Anti-cavitation device and method of airborne liquid metal strong pre-cooling system

Abstract

The invention relates to the technical field of aircraft engines, in particular to an anti-cavitation device and method for an airborne liquid metal strong pre-cooling system, and the anti-cavitation device and method are used for an air inlet pre-cooling system of an aircraft and comprise a shell, an inlet pipeline, a cyclone separator and an ejector. A separation cavity is formed in the shell; the inlet pipeline is connected with the shell and used for inputting cooling fluid into the separation cavity. The cyclone separator is arranged in the separation cavity and can rotate in the separation cavity, and the cooling fluid is rotated for gas-liquid separation; the ejector is arranged at the top of the shell and connected with the separation cavity, high-speed fluid can pass through the ejector, the high-speed fluid generates a low-pressure area in the ejector, and gas in the separation cavity is led out to the ejector. Bubbles gathered in the rotational flow center of the separation cavity can be actively pumped away, and the problems of pump inlet pressure instability and cavitation caused by gas separation in a local low-pressure area when a liquid metal cooling loop is under severe working conditions such as posture sudden change are solved.

Description

Technical Field

[0001] This disclosure relates to the field of aircraft engine technology, and in particular to an anti-cavitation device and method for an airborne liquid metal strong precooling system. Background Technology

[0002] As aviation technology advances into the hypersonic realm, strong precooling systems have become one of the core technologies of modern hypersonic vehicles. Liquid metal, due to its excellent thermal conductivity, is widely used as a cooling medium. However, during system operation, the precipitation of dissolved gases in localized low-pressure areas becomes a critical issue restricting system performance. When liquid metal flows through localized low-pressure areas such as pump inlets, valves, and pipe reduction points, its ability to dissolve gases decreases, and supersaturated gases rapidly precipitate, forming bubbles. These bubbles accumulate at the pump inlet, causing a sharp drop in the effective net positive suction head (NPSHa), falling below the required net positive suction head (NPSHr) for the pump. This leads to cavitation, resulting in a sudden drop in flow rate, pump performance deterioration, and even damage, severely impacting the normal operation of the system.

[0003] While existing technologies offer some solutions, such as simple system pressurization, increasing pipe diameter, or traditional degassing devices, these suffer from insufficient efficiency, slow response, and increased weight and structural burden in the harsh environment of aviation. In particular, the high density, high surface tension, high gas solubility, and rapid precipitation characteristics of liquid metals render traditional degassing methods for water or aviation fuel directly unsuitable. Summary of the Invention

[0004] This disclosure is made in view of the above-mentioned problems. This disclosure provides an anti-cavitation device and method for an airborne liquid metal forced precooling system.

[0005] According to one aspect of this disclosure, an anti-cavitation device for an airborne liquid metal precooling system is provided for use in an aircraft's air intake precooling system, comprising: The outer casing has a separation cavity inside. An inlet pipe, which is connected to the outer casing, is used to supply cooling fluid to the separation chamber; A hydrocyclone separator is disposed in the separation chamber and is capable of rotating within the separation chamber to rotate the cooling fluid for gas-liquid separation; An ejector is disposed on the top of the housing and connected to the separation chamber. The ejector is capable of drawing gas from the separation chamber to the ejector by a high-speed fluid that generates a low-pressure zone within the ejector.

[0006] Furthermore, according to one aspect of this disclosure, an anti-cavitation device for an airborne liquid metal precooling system includes: A first housing is disposed inside the outer shell, and the separation cavity is disposed inside the first housing; A second housing is disposed on the outside of the outer shell, and an installation space is provided between the first housing and the second housing.

[0007] Furthermore, according to one aspect of this disclosure, an anti-cavitation device for an airborne liquid metal precooling system includes a cyclone separator comprising: A rotating shaft is connected to the ejector. An output channel is provided axially inside the rotating shaft, through which gas can be drawn from the lower end of the rotating shaft to the ejector. A guide vane is disposed on the outside of the rotating shaft, and the rotating shaft can drive the guide vane to rotate.

[0008] Furthermore, according to one aspect of this disclosure, an anti-cavitation device for an airborne liquid metal precooling system includes an ejector comprising: The main body pipeline is a Venturi tube structure; A drainage pipe, the first end of which is connected to the diameter-reduced section of the main pipe, and the second end of which extends into the rotating shaft.

[0009] Furthermore, according to one aspect of this disclosure, in an anti-cavitation device for an airborne liquid metal precooling system, the ejector further includes: The reinjection pipeline has a first end connected to the outlet end of the main pipeline and a second end connected to the upstream low-pressure area of ​​the system, which can transport the return liquid to the upstream low-pressure area of ​​the system.

[0010] Furthermore, according to one aspect of this disclosure, an anti-cavitation device for an airborne liquid metal precooling system further includes: A composite sensor is installed in the reinjection pipeline to monitor the gas concentration and pressure in the return liquid in real time. A PID controller is provided, which is installed in the installation space. The composite sensor is connected to the PID controller via a cable and can transmit the detection signal to the PID controller.

[0011] Furthermore, according to one aspect of this disclosure, an anti-cavitation device for an airborne liquid metal precooling system further includes: Multiple ultrasonic transducers are installed in the installation space and electrically connected to the PID controller. When the attitude angle change rate of the aircraft is greater than 15° / s, the ultrasonic transducers are activated to generate a sound field, forming an acoustic radiation pressure trap at the vortex center of the separation chamber, which suspends and fixes the gas in the separation area.

[0012] Furthermore, according to one aspect of this disclosure, an anti-cavitation device for an airborne liquid metal precooling system further includes: A three-axis accelerometer is installed in the mounting space and is electrically connected to the PID controller. The three-axis accelerometer detects the attitude changes of the aircraft in real time and can transmit the detection signal to the PID controller.

[0013] According to another aspect of this disclosure, an anti-cavitation method for an airborne liquid metal intensive precooling system is provided, implemented using the anti-cavitation device for an airborne liquid metal intensive precooling system as described in any of the above technical solutions, comprising: Signal acquisition: A three-axis accelerometer is used to monitor the aircraft's attitude changes in real time and transmit the signals to the PID controller; Threshold judgment: The PID controller judges the rate of change of the aircraft's attitude angle. When the rate of change is no greater than 15° / s, the system is in low power mode and relies only on the passive inertial adjustment of the guide vanes of the cyclone separator. Active control activation: When the aircraft's attitude angle change rate is greater than 15° / s, the PID controller triggers the ultrasonic transducer to start, generating an acoustic radiation pressure trap. Closed-loop feedback: The composite sensor installed on the ejector monitors the gas concentration and pressure of the reinjected fluid in real time and feeds the detection signal back to the PID controller, forming a pressure-concentration dual closed-loop control system.

[0014] Furthermore, according to one aspect of this disclosure, a method for resisting cavitation in an airborne liquid metal precooling system further includes: Objective function establishment: Establish a comprehensive objective function J = α·(NPSHr-NPSHa)² + β· ·ΔT_loss; (NPSHr-NPSHa) is the cavitation margin of the driving pump, and its squared term represents the penalty for deviating from the safety margin. ·ΔT_loss) is the energy loss of the system, and α and β are weighting coefficients that can be adjusted between "safety" and "energy efficiency" according to different flight mission requirements; System protection strategy: When the calculated objective function value J exceeds the preset safety threshold, the system will no longer pursue the maximum cooling efficiency, but will prioritize the implementation of the protection strategy, actively reduce the speed of the drive pump to reduce the system flow, thereby reducing the pressure drop in the local low-pressure area, increasing (NPSHa) i.e., the effective net positive suction head, avoiding cavitation and protecting the safety of the system.

[0015] According to an embodiment of this disclosure, an anti-cavitation device and method for an airborne liquid metal pre-cooling system utilizes centrifugal force to separate liquid metal from lighter air bubbles via a cyclone separator. The air bubbles are collected in the central low-pressure zone of the cyclone separator. An ejector uses a small stream of liquid metal from the high-pressure side of the system (such as the pump outlet) as the working fluid to generate a high-speed jet, creating a low pressure in the separation chamber. This actively and continuously "draws away" the separated gas from the pump inlet area and pressurizes the gas-liquid mixture before sending it back to the upstream low-pressure zone of the system, achieving gas re-dissolution or collection. This method can solve the problems of pump inlet pressure instability and cavitation caused by gas precipitation in the local low-pressure zone under harsh operating conditions such as sudden attitude changes in the liquid metal cooling circuit. It plays a crucial role in improving the reliability and safety of hypersonic vehicle propulsion systems. It can be applied to: wide-speed-range aero-engines, pre-cooled aero-engines, variable-cycle engines, and hypersonic turbine-based combined propulsion systems.

[0016] It should be understood that both the foregoing general description and the following detailed description are exemplary and intended to provide further illustration of the claimed technology. Attached Figure Description

[0017] The above and other objects, features, and advantages of this disclosure will become more apparent from the more detailed description of the embodiments thereof in conjunction with the accompanying drawings. The drawings are provided to further illustrate the embodiments of this disclosure and form part of the specification. They are used together with the embodiments of this disclosure to explain the disclosure and do not constitute a limitation thereof. In the drawings, the same reference numerals generally represent the same components or steps.

[0018] Figure 1 This is a schematic diagram of the anti-cavitation device of an airborne liquid metal precooling system according to an embodiment of the present disclosure; Figure 2 This is a schematic diagram illustrating the working principle of the ejector of the anti-cavitation device according to an embodiment of the present disclosure; Figure 3 This is a schematic diagram of the gas-liquid separation process within the separation chamber of the anti-cavitation device according to an embodiment of the present disclosure; Figure 4 This is a control logic flowchart of an anti-cavitation method for an airborne liquid metal precooling system according to an embodiment of the present disclosure; Figure 5 This is a flowchart of an anti-cavitation method for an airborne liquid metal precooling system according to an embodiment of the present disclosure.

[0019] Explanation of reference numerals in the attached figures: 1. Outer shell, 11. First shell, 12. Second shell, 13. Installation space, 14. Separation chamber, 2. Ejector, 21. Main body pipeline, 22. Drainage pipeline, 23. Recirculation pipeline, 3. Swirl separator, 31. Rotary shaft, 32. Guide vane, 4. Inlet pipeline, 5. Composite sensor, 6. Cable, 7. PID controller, 8. Ultrasonic transducer, 9. Triaxial accelerometer. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this disclosure more apparent, exemplary embodiments according to this disclosure will now be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of this disclosure, and not all embodiments of this disclosure. It should be understood that this disclosure is not limited to the exemplary embodiments described herein.

[0021] (I) Current Status of Hypersonic Vehicle Precooling Systems: With the rapid development of aerospace technology, hypersonic vehicles (flying at Mach numbers greater than 5) have become a research focus. During flight, these vehicles experience extremely high aerodynamic heating, reaching temperatures of thousands of degrees Celsius, due to intense friction and compression with the air. To protect the vehicle structure and ensure normal engine operation, a highly efficient thermal management system is essential. A strong pre-cooling system is one of the core technologies of hypersonic vehicles, especially those using ramjet or combined cycle engines. Its function is to rapidly reduce the temperature of air before it enters the engine combustion chamber via a heat exchanger, thereby improving engine efficiency and thrust, and protecting engine components from high-temperature damage.

[0022] (II) Advantages and challenges of liquid metal cooling media: In high-intensity precooling systems, the choice of cooling medium is crucial. Traditional coolants, such as aviation fuel and water, suffer from insufficient specific heat capacity and are prone to decomposition or vaporization under hypersonic flight conditions. In contrast, liquid metals (such as gallium-indium-tin alloys and sodium-potassium alloys) exhibit significant advantages due to their unique physical properties. Extremely high thermal conductivity: The thermal conductivity of liquid metal is much higher than that of traditional fluids, enabling extremely high heat exchange efficiency and meeting the huge heat load requirements of hypersonic aircraft.

[0023] High boiling point and low vapor pressure: Liquid metals remain liquid over a wide temperature range, are not easily vaporized, and can work stably under high temperature and high pressure environments.

[0024] High density: Its high density characteristic allows it to require a relatively small circulation flow rate for the same heat dissipation capacity, which helps to reduce the size of the pump and the weight of the system.

[0025] However, these excellent properties of liquid metals also bring unique challenges, especially in airborne dynamic environments where their physical behavior is far more complex than that of traditional fluids.

[0026] (III) Gas evolution and cavitation problems: Liquid metals dissolve a certain amount of gas (such as oxygen and nitrogen) at high temperatures. According to Henry's Law, the solubility of a gas is directly proportional to its pressure. When liquid metal circulates in a cooling circuit, flowing through localized low-pressure areas such as pump inlets, valves, and pipe narrowing, its ability to dissolve gases decreases sharply, causing supersaturated gas to rapidly precipitate and form bubbles. This process is particularly intense and complex in airborne dynamic low-pressure environments.

[0027] These precipitated bubbles can lead to a series of serious consequences: 1. Cavitation: The accumulation of air bubbles at the pump inlet significantly reduces the effective net positive suction head (NPSHa). Cavitation occurs when NPSHa falls below the required net positive suction head (NPSHr) specified in the pump's design. Cavitation causes a sharp drop in pump flow rate and head, reduces efficiency, and generates intense vibration and noise. In severe cases, the collapse of air bubbles can generate microjet streams and shock waves, causing severe erosion damage to the pump impeller and casing, and even leading to complete pump failure.

[0028] 2. System pressure instability: The formation and aggregation of bubbles can change the compressibility of the fluid, causing system pressure fluctuations and affecting the stable operation of the entire cooling circuit.

[0029] 3. Decreased heat exchange performance: The presence of bubbles increases thermal resistance, reduces the heat exchange efficiency of the heat exchanger, and affects the pre-cooling effect.

[0030] (iv) Limitations of existing technology: While the industry has developed some mature degassing technologies to address the issue of gases in fluids, these technologies have significant limitations when applied to airborne liquid metal systems. System pressurization: This method suppresses gas evolution by increasing the operating pressure of the entire system. However, this increases the structural weight and design complexity of the system, which is unacceptable for aircraft.

[0031] Increasing the pipe diameter reduces flow velocity and minimizes local pressure loss. However, this occupies valuable onboard space and increases system weight.

[0032] Traditional degassing devices include gravity separators and filter-type degassers. These devices are typically bulky, heavy, and slow to respond, failing to meet the rapid response requirements under sudden changes in aircraft attitude. Furthermore, most of them are designed for conventional fluids such as water or oil, and their degassing efficiency is significantly reduced for high-density, high-surface-tension liquid metals.

[0033] Existing technologies have not solved the problem of in-situ suppression, separation, and re-dissolution of bubbles in liquid metal under conditions of sudden changes in three-axis attitude and closed-loop circulation in hypersonic vehicles.

[0034] This disclosure provides an anti-cavitation device and method for an airborne liquid metal precooling system, which can solve the problems of pump inlet pressure instability and cavitation caused by gas evolution in local low-pressure areas under harsh operating conditions such as sudden attitude changes in the liquid metal cooling circuit.

[0035] The embodiments of this disclosure will now be described in detail with reference to the accompanying drawings.

[0036] like Figure 1 , Figure 2 , Figure 3 As shown, this disclosure provides an anti-cavitation device for an airborne liquid metal strong precooling system, used in the air intake precooling system of an aircraft, i.e., an airborne liquid metal strong precooling system. The device includes: a shell 1, an inlet pipe 4, a cyclone separator 3, and an ejector 2. The housing is connected to the inlet pipe of the drive pump, which can deliver cooling fluid to the drive pump. The housing 1 has a separation chamber 14 inside. The inlet pipe 4 is connected to the outer casing 1 and is used to input cooling fluid into the separation chamber 14, which is usually liquid metal, such as Ga-In-Sn alloy; The cyclone separator 3 is installed in the separation chamber 14 and can rotate within the chamber to perform gas-liquid separation by rotating the cooling fluid. When liquid metal flows through, it generates a strong rotational motion. Under the action of centrifugal force, the denser liquid metal is thrown towards the wall of the separation chamber 14, while the less dense bubbles are pushed towards the central low-pressure zone, thus achieving gas-liquid separation. The cyclone separator 3 uses centrifugal force to separate the liquid metal from the lighter bubbles, and the bubbles are collected in the central low-pressure zone of the cyclone separator 3. The function of the cyclone separator 3 is to perform gas-liquid separation before the liquid metal enters the drive pump, thereby effectively preventing bubbles from accumulating at the pump inlet and causing cavitation. The ejector 2 is located on the top of the housing 1 and connected to the separation chamber 14. The ejector 2 is able to pass high-speed fluid, which generates a low-pressure zone in the ejector 2, drawing the gas in the separation chamber 14 out to the ejector 2.

[0037] Ejector 2 and cyclone separator 3 are tightly integrated to form a functionally coupled unit. Ejector 2 uses a small stream of liquid metal from the high-pressure side of the system (such as the pump outlet) as the working fluid to generate a high-speed jet, creating a low pressure in the separation chamber 14. This actively and continuously "draws" the separated gas from the pump inlet area and pressurizes the gas-liquid mixture before sending it back to the upstream low-pressure area of ​​the system, achieving gas redissolution or collection.

[0038] This device cleverly utilizes a small amount of high-pressure fluid at the pump outlet as the ejector power, achieving energy recycling within the system without the need for an additional power source, thus meeting the stringent energy and weight requirements of aircraft.

[0039] In some possible implementations, such as Figure 1 , Figure 2 As shown, the outer casing 1 includes: a first casing 11 and a second casing 12; The first housing 11 is disposed inside the outer shell 1, and the separation cavity 14 is disposed inside the first housing 11; The second housing 12 is disposed on the outside of the outer housing 1. An installation space 13 is provided between the first housing 11 and the second housing 12. The installation space 13 can be in a vacuum state and is used to install various electronic components.

[0040] The outer shell 1 has an overall inverted conical structure and can be constructed using vacuum brazing. The inner first shell 11 can be made of a tungsten-molybdenum alloy resistant to liquid metal corrosion, while the outer second shell 12 can be made of a pressure-bearing titanium alloy. The inner layer is made of tungsten-molybdenum alloy because liquid metals (such as Ga-In-Sn alloys) are extremely corrosive, which ordinary metal materials cannot withstand. Tungsten-molybdenum alloy has excellent high-temperature resistance and corrosion resistance, ensuring that the cyclone chamber maintains structural integrity and a smooth surface even after prolonged contact with liquid metal, thus maintaining stable separation efficiency. The outer layer uses a high-strength titanium alloy primarily to withstand the high pressure inside the system and the high overload under airborne conditions, ensuring the mechanical strength and reliability of the entire device.

[0041] The first housing 11 and the second housing 12 employ a "vacuum brazing encapsulation" technology to integrate and seal key electronic components such as the PID controller 7 and the ultrasonic transducer 8, forming an "indivisible multi-field coupling flow guiding module." This highly integrated design not only significantly saves space and weight, meeting the aircraft's extreme pursuit of lightweight design, but also effectively isolates the system from the corrosive effects of liquid metal and the external environment through vacuum encapsulation, significantly improving the reliability and lifespan of electronic components and solving the problem of stable operation of electronic systems in extreme environments.

[0042] In some possible implementations, such as Figure 1 , Figure 3 As shown, the cyclone separator 3 includes: a rotating shaft 31 and guide vanes 32; The rotating shaft 31 has an inverted conical structure. The ejector 2 is connected to the rotating shaft 31. An output channel is provided inside the rotating shaft 31 along the axial direction. Gas can be drawn out from the lower end of the rotating shaft 31 through the output channel to the ejector 2. The guide vane 32 is spiral-shaped, and two or more sets of guide vanes 32 can be provided. The guide vane 32 is located on the outside of the rotating shaft 31, and the rotating shaft 31 can drive the guide vane 32 to rotate.

[0043] In some possible implementations, such as Figure 1 , Figure 2 As shown, the ejector 2 includes: a body conduit 21 and a drainage conduit 22; The main pipe 21 is a Venturi tube structure with a diameter reduction section in the middle; The first end of the drainage pipe 22 is connected to the diameter reduction section of the main pipe 21, and the second end of the drainage pipe 22 extends into the rotating shaft 31.

[0044] The ejector 2 is powered by a small stream of high-pressure liquid metal from the high-pressure side of the system (such as the pump outlet). This high-pressure fluid forms a high-speed jet through the nozzle inside the ejector 2, creating a low-pressure zone around the jet according to the Venturi effect. This low-pressure zone is connected to the gas collection port at the center of the cyclone separator 3 through the drainage pipe 22, thereby actively and continuously "drawing away" the separated gas and a small amount of liquid metal, and actively drawing in the gas-liquid mixture accumulated at the center of the cyclone separator 3.

[0045] In some possible implementations, such as Figure 1 , Figure 2 As shown, the ejector 2 also includes a return line 23, the first end of which is connected to the outlet end of the main body line 21, and the second end of which is connected to the upstream low-pressure area of ​​the system, which can transport the return liquid to the upstream low-pressure area of ​​the system.

[0046] After being pressurized in ejector 2, the gas-liquid mixture is sent back to the upstream low-pressure area of ​​the system (such as the radiator inlet) through reinjection line 23, providing sufficient time and space for the gas to redissolve or collect in the expansion tank.

[0047] Ejector 2 not only acts as a "vacuum pump," but more importantly, it stabilizes the separation process by maintaining a low pressure at the center of the cyclone separator 3, preventing "gas blockage" and pressure fluctuations caused by excessive gas accumulation. The extracted gas-liquid mixture is pressurized inside ejector 2 and then sent back to the upstream of the system (such as the radiator inlet) through reinjection pipe 23. Here, the gas has more time to redissolve or collect in the expansion tank, forming a complete closed-loop processing flow.

[0048] In some possible implementations, such as Figure 1 , Figure 3 As shown, the device also includes: a composite sensor 5 and a PID controller 7; The composite sensor 5 is installed in the reinjection pipeline 23 to monitor the gas concentration and pressure in the return liquid in real time. The PID controller 7 is located in the installation space 13, specifically it can be installed and fixed in the first housing 11. The composite sensor 5 is connected to the PID controller 7 through the cable 6, and can transmit the detection signal to the PID controller 7.

[0049] Cable 6 can be a shielded twisted pair. The in-situ sound velocity-concentration composite sensor 5 can monitor the gas concentration and pressure in the return liquid in real time, providing the PID controller 7 with direct feedback on the system's cavitation status. This feedback signal, together with the attitude signal from the triaxial accelerometer 9 (MEMS accelerometer), constitutes a pressure-concentration dual closed-loop control system, enabling the controller to more accurately and quickly adjust the ejection rate and the operating status of each actuator, achieving proactive and intelligent management of cavitation risks.

[0050] In some possible implementations, such as Figure 1 , Figure 3 As shown, the device also includes: multiple ultrasonic transducers 8, which are disposed in the installation space 13, specifically installed and fixed to the first housing 11. The ultrasonic transducers 8 are electrically connected to the PID controller 7, which can be connected via a flexible circuit board. When the attitude angle change rate of the aircraft is greater than 15° / s, the ultrasonic transducers 8 are activated to generate a sound field, forming an acoustic radiation pressure trap at the swirling center of the separation chamber 14, which suspends and fixes the gas in the separation area.

[0051] Multiple ultrasonic transducers 8 form an array, which can be evenly distributed in the first housing 11, forming an "inertial-acoustic field" coupled control with the swirling separator 3. When the aircraft's attitude angle change rate exceeds 15° / s, the ultrasonic field is activated, forming an acoustic radiation pressure trap at the center of the swirling flow, suspending and fixing the bubbles in the separation zone, preventing bubbles from escaping due to blade adjustment lag. This setting reflects the intelligence and energy efficiency of the control strategy.

[0052] The ultrasonic transducer array generates a high-frequency sound field, forming an "acoustic radiation pressure trap" at the center of the vortex to capture and trap tiny bubbles that the inertial blades cannot respond to in rapid changes in aircraft attitude. However, continuously operating the ultrasonic transducers consumes a large amount of electrical energy, which is unacceptable for energy-constrained aircraft. Therefore, this embodiment adopts a hierarchical control strategy: when the aircraft attitude changes relatively smoothly (attitude angle change rate < 15° / s), only passive inertial blades are used for adjustment, and the ultrasonic field remains off, thus saving power consumption. Only when the attitude changes drastically (attitude angle change rate > 15° / s), such as when encountering strong airflow disturbances or performing high-maneuvering flight, will the PID controller 7 trigger the ultrasonic transducer 8 to start in order to cope with high-frequency, rapid disturbances. This event-triggered control method ensures that energy is used effectively, which is a typical optimization approach in airborne system design. The threshold setting (15° / s) is based on the analysis of typical flight conditions, balancing the relationship between system response speed and energy consumption.

[0053] The "inertial-acoustic field" multi-field coupling control strategy is an intelligent, hierarchical adaptive control system. The inertial field is implemented by guide vanes 32, primarily addressing low-frequency, large-amplitude attitude changes (such as aircraft turning and climbing). The acoustic field is implemented by ultrasonic transducers; when the attitude angle change rate exceeds 15° / s, the system identifies it as a high-frequency disturbance (such as airflow buffeting), and the ultrasonic field is activated. The ultrasonic waves form a powerful acoustic radiation pressure trap at the center of the vortex, effectively "suspending and fixing" tiny bubbles in the separation zone, preventing them from escaping due to blade adjustment lag. This collaborative work of multiple physical fields, addressing disturbances of different frequencies and amplitudes in a hierarchical manner, achieves refined and intelligent management of the gas-liquid separation process.

[0054] In some possible implementations, such as Figure 1 , Figure 3 As shown, the device also includes a triaxial accelerometer 9, which is disposed in the installation space 13, specifically it can be installed and fixed to the first housing 11. The triaxial accelerometer 9 is electrically connected to the PID controller 7 and can be connected through a flexible circuit board to detect the attitude changes of the aircraft in real time and can transmit the detection signal to the PID controller 7.

[0055] The use of flexible printed circuit boards (FPCs) is an ideal solution for achieving complex electrical connections in such a highly integrated and compact space. They have good flexibility, bend resistance and space utilization, and can ensure that signal and power transmission remain stable and reliable when the components inside the module move relative to each other.

[0056] Multiple electronic components are connected to the central PID controller 7 via a flexible circuit board, forming a closed-loop control system. The PID controller 7 acts as the "brain," receiving signals from various sensors (such as attitude information from the MEMS accelerometer) in real time. Based on preset control logic and algorithms, it issues commands to each actuator, achieving precise, dynamic, and adaptive control of the swirling separation process. This modular design, which highly integrates sensing, control, execution, and drive circuits, is a key feature distinguishing it from existing technologies. It enables the entire device to intelligently respond to drastic changes in flight attitude, achieving a leap from "passive separation" to "active control."

[0057] In some possible implementations, such as Figure 4 , Figure 5 As shown, an anti-cavitation method for an airborne liquid metal precooling system is implemented using the anti-cavitation device of the airborne liquid metal precooling system described in any of the above embodiments, comprising: Signal acquisition: The attitude changes of the aircraft are monitored in real time using a three-axis accelerometer 9, and the signals are transmitted to the PID controller 7; Threshold judgment: The PID controller 7 judges the rate of change of the aircraft's attitude angle. When the rate of change is no greater than 15° / s, the system is in low power consumption mode and relies only on the passive inertial adjustment of the guide vanes 32 of the cyclone separator 3. Active control activation: When the aircraft's attitude angle change rate is greater than 15° / s, the PID controller 7 triggers the ultrasonic transducer 8 to start, generating an acoustic radiation pressure trap. Closed-loop feedback: The composite sensor 5 installed on the ejector 2 monitors the gas concentration and pressure of the reinjected fluid in real time and feeds back the detection signal to the PID controller 7, forming a pressure-concentration dual closed-loop control system.

[0058] In some possible implementations, such as Figure 5 As shown, the method also includes: Objective function establishment: Establish a comprehensive objective function J = α·(NPSHr-NPSHa)² + β· ·ΔT_loss; (NPSHr-NPSHa) is the cavitation margin of the driving pump, and its squared term represents the penalty for deviating from the safety margin. ·ΔT_loss) is the energy loss of the system, and α and β are weighting coefficients that can be adjusted between "safety" and "energy efficiency" according to different flight mission requirements; System protection strategy: When the calculated objective function value J exceeds the preset safety threshold, the system will no longer pursue the maximum cooling efficiency, but will prioritize the implementation of the protection strategy, actively reduce the speed of the drive pump to reduce the system flow, thereby reducing the pressure drop in the local low-pressure area, increasing the effective net positive suction head (NPSHa), avoiding cavitation, and protecting the safety of the system.

[0059] By introducing a quantified objective function J, this embodiment transforms the abstract "anti-cavitation" objective into a calculable and optimizable mathematical problem. This allows the control system to autonomously assess the degree of danger of the current operating condition based on real-time monitored data and take corresponding protective measures. Compared to traditional threshold-based alarm protection methods, this model-based predictive control method has higher sensitivity and foresight, enabling intervention before cavitation occurs. This maximizes the protection of the core component (drive pump) and ensures the stable operation of the entire cooling system.

[0060] The objective function J is the mathematical core of the method in this embodiment, integrating two key performance indicators. The first term, "α·(NPSHr-NPSHa)²", is directly related to the core physical condition for cavitation. The difference between NPSHr (the pump's required net positive suction head) and NPSHa (the device's effective net positive suction head) is a key parameter for measuring cavitation risk. Cavitation occurs when NPSHa is less than NPSHr. This term is in square form, meaning that when NPSHa approaches or even falls below NPSHr, the value of the objective function J increases sharply, thus sending a strong warning signal to the control system. The second term, "β· ·ΔT_loss represents the system's heat loss, where ΔT_loss represents mass flow rate, and ΔT_loss represents temperature rise loss. The introduction of this term reflects the consideration of both anti-cavitation effects and overall system energy efficiency. By adjusting the weighting coefficients α and β, a trade-off between "safety" and "energy efficiency" can be struck according to different flight mission requirements. For example, during the cruise phase, β can be appropriately increased to pursue higher energy efficiency; while during high-maneuverability flight phases, α should be increased to ensure absolute safety. The construction of this multi-objective optimization function makes the control method of this invention more flexible and intelligent.

[0061] The system's protection strategy is: "When J > threshold, prioritize reducing pump speed to protect the system." This is an active protection logic based on risk assessment. The control system calculates the objective function J in real time and compares it with a preset safety threshold. When the J value exceeds the threshold, it means that the system's cavitation risk has reached an unacceptable level, or the system's energy efficiency loss is too large. At this time, the control system triggers the protection program, and its primary action is to "prioritize reducing pump speed." Reducing the pump speed directly reduces the pump's demand on NPSHr, thereby rapidly increasing the safety margin between NPSHA and NPSHr, fundamentally eliminating the cavitation risk. This is a fundamental protection measure, more effective and reliable than traditional "stopgap" methods such as bypass pressure relief. At the same time, reducing the pump speed also reduces the system's energy consumption and heat loss. This "priority" strategy reflects the principle of putting system safety first under extreme operating conditions.

[0062] The above description, with reference to the accompanying drawings, illustrates an anti-cavitation device and method for an airborne liquid metal precooling system according to embodiments of the present disclosure, which has the following advantages: 1. It fundamentally solves the cavitation problem: Through integrated active control of "separation-extraction-redissolution", it inhibits the accumulation of bubbles at the pump inlet from the source, minimizes the negative impact of gas evolution, and ensures the stable operation of the core component (pump). It is a "root cause" rather than a "symptom-treating" solution.

[0063] 2. Excellent dynamic adaptability: The multi-field coupling control strategy enables this device to perfectly adapt to extreme conditions such as three-axis attitude change of hypersonic vehicles, solving the challenges that traditional degassing devices cannot handle.

[0064] 3. High-efficiency energy utilization and lightweight design: By utilizing the high-pressure fluid energy of the system itself through the ejector, there is no need to introduce an external power source, avoiding increased weight and potential failure points, achieving a highly efficient energy cycle, which is in line with the design concept of aircraft.

[0065] 4. Significant synergistic effect: It is not a simple stacking of multiple components, but rather achieves a synergistic effect of "1+1>2" through ingenious structural design and intelligent control strategies (such as multi-field coupling). The ejector stabilizes the cyclone separator; the acoustic field responds to different disturbances, ensuring the robustness and efficiency of the system under various operating conditions.

[0066] The basic principles of this disclosure have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in this disclosure are merely examples and not limitations, and should not be considered as essential features of each embodiment of this disclosure. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the scope of this disclosure to the necessity of employing the aforementioned specific details for implementation.

[0067] The block diagrams of devices, apparatuses, devices, and systems disclosed herein are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As those skilled in the art will recognize, these devices, apparatuses, devices, and systems can be connected, arranged, and configured in any manner. Words such as “comprising,” “including,” “having,” etc., are open-ended terms meaning “including but not limited to,” and are used interchangeably with them. The terms “or” and “and” as used herein refer to the terms “and / or,” and are used interchangeably with them unless the context clearly indicates otherwise. The term “such as” as used herein refers to the phrase “such as but not limited to,” and is used interchangeably with it.

[0068] Additionally, as used herein, the "or" used in a list of items beginning with "at least one" indicates a separate list, such that a list of, for example, "at least one of A, B, or C" means A or B or C, or AB or AC or BC, or ABC (i.e., A and B and C). Furthermore, the word "exemplary" does not imply that the described example is preferred or better than other examples.

[0069] It should also be noted that in the systems and methods disclosed herein, the components or steps can be decomposed and / or recombined. These decompositions and / or recombinations should be considered as equivalent solutions to this disclosure.

[0070] Various changes, substitutions, and modifications can be made to the technology described herein without departing from the teachings defined by the appended claims. Furthermore, the scope of the claims of this disclosure is not limited to the specific aspects of the processes, machines, manufactures, events, means, methods, and actions described above. Currently existing or later-developed processes, machines, manufactures, events, means, methods, or actions that perform substantially the same function or achieve substantially the same result as the corresponding aspects described herein can be utilized. Therefore, the appended claims include such processes, machines, manufactures, events, means, methods, or actions within their scope.

[0071] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use this disclosure. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects without departing from the scope of this disclosure. Therefore, this disclosure is not intended to be limited to the aspects shown herein, but rather to be carried out within the widest scope consistent with the principles and novel features disclosed herein.

[0072] The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of this disclosure to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations thereof.

Claims

1. An anti-cavitation device for an airborne liquid metal precooling system, used in the air intake precooling system of an aircraft, characterized in that, include: The outer shell (1) has a separation cavity (14) inside. An inlet pipe (4) is connected to the outer casing (1) and is used to input cooling fluid into the separation chamber (14); A cyclone separator (3) is disposed in the separation chamber (14) and can rotate in the separation chamber (14) to rotate the cooling fluid for gas-liquid separation; Ejector (2), which is located on the top of the housing (1) and connected to the separation chamber (14), is capable of passing high-speed fluid, which generates a low-pressure zone in the ejector (2) to draw the gas in the separation chamber (14) to the ejector (2).

2. The anti-cavitation device for an airborne liquid metal precooling system according to claim 1, characterized in that, The outer casing (1) includes: The first housing (11) is disposed inside the outer shell (1), and the separation cavity (14) is disposed inside the first housing (11); The second housing (12) is disposed on the outside of the outer shell (1), and an installation space (13) is provided between the first housing (11) and the second housing (12).

3. The anti-cavitation device for an airborne liquid metal precooling system according to claim 2, characterized in that, The cyclone separator (3) includes: A rotating shaft (31) is connected to the ejector (2). An output channel is provided axially inside the rotating shaft (31), and gas can be drawn out from the lower end of the rotating shaft (31) through the output channel to the ejector (2). The guide vane (32) is disposed on the outside of the rotating shaft (31), and the rotating shaft (31) can drive the guide vane (32) to rotate.

4. The anti-cavitation device for an airborne liquid metal precooling system according to claim 3, characterized in that, The ejector (2) includes: The main body pipeline (21) is a Venturi tube structure with a diameter reduction section in the middle; The drainage pipe (22) has its first end connected to the diameter reduction section of the main pipe (21), and its second end extends into the rotating shaft (31).

5. The anti-cavitation device for an airborne liquid metal precooling system according to claim 4, characterized in that, The ejector (2) also includes: The reinjection pipeline (23) has its first end connected to the outlet end of the main pipeline (21) and its second end connected to the upstream low-pressure area of ​​the system, which can transport the return liquid to the upstream low-pressure area of ​​the system.

6. The anti-cavitation device for an airborne liquid metal precooling system according to claim 5, characterized in that, Also includes: A composite sensor (5) is installed in the reinjection pipeline (23) to monitor the gas concentration and pressure in the reflux liquid in real time. A PID controller (7) is provided in the installation space (13). The composite sensor (5) is connected to the PID controller (7) via a cable (6) and can transmit the detection signal to the PID controller (7).

7. The anti-cavitation device for an airborne liquid metal precooling system according to claim 6, characterized in that, Also includes: Multiple ultrasonic transducers (8) are installed in the installation space (13). The ultrasonic transducers (8) are electrically connected to the PID controller (7). When the attitude angle change rate of the aircraft is greater than 15° / s, the ultrasonic transducers (8) start to generate a sound field and form an acoustic radiation pressure trap at the swirling center of the separation chamber (14) to suspend and fix the gas in the separation area.

8. The anti-cavitation device for an airborne liquid metal precooling system according to claim 6, characterized in that, Also includes: A three-axis accelerometer (9) is installed in the installation space (13). The three-axis accelerometer (9) is electrically connected to the PID controller (7) to detect the attitude change of the aircraft in real time and can transmit the detection signal to the PID controller (7).

9. A method for preventing cavitation in an airborne liquid metal precooling system, implemented using the anti-cavitation device of the airborne liquid metal precooling system according to any one of claims 1-8, characterized in that, include: Signal acquisition: The attitude changes of the aircraft are monitored in real time using a three-axis accelerometer (9), and the signals are transmitted to the PID controller (7); Threshold judgment: The PID controller (7) judges the rate of change of the attitude angle of the aircraft. When the rate of change is not greater than 15° / s, the system is in low power mode and relies only on the passive inertial adjustment of the guide vanes (32) of the cyclone separator (3). Active control start-up: When the attitude angle change rate of the aircraft is greater than 15° / s, the PID controller (7) triggers the ultrasonic transducer (8) to start, generating an acoustic radiation pressure trap; Closed-loop feedback: The composite sensor (5) installed on the ejector (2) monitors the gas concentration and pressure of the reinjected fluid in real time and feeds back the detection signal to the PID controller (7) to form a pressure-concentration dual closed-loop control system.

10. The anti-cavitation method for an airborne liquid metal precooling system according to claim 9, characterized in that, Also includes: Objective function establishment: Establish a comprehensive objective function J = α·(NPSHr-NPSHa)² + β· ·ΔT_loss; (NPSHr-NPSHa) is the cavitation margin of the driving pump, and its squared term represents the penalty for deviating from the safety margin. ·ΔT_loss) is the energy loss of the system, and α and β are weighting coefficients that can be adjusted between "safety" and "energy efficiency" according to different flight mission requirements; System protection strategy: When the calculated objective function value J exceeds the preset safety threshold, the system will no longer pursue the maximum cooling efficiency, but will prioritize the implementation of the protection strategy, actively reduce the speed of the drive pump to reduce the system flow, thereby reducing the pressure drop in the local low-pressure area, increasing (NPSHa) i.e., the effective net positive suction head, avoiding cavitation and protecting the safety of the system.

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