Power system of cross-medium aircraft based on aluminum-based metal fuel

Abstract

The invention aims to provide a power system of a cross-medium aircraft based on aluminum-based metal fuel, and belongs to the field of cross-medium power devices. The gas inlet device comprises a water inlet channel and a gas inlet channel, the water inlet channel and the gas inlet channel switch passing media through a switching valve, the nozzle comprises a first-stage pipeline, a second-stage pipeline and a third-stage pipeline, the first-stage pipeline is connected with a metal powder supply system, the second-stage pipeline is connected with the gas inlet device, and the third-stage pipeline is connected with a methane supply system. A centrifugal compressor is arranged between the second-stage pipeline and the air inlet device, the end of the nozzle pipeline extends to the combustion chamber, the combustion chamber is connected with a power turbine, and the rear portion of the power turbine is connected with an exhaust nozzle and a propeller. Two sets of independent systems are replaced by highly integrated design, the energy conversion efficiency is better than that of a traditional dual-power system, chemical energy is directly converted into mechanical energy, and loss caused by multiple times of energy conversion is avoided.

Description

Technical Field

[0001] The present invention relates to a transmedium aircraft, specifically a transmedium aircraft based on metallic fuel. Background Technology

[0002] Existing dual-mode centrifugal engines use aluminum- and magnesium-based solid propellants that can react with air and water as fuel. They are equipped with valved air intakes and water inlets, as well as pre-installed oxidizer tanks. An optimal water-fuel ratio is determined to maximize the engine's specific impulse, enabling high-speed entry and exit of the vehicle from water, avoiding stalling during medium transitions, and improving the vehicle's reliability. The core idea is to use a single power system that utilizes the reaction of metallic fuel with different media (air or water) to achieve continuous power output in the air and underwater.

[0003] Current cross-medium propulsion devices typically employ two independent power systems mechanically combined together. This architecture has fundamental flaws: at the system level, the power unit and its associated structures in non-operating states create significant mass redundancy, leading to a deterioration in thrust-to-weight ratio and a decrease in energy efficiency; at the component level, core components such as compressors and combustors optimized for a single medium face severe cross-domain adaptability challenges, such as sudden load changes and cavitation risks in aerodynamic blade profiles under underwater conditions, and the difficulty in incorporating the differences in combustion characteristics of aluminum-based fuels with different oxidizers into fixed-structure combustors; at the control level, the master-slave switching strategy used in discrete systems introduces second-level power interruption windows, and the lack of multivariate coordination mechanisms causes thrust oscillations. The essence of these problems lies in the fact that traditional solutions attempt to solve the medium adaptability problem through subsystem superposition rather than thermodynamic cycle innovation, resulting in a constant and difficult trade-off between structural efficiency, operating condition adaptability, and power continuity.

[0004] Regarding the smoothness and reliability of mode transitions, existing technologies employ valve switching and pre-placed oxidants to ensure thrust during mode transitions. However, the response speed, sealing reliability, and operational stability of mechanical valves under complex cross-media environments (such as large impacts and pressure changes) may face challenges. Summary of the Invention

[0005] The purpose of this invention is to provide a propulsion system for a cross-medium aircraft based on aluminum-based metal fuel that can operate efficiently in air and water through adaptive structures such as adjustable blades, intelligent tail nozzles and variable transmission, thereby eliminating the weight burden at the source.

[0006] The objective of this invention is achieved as follows: This invention discloses a propulsion system for a cross-medium aircraft based on aluminum-based metal fuel, characterized by comprising an air intake device, a nozzle, a combustion chamber, a power turbine, and a tail nozzle. The air intake device includes a water intake channel and an air intake channel, which switch the medium passing through via a switching valve connected to a hydraulic actuator. The nozzle includes a first-stage pipe, a second-stage pipe, and a third-stage pipe. The first-stage pipe is connected to a metal powder supply system, the second-stage pipe is connected to the air intake device, and the third-stage pipe is connected to a methane supply system. A centrifugal compressor is installed between the second-stage pipe and the air intake device. The tail ends of the first-stage, second-stage, and third-stage pipes converge to form a concentric nozzle pipeline. The first-stage pipe has the smallest diameter and is located at the innermost point, while the third-stage pipe has the largest diameter and is located at the outermost point. The second-stage pipe is located between the first-stage and third-stage pipes. The end of the nozzle pipeline extends towards the combustion chamber, which is connected to the power turbine. The tail nozzle and a propeller are connected to the rear of the power turbine.

[0007] The present invention may also include: 1. The centrifugal compressor comprises at least five stages of rotating impellers and guide vanes arranged alternately.

[0008] 2. The guide vane is connected to an electric servo drive mechanism, which adjusts the angle of the guide vane.

[0009] 3. A V-type flame stabilizer is installed in the combustion chamber. The V-type flame stabilizer is located outside the end of the nozzle pipeline.

[0010] 4. The metal powder supply system includes a powder storage box and a powder conveying pipeline. The powder storage box stores aluminum powder. The powder conveying pipeline is connected to the powder storage box and the combustion chamber respectively. The powder storage box is connected to the first-stage pipeline. The high-precision gas in the combustion chamber preheats the aluminum powder through the powder conveying pipeline. The inner wall of the third-stage pipeline is equipped with spiral guide vanes.

[0011] 5. A variable speed transmission mechanism is installed between the power turbine and the propeller.

[0012] 6. A medium density sensor is installed on the outside of the air intake device. When passing through the water-air interface, the medium density sensor detects the change in medium density and controls the switching valve through the hydraulic actuator based on the change in medium density.

[0013] 7. When flying in air, a small amount of methane is first injected to form a combustible premixed gas with air. The combustible premixed gas is ignited to provide sufficient heat for the aluminum powder-air mixture to ignite. When flying underwater, a local high-temperature flame zone is first formed in the combustion chamber by methane injection and ignition. Then aluminum powder and water are injected. The methane combustion provides initial energy to ensure that the aluminum powder-water reaction quickly enters a stable combustion state in the low-temperature and high-pressure underwater environment.

[0014] The advantages of this invention are as follows: This invention has significant advantages in terms of energy density. The volumetric energy density of aluminum powder is more than three times that of traditional aviation fuel and about twice that of magnesium powder. At the same time, since it does not need to carry an additional oxidant, it greatly improves space utilization and allows the volume of the entire power system to be significantly reduced.

[0015] By replacing two independent systems with a highly integrated design, it outperforms traditional dual-power systems in terms of energy conversion efficiency, directly converting chemical energy into mechanical energy and avoiding the losses caused by multiple energy conversions. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a schematic diagram of the combustion chamber nozzle. Figure 3 This is a schematic diagram of the cross-sectional structure of the combustion chamber nozzle duct; Figure 4 A schematic diagram of the structure of the system for supplying high-temperature gas generated by combustion in the combustion chamber to metal powder.

[0017] In the diagram: 1. Air intake channel (air), 2. Water intake channel (water), 3. Centrifugal compressor, 4. Compressor blade, 5. Nozzle, 6. Cross section, 7. V-type flame stabilizer, 8. Power turbine, 9. Combustion chamber, 10. Tail nozzle, 11. Propeller, 12. Metal powder supply system, 13. CH4 supply system, 14. Stage 1 pipe, 15. Stage 2 pipe, 16. Stage 3 pipe, 17. Duct blade. Detailed Implementation

[0018] The invention will now be described in more detail with reference to the accompanying drawings: Combination Figure 1-4 This invention includes an intake device, a dual-mode combustion chamber, and a centrifugal compressor, turbine assembly, and exhaust nozzle connected thereto. The intake device draws in the combustion medium, which is then compressed by the compressor and transported to the combustion chamber to react with metallic fuel. The resulting high-temperature, high-pressure gas drives the turbine, and the exhaust nozzle injects gas to provide power. The compressor, combustion chamber, turbine, and exhaust nozzle form a continuous power chain, capable of operating in both air and underwater environments, maintaining power continuity during medium switching. The specific device and operation are as follows: The air intake system has two channels at the front, each equipped with a multi-layer filter and a grid-type filtration structure, which merge into a single isolation channel at the rear. In air mode, air passes through the multi-layer filter to remove particulate matter; in underwater mode, water flows through the grid-type filtration structure to intercept impurities, and the purified medium enters the isolation channel to stabilize its flow rate and pressure. When crossing the water-air interface, a distributed sensor module detects changes in medium density and transmits the data to the intelligent control unit. The control unit then uses a hydraulic actuator to switch the air intake channels.

[0019] The metal powder supply system consists of a powder storage tank, a piston, a powder fluidization device, liquid oxygen, and a powder delivery pipeline, which is connected to the combustion chamber. Aluminum powder is stored in the powder storage tank. Oxygen is injected into the tank from a fluidizing gas cylinder to fluidize the powder. A portion of the combustion chamber's fuel gas is also introduced into the tank to transport and preheat the metal powder. The piston pushes the fluidized aluminum powder through the powder delivery pipeline into the combustion chamber, where it is atomized and sprayed out through an annular nozzle. This device significantly increases the contact area between the aluminum powder and the oxidant, improving combustion efficiency.

[0020] The compressor is located between the intake device and the combustion chamber, and is connected to the combustion chamber via nozzles. It is a centrifugal compressor. The system alternates between stationary and rotating guide vanes. The guide vanes utilize an electrically driven servo mechanism, enabling real-time adjustment of the vane angle within a short time to ensure optimal compression of the medium flow in both air and underwater modes. The filtered medium is compressed by the compressor at the front of the combustion chamber, increasing its density. It is then sprayed through nozzles along with methane supplied by the methane supply system, where it mixes thoroughly with aluminum powder in the ramjet engine's combustion chamber.

[0021] The combustion chamber houses a metallic fuel injection and ignition system, a V-type flame stabilizer, a rectifier, and a CH4 supply system. The CH4 supply system consists of a miniature gas cylinder, an electronic control valve, and nozzles. In air mode, the intelligent control unit, combining media density sensor and flight status information, automatically activates the CH4 supply device before switching media. A small amount of CH4 is first injected to form a combustible premixed gas with the air entering the combustion chamber. A high-energy electric spark ignites this premixed gas within milliseconds. The instantaneous flame provides sufficient heat to ignite the aluminum powder-air mixture injected into the main combustion chamber. The aluminum powder reacts violently with oxygen in the air. This releases high-temperature energy. In underwater mode, the ignition system utilizes CH4 combustion-assisted combustion to initiate a self-sustaining reaction between aluminum powder and water: within the combustion chamber, a localized high-temperature flame zone is first formed through CH4 injection and ignition, rapidly heating the reaction environment. Subsequently, aluminum powder and water are injected, and the aluminum powder reacts with the water and dissolved oxygen (…). This design generates high-temperature, high-pressure combustion gas. It lowers the temperature threshold for direct ignition of aluminum powder in air, shortens ignition delay, and improves ignition reliability. In a low-temperature, high-pressure underwater environment, CH4 combustion provides initial energy, ensuring the aluminum powder-water reaction quickly enters a stable combustion state. Simultaneously, the generated high-temperature steam forms a continuous, high-energy propulsion gas flow. Seamless switching between the two modes is achieved through dynamic adjustment of the metal fuel injection rate and ignition mode, avoiding thrust fluctuations during cross-medium switching. Furthermore, a V-shaped flame stabilizer inside the combustion chamber anchors the flame through the recirculation zone, ensuring stable combustion; a rectifier ensures a uniform flow field distribution.

[0022] The turbine assembly is located downstream of the combustion chamber. A portion of the high-temperature combustion gases in the combustion chamber impact the turbine blades, driving the turbine to rotate at high speed. The turbine shaft directly drives the propeller at the tail via a mechanical linkage (generating thrust in the air / providing thrust underwater).

[0023] The propeller employs a backward-curved design to reduce cavitation corrosion. A variable-speed transmission mechanism is installed between the turbine and the propeller, which can provide low-speed, high-torque propulsion in underwater mode and high-speed, high-thrust propulsion in air mode, thereby optimizing propulsion efficiency under different media.

[0024] To achieve efficient and smooth mode switching and stable operation across media, the power system also includes a control system composed of distributed sensor modules, hydraulic actuators, and an intelligent control unit. The sensor modules include a medium density sensor, a flight speed laser velocimeter, a combustion chamber pressure and temperature composite probe, and a tail nozzle thrust sensor, which can acquire power system operating parameters in real time. The intelligent control unit incorporates a model predictive control (MPC) based algorithm, integrates sensor data, and performs multi-variable coordinated control of compressor speed, nozzle fuel injection rate, and turbine load distribution. The hydraulic actuator drives adjustable compressor blades through a high-speed proportional valve to achieve dynamic response in a short time, ensuring stable power output and seamless thrust during air-to-water cross-media switching, and maintaining optimal propulsion efficiency and system safety in different flight phases such as cruise, acceleration, and descent.

[0025] Aluminum powder was chosen as fuel because it has extremely high energy density, between that of boron and magnesium. Its calorific value reaches 31.09 megajoules per kilogram, and its volumetric calorific value is as high as 83.89 megajoules per cubic decimeter. At the same time, it is more stable than boron, and it can directly use air or water as an oxidant source without the need to carry an additional oxidant.

[0026] When the average particle size of aluminum powder is approximately 20 μm, the highest combustion efficiency is often achieved, which significantly reduces problems such as agglomeration and sintering.

[0027] The air intake device is used to provide the necessary medium for combustion reactions in different environments. In air mode, it draws in air, and in underwater mode, it draws in filtered water.

[0028] A centrifugal compressor is positioned between the intake device and the combustion chamber. It consists of alternating multi-stage rotating impellers and stationary guide vanes, used to compress air or water to increase the medium density and enhance the reaction efficiency of the combustion chamber. The multi-stage structure allows for gradual increases in medium pressure, avoiding inefficiency or flow separation caused by single-stage compression.

[0029] The dual-mode combustion chamber is located downstream of the compressor and contains a metal fuel injection and ignition system. In air mode, aluminum powder fuel burns with air, releasing heat. In underwater mode, aluminum powder fuel reacts with water and dissolved oxygen to produce high-temperature, high-pressure gas. This generates high-temperature, high-pressure gas.

[0030] The turbine assembly is located downstream of the combustion chamber and uses high-temperature, high-pressure gas to drive the turbine to rotate, providing power for the propeller or other propulsion devices.

[0031] The tail nozzle is located behind the turbine and provides reverse thrust by injecting high-temperature and high-pressure gas to control the thrust magnitude; The compressor, combustion chamber, turbine, and exhaust nozzle form a continuous power chain that can be used in both air and underwater environments, and maintain power continuity during medium switching.

[0032] The multi-stage centrifugal compressor includes no fewer than five stages of rotating impellers and guide vanes arranged alternately. The guide vanes adopt an electric servo drive structure, which can complete the real-time adjustment of the blade angle in a short time to ensure that the medium flow is always in the optimal compression state in both air mode and underwater mode.

[0033] The dual-mode combustion chamber is equipped with a V-shaped flame stabilizer and a rectifier to ensure the stability of the combustion process and the uniform distribution of the flow field in air mode and underwater mode. Through dynamic adjustment of fuel injection rate and ignition mode, seamless switching between the two modes is achieved, avoiding thrust fluctuations when switching between media.

[0034] The combustion chamber end duct system is connected to the combustion chamber outlet and the metal powder supply system. A portion of the high-temperature and high-pressure gas generated in the combustion chamber flows to the metal powder supply system through the duct system to preheat the metal powder, so that it reaches a higher activation state before entering the combustion chamber, shortening the ignition delay and increasing the reaction rate. At the same time, the high-temperature and high-pressure gas discharged from the duct can be discharged through an independent nozzle as an auxiliary jet to provide additional thrust for the aircraft when switching between media or when the main thrust is insufficient.

[0035] A variable speed transmission mechanism is provided between the turbine and the propeller. This transmission mechanism can automatically reduce the turbine output speed in underwater mode to obtain low-speed, high-torque propulsion force according to the control system signal, and increase the transmission ratio in air mode to provide high-speed, high-thrust, thus ensuring the optimization of propulsion efficiency under different media.

[0036] The combustion chamber includes a dual-mode ignition system, which employs different ignition strategies in air mode and underwater mode, and introduces a CH4 supply system as an auxiliary ignition means to ensure rapid, stable and controllable ignition in different media environments. The specific implementation method is as follows: In air flight mode, the ignition system adopts a composite scheme of CH4-air premixed combustion + high-energy electric spark ignition.

[0037] The CH4 supply system consists of a miniature gas cylinder, an electronically controlled valve, and nozzles. Upon aircraft startup, the control unit first injects a small amount of CH4 to form a combustible premixed gas with air. A high-energy electric spark ignites this premixed gas within milliseconds, and the instantaneous flame provides sufficient heat to ignite the aluminum powder-air mixture injected into the main combustion chamber. This design lowers the temperature threshold for direct ignition of aluminum powder, shortens the ignition delay, and improves ignition reliability. In underwater flight mode, the ignition system utilizes CH4 to initiate a self-sustaining reaction between aluminum powder and water: within the combustion chamber, a localized high-temperature flame zone is first formed through CH4 injection and ignition, rapidly heating the reaction environment; subsequently, aluminum powder and water are injected to initiate the reaction. The reaction. CH4 combustion provides initial energy, ensuring that the aluminum powder-water reaction quickly enters a stable combustion state in the low-temperature, high-pressure underwater environment. Simultaneously, the generated high-temperature water vapor forms a continuous, high-energy propulsion gas flow. The dual-mode ignition system is managed by an intelligent control unit. Combining media density sensor and flight status information, it automatically activates the CH4 supply device before cross-media switching, controlling the injection quantity and ignition timing to achieve seamless switching between air-mode CH4-air premixed ignition and underwater mode CH4 combustion-supporting ignition. This ensures uninterrupted thrust during startup and mode switching of the cross-media propulsion system.

[0038] The propulsion system also includes a distributed sensor module, a hydraulic actuator, and an intelligent control unit. Its implementation is as follows: the sensor module includes a medium density sensor, a flight speed laser velocimeter, a combustion chamber pressure-temperature composite probe, and a tail nozzle thrust sensor, capable of acquiring real-time propulsion system operating parameters; the intelligent control unit incorporates a model predictive control (MPC) based algorithm, fusing sensor data to perform multi-variable coordinated control of compressor speed, nozzle fuel injection rate, and turbine load distribution; the hydraulic actuator drives adjustable compressor blades through a high-speed proportional valve, achieving dynamic response in a short time, ensuring stable power output and seamless thrust transition during air-to-water medium switching, and maintaining optimal propulsion efficiency and system safety during different flight phases such as cruise, acceleration, and descent.

[0039] The core structure of this power system is as follows: Figure 1As shown, a modular integrated design concept is adopted, in which the air intake device, centrifugal compressor 3, dual-mode combustion chamber 9, power turbine 8, and tail nozzle 10 are sequentially connected through an optimized structure. This layout not only ensures the compactness of the system structure but also ensures the optimization of the medium flow path, effectively reducing energy loss. The air intake device innovatively adopts a dual-channel independent design, including an air intake channel 1 specifically for air mode and a water intake channel 2 suitable for underwater mode. The two channels are automatically selected through an intelligently controlled switching valve, ensuring that the aircraft can obtain a stable medium supply in different medium environments.

[0040] Centrifugal compressor 3, as the core compression component of the system, adopts a multi-stage impeller structure combined with adjustable guide vanes. When the medium enters the compressor, the rotating impeller converts mechanical energy into the kinetic and pressure energy of the medium, achieving effective compression of air or water. Particularly noteworthy is that the guide vanes achieve real-time angle adjustment via an electric servo mechanism, automatically optimizing the flow state according to the medium characteristics and operating mode, ensuring high compression efficiency under different operating conditions. This adaptive adjustment mechanism greatly enhances the system's adaptability to complex working environments.

[0041] Dual-mode combustion chamber 9 Figure 2 As shown, the carefully arranged multiple sets of nozzles 5 at the front of the combustion chamber ensure that the fuel and medium are fully mixed before entering the combustion chamber. The internal structure of the nozzles has been specially optimized, such as... Figure 3 As shown, its cross-section 6 adopts a unique layered design, with each conduit remaining isolated from the others. This structure effectively prevents premature mixing and unstable reactions of the fuel, creating ideal conditions for stable combustion.

[0042] The V-shaped flame stabilizer 7 installed in the combustion chamber maintains flame continuity by generating a stable recirculation zone. Its special structural design ensures combustion stability across a wide flow velocity range. The combustion chamber's operation varies depending on the mode: in air mode, aluminum powder fuel mixes with compressed air, undergoing a vigorous oxidation reaction and releasing a large amount of heat energy; in underwater mode, aluminum powder reacts with pressurized water under specific conditions to generate the high-temperature, high-pressure gas required for propulsion. The entire combustion process is adjusted in real time through a sophisticated control system to ensure optimal combustion performance in different media environments.

[0043] like Figure 4As shown, an innovative multi-stage duct system is installed at the end of the combustion chamber, a design that perfectly combines efficient heat recovery and fuel pretreatment. This system guides a portion of the high-temperature gases generated during combustion to the metal powder supply system 12 via a carefully designed pipeline network, effectively preheating the aluminum powder. The spiral guide vanes 17 installed on the inner wall of the pipes not only extend the residence time of the high-temperature gases within the pipes but also significantly enhance heat exchange efficiency. The metal powder supply system adopts a fully enclosed design, using internally stored liquid oxygen as an oxidant. A precisely controlled delivery system ensures that the aluminum powder enters the combustion chamber in optimal condition. The preheated aluminum powder has a significantly increased temperature, which greatly improves ignition performance and effectively shortens the ignition delay time, enhancing the overall system response speed.

[0044] The dual-mode ignition system integrates an advanced CH4 supply system 13, employing an intelligent control strategy to ensure reliable ignition under different media environments. In air mode, the system first injects an appropriate amount of CH4 to form a uniform combustible premixed gas with air. A high-voltage electric spark ignites the premixed gas, generating a high-temperature flame that provides sufficient heat for subsequent aluminum powder ignition. This staged ignition method is scientifically sound and effectively overcomes the technical challenge of directly igniting aluminum powder. In underwater mode, considering the cooling effect of water and the high environmental pressure, the system uses a CH4 pre-combustion method to first establish a high-temperature zone, creating favorable conditions for the rapid initiation of the aluminum powder-water reaction. The intelligent control system automatically optimizes the CH4 injection quantity and ignition timing by analyzing the media parameters fed back from sensors in real time, ensuring optimal ignition performance under various conditions.

[0045] The power regulation system organically connects the power turbine 8 and the propeller 11 via a continuously variable transmission (CVT). This design allows the system to automatically adjust the transmission ratio according to different propulsion requirements. When the aircraft requires high torque propulsion in an underwater environment, the system automatically increases the transmission ratio; while in an air environment, when high-speed propulsion is required, the transmission ratio decreases accordingly. This adaptive adjustment mechanism ensures that the propulsion system always operates at its optimal state. At critical moments when the aircraft is transitioning between different media, the exhaust nozzle 10 provides sufficient transitional power by changing the gas injection velocity, ensuring stable flight attitude.

Claims

1. A propulsion system for a transmedium-based aircraft using aluminum-based metallic fuel, characterized by: The system includes an intake device, nozzles, a combustion chamber, a power turbine, and a tailpipe. The intake device includes a water inlet channel and an air inlet channel, which switch the medium passing through them via a switching valve connected to a hydraulic actuator. The nozzle includes a primary pipe, a secondary pipe, and a tertiary pipe. The primary pipe connects to a metal powder supply system, the secondary pipe connects to the intake device, and the tertiary pipe connects to a methane supply system. A centrifugal compressor is installed between the secondary pipe and the intake device. The tail ends of the primary, secondary, and tertiary pipes converge to form a concentric nozzle pipeline. The primary pipe has the smallest diameter and is located at the innermost point, while the tertiary pipe has the largest diameter and is located at the outermost point. The secondary pipe is located between the primary and tertiary pipes. The end of the nozzle pipeline extends into the combustion chamber, which connects to the power turbine. The tailpipe and propeller are connected to the rear of the power turbine.

2. The propulsion system for a transmedium-based aircraft based on aluminum-based metal fuel according to claim 1, characterized in that: The centrifugal compressor includes at least five stages of rotating impellers and guide vanes arranged alternately.

3. The propulsion system for a transmedium-based aircraft based on aluminum-based metal fuel according to claim 2, characterized in that: The guide vane is connected to an electric servo drive mechanism, which adjusts the angle of the guide vane.

4. The propulsion system for a transmedium-based aircraft based on aluminum-based metal fuel according to claim 1, characterized in that: A V-shaped flame stabilizer is installed in the combustion chamber, located outside the nozzle line end.

5. The propulsion system for a transmedium-based aircraft based on aluminum-based metal fuel according to claim 1, characterized in that: The metal powder supply system includes a powder storage box and a powder conveying pipeline. The powder storage box stores aluminum powder. The powder conveying pipeline is connected to the powder storage box and the combustion chamber. The powder storage box is connected to a primary pipeline. The high-resolution gas in the combustion chamber preheats the aluminum powder through the powder conveying pipeline. The inner wall of the tertiary pipeline is equipped with spiral guide vanes.

6. The propulsion system for a transmedium-based aircraft based on aluminum-based metal fuel according to claim 1, characterized in that: A variable speed transmission mechanism is installed between the power turbine and the propeller.

7. The propulsion system for a transmedium-based aircraft based on aluminum-based metal fuel according to claim 1, characterized in that: A medium density sensor is installed on the outside of the air intake device. When the air passes through the water-air interface, the medium density sensor detects the change in medium density and controls the switching valve through the hydraulic actuator based on the change in medium density.

8. The propulsion system for a transmedium-based aircraft based on aluminum-based metal fuel according to claim 1, characterized in that: in When flying in air, a small amount of methane is first injected to form a combustible premixed gas with air. The combustible premixed gas is ignited to provide sufficient heat for the aluminum powder-air mixture to ignite. When flying underwater, a local high-temperature flame zone is first formed in the combustion chamber by methane injection and ignition. Then aluminum powder and water are injected. The methane combustion provides initial energy to ensure that the aluminum powder-water reaction quickly enters a stable combustion state in the low-temperature, high-pressure underwater environment.

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