Hydrogen turbo hybrid electric propulsion system

Abstract

This invention proposes a hydrogen turbine hybrid electric propulsion system, comprising a hydrogen turbine engine, a generator, an electric motor, a battery, and a ducted fan. The generator is a superconducting generator. The hydrogen turbine engine includes a compressor, a hydrogen combustion chamber, a gas turbine, a free turbine, a nozzle, a hydrogen storage device, and a heat exchanger. The hydrogen storage device provides a liquid hydrogen environment to the superconducting generator. The free turbine is coaxially mounted with the superconducting generator. The liquid hydrogen from the superconducting generator exchanges heat with the gas in the engine in the heat exchanger, converting it into hydrogen gas, which then enters the hydrogen combustion chamber through a hydrogen supply pipe. In this invention, the hydrogen supply pipe of the hydrogen turbine engine is located inside an air pipe. This introduces more gas, reducing the temperature of the main combustion zone in the combustion chamber and decreasing the generation of nitrogen oxides. Furthermore, the air pipe acts as a heat insulation pipe, effectively reducing the surface temperature of the hydrogen supply pipe. Simultaneously, the air inside the pipe impacts the combustion chamber head, reducing the temperature of the head panel and generating a complex vortex structure at the combustion chamber head, further enhancing the mixing of hydrogen and air. The inconsistent natural frequencies of the vortices prevent thermal oscillation problems.

Description

Technical Field

[0001] This invention relates to a hydrogen turbine hybrid electric propulsion system, belonging to the field of new energy and power technology. Background Technology

[0002] A fuel-electric hybrid propulsion system is a novel propulsion system that uses a fuel turbine engine to drive a generator to produce electricity, which in turn powers electric motors distributed on the wings or fuselage to drive fans / propellers, generating thrust. Compared to traditional turbine engines, the turbine-electric hybrid propulsion system regulates system power output through batteries, keeping the turbine core operating at its optimal point and improving overall efficiency throughout flight. Simultaneously, by incorporating distributed propulsion technology, it significantly increases the equivalent bypass ratio, improves the aircraft's aerodynamic structure and efficiency, reduces fuel consumption, noise and emissions, and substantially enhances the aircraft's overall performance. However, the use of traditional fuels inevitably produces carbon emissions. With increasing global warming and frequent extreme weather events, developing clean and green energy has become a global consensus. Hydrogen-fueled turbine-electric hybrid propulsion systems are the preferred method to avoid carbon emissions. Furthermore, the power density of traditional high-power electric motors is generally low, with megawatt-class motors having a power density of approximately 0.5–2.5 kW / kg, which limits further increases in the power and power density of eddy electric systems.

[0003] The main difference between hydrogen fuel and aviation kerosene is that hydrogen has a higher flame propagation speed, about 6 times that of aviation kerosene, which can easily lead to backfire. At the same time, the adiabatic flame temperature of hydrogen combustion is higher, about 120K higher than that of aviation kerosene, and the amount of NOx generated increases sharply at the higher combustion temperature.

[0004] Currently, hydrogen combustion in aero-engines generally employs clustered micro-mixing combustion technology. This technology uses numerous injection units with characteristic dimensions on the millimeter scale, each of which can be considered a miniature combustion chamber where hydrogen and air mix and burn, forming multiple small-scale diffusion flames. Compared to traditional injection methods, this technology uses high-speed jets instead of the swirling flow of traditional combustion chambers, resulting in higher injection velocities than the flame propagation speed of hydrogen, significantly reducing the risk of backfire. However, its combustion organization is diffusion combustion, and its combustion is relatively complete, leading to higher flame temperatures and consequently higher NOx emissions. Most importantly, clustered micro-mixing combustion technology consists of a series of small-scale flames, making it highly susceptible to high-frequency combustion instabilities, which can cause severe thermoacoustic oscillations. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a hydrogen turbine hybrid electric propulsion system that overcomes thermal oscillation and prevents backfire, thereby realizing the green and low-carbon transformation of aero engines.

[0006] The technical solution of this invention: A hydrogen turbine hybrid electric propulsion system, comprising a hydrogen turbine engine, a generator, an electric motor, a battery, and a ducted fan. The generator is a superconducting generator. The hydrogen turbine engine includes a compressor, a hydrogen combustion chamber, a gas turbine, a free turbine, a nozzle, a hydrogen storage device, and a heat exchanger. The hydrogen storage device provides a liquid hydrogen environment to the superconducting generator. The free turbine is coaxially arranged with the superconducting generator. The liquid hydrogen from the superconducting generator exchanges heat with the gas in the engine in the heat exchanger and is converted into hydrogen gas, which enters the hydrogen combustion chamber through a hydrogen supply pipe.

[0007] The hydrogen supply pipe is set in the air pipe to form a gas supply unit. The air compressed by the compressor enters the hydrogen combustion chamber and is split into two paths. One path enters the interior of the flame tube directly through the air hole on the wall of the flame tube, and the other path is split into multiple paths and connected to the air pipe. The gas supply unit enters from the rear end of the flame tube and extends to the front of the flame tube. The hydrogen supply pipe and the air pipe spray hydrogen and air respectively towards the head of the flame tube. In the flame tube, the air and hydrogen are mixed and combusted at constant pressure.

[0008] The beneficial effects of this invention compared to the prior art are as follows:

[0009] (1) The hydrogen supply pipe of the hydrogen turbine engine of the present invention is set inside the air pipe. On the one hand, more gas is introduced, which can reduce the temperature of the main combustion zone of the combustion chamber and reduce the generation of nitrogen oxides. On the other hand, the air pipe can be used as a heat insulation pipe, which can effectively reduce the temperature of the surface of the hydrogen supply pipe. At the same time, the air inside the pipe impacts the head of the combustion chamber, which can reduce the temperature of the head panel and generate a complex vortex structure at the head of the combustion chamber, further enhancing the mixing of hydrogen and air. The inconsistent natural frequency of the vortex avoids the problem of thermal oscillation.

[0010] (2) The hydrogen turbine engine of the present invention adopts a diffusion combustion organization method, which does not premix hydrogen with air, thus avoiding backfire problems. The hydrogen supply direction is opposite to the mainstream, which strengthens the mixing of hydrogen and air and improves combustion efficiency.

[0011] (3) This invention combines hydrogen fuel with superconducting motor technology. On the one hand, it can significantly reduce the weight of the motor and its associated cables. The megawatt-level superconducting motor can easily reach more than 10kW / kg. On the other hand, the energy of the motor heat is recovered through liquid hydrogen, which improves the efficiency of the entire system. Moreover, hydrogen fuel combustion is stable and efficient. Its combustion products do not contain carbon, but only water and some nitrogen oxides, which are more environmentally friendly.

[0012] (4) The hydrogen turbine engine of this invention adopts a mature single-shaft turbojet engine for adaptive modification, and adds a free turbine at its outlet to drive a superconducting generator, which reduces the design difficulty of the entire eddy electric propulsion system and shortens the design cycle.

[0013] (5) The present invention effectively improves power density, and higher power density can improve the payload and range of the aircraft. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the hydrogen turbine hybrid electric propulsion system of the present invention;

[0015] Figure 2 This is a simplified structural diagram of the hydrogen turbine hybrid electric propulsion system of the present invention;

[0016] Figure 3 This is a schematic diagram of the hydrogen turbine engine principle of the present invention;

[0017] Figure 4 This is a schematic diagram of the hydrogen combustion chamber principle of the present invention;

[0018] Figure 5 This is an example of the arrangement of hydrogen supply pipes and air pipes according to the present invention. Detailed Implementation

[0019] The present invention will now be described in detail with reference to specific examples and accompanying drawings.

[0020] The present invention is as follows Figure 1 As shown, a hydrogen turbine hybrid electric propulsion system is provided, including a hydrogen turbine engine, a superconducting generator, a generator controller, an electric motor, a battery, a motor controller, and a ducted fan. The hydrogen turbine engine outputs mechanical energy to drive the superconducting generator, the generator controller controls the superconducting generator to generate electricity to provide electrical energy to the electric motor, and at the same time stores some of the electrical energy in the battery. The motor controller controls the electric motor to drive the ducted fan to generate power.

[0021] This invention uses a hydrogen fuel turbine engine to drive a superconducting generator to generate electricity, which in turn generates thrust for electric motors distributed on the wings or fuselage to drive fans / propellers.

[0022] The hydrogen turbine engine of this invention, such as Figure 2 , 3 As shown in Figure 4, the system includes a compressor 1, a hydrogen combustion chamber 2, a gas turbine 3, a free turbine 4, a nozzle 5, a hydrogen storage device 7, and a heat exchanger 8. The hydrogen storage device 7 provides a liquid hydrogen environment for the superconducting generator 6. The free turbine 4 is coaxially arranged with the superconducting generator 6. The liquid hydrogen from the superconducting generator 6 exchanges heat with the gas in the engine in the heat exchanger 8 and is converted into hydrogen. The hydrogen enters the hydrogen combustion chamber 2 through a hydrogen supply pipe, which is set in an air pipe to form an air supply unit. Multiple air supply units are evenly distributed circumferentially inside the flame tube. The air compressed by the compressor enters the hydrogen combustion chamber and is split into two paths. One path directly enters the flame tube through the air holes on the flame tube wall, and the other path is split into multiple paths connected to the air pipe. The air supply unit enters from the rear end of the flame tube and extends to the front of the flame tube. The hydrogen supply pipe and the air pipe spray hydrogen and air respectively towards the head of the flame tube. In the flame tube, the air and hydrogen are mixed and combusted at constant pressure.

[0023] Furthermore, the nozzle 5 of the present invention is annular and uses circumferential exhaust, with the superconducting generator 6 located in the middle of the annular nozzle 5.

[0024] This invention realizes the application of hydrogen fuel in a hybrid electric propulsion system. By combining the cryogenic conditions of liquid hydrogen with superconducting motor technology, a superconducting generator is introduced into the system. Compared with existing fuel-powered eddy current systems, this further reduces system weight and increases the power and power density of the eddy current system. Since the use of hydrogen fuel produces no carbon emissions, and the energy generated by the superconducting generator is recovered through liquid hydrogen, it aligns with the green and low-carbon development direction of the power industry.

[0025] The invention introduces a hydrogen supply pipe that enters from the rear end of the flame tube and extends to the front of the flame tube, spraying hydrogen towards the head of the flame tube. The hydrogen flow direction is opposite to the mainstream, increasing the dwell time and improving the mixing efficiency.

[0026] This invention employs a diffusion combustion method, where hydrogen is mixed with air and combusted within the flame tube. Since hydrogen and air are not premixed, there is no backfire issue. To improve combustion efficiency, the hydrogen supply direction is opposite to the mainstream direction to enhance hydrogen-air mixing.

[0027] To avoid directly exposing the hydrogen supply pipe to high temperatures, this invention adds an air pipe outside the hydrogen supply pipe. This serves two purposes: firstly, it introduces more gas, reducing the temperature of the main combustion zone in the combustion chamber and decreasing nitrogen oxide formation; secondly, it acts as a heat insulation pipe, effectively lowering the surface temperature of the hydrogen supply pipe. Simultaneously, the air inside the air pipe impacts the flame tube head, reducing the temperature of the head panel and generating both hydrogen and air vortices at the flame tube head, further enhancing the mixing of hydrogen and air. The different natural frequencies of the two vortices prevent thermal oscillation problems.

[0028] Furthermore, the present invention as follows Figure 5 As shown, multiple gas supply units are installed in the hydrogen combustion chamber flame tube. Each gas supply unit consists of a hydrogen supply pipe and an air pipe, which are coaxially arranged, with the hydrogen supply pipe located at the center.

[0029] Furthermore, the hydrogen supply pipe is made of stainless steel, and the air pipe is made of high-temperature alloy.

[0030] Furthermore, the pressure of the hydrogen ejected from the hydrogen supply pipe is at least one order of magnitude greater than the pressure of the air ejected from the air pipe.

[0031] Furthermore, an electric igniter is installed on the head panel of the hydrogen combustion chamber flame tube of the present invention.

[0032] This invention uses a distributed ducted fan as the propulsion system, which has a high equivalent bypass ratio, high propulsion efficiency, and low noise.

[0033] The hydrogen turbine engine of this invention is an adaptive modification of a mature single-shaft turbojet engine. A free turbine is added to its outlet to drive a superconducting high-speed generator, which reduces the design difficulty of the entire engine and shortens the design cycle.

[0034] The present invention preferably uses a single-stage centrifugal compressor, the hydrogen combustion chamber is an annular reflux combustion chamber, the turbine is a single-stage axial flow turbine, and the free turbine is also a single-stage axial flow turbine.

[0035] The preferred superconducting generator of this invention is a rotor semi-superconducting, superconducting synchronous single-pole induction AC generator, which consists of a solid cast, strongly magnetic, low-loss rotor, a highly saturated, directional magnetic stator, a static DC, near-zero loss superconducting excitation winding, and a molded, high-efficiency heat-exchanging armature winding.

[0036] The design of the generator controller and motor controller is based on well-known technologies in the field, and the preferred battery is a high-energy-density lithium battery.

[0037] The operating sequence of this invention during flight missions is as follows:

[0038] a. During takeoff, the battery and superconducting generator work together to drive the ducted fan to provide upward lift, and the aircraft takes off vertically. After reaching a safe altitude, the ducted fan tilts, and the aircraft gradually turns to level flight.

[0039] b. In the air, the engine operates at rated power to drive the superconducting motor to generate electricity. A portion of the generated power is used to drive the ducted fan to produce thrust, and the remainder is used to charge the battery. Once the battery is fully charged, the engine operating conditions are adjusted to meet the propulsion power requirements for level flight.

[0040] c. During landing, the superconducting generator and battery drive the ducted fan to switch the aircraft to vertical takeoff and landing mode. Then, the generator and battery drive the ducted fan to descend vertically. After the aircraft lands on the ground, the superconducting generator stops.

[0041] In summary, the above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0042] The parts of this invention not described in detail are techniques known to those skilled in the art.

Claims

1. A hydrogen turbine hybrid electric propulsion system, comprising a hydrogen turbine engine, a generator, an electric motor, a battery, and a ducted fan, characterized in that: The generator is a superconducting generator, and the hydrogen turbine engine includes a compressor, a hydrogen combustion chamber, a gas turbine, a free turbine, a nozzle, a hydrogen storage device, and a heat exchanger. The hydrogen storage device provides a liquid hydrogen environment for the superconducting generator. The free turbine is coaxially arranged with the superconducting generator. The liquid hydrogen from the superconducting generator exchanges heat with the gas in the engine in the heat exchanger and is converted into hydrogen gas, which enters the hydrogen combustion chamber through the hydrogen supply pipe. The hydrogen supply pipe is set in the air pipe to form a gas supply unit. The air compressed by the compressor enters the hydrogen combustion chamber and is split into two paths. One path enters the interior of the flame tube directly through the air hole on the wall of the flame tube, and the other path is split into multiple paths and connected to the air pipe. The gas supply unit enters from the rear end of the flame tube and extends to the front of the flame tube. The hydrogen supply pipe and the air pipe spray hydrogen and air respectively towards the head of the flame tube. In the flame tube, the air and hydrogen are mixed and combusted at constant pressure.

2. The hydrogen turbine hybrid electric propulsion system according to claim 1, characterized in that: The gas supply units are evenly distributed circumferentially inside the flame tube of the hydrogen combustion chamber, and the hydrogen supply pipe and air pipe are coaxially arranged, with the hydrogen supply pipe located at the center.

3. The hydrogen turbine hybrid electric propulsion system according to claim 2, characterized in that: The nozzle is annular and uses circumferential exhaust, with a superconducting generator located in the middle of the annular nozzle.

4. The hydrogen turbine hybrid electric propulsion system according to claim 3, characterized in that: The ducted fan is a distributed ducted fan.

5. A hydrogen turbine hybrid electric propulsion system according to claim 3, characterized in that: The compressor is a single-stage centrifugal compressor, the hydrogen combustion chamber is an annular reflux combustion chamber, the turbine is a single-stage axial flow turbine, and the free turbine is a single-stage axial flow turbine.

6. The hydrogen turbine hybrid electric propulsion system according to claim 3, characterized in that: The superconducting generator is a rotor semi-superconducting, superconducting synchronous single-pole induction AC generator.

7. A hydrogen turbine hybrid electric propulsion system according to claim 3, characterized in that: The hydrogen supply pipe is made of stainless steel, and the air pipe is made of high-temperature alloy.

8. A hydrogen turbine hybrid electric propulsion system according to claim 3, characterized in that: The hydrogen pressure ejected from the hydrogen supply pipe is at least one order of magnitude greater than the air pressure ejected from the air pipe.

9. A hydrogen turbine hybrid electric propulsion system according to claim 3, characterized in that: An electric igniter is installed on the head panel of the hydrogen combustion chamber flame tube.

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