A method and device for determining the air-entrained state of a liquid propellant pipeline clamp

Abstract

The present invention provides a method and device for determining the air-entrained state of a liquid propellant pipeline, belonging to the technical field of liquid rocket engine tests. The method includes the following steps: sequentially exciting a plurality of ultrasonic transducers fixedly arranged at intervals along the circumferential direction on the outer wall of the pipeline to be measured, and the plurality of ultrasonic transducers emit ultrasonic waves; determining the air-entrained state in the pipeline to be measured according to the reflected waves of the ultrasonic waves emitted by the plurality of ultrasonic transducers. Specifically, if there are reflected waves for both the ultrasonic waves emitted by the uppermost ultrasonic transducer and the ultrasonic waves emitted by the lowermost ultrasonic transducer, then calculate half of the sound path of the reflected wave propagation. If half of the sound path is not equal to the inner diameter of the pipeline to be measured, then there are bubbles in the liquid in the pipeline to be measured, which is the air-entrained state. The present invention can accurately detect the air-entrained state in an opaque pipeline of a corrosive propellant.

Description

Technical Field

[0001] The invention belongs to the technical field of liquid rocket engine testing, and in particular relates to a method and a device for determining the air entrainment state of a liquid propellant pipeline. Background Art

[0002] When a liquid rocket engine is tested on the ground, the engine is usually fixed on a test bench, and the propellant stored in the propellant container is delivered to the engine through a propellant supply pipeline. During the test preparation, it is necessary to install the engine inlet pipeline and connect it to the test bench propellant supply pipeline, and conduct the test after completing the sealing inspection and other work. Before the engine test, the propellant needs to be filled to the inlet of the engine valve, and the propellant in the pipeline is in a pure liquid state and cannot be mixed with gas. Otherwise, the liquid propellant in the gas-entrained state will enter the engine, causing the engine mixing ratio to deviate from the design value, which may cause the engine to work abnormally at the least, and may cause the engine to burn or even explode in severe cases. Therefore, before the engine test, the residual gas in the propellant supply pipeline must be drained before the test can be carried out.

[0003] The propellant filling process before the engine test is to pre-increase a certain pressure in the propellant container, then open the container outlet valve, and the propellant flows from the container into the supply pipe. Since there is no propellant liquid in the propellant supply pipe during the test preparation process, before the propellant is filled, the pipe is filled with air or positive pressure sealed nitrogen. During the filling process, the gas in the pipe is squeezed to the end of the pipe as the propellant is filled and flows. High-point exhaust ports and low-point discharge ports are generally provided on the engine inlet pipe to discharge the gas in the pipe. A certain amount of propellant is discharged by opening the high-point exhaust port and the low-point discharge port, and the discharged propellant is recovered until there is no gas in the pipe before the test is carried out.

[0004] However, since liquid rocket propellants are generally toxic, harmful, highly corrosive, flammable and explosive, the propellant supply pipelines used are generally stainless steel pipes, and the fluid state in the pipeline cannot be observed. Therefore, it is impossible to detect whether the propellant in the pipeline is full of liquid and free of air, and it is impossible to accurately determine whether the gas in the pipeline has been completely eliminated, posing a major quality risk. Summary of the invention

[0005] In order to overcome the shortcomings of the above-mentioned prior art, the present invention provides a method for determining the gas inclusion state of a liquid propellant pipeline, comprising the following steps:

[0006] A plurality of ultrasonic transducers fixedly arranged at intervals along the circumferential direction on the outer wall of the pipeline to be tested are excited in sequence, and the plurality of ultrasonic transducers emit ultrasonic waves;

[0007] The air inclusion state in the pipeline to be tested is determined according to the reflected waves of ultrasonic waves emitted by multiple ultrasonic transducers, specifically:

[0008] If there are reflected waves for the ultrasonic waves emitted by the uppermost ultrasonic transducer and the lowermost ultrasonic transducer, then calculate half of the sound path traveled by the reflected wave. If half of the sound path is not equal to the inner diameter of the pipeline to be measured, then there are air bubbles in the liquid in the pipeline to be measured, which is the air-entrained state.

[0009] Preferably, if there are reflected waves for the ultrasonic waves emitted by the uppermost ultrasonic transducer and the lowermost ultrasonic transducer, then calculate half of the sound path traveled by the reflected wave. If half of the sound path is equal to the inner diameter of the pipeline to be measured, then the pipeline to be measured is in the full-pipe state; if there are no reflected waves for the ultrasonic waves emitted by the uppermost ultrasonic transducer and the lowermost ultrasonic transducer, then the pipeline to be measured is in the empty-pipe state; if there is no reflected wave for the ultrasonic wave emitted by the uppermost ultrasonic transducer and there is a reflected wave for the ultrasonic wave emitted by the lowermost ultrasonic transducer, then the pipeline to be measured is in the half-pipe state; the full-pipe state, the empty-pipe state, and the half-pipe state are all non-air-entrained states.

[0010] Preferably, before determining the air-entrained state in the pipeline to be measured based on the ultrasonic waves emitted by multiple ultrasonic transducers, it also includes filtering and conditioning the reflected waves of the ultrasonic waves emitted by the ultrasonic transducers.

[0011] The present invention also provides a determination device for a method for determining the air-entrained state of a liquid propellant pipeline, including:

[0012] Multiple ultrasonic transducers for emitting ultrasonic waves; the ultrasonic transducers are fixedly arranged at intervals along the circumferential direction on the outer wall of the pipeline to be measured;

[0013] An ultrasonic wave transceiver for exciting the ultrasonic transducers to emit ultrasonic waves and receiving the reflected waves of the ultrasonic waves;

[0014] An upper computer for receiving the reflected waves of the ultrasonic waves sent by the ultrasonic wave transceiver and determining the air-entrained state in the pipeline to be measured according to the received reflected waves. Specifically, if there are reflected waves for the ultrasonic waves emitted by the uppermost ultrasonic transducer and the lowermost ultrasonic transducer, then calculate half of the sound path traveled by the reflected wave. If half of the sound path is not equal to the inner diameter of the pipeline to be measured, then there are air bubbles in the liquid in the pipeline to be measured, which is the air-entrained state.

[0015] Preferably, the number of the ultrasonic transducers is 8, and the surfaces of the ultrasonic transducers are uniformly coated with a liquid or solid coupling agent.

[0016] Preferably, the ultrasonic transducers are MEMS ultrasonic transducers.

[0017] Preferably, the ultrasonic transducers are signal-connected to the ultrasonic wave transceiver, and the ultrasonic wave transceiver is signal-connected to the upper computer.

[0018] The method for determining the air entrapment state of a liquid propellant pipeline clamp provided by the present invention has the following beneficial effects: By sequentially exciting multiple ultrasonic transducers fixedly arranged at intervals on the outer wall of the pipeline to be measured, and based on the reflected waves of the ultrasonic waves generated by the ultrasonic transducers, the air entrapment state in the pipeline to be measured can be determined. If there are reflected waves for both the ultrasonic waves emitted by the uppermost ultrasonic transducer and the ultrasonic waves emitted by the lowermost ultrasonic transducer, then calculate half of the acoustic path traveled by the reflected wave. If half of the acoustic path is not equal to the inner diameter of the pipeline to be measured, then there are air bubbles in the liquid in the pipeline to be measured, which is the air entrapment state. This method realizes the accurate detection of the air entrapment state in the opaque pipeline of corrosive propellants. Description of the Drawings

[0019] To more clearly illustrate the embodiments of the present invention and their design schemes, the accompanying drawings required for the present embodiments will be briefly introduced below. The accompanying drawings in the following description are only partial embodiments of the present invention. For those of ordinary skill in the art, other accompanying drawings can be obtained based on these drawings without creative efforts.

[0020] Figure 1 It is a flowchart of the method for determining the air entrapment state of a liquid propellant pipeline clamp in an embodiment of the present invention;

[0021] Figure 2 It is a schematic diagram for solving the empty pipe state;

[0022] Figure 3 It is a schematic diagram for solving the half-pipe state;

[0023] Figure 4 It is a schematic diagram for solving the air entrapment state;

[0024] Figure 5 It is a schematic diagram for solving the full pipe state;

[0025] Figure 6 It is a liquid propellant pipeline air entrapment detection device;

[0026] Figure 7 It is a schematic diagram of the layout of ultrasonic transducers in the propellant pipeline.

[0027] Description of the reference numerals:

[0028] 1 - Pipeline to be measured; 2 - Special fixture; 3 - Ultrasonic transducer; 4 - Data transmission line; 5 - Ultrasonic wave transceiver device; 6 - Host computer; 7 - Coupling agent; 8 - Air bubble. Detailed Embodiments

[0029] To enable those skilled in the art to better understand the technical solutions of the present invention and implement them, the present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and cannot be used to limit the protection scope of the present invention.

[0030] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the technical solutions of the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0031] In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. In the description of the present invention, it should be noted that unless otherwise clearly specified or limited, the terms "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. In the description of the present invention, unless otherwise stated, the meaning of "a plurality" is two or more, which will not be elaborated here.

[0032] Embodiment

[0033] The present invention provides a method for determining the air state of a liquid propellant pipeline clamp, specifically as Figure 1 shown, including the following steps:

[0034] Step 1: Fix a plurality of ultrasonic transducers at intervals along the circumferential direction on the outer wall of the pipeline to be measured.

[0035] Evenly coat the surface of the ultrasonic transducer with a liquid or solid couplant to ensure that the ultrasonic signal can be effectively transmitted into the pipeline. Fix N ultrasonic transducers with couplant on the outer wall of the propellant pipeline evenly or unevenly through a special fixture to ensure that each ultrasonic transducer is accurately fixed and its position does not change. The application of the couplant can reduce the acoustic impedance difference between the ultrasonic transducer and the pipe wall, thereby optimizing the transmission efficiency of ultrasonic waves and ensuring the detection accuracy and stability.

[0036] In this embodiment, according to the outer diameter of the pipeline and the layout requirements of the ultrasonic transducers, the 3D printing technology can be used to accurately print the shape of the special fixture to improve the detection freedom.

[0037] Step 2: Excite the plurality of ultrasonic transducers in sequence, and the plurality of ultrasonic transducers emit ultrasonic waves.

[0038] Step 3: If there are reflected waves in the ultrasonic waves emitted by both the uppermost ultrasonic transducer and the lowermost ultrasonic transducer, calculate half of the acoustic path traveled by the reflected wave. If half of the acoustic path is not equal to the inner diameter of the pipeline to be measured, there are air bubbles in the liquid in the pipeline to be measured, which is the air-entrained state.

[0039] First, before determining the air-entrained state in the pipeline to be measured, perform filtering and demodulation on the ultrasonic transducer. Through filtering, irrelevant frequency components can be removed, and only the signals related to the reflected wave are retained; through demodulation, the flight time of the reflected wave can be accurately extracted from the complex signals; by analyzing the signals after filtering and demodulation, the flight time of the reflected wave can be accurately calculated, and the distance (acoustic path) traveled by the reflected wave can be deduced therefrom.

[0040] Second, determine the air-entrained state in the pipeline to be measured. The specific steps are as follows:

[0041] (1) Analyze whether there is a reflected wave signal greater than the wall path in the ultrasonic wave emitted by the uppermost ultrasonic transducer. If there is a reflected wave, it may be a full pipe or air-entrained state, and proceed to the next judgment; if there is no reflected wave, it may be a half-full pipe and an empty pipe, and further judgment is required.

[0042] (2) Analyze whether there is a reflected wave in the ultrasonic wave emitted by the lowermost ultrasonic transducer. According to the actual situation, it can be divided into: if there is a reflected wave in the ultrasonic wave emitted by the uppermost ultrasonic transducer and there is a reflected wave in the ultrasonic wave emitted by the lowermost ultrasonic transducer, calculate half of the acoustic path traveled by the reflected wave. If half of the acoustic path is the inner diameter of the pipeline to be measured, it is a full pipe; otherwise, it is a bubble. The distribution state of the bubble can be calculated by the ellipse algorithm based on the flight time; if there is no reflected wave in the ultrasonic wave emitted by the uppermost ultrasonic transducer and there is no reflected wave in the ultrasonic wave emitted by the lowermost ultrasonic transducer, it can be judged as an empty pipe state; if there is no reflected wave in the ultrasonic wave emitted by the uppermost ultrasonic transducer and there is a reflected wave in the ultrasonic wave emitted by the lowermost ultrasonic transducer, it is a half-full pipe state, and the half-full pipe liquid level height can be obtained by calculating half of the acoustic path of the lowermost ultrasonic transducer.

[0043] The above steps can be used to implement algorithm programming through programming software such as MATLAB and Python, and transmitted to the upper computer to achieve continuous monitoring of air entrainment in the liquid propellant pipeline.

[0044] In addition, in this embodiment, the specific meanings of the empty pipe state, full pipe state, half-full pipe state, and air-entrained state are as follows:

[0045] Empty pipe state: The state where the pipeline is filled with air. Since the reflection coefficients of air and the pipe wall are large, after the ultrasonic wave contacts the interface between the pipe wall and air, most of the ultrasonic waves are reflected and cannot propagate in the air in the pipeline, but can only propagate in the pipe wall.

[0046] Full pipe state: It refers to the state where the pipe is filled with liquid. Since the pipe is filled with liquid, the reflection coefficients of the liquid and the pipe wall are relatively small, ultrasonic waves can propagate in the pipe, and the ultrasonic transducer opposite to the ultrasonic transducer emitting ultrasonic waves can receive or emit ultrasonic signals.

[0047] Half pipe state: A state where half of the pipe is air and the other half is liquid. The ultrasonic waves emitted by the ultrasonic transducer on the lower side of the liquid can pass through the interface of the pipe to be measured, but cannot pass through the interface between the liquid and the air. The ultrasonic transducer opposite to the ultrasonic transducer on the lower side of the liquid cannot receive the ultrasonic signal, but the ultrasonic waves will be reflected at the interface between the liquid and the air, generating a reflected wave, and the reflected wave is received by the ultrasonic transducer on the lower side of the liquid; the ultrasonic waves emitted by the ultrasonic transducer on the upper side of the air cannot pass through the interface between the liquid and the steel pipe and can only propagate within the pipe wall.

[0048] Air-entrained state: A state where the liquid in the pipe contains bubbles. The ultrasonic waves emitted by the ultrasonic transducers outside the pipe will all propagate into the pipe and will undergo acoustic reflection when touching the bubbles, generating a reflected wave. The size, quantity, and position of the bubbles will all affect each channel and the time for the transmitted wave to propagate to each ultrasonic transducer.

[0049] The ultrasonic waves emitted by the ultrasonic transducers proposed in the present invention are reflected when encountering gas, and the reflected wave signals are received by the other ultrasonic transducers, and are subjected to analog-to-digital conversion and preprocessing (filtering and demodulation processing) through the ultrasonic transceiver device, and then sent to the host computer. The host computer analyzes the reflected wave information to detect the air-entrained, half pipe, bubble, and full pipe states. The specific calculation schematic diagrams are respectively as Figure 2 , Figure 3 , Figure 4 and Figure 5 shown, where white represents air, light gray represents liquid, and dark gray represents the pipe wall.

[0050] In summary, the present invention sequentially energizes multiple ultrasonic transducers fixedly arranged at intervals on the outer wall of the pipe to be measured, and determines the air-entrained state in the pipe to be measured according to the reflected waves of the ultrasonic waves generated by the ultrasonic transducers. If there are reflected waves for both the ultrasonic waves emitted by the uppermost ultrasonic transducer and the ultrasonic waves emitted by the lowermost ultrasonic transducer, calculate half of the sound path of the reflected wave propagation. If the sound path is the diameter, the pipe to be measured is in the full pipe state, otherwise it is in the air-entrained state; if there are no reflected waves for both the ultrasonic waves emitted by the uppermost ultrasonic transducer and the ultrasonic waves emitted by the lowermost ultrasonic transducer, the pipe to be measured is in the empty pipe state; if there is no reflected wave for the ultrasonic waves emitted by the uppermost ultrasonic transducer and there is a reflected wave for the ultrasonic waves emitted by the lowermost ultrasonic transducer, the pipe to be measured is in the half pipe state. It can be seen that this method realizes the accurate detection of the air-entrained state in the opaque pipe of corrosive propellant.

[0051] The present invention also provides a determination device based on a method for determining the air entrainment state of a liquid propellant pipeline clamp, including a plurality of ultrasonic transducers 3, an ultrasonic transceiver device 5, and a host computer 6, as Figure 6 shown. The plurality of ultrasonic transducers 3 are used to emit ultrasonic waves; the ultrasonic transceiver device 5 is used to excite the ultrasonic transducers 3 to emit ultrasonic waves and receive the reflected waves of the ultrasonic waves; the host computer 6 is used to receive the reflected waves of the ultrasonic waves sent by the ultrasonic transceiver device 5 and determine the air entrainment state in the pipeline 1 to be measured according to the received reflected waves.

[0052] In this embodiment, the number of ultrasonic transducers 3 is 8. The 8 ultrasonic transducers 3 are installed on the outer wall of the pipeline 1 to be measured through a special fixture 2. A coupling agent 7 (such as medical gel) is provided between the ultrasonic transducers 3 and the outer wall of the pipeline 1 to be measured. Specifically, the special coupling agent 7 for ultrasonic detection is evenly applied to the position to be detected on the pipeline 1 to be measured, and then the special fixture 2 together with the ultrasonic transducers 3 is installed and fixed on the pipeline 1 to be measured, and it is ensured that the ultrasonic transducers 3 are in close contact with the outer wall surface of the pipeline, as Figure 7 shown. In addition, the ultrasonic transducers 3 in this embodiment are MEMS ultrasonic transducers.

[0053] Working principle: The host computer 6 runs the control program of the ultrasonic transceiver device 5, so that the ultrasonic transceiver device 5 sequentially excites the ultrasonic transducers 3. The ultrasonic transducers 3 generate ultrasonic waves. The ultrasonic transceiver device 5 receives the reflected waves of the ultrasonic waves and transmits the received reflected waves to the host computer 6 through the data transmission line 4. The host computer 6 determines the air entrainment state in the pipeline 1 to be measured according to the received reflected waves, so as to judge whether there are bubbles 8 in the pipeline.

[0054] In this embodiment, the ultrasonic transducers 3 are signal-connected to the ultrasonic transceiver device 5 through the data transmission line 4, and the ultrasonic transceiver device 5 is signal-connected to the host computer 6 through the data transmission line 4. Specifically, the written control program is imported into the host computer 6. The host computer 6 controls the sequential excitation (sequentially exciting clockwise) of the plurality of ultrasonic transducers 3 through the ultrasonic transceiver device 5, and the excitation time interval is greater than the time used for the farthest transmission path (the farthest sound path) of the ultrasonic wave to ensure the integrity of the reflected wave signal.

[0055] By arranging the ultrasonic transducers 3 outside the pipeline 1 to be measured, the present invention can meet the non-destructive detection requirements for the air entrainment state inside the propellant pipeline. The ultrasonic transducers 3 based on MEMS have characteristics such as micron-scale size, convenient for array design, and easy to integrate with ICs, and are very suitable for high-precision detection and continuous detection of the air entrainment state in small-diameter propellant supply pipelines. The small volume and integration advantages of such ultrasonic transducers 3 make their layout more flexible in complex pipeline systems and contribute to realizing real-time monitoring and high-resolution gas distribution detection.

[0056] The above-described embodiments are only preferred specific embodiments of the present invention, and the protection scope of the present invention is not limited thereto. Any simple changes or equivalent substitutions of technical solutions that can be obviously obtained by those skilled in the art within the technical scope disclosed by the present invention all fall within the protection scope of the present invention.

Claims

1. A method for determining the gas state of a liquid propellant pipeline clamp, characterized in that, The steps are as follows: Successively excite a plurality of ultrasonic transducers fixedly arranged at intervals along the circumferential direction on the outer wall of the pipeline to be measured, and the plurality of ultrasonic transducers emit ultrasonic waves; Judge the air-entrained state in the pipeline to be measured according to the reflected waves of the ultrasonic waves emitted by the plurality of ultrasonic transducers. Specifically: If there are reflected waves for both the ultrasonic waves emitted by the uppermost ultrasonic transducer and the ultrasonic waves emitted by the lowermost ultrasonic transducer, calculate half of the sound path of the reflected wave propagation. If half of the sound path is not equal to the inner diameter of the pipeline to be measured, there are air bubbles in the liquid in the pipeline to be measured, which is the air-entrained state; It also includes: If there are reflected waves for both the ultrasonic waves emitted by the uppermost ultrasonic transducer and the ultrasonic waves emitted by the lowermost ultrasonic transducer, calculate half of the sound path of the reflected wave propagation. If half of the sound path is the inner diameter of the pipeline to be measured, the pipeline to be measured is in a full-pipe state; If there are no reflected waves for both the ultrasonic waves emitted by the uppermost ultrasonic transducer and the ultrasonic waves emitted by the lowermost ultrasonic transducer, the pipeline to be measured is in an empty-pipe state; If there is no reflected wave for the ultrasonic waves emitted by the uppermost ultrasonic transducer and there is a reflected wave for the ultrasonic waves emitted by the lowermost ultrasonic transducer, the pipeline to be measured is in a half-pipe state; The full-pipe state, the empty-pipe state and the half-pipe state are all non-air-entrained states.

2. The method for determining the gas state of the liquid propellant pipeline clamp according to claim 1, characterized in that Before judging the air-entrained state in the pipeline to be measured according to the ultrasonic waves emitted by the plurality of ultrasonic transducers, it also includes filtering and conditioning the reflected waves of the ultrasonic waves emitted by the ultrasonic transducers.

3. A determination device for the gas state of a liquid propellant pipeline clamp according to the determination method described in any one of claims 1-2, characterized in that, It includes: A plurality of ultrasonic transducers for emitting ultrasonic waves; the ultrasonic transducers are fixedly arranged at intervals along the circumferential direction on the outer wall of the pipeline to be measured; An ultrasonic wave transceiver device for exciting the ultrasonic transducers to emit ultrasonic waves and receiving the reflected waves of the ultrasonic waves; An upper computer for receiving the reflected waves of the ultrasonic waves sent by the ultrasonic wave transceiver device and judging the air-entrained state in the pipeline to be measured according to the received reflected waves. Specifically: If there are reflected waves for both the ultrasonic waves emitted by the uppermost ultrasonic transducer and the ultrasonic waves emitted by the lowermost ultrasonic transducer, calculate half of the sound path of the reflected wave propagation. If half of the sound path is not equal to the inner diameter of the pipeline to be measured, there are air bubbles in the liquid in the pipeline to be measured, which is the air-entrained state.

4. The determination device according to claim 3, wherein The number of the ultrasonic transducers is 8, and the surfaces of the ultrasonic transducers are uniformly coated with liquid or solid coupling agents.

5. The determination device according to claim 3, wherein The ultrasonic transducers are MEMS ultrasonic transducers.

6. The determination device according to claim 3, characterized in that, The ultrasonic transducers are signal-connected to the ultrasonic wave transceiver device, and the ultrasonic wave transceiver device is signal-connected to the upper computer.

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