A simulation test system and method for consistent droplet generator spraying characteristics

Abstract

This invention discloses a method and system for simulating the consistency of droplet generator spreading characteristics between ground and space, used to obtain the spreading characteristics of droplet generators in a vacuum environment. It can equivalently convert ground test results into space test results, solving the problem of equivalent measurement for consistency between ground and space. By scaling down the operating parameters of the jet spreader under rated conditions, it overcomes the adverse effects caused by ground test environment limitations leading to excessively thick droplets that do not match the actual spreading effect in the space environment, thus achieving equivalent measurement for consistency between ground and space. Furthermore, by placing several droplet collectors with the same surface area and material at different locations and measuring the mass increment of multiple droplet collectors, it achieves measurement of liquid film thickness uniformity.

Description

Technical Field

[0001] This invention belongs to the field of space thermal control technology, specifically relating to a method and system for simulating the consistency of droplet generator dispensing characteristics between space and ground. Background Technology

[0002] The droplet radiator, a novel space thermal control device, mainly consists of a droplet generator, a droplet collector, a circulating pump, a heat exchanger, and fluid piping. Its basic working principle is as follows: the heat exchange medium is heated by flowing through the space payload heat exchanger and then supplied to the droplet generator. Within the droplet generator's collection chamber, the medium is excited by piezoelectric ceramics, generating pressure and flow oscillations at a certain frequency, which are then ejected into the space environment through nozzles to form a jet. Under the action of fluid oscillation, the initial surface wave of the jet forms at the nozzle exit and gradually develops, eventually breaking into a large number of uniformly sized droplets. These droplets radiate heat into the space environment through their large surface area. The cooled droplets are collected by the liquid pump and recycled. Therefore, the size, uniformity, and number of droplets per unit area generated by the droplet generator all affect the heat dissipation of the droplet radiator, while the distribution range of the droplets affects their collection and reuse. Thus, the distribution characteristics of the droplet generator in the space environment are particularly important for the design of the droplet radiator. Summary of the Invention

[0003] To address the limitations of existing ground-based testing methods that make it difficult to accurately simulate the dispensing characteristics of droplet generators in a vacuum environment, this invention aims to provide a method and system for simulating the consistency of droplet generator dispensing characteristics between ground and space, used to obtain the dispensing characteristics of droplet generators in a vacuum environment. This invention's method and system can equivalently convert ground-based test results into space-based test results, solving the problem of equivalent measurement for consistency between ground and space.

[0004] To achieve the above-mentioned technical objectives, the present invention employs the following technical solution:

[0005] A method for simulating the consistency of droplet generator dispensing characteristics between top and bottom surfaces, the method comprising the following steps:

[0006] Step 1: Based on the existing working parameters of the droplet generator and the structural parameters of the spray disk, calculate the rated working conditions in the space environment, that is, the known motor speed n, the droplet velocity ν, and the diameter D of the spreading circle formed by the droplets in the space environment.

[0007] Step 2: Based on the size of the vacuum chamber, give the spray distance L0 under the ground test conditions, and calculate the diameter D0 of the spray circle formed by the droplets under the ground test conditions;

[0008] Step 3: Under the condition that the maximum nozzle distribution circle radius R of the injection disk is consistent under the space environment and ground test conditions, given the droplet velocity V0 under the ground test conditions, calculate the motor speed n0 under the ground test conditions;

[0009] Step 4: Based on the principle of consistent application characteristics between the ground and the surface, i.e., the principle of consistent liquid film thickness, calculate the required flow rate q0 of the working fluid under the ground test conditions;

[0010] Step 5: Set the pre-spray pressure P0 under ground test conditions. According to the flow rate formula, obtain the number of nozzles m of the equivalent injection disk and calculate the nozzle radius r of the equivalent injection disk, or calculate the number of nozzles m of the equivalent injection disk based on the nozzle radius r of the equivalent injection disk.

[0011] Further, step 1 calculates the rated operating conditions under space conditions, i.e., given the motor speed n, droplet velocity ν, and the diameter D of the spreading circle formed by the droplets under space conditions, the expression for D is:

[0012]

[0013] In the formula, L is the spray distance of the droplet in the space environment (meters); ν is the droplet velocity ν in the space environment (meters / second); n is the motor speed in the space environment (revolutions / minute); R is the radius of the maximum nozzle distribution circle of the spray disk (meters); and D is the diameter of the spreading circle formed by the droplet in the space environment (meters).

[0014] Further, in step 2: based on the size of the vacuum chamber, calculate the diameter D0 of the spreading circle formed by the droplets under ground test conditions. The expression for D0 is:

[0015]

[0016] In the formula, L is the spray distance of the droplet in the space environment (in meters); D is the diameter of the spreading circle formed by the droplet in the space environment (in meters); L0 is the spray distance of the droplet under the ground test conditions (in meters); and D0 is the diameter of the spreading circle formed by the droplet under the ground test conditions (in meters).

[0017] Further, in step 3, the motor speed n0 under ground test conditions is calculated to ensure that the maximum nozzle distribution circle radius R of the injection disk is the same under both space and ground test conditions. Given the droplet velocity V0 under ground test conditions, the expression for n0 is:

[0018]

[0019] In the formula, L is the spray distance of the droplet in the space environment (meters); D is the diameter of the spreading circle formed by the droplet in the space environment (meters); V is the droplet velocity in the space environment (meters / second); n is the motor speed in the space environment (revolutions / minute); L0 is the spray distance of the droplet under ground test conditions (meters); D0 is the diameter of the spreading circle formed by the droplet under ground test conditions (meters); V0 is the droplet velocity under ground test conditions (meters / second); and n0 is the motor speed under ground test conditions (revolutions / minute).

[0020] Further, in step 4: based on the principle of consistent application characteristics between ground and surface, i.e., consistent liquid film thickness, the required flow rate q0 of the working fluid under ground test conditions is calculated. The expression for q0 is:

[0021]

[0022] In the formula, q is the flow rate of the working medium in the space environment (kg / s); D is the diameter of the spreading circle formed by the droplets in the space environment (m); q0 is the flow rate of the working medium under the ground test conditions (kg / s); and D0 is the diameter of the spreading circle formed by the droplets under the ground test conditions (m).

[0023] The simulation experiment system constructed using the simulation experiment method of the present invention includes at least a droplet generator test piece, a high-speed camera system, a vacuum system, a host computer, and a droplet collector. The droplet generator test piece is placed inside the vacuum system and includes a storage tank, a distributor, and a controller connected in series. The distributor is connected to the droplet collector. The high-speed camera system includes a high-speed camera, a high-speed camera acquisition unit, a screen, and a light source. The high-speed camera is connected to a control trigger, and the high-speed camera and the screen are respectively deployed on opposite sides of the vacuum chamber. The host computer is connected to the controller and the control trigger.

[0024] Observation windows A and B are located on opposite sides of the vacuum chamber, corresponding to the light screen and high-speed camera, respectively. The storage tank is also connected to a gas source.

[0025] Compared with existing technologies, the present invention has the following technical advantages:

[0026] 1. This invention proposes a simulation test method and system for the consistency of droplet generator spreading characteristics between ground and air, which can obtain the spreading characteristics of droplet generator in a vacuum environment under ground test conditions.

[0027] 2. This invention overcomes the adverse effects caused by the limitation of ground test environment conditions, which leads to excessively thick droplet thickness when using a jet spreader under rated conditions, resulting in a failure to meet the actual spreading effect in the space environment. This invention achieves equivalent measurement with consistent performance between ground and space.

[0028] 3. This invention achieves the measurement of liquid film thickness uniformity by placing several droplet collectors with the same surface area and material at different locations and measuring the mass increment of multiple droplet collectors. Attached Figure Description

[0029] Figure 1 This invention provides a simulation test method for the consistency of droplet generator spraying characteristics between the sky and the ground.

[0030] Figure 2 This diagram illustrates different spraying and spreading distances.

[0031] Figure 3 This is a schematic diagram of the structural principle of the droplet generator spraying characteristic uniformity simulation test system of the present invention.

[0032] The symbols and numbers in the diagram represent the following meanings: 1—Droplet generator test piece; 2—Storage tank; 3—Distributor; 4—Controller; 5—Vacuum system; 6—Droplet collector; 7—Host computer; 8—Gas source; 9—Manual valve; 10—LED light source; 11—Light screen; 12—High-speed camera; 13—High-speed camera acquisition; 14—Control trigger; 15—Cable; 16—Pipeline; 20—Vacuum chamber; 21—Observation window A; 22—Observation window B; 23—Breakthrough port. Detailed Implementation

[0033] Ground-based tests simulating a vacuum environment require placing the entire spraying process within a vacuum chamber. Therefore, due to the size limitations of the vacuum chamber, the spraying distance is significantly shorter than the actual spraying distance in a vacuum. If spraying is performed under standard operating conditions, the number of droplets per unit area at the shorter spraying distance under ground-based test conditions is far greater than the number of droplets per unit area under vacuum conditions. Assuming the sprayed and spread particles are uniformly distributed, the consistency of the number of droplets per unit area can be converted into an evaluation based on the consistency of the liquid film thickness. The number of droplets per unit area directly affects the radiative heat dissipation efficiency, and the droplet spread range directly relates to the design of the droplet collector. Therefore, the test conditions for the spraying process and the number of nozzles on the spraying disk need to be redesigned to ensure that the spraying effect is the same as the effect under rated operating conditions in a space environment, thereby achieving equivalent measurement with consistent ground-to-ground performance. Determining the structural and operating parameters of the equivalent spraying disk is the problem that the equivalent ground-to-ground measurement method needs to solve.

[0034] Meanwhile, the uniformity of the liquid film thickness formed by the working fluid significantly affects the radiative heat dissipation efficiency. Multiple droplet collectors with the same surface area and material can be placed at different locations within the effective range of spraying and spreading at equal distances. The uniformity of the liquid film thickness can be evaluated by measuring the mass increment of these multiple droplet collectors. When operating in a space environment, the droplet generator product needs to form a certain number of droplet particles at a specific spraying distance. The design of the equivalent spray disk is primarily to achieve consistent measurements between ground and space, overcoming the limitations of ground-based test environments (mainly due to varying spraying distances) that lead to excessively high liquid particle density when using a sprayer under rated operating conditions, which does not reflect the actual spreading effect in a space environment.

[0035] See Figures 1-2 This invention is a simulation test method for the consistency of droplet generator spreading characteristics in space. First, based on the existing working parameters of the droplet generator and the structural parameters of the spray disk, the rated working condition in the space environment is calculated (the motor speed n, the droplet velocity ν, and the spreading circle diameter D formed by the droplets in the space environment are known).

[0036] The second step is to calculate the diameter D0 of the droplet spraying circle under the ground test conditions based on the size of the vacuum chamber and the spraying distance L0 under the ground test conditions.

[0037] The third step is to ensure that the maximum nozzle distribution circle radius R of the injection disk is the same under both space and ground test conditions, and to calculate the electrode rotation speed n0 under the given droplet velocity V0 under the ground test conditions.

[0038] The fourth step is to calculate the required flow rate q0 of the working fluid under the ground test conditions, based on the principle of consistent spreading characteristics between the ground and the sky, that is, the principle of consistent liquid film thickness.

[0039] Fifth step: Given the pre-spray pressure P0 under ground test conditions, calculate the nozzle radius r of the equivalent injection disk based on the flow rate formula and the number of nozzles m of the equivalent injection disk, or calculate the number of nozzles m of the equivalent injection disk based on the nozzle radius r of the equivalent injection disk.

[0040] Specifically, in step 1, based on the existing operating parameters of the droplet generator and the structural parameters of the spray disk, the rated operating conditions in the space environment are calculated. The known motor speed n, droplet velocity ν, and the diameter D of the spreading circle formed by the droplets in the space environment are given. The expression for D is:

[0041]

[0042] In the formula, L is the spray distance of the droplet in the space environment (meters); ν is the droplet velocity in the space environment (meters / second); n is the motor speed in the space environment (revolutions / minute); R is the radius of the maximum nozzle distribution circle of the spray disk (meters); and D is the diameter of the spreading circle formed by the droplet in the space environment (meters).

[0043] Step 2: Based on the size of the vacuum chamber, calculate the diameter D0 of the droplet spreading circle under ground test conditions. The expression for D0 is:

[0044]

[0045] In the formula, L is the spray distance of the droplet in the space environment (meters); D is the diameter of the spreading circle formed by the droplet in the space environment (meters); L0 is the spray distance of the droplet under ground test conditions (meters); and D0 is the diameter of the spreading circle formed by the droplet under ground test conditions (meters).

[0046] Step 3: Calculate the motor speed n0 under ground test conditions, ensuring that the maximum nozzle distribution circle radius R of the injection disk is the same under both space and ground test conditions. Given the droplet velocity V0 under ground test conditions, the expression for n0 is:

[0047]

[0048] In the formula, L is the spray distance of the droplet in the space environment (meters); D is the diameter of the spreading circle formed by the droplet in the space environment (meters); V is the droplet velocity in the space environment (meters / second); n is the motor speed in the space environment (revolutions / minute); L0 is the spray distance of the droplet under ground test conditions (meters); D0 is the diameter of the spreading circle formed by the droplet under ground test conditions (meters); V0 is the droplet velocity under ground test conditions (meters / second); and n0 is the motor speed under ground test conditions (revolutions / minute).

[0049] Step 4: Based on the principle of consistent application characteristics between ground and surface, i.e., the principle of consistent liquid film thickness, calculate the required flow rate q0 of the working fluid under ground test conditions. The expression for q0 is:

[0050]

[0051] In the formula, q is the flow rate of the working medium in the space environment (kg / s); D is the diameter of the spreading circle formed by the droplets in the space environment (m); q0 is the flow rate of the working medium under the ground test conditions (kg / s); and D0 is the diameter of the spreading circle formed by the droplets under the ground test conditions (m).

[0052] Step 5: Given the pre-spray pressure P0 under the ground test conditions, calculate the nozzle radius r of the equivalent injection disk based on the flow rate formula and the number of nozzles m of the equivalent injection disk, or calculate the number of nozzles m of the equivalent injection disk based on the nozzle radius r of the equivalent injection disk.

[0053] See Figure 3 The droplet generator spreading characteristic consistency simulation test system refers to the test system that completes the spreading of droplets using a droplet generator. The simulation test system built using the simulation test method described in this invention includes at least a droplet generator test piece 1, a high-speed camera system 17, a vacuum system 5, a host computer 7, and a droplet collector 6. The high-speed camera system 17 mainly includes a high-speed camera 12, a high-speed camera acquisition unit 13, a light screen 11, and an LED light source 10. Its main function is to capture the spraying and spreading of droplets during the operation of the droplet generator test piece, used to measure parameters such as droplet size and velocity. The vacuum system 5 is a VTM-3000 thermal vacuum chamber system, whose main function is to create a vacuum environment to simulate a space working environment. The host computer 7's main functions are to control the controller's operation, receive telemetry data from the controller, and trigger high-speed photography.

[0054] The droplet generator test piece 1 is placed within the vacuum system 5. The droplet generator test piece 1 includes a storage tank 2, a spreader 3, and a controller 4 connected in series. The storage tank 2 is also connected to a gas source 8. The spreader 3 is docked with a droplet collector 6. A high-speed camera 12 is connected to a control trigger 14. The high-speed camera 12 and a light screen 11 are respectively deployed on opposite sides of the vacuum chamber 20. The host computer 7 is connected to both the controller 4 and the control trigger 14. Observation windows A21 and B22 are respectively opened on opposite sides of the vacuum chamber 20, corresponding to the light screen 11 and the high-speed camera 12.

Claims

1. A method for simulating the consistency of droplet generator spray characteristics across terrain, characterized in that: The method includes the following steps: Step 1: Based on the existing operating parameters of the droplet generator and the structural parameters of the jet disk, calculate the rated operating conditions under space conditions, i.e., the motor speed under known space conditions. n Droplet velocity in space environment ν and the diameter of the spreading circle formed by droplets in the space environment D； Step 2: Determine the spray distance under ground test conditions based on the size of the vacuum chamber. L 0. Calculate the diameter of the spreading circle formed by the droplet under the ground test conditions. D 0; Step 3: Under the condition that the maximum nozzle distribution circle radius R of the injection disk is consistent under the space environment and ground test conditions, given the droplet velocity V0 under the ground test conditions, calculate the motor speed n0 under the ground test conditions; Step 4: Based on the principle of consistent application characteristics between ground and surface, i.e., the principle of consistent liquid film thickness, calculate the required flow rate q0 of the working fluid under ground test conditions; Step 5: Set the pre-spray pressure P0 under ground test conditions, obtain the number of nozzles m of the equivalent spray disk according to the flow rate formula, and calculate the nozzle radius r of the equivalent spray disk, or calculate the number of nozzles m of the equivalent spray disk according to the nozzle radius r of the equivalent spray disk. By scaling down the operating parameters of the sprayer under rated conditions, equivalent measurement with consistent top and bottom performance is achieved.

2. The method for simulating the consistency of droplet generator spraying characteristics under varying conditions as described in claim 1, characterized in that: Step 1 calculates the rated operating conditions under the space environment, i.e., under the known motor speed. n Droplet velocity in space environment ν and the diameter of the spreading circle formed by droplets in the space environment D , D The expression is: In the formula L —Droplet ejection distance in a space environment, in meters; ν —Droplet velocity in a space environment, unit: meters per second; n —Motor speed in a confined space environment, unit: revolutions per minute; R —Relative of the maximum nozzle distribution circle of the injection plate, in meters; D —Diameter of the spreading circle formed by droplets in a space environment, in meters.

3. The method for simulating the consistency of droplet generator spraying characteristics under varying conditions as described in claim 1, characterized in that: Step 2: Calculate the diameter of the droplet distribution circle under ground test conditions based on the size of the vacuum chamber. D 0, D The expression for 0 is: In the formula L —Droplet ejection distance in a space environment, in meters; D —Diameter of the spreading circle formed by droplets in a space environment, in meters; L 0—Droplet ejection distance under ground test conditions, unit: meters; D 0—Diameter of the spreading circle formed by the droplet under ground test conditions, in meters.

4. The method for simulating the consistency of droplet generator spraying characteristics under varying conditions as described in claim 1, characterized in that: Step 3: Calculate the motor speed n0 under ground test conditions, ensuring that the maximum nozzle distribution circle radius R of the injection disk is the same under both space and ground test conditions. Given the droplet velocity V0 under ground test conditions, the expression for n0 is: In the formula, L is the spray distance of the droplet in the space environment (meters); D is the diameter of the spreading circle formed by the droplet in the space environment (meters); V is the droplet velocity in the space environment (meters / second); n is the motor speed in the space environment (revolutions / minute); and L0 is the spray distance of the droplet under ground test conditions (meters). D0—Diameter of the spreading circle formed by the droplet under ground test conditions, in meters; V0—Droplet velocity under ground test conditions, unit: m / s; n0—Motor speed under ground test conditions, unit: rpm.

5. The method for simulating the consistency of droplet generator spraying characteristics under varying conditions as described in claim 1, characterized in that: Step 4: Based on the principle of consistent application characteristics between the ground and surface, i.e., consistent liquid film thickness, calculate the required flow rate of the working fluid under ground test conditions. q 0, q The expression for 0 is: In the formula q —Flow rate of the working fluid in the space environment, unit: kg / s; D —Diameter of the spreading circle formed by droplets in a space environment, in meters; —Flow rate of the working fluid under ground test conditions, in kg / s; D 0—Diameter of the spreading circle formed by the droplet under ground test conditions, in meters.

6. A simulation experiment system constructed using the simulation experiment method according to any one of claims 1-5, characterized in that: The simulation experiment system includes at least a droplet generator test piece (1), a high-speed camera system, a vacuum system (5), a host computer (7), and a droplet collector (6). The droplet generator test piece (1) is placed inside the vacuum system (5). The droplet generator test piece (1) includes a storage tank (2), a spreader (3), and a controller (4) connected in series. The spreader (3) is connected to the droplet collector (6). The high-speed camera system includes a high-speed camera (12), a high-speed camera acquisition unit (13), a light screen (11), and a light source (10). The high-speed camera (12) is connected to a control trigger (14). The high-speed camera (12) and the light screen (11) are respectively deployed on opposite sides of the vacuum chamber (20). The host computer (7) is connected to the controller (4) and the control trigger (14).

7. The simulation experiment system constructed by the simulation experiment method as described in claim 6, characterized in that: The vacuum chamber (20) has observation windows A (21) and B (22) on opposite sides, respectively. Observation windows A (21) and B (22) correspond to the light screen (11) and the high-speed camera (12) respectively.

8. The simulation experiment system constructed by the simulation experiment method as described in claim 6, characterized in that: The storage tank (2) is also connected to the gas source (8).

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