other components of the receptor satellite. The total flow resistance of the supplement system at the set expected stable flow needs to be explored through single machine development and ground system test. The set flow is the volumetric flow, and the system total flow resistance of different components is different, p f unit: MPa.

[0062] Step 2, get the storage tank pressure of the service satellite and the receiver satellite through the on-board pressure sensor, so as to give the head of the electric pump under the set expected stable flow h .

[0063] The real-time pressure of the storage tank of the service satellite is p b , in MPa, and the real-time pressure of the storage tank of the receiver satellite is p s , in MPa, so the head of the electric pump under the set expected stable flow is

[0064] p h = p f - p b + p s

[0065] Step 3, if p h ≤ 0, the system pressure does not need to be increased by the electric pump, the electric pump is not started, and the system will automatically form a stable filling balance point under a certain flow, and the stable transmission flow becomes smaller and smaller as the pressure difference between the two storage tanks decreases.

[0066] Step 4, if p h > 0, the speed requirement of the electric pump under the set expected stable flow is obtained through the flow-speed-head formula of the electric pump;

[0067] comprising the following steps

[0068] 4-1) the linear speed u2 corresponding to the blade outlet of the electric pump is obtained through the flow-speed-head formula of the centrifugal pump, and the flow-speed-head formula of the centrifugal pump is as follows

[0069]

[0070] The linear speed u2 is in m / s, wherein β2 is the blade outlet installation angle of the electric pump, F2 is the blade outlet flow area of the electric pump, the blade outlet installation angle and the blade outlet flow area are known quantities, Q is the instantaneous flow of the electric pump, ρ is the density of the supplemented fluid, and k is the head loss coefficient of the electric pump. This equation is a quadratic equation in u2, and it can be seen that the equation has two positive and negative roots, and the positive root is the required u2.

[0071]

[0072] In the case, β2 < 90°.

[0073] 4-2) the speed n of the electric pump is obtained through the electric pump outlet linear speed formula

[0074]

[0075] in r / min, wherein D2 is the diameter of the blade outlet.

[0076] Step 5, the rotational speed of the electric pump is controlled according to the requirement of the rotational speed of the electric pump by using the conventional PID method;

[0077] Step 6, the real-time supplement amount and the cumulative supplement amount are measured by the ultrasonic flowmeter, if the cumulative supplement amount requirement is reached without starting the electric pump, the supplement is stopped according to the requirement, if the supplement flow exceeds the set range Q±ΔQ with the electric pump started, step 2 is returned to carry out a new round of rotational speed adjustment of the electric pump.

[0078] The propulsion system of GEO orbit satellite is mostly a drop pressure system, especially the system pressure in the final stage can be relatively low, for this type of satellite supplement, the flow stability control mainly depends on the total supplement amount. In the case of large total supplement amount, the initial supplement process is generally driven by the pressure difference between the service satellite and the receiver satellite, when the supplement amount reaches a certain value, the pressure difference driving cannot meet the supplement speed requirement, so the head of the electric pump is needed to provide power for the propellant to flow at the set speed. In the case of small total supplement amount, the pressure difference driving can meet the supplement task requirement.

[0079] The contents not described in detail in the specification of the present application are the known technology of the person skilled in the art.

[0080] It should be noted that the above is only a schematic description and explanation of the present application, and the person skilled in the art should understand that any modification and replacement of the present application belongs to the protection scope of the present application.

Claims

1. A method for stabilizing flow control of an on-orbit refueling system of a drop-pressure to drop-pressure propulsion system, characterized in that: The steps include: Step 1) obtaining the total flow resistance of the replenishment system between the service satellite and the recipient satellite at the desired stable flow rate during the ground development phase; Step 2) obtaining real-time tank pressure parameters of the service satellite and the recipient satellite via an onboard pressure sensor in orbit, and providing a real-time expected head of the electric pump at the set expected stable flow rate based on the total flow resistance of the replenishment system at the expected stable flow rate. If the real-time expected head of the electric pump is not greater than zero, proceed to step 3); if it is greater than zero, proceed to step 4); Step 3) The refueling system uses the tank pressure differential between the service satellite and the recipient satellite to drive a stable flow of propellant. The total amount of refueling is measured by an ultrasonic flow meter. If the total amount of refueling driven by the tank pressure differential meets the requirements, the refueling mission is terminated directly. If not, the process switches to step 2). Step 4) Obtain the speed requirement of the electric pump under the desired stable flow rate through the flow rate, speed and head formula of the electric pump; Step 5), controlling the electric pump to run at the required speed, driving the propellant to be stably transmitted according to the set desired flow range; Step 6) During the electric pump driving and replenishing process, the instantaneous replenishing flow rate and the cumulative replenishing total amount are measured by the ultrasonic flow meter. If the cumulative replenishing total amount meets the requirement, the replenishing task is terminated. If the cumulative replenishing total amount does not meet the requirement, the replenishing process needs to be judged by the instantaneous replenishing flow rate. If the instantaneous replenishing flow rate exceeds the set expected flow rate range, return to step 2). If it does not exceed, continue to drive at the current speed until the cumulative replenishing total amount meets the requirement.

2. The flow stabilization control method for on-orbit refueling of a drop-pressure-to-drop-pressure propulsion system according to claim 1, characterized in that: In the step 1), the total flow resistance of the replenishment system between the service satellite and the recipient satellite under the expected stable flow rate is obtained by means of a cold flow test during the ground development stage.

3. The flow stabilization control method for on-orbit refueling of a drop-pressure-to-drop-pressure propulsion system according to claim 1, characterized in that: In step 1), the replenishment system involves the following components of the service satellite: a tank, a pipe-valve assembly, an electric pump, a flow meter, and a floating disconnect, and also involves the following components of the recipient satellite: a tank, a pipe-valve assembly, and a floating disconnect. The total flow resistance of the replenishment system at a set expected stable flow rate is tested through single-unit development and ground system testing. The set expected stable flow rate is a volumetric flow rate, and the total flow resistance of the replenishment system corresponding to different component propellants is different.

4. The flow stabilization control method for on-orbit refueling of a drop-pressure-to-drop-pressure propulsion system according to claim 1, characterized in that: In step 2), the service satellite and the receptor satellite are a drop-pressure system during the replenishment process, and the upstream high-pressure gas source cannot be supplied. As the propellant is replenished, the tank pressure of the service satellite becomes lower and lower, and the tank pressure of the receptor satellite becomes higher and higher. The tank pressure difference between the service satellite and the receptor satellite is a dynamic time-varying variable, and the expected head requirement for the electric pump is also a dynamic time-varying variable.

5. The flow stabilization control method for on-orbit refueling of a drop-pressure-to-drop-pressure propulsion system according to claim 1, characterized in that: In step 2), the gas path between the service satellite and the recipient satellite is not connected, and only the liquid path is connected to transmit the propellant.

6. The flow stabilization control method for on-orbit refueling of a drop-pressure-to-drop-pressure propulsion system according to claim 1, characterized in that: In step 3), the instantaneous supplementary flow driven by the tank pressure difference will decrease monotonically as the tank pressure difference between the service satellite and the recipient satellite continues to decrease. At the beginning of system design, the maximum tank pressure difference condition between the service satellite and the recipient satellite should be considered, and the total flow resistance of the supplementary system should be designed to ensure that the instantaneous supplementary flow is within the safe supplementary flow range.

7. The flow stabilization control method for on-orbit refueling of a drop-pressure-to-drop-pressure propulsion system according to claim 1, characterized in that: In the step 4), the electric pump adopts a centrifugal pump solution, and in the calculation formula of its flow, speed and head, under the condition of setting the expected stable flow, the head is a quadratic equation of the blade outlet linear velocity. The electric pump blade outlet linear velocity is inversely calculated by this formula to further obtain the expected speed of the electric pump under the set expected stable flow.

8. The flow stabilization control method for on-orbit refueling of a drop-pressure-to-drop-pressure propulsion system according to claim 1, characterized in that: In step 5), a classical control method is used to control the electric pump motor to run at a desired speed, driving the propellant to be transferred within a set desired flow range; In step 6), an ultrasonic flow meter is used to measure the instantaneous supplementary flow rate and the cumulative total amount of supplementary flow, and the number of times the electric pump speed is adjusted is reduced by setting the desired flow range.

9. The flow stabilization control method for on-orbit refueling of a drop-pressure-to-drop-pressure propulsion system according to claim 1, characterized in that: The service satellite is the active propellant replenisher in the on-orbit refueling mission, and the recipient satellite is the passive propellant receiver.

10. The flow stabilization control method for on-orbit refueling of a drop-pressure-to-drop-pressure propulsion system according to claim 1, characterized in that: The step 4) comprises: 4-1) The electric pump adopts a centrifugal pump, and the linear velocity u2 corresponding to the outlet of the electric pump blade is obtained by the centrifugal pump flow rate, speed and head formula; 4-2) Obtain the electric pump speed n using the electric pump outlet linear velocity formula.

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