Method and device for judging gas entrapment state of liquid propellant pipeline

Abstract

The invention provides a method and device for judging the gas entrapment state of a liquid propellant pipeline, and belongs to the technical field of liquid rocket engine tests.The method comprises the following steps that multiple ultrasonic transducers fixedly arranged on the outer wall of a to-be-tested pipeline at intervals in the circumferential direction are sequentially excited, and the multiple ultrasonic transducers emit ultrasonic waves; the gas entrapment state in the to-be-detected pipeline is judged according to the reflected waves of the ultrasonic waves emitted by the ultrasonic transducers, specifically, if the ultrasonic waves emitted by the ultrasonic transducer at the uppermost end and the ultrasonic waves emitted by the ultrasonic transducer at the lowermost end both have the reflected waves, half of the sound path distance of the propagation of the reflected waves is calculated; if the half sonic path distance is not equal to the inner diameter of the to-be-detected pipeline, bubbles exist in the liquid in the to-be-detected pipeline, and the gas entrapment state is achieved. According to the invention, the gas entrapment state in the non-transparent pipeline of the corrosive propellant can be accurately detected.

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: Sequentially exciting a plurality of ultrasonic transducers that are fixedly arranged at intervals along the circumferential direction on the outer wall of the pipeline to be tested, so that the plurality of ultrasonic transducers emit ultrasonic waves; 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: If both the ultrasonic waves emitted by the uppermost ultrasonic transducer and the ultrasonic waves emitted by the lowermost ultrasonic transducer have reflected waves, then calculate half the sound path of the reflected wave propagation. If the half sound path is not equal to the inner diameter of the pipe to be tested, there are bubbles in the liquid in the pipe to be tested, which is an air inclusion state.

[0006] Preferably, if both the ultrasonic wave emitted by the uppermost ultrasonic transducer and the ultrasonic wave emitted by the lowermost ultrasonic transducer have reflected waves, half the sound path of the reflected wave propagation is calculated, and if half the sound path is the inner diameter of the pipe to be tested, the pipe to be tested is in a full pipe state; if both the ultrasonic wave emitted by the uppermost ultrasonic transducer and the ultrasonic wave emitted by the lowermost ultrasonic transducer have no reflected waves, the pipe to be tested is in an empty pipe state; if the ultrasonic wave emitted by the uppermost ultrasonic transducer has no reflected waves and the ultrasonic wave emitted by the lowermost ultrasonic transducer has reflected waves, the pipe to be tested is in a half-pipe state; the full pipe state, the empty pipe state and the half-pipe state are all non-air-entrapped states.

[0007] Preferably, before determining the air inclusion state in the pipeline to be tested based on the ultrasonic waves emitted by the multiple ultrasonic transducers, the method further includes filtering and adjusting the reflected waves of the ultrasonic waves emitted by the ultrasonic transducers.

[0008] The present invention also provides a determination device based on the method for determining the gas inclusion state of a liquid propellant pipeline, comprising: 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 tested; An ultrasonic transceiver, used to excite the ultrasonic transducer to transmit ultrasonic waves and receive reflected waves of the ultrasonic waves; The upper computer is used to receive the reflected wave of the ultrasonic wave sent by the ultrasonic transceiver, and determine the air inclusion state in the pipeline to be tested according to the received reflected wave. Specifically, if both the ultrasonic wave emitted by the uppermost ultrasonic transducer and the ultrasonic wave emitted by the lowermost ultrasonic transducer have reflected waves, then calculate half the sound path of the reflected wave propagation. If the half sound path is not equal to the inner diameter of the pipeline to be tested, there are bubbles in the liquid in the pipeline to be tested, which is the air inclusion state.

[0009] Preferably, the number of the ultrasonic transducers is 8, and the surface of the ultrasonic transducers is evenly coated with a liquid or solid coupling agent.

[0010] Preferably, the ultrasonic transducer is a MEMS ultrasonic transducer.

[0011] Preferably, the ultrasonic transducer is signal-connected to an ultrasonic transceiver, and the ultrasonic transceiver is signal-connected to a host computer.

[0012] The method for determining the gas-entrained state of a liquid propellant pipeline provided by the present invention has the following beneficial effects: the present invention sequentially excites a plurality of ultrasonic transducers fixedly arranged at intervals on the outer wall of the pipeline to be tested, and can determine the gas-entrained state in the pipeline to be tested according to the reflected waves of the ultrasonic waves generated by the ultrasonic transducers. If both the ultrasonic waves emitted by the uppermost ultrasonic transducer and the ultrasonic waves emitted by the lowermost ultrasonic transducer have reflected waves, then half the sound path of the reflected wave propagation is calculated. If the half sound path is not equal to the inner diameter of the pipeline to be tested, bubbles exist in the liquid in the pipeline to be tested, which is the gas-entrained state. The method realizes the accurate detection of the gas-entrained state in the opaque pipeline of corrosive propellants. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the embodiment of the present invention and its design scheme, the following briefly introduces the drawings required for this embodiment. The drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0014] Figure 1 It is a flow chart of a method for determining the gas entrainment state of a liquid propellant pipeline according to an embodiment of the present invention; Figure 2 This is a schematic diagram of air traffic control status solution; Figure 3 This is a schematic diagram of the half-pipe state solution; Figure 4 This is a schematic diagram of the air entrainment state solution; Figure 5 This is a schematic diagram of the solution for the full pipe state; Figure 6 It is a device for detecting air inclusion in liquid propellant pipelines; Figure 7 Schematic diagram of the layout of ultrasonic transducers in the propellant pipeline.

[0015] Description of reference numerals: 1- pipeline to be tested; 2- special fixture; 3- ultrasonic transducer; 4- data transmission line; 5- ultrasonic transceiver; 6- host computer; 7- coupling agent; 8- air bubble. DETAILED DESCRIPTION

[0016] In order to enable those skilled in the art to better understand the technical solution of the present invention and implement it, the present invention is 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 solution of the present invention, and cannot be used to limit the scope of protection of the present invention.

[0017] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the technical solutions of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0018] In addition, the terms "first", "second", etc. are used for descriptive purposes only and are not to 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 a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances. In the description of the present invention, unless otherwise specified, "plurality" means two or more, which will not be described in detail here.

[0019] Example The present invention provides a method for determining the gas entrainment state of a liquid propellant pipeline, specifically, Figure 1 As shown, the following steps are included: Step 1: A plurality of ultrasonic transducers are fixedly arranged at intervals along the circumferential direction on the outer wall of the pipeline to be tested.

[0020] Liquid or solid coupling agent is evenly coated on the surface of the ultrasonic transducer to ensure that the ultrasonic signal can be effectively transmitted to the inside of the pipe. N ultrasonic transducers with coupling agent are evenly or unevenly fixed to the outer wall of the propellant pipe through a special clamp to ensure that each ultrasonic transducer is accurately fixed and the position does not change. The application of coupling agent can reduce the difference in acoustic impedance between the ultrasonic transducer and the pipe wall, thereby optimizing the transmission efficiency of the ultrasonic wave and ensuring the detection accuracy and stability.

[0021] In this embodiment, according to the outer diameter of the pipeline and the layout requirements of the ultrasonic transducer, the shape of the special fixture can be accurately printed using 3D printing technology to improve the freedom of detection.

[0022] Step 2: Excite the multiple ultrasonic transducers in sequence, and the multiple ultrasonic transducers emit ultrasonic waves.

[0023] Step 3: If both the ultrasonic waves emitted by the uppermost ultrasonic transducer and the ultrasonic waves emitted by the lowermost ultrasonic transducer have reflected waves, calculate half the sound path of the reflected wave propagation. If the half sound path is not equal to the inner diameter of the pipe to be tested, there are bubbles in the liquid in the pipe to be tested, which is an air inclusion state.

[0024] First, before determining the air inclusion state in the pipeline to be tested, the ultrasonic transducer is first filtered and demodulated. The filtering process can remove irrelevant frequency components and only retain signals related to the reflected wave. The demodulation process can accurately extract the flight time of the reflected wave from the complex signal. By analyzing the filtered and demodulated signal, the flight time of the reflected wave can be accurately calculated, and the distance (sound path) of the reflected wave propagation can be deduced from it.

[0025] Secondly, determine the air inclusion state in the pipeline to be tested. The specific steps are as follows: (1) Analyze whether there is a reflected wave signal greater than the pipe wall path emitted by the ultrasonic transducer at the top. If there is a reflected wave, it may be a full pipe or air-entrained state, and the next step of judgment is carried out; if there is no reflected wave, it may be a half-pipe or empty pipe, and the next step of judgment is required.

[0026] (2) Analyze whether there is a reflected wave from the ultrasonic wave emitted by the lowest ultrasonic transducer. According to the actual situation, it can be divided into the following: if the ultrasonic wave emitted by the uppermost ultrasonic transducer has a reflected wave and the ultrasonic wave emitted by the lowermost ultrasonic transducer has a reflected wave, calculate half the sound path of the reflected wave propagation. If half the sound path is the inner diameter of the pipe to be tested, it is a full pipe. Otherwise, it is a bubble. The distribution state of the bubbles can be calculated by the ellipse algorithm based on the flight time; if the ultrasonic wave emitted by the uppermost ultrasonic transducer has no reflected wave and the ultrasonic wave emitted by the lowermost ultrasonic transducer also has no reflected wave, it can be judged as an empty pipe state; if the ultrasonic wave emitted by the uppermost ultrasonic transducer has no reflected wave and the ultrasonic wave emitted by the lowermost ultrasonic transducer has a reflected wave, it is a half-pipe state. The height of the half-pipe liquid level can be obtained by calculating half the sound path of the lowermost ultrasonic transducer.

[0027] The above steps can be implemented by algorithm programming through programming software such as MATLAB and Python, and transmitted to the host computer to achieve continuous monitoring of gas entrainment in liquid propellant pipelines.

[0028] In addition, in this embodiment, the specific meanings of the empty tube state, full tube state, half tube state and air inclusion state are as follows: Empty pipe state: the state in which the pipe is filled with air. Due to the large reflection coefficient between air and pipe wall, when ultrasonic waves contact the interface between pipe wall and air, most of them are reflected and cannot propagate in the air in the pipe, but only in the pipe wall.

[0029] Full pipe state: refers to the state in which the pipe is full of liquid. Since the pipe is full of liquid, the reflection coefficient between the liquid and the pipe wall is relatively small, and ultrasonic waves can propagate in the pipe, and the ultrasonic transducer opposite to the ultrasonic transducer emitting ultrasonic waves can receive or transmit ultrasonic signals.

[0030] Half-pipe state: half of the pipe is air and the other half is liquid. The ultrasonic wave emitted by the ultrasonic transducer on the lower side of the liquid can pass through the interface of the pipe to be tested, 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 wave will be reflected at the interface between the liquid and the air, generating a reflected wave, which is received by the ultrasonic transducer on the lower side of the liquid; the ultrasonic wave 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.

[0031] Air inclusion state: the state in which the liquid in the pipe contains bubbles. The ultrasonic waves emitted by the ultrasonic transducer outside the pipe will propagate into the pipe, and when they touch the bubbles, acoustic reflection will occur, generating reflected waves. The size, number, and position of the bubbles will affect each channel and the time it takes for the emitted waves to propagate to each ultrasonic transducer.

[0032] The ultrasonic wave emitted by the ultrasonic transducer proposed in the present invention is reflected when it hits the gas, and the reflected wave signal is received by other ultrasonic transducers, and is converted into digital and preprocessed (filtered and regulated) by the ultrasonic transceiver, and sent to the host computer. The host computer realizes the detection of empty pipe, half pipe, bubble and full pipe status by analyzing the reflected wave information. The specific solution schematic diagrams are shown in FIG. Figure 2 , Figure 3 , Figure 4 and Figure 5 As shown, white is air, light gray is liquid, and dark gray is the tube wall.

[0033] In summary, the present invention sequentially excites a plurality of ultrasonic transducers fixedly arranged on the outer wall of the pipeline to be tested, and determines the air-entrained state in the pipeline to be tested according to the reflected wave of the ultrasonic wave generated by the ultrasonic transducer. If both the ultrasonic wave emitted by the uppermost ultrasonic transducer and the ultrasonic wave emitted by the lowermost ultrasonic transducer have reflected waves, then the half-sound path of the reflected wave propagation is calculated. If the sound path is the diameter, the pipeline to be tested is in a full pipe state, otherwise it is in an air-entrained state; if both the ultrasonic wave emitted by the uppermost ultrasonic transducer and the ultrasonic wave emitted by the lowermost ultrasonic transducer have no reflected waves, then the pipeline to be tested is in an empty pipe state; if the ultrasonic wave emitted by the uppermost ultrasonic transducer has no reflected waves, and the ultrasonic wave emitted by the lowermost ultrasonic transducer has reflected waves, then the pipeline to be tested is in a half-pipe state. It can be seen that this method realizes the accurate detection of the air-entrained state in the opaque pipeline of corrosive propellant.

[0034] The present invention also provides a determination device based on the method for determining the gas inclusion state of a liquid propellant pipeline, comprising a plurality of ultrasonic transducers 3, an ultrasonic transceiver 5 and a host computer 6, such as Figure 6 As shown. Multiple ultrasonic transducers 3 are used to transmit ultrasonic waves; the ultrasonic transceiver 5 is used to excite the ultrasonic transducer 3 to transmit ultrasonic waves and receive reflected waves of the ultrasonic waves; the host computer 6 is used to receive reflected waves of the ultrasonic waves sent by the ultrasonic transceiver 5 and determine the air inclusion state in the pipeline 1 to be tested according to the received reflected waves.

[0035] In this embodiment, the number of ultrasonic transducers 3 is 8, and the 8 ultrasonic transducers 3 are installed on the outer wall of the pipeline 1 to be tested through a special fixture 2, and a coupling agent 7 (such as medical gel) is provided between the ultrasonic transducer 3 and the outer wall of the pipeline 1 to be tested. Specifically, the ultrasonic detection special coupling agent 7 is evenly applied to the detected position on the pipeline 1 to be tested, and then the special fixture 2 and the ultrasonic transducer 3 are installed and fixed on the pipeline 1 to be tested, and it is ensured that the ultrasonic transducer 3 is closely attached to the outer wall of the pipeline, such as Figure 7 In addition, the ultrasonic transducer 3 in this embodiment is a MEMS ultrasonic transducer.

[0036] Working principle: the upper computer 6 runs the control program of the ultrasonic transceiver 5, so that the ultrasonic transceiver 5 sequentially excites the ultrasonic transducer 3, the ultrasonic transducer 3 generates ultrasonic waves, the ultrasonic transceiver 5 receives the reflected waves of the ultrasonic waves, and transmits the received reflected waves to the upper computer 6 through the data transmission line 4. The upper computer 6 determines the air entrainment state in the pipeline 1 to be tested according to the received reflected waves, thereby judging whether there are bubbles 8 in the pipeline.

[0037] In this embodiment, the ultrasonic transducer 3 is connected to the ultrasonic transceiver 5 by signal through the data transmission line 4, and the ultrasonic transceiver 5 is connected to the host computer 6 by signal through the data transmission line 4. Specifically, the written control program is imported into the host computer 6, and the host computer 6 controls the sequential excitation (clockwise sequential excitation) of multiple ultrasonic transducers 3 through the ultrasonic transceiver 5, and the excitation time interval is greater than the time used for the farthest transmission path (farthest sound path) of the ultrasonic wave to ensure the integrity of the reflected wave signal.

[0038] The present invention can realize the demand for nondestructive detection of the gas-entrained state inside the propellant pipeline by arranging an ultrasonic transducer 3 outside the pipeline 1 to be tested. The MEMS-based ultrasonic transducer 3 has the characteristics of micron-level size, convenient array design, and easy integration with IC, and is very suitable for high-precision detection and continuous detection of the gas-entrained state in a small-diameter propellant supply pipeline. The small size and integration advantages of the ultrasonic transducer 3 make its arrangement in a complex pipeline system more flexible, and help to realize real-time monitoring and high-resolution gas distribution detection.

[0039] The embodiments described above are only preferred specific implementation modes of the present invention, and the protection scope of the present invention is not limited thereto. Any simple changes or equivalent replacements of the technical solutions that can be obviously obtained by any technician familiar with the field within the technical scope disclosed in the present invention belong to the protection scope of the present invention.

Claims

1. A method for determining the gas inclusion state of a liquid propellant pipeline, characterized in that: The steps include: 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; 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: If both the ultrasonic waves emitted by the uppermost ultrasonic transducer and the ultrasonic waves emitted by the lowermost ultrasonic transducer have reflected waves, then calculate half the sound path of the reflected wave propagation. If the half sound path is not equal to the inner diameter of the pipe to be tested, there are bubbles in the liquid in the pipe to be tested, which is an air inclusion state.

2. The method for determining the gas inclusion state of a liquid propellant pipeline according to claim 1, characterized in that: Also includes: If both the ultrasonic wave emitted by the uppermost ultrasonic transducer and the ultrasonic wave emitted by the lowermost ultrasonic transducer have reflected waves, then half the sound path of the reflected wave propagation is calculated, and if half the sound path is the inner diameter of the pipe to be tested, the pipe to be tested is in a full pipe state; if both the ultrasonic wave emitted by the uppermost ultrasonic transducer and the ultrasonic wave emitted by the lowermost ultrasonic transducer have no reflected waves, then the pipe to be tested is in an empty pipe state; if the ultrasonic wave emitted by the uppermost ultrasonic transducer has no reflected waves and the ultrasonic wave emitted by the lowermost ultrasonic transducer has reflected waves, then the pipe to be tested is in a half-pipe state; the full pipe state, the empty pipe state and the half-pipe state are all non-air-entrapped states.

3. The method for determining the gas inclusion state of a liquid propellant pipeline according to claim 1, characterized in that: Before determining the air inclusion state in the pipeline to be tested according to the ultrasonic waves emitted by the multiple ultrasonic transducers, the method further includes filtering and adjusting the reflected waves of the ultrasonic waves emitted by the ultrasonic transducers.

4. A determination device based on the method for determining the gas inclusion state of a liquid propellant pipeline according to any one of claims 1 to 3, characterized in that: include: 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 tested; An ultrasonic transceiver, used to excite the ultrasonic transducer to transmit ultrasonic waves and receive reflected waves of the ultrasonic waves; The upper computer is used to receive the reflected wave of the ultrasonic wave sent by the ultrasonic transceiver, and determine the air inclusion state in the pipeline to be tested according to the received reflected wave. Specifically, if both the ultrasonic wave emitted by the uppermost ultrasonic transducer and the ultrasonic wave emitted by the lowermost ultrasonic transducer have reflected waves, then calculate half the sound path of the reflected wave propagation. If the half sound path is not equal to the inner diameter of the pipeline to be tested, there are bubbles in the liquid in the pipeline to be tested, which is the air inclusion state.

5. The device for determining the air inclusion state of a liquid propellant pipeline according to claim 4, characterized in that: The number of the ultrasonic transducers is 8, and the surfaces of the ultrasonic transducers are uniformly coated with liquid or solid coupling agent.

6. The device for determining the gas inclusion state of a liquid propellant pipeline according to claim 4, characterized in that: The ultrasonic transducer is a MEMS ultrasonic transducer.

7. The device for determining the air inclusion state of a liquid propellant pipeline according to claim 4, characterized in that: The ultrasonic transducer is signal-connected to an ultrasonic transceiver, and the ultrasonic transceiver is signal-connected to a host computer.

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