A centripetal turbine-driven single-shaft hybrid micro-turbofan engine

Abstract

The present invention discloses a centrifugal turbine-driven single-shaft mixed-displacement micro-turbofan engine, which relates to the technical field of aircraft engines and includes an outer duct, an inner duct, a main shaft, a centrifugal fan, a centrifugal compressor, a centrifugal turbine, a combustion chamber, a mixer, and an air jet; the centrifugal fan, the centrifugal compressor, and the centrifugal turbine are all coaxial with the main shaft and are respectively fixed to the main shaft; the centrifugal fan is located at the air inlet, and the centrifugal fan is used to send air to the outer duct and the inner duct, the combustion chamber is arranged in the inner duct, the centrifugal compressor and the centrifugal turbine are both located in the inner duct, and the combustion chamber is located between the centrifugal compressor and the centrifugal turbine; the air outlet of the outer duct and the air outlet of the inner duct are respectively communicated with the air inlet end of the mixer, and the air outlet end of the mixer is communicated with the air inlet end of the air jet. The centrifugal turbine-driven single-shaft mixed-displacement micro-turbofan engine of the present invention has a simple structure and low cost.

Description

Technical Field

[0001] The present invention relates to the technical field of aircraft engines, in particular to a single-shaft mixed-displacement micro-turbofan engine driven by a centripetal turbine. Background Art

[0002] Most aircraft, including drones, loitering missiles, and jetpacks, are powered by turbofan or turbojet engines. The basic thermodynamic process is as follows: a compressor compresses air, which is then injected and burned in a combustion chamber. The hot gases expand through the turbine, generating work and driving the compressor. Excess work is converted into engine thrust, powering the aircraft. Turbojets can be categorized as turbojets or turbofans. Micro turbojets typically have a thrust of less than 100 kg, while small turbojets have a thrust between 100 and 900 kg.

[0003] Working principle of turbofan engine: After being compressed by the fan, the air flow is divided into two air flows, the outer duct air flow and the inner duct air flow. The inner duct air flow is then compressed by the compressor to provide pressure, and is burned by fuel injection in the combustion chamber. The gas expands through the turbine to do work, driving the compressor and the fan. The expanded gas enters the mixer, and the outer duct air flow also enters the mixer at the same time. After the inner and outer duct air flows are mixed, the gas temperature drops, and a jet is formed through the nozzle to generate thrust. Compared with turbojet engines, turbofan engines have a high total pressure ratio (fan and compressor cascade compression) and a low exhaust temperature of the inner and outer duct mixers. Therefore, the specific fuel consumption (sfc-specified fuel comsume is the fuel consumption per unit time to produce unit thrust) can be reduced by more than 25%.

[0004] Existing micro-turbofan engines often use axial compressors and axial turbines. Although the overall compression efficiency of the axial compressor is high, the pressure ratio of a single-stage axial compressor is only about 1.75, which is low. Therefore, it is often necessary to set up a multi-stage axial compressor, resulting in a complex structure and high cost. Similarly, although the overall efficiency of the axial turbine is high, the maximum pressure drop ratio of a single-stage axial turbine is only about 2.4, which is low. Therefore, it is often necessary to set up a multi-stage axial turbine, resulting in a complex structure of the engine. In addition, the axial turbine has high requirements for materials, which increases the manufacturing cost. Summary of the Invention

[0005] The purpose of the present invention is to provide a single-shaft mixed-displacement micro-turbofan engine driven by a centripetal turbine to solve the problems existing in the above-mentioned prior art, simplify the structure of the turbofan engine, and thereby reduce the cost of the turbofan engine.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] The present invention provides a single-shaft mixed-displacement micro-turbofan engine driven by a centripetal turbine, comprising an outer duct, an inner duct, a main shaft, a centrifugal fan, a centrifugal compressor, a centrifugal turbine, a combustion chamber, a mixer and an air jet; the centrifugal fan, the centrifugal compressor and the centrifugal turbine are all coaxial with the main shaft and are respectively fixed to the main shaft; the centrifugal fan is located at the air inlet, the centrifugal fan is used to send air to the outer duct and the inner duct, the combustion chamber is arranged in the inner duct, the centrifugal compressor and the centrifugal turbine are both located in the inner duct, and the combustion chamber is located between the centrifugal compressor and the centrifugal turbine; the air outlet of the outer duct and the air outlet of the inner duct are respectively communicated with the air inlet end of the mixer, and the air outlet end of the mixer is communicated with the air inlet end of the air jet.

[0008] Preferably, the static pressure of the gas entering the air inlet end of the mixer through the outer duct is equal to the static pressure of the gas entering the air inlet end of the mixer through the inner duct.

[0009] Preferably, the pressure ratio of the centrifugal compressor is greater than the pressure drop ratio of the centripetal turbine.

[0010] Preferably, it also includes a fan guide for guiding the airflow of the centrifugal fan, a compression guide for guiding the airflow of the centrifugal compressor, and a turbine guide for guiding the airflow of the centripetal turbine. The main shaft passes through the wheel disc of the fan guide, the wheel disc of the compression guide, and the wheel disc of the turbine guide. The wheel disc of the fan guide, the wheel disc of the compression guide, and the wheel disc of the turbine guide are respectively rotatably matched with the main shaft and are respectively fixed to the casing of the turbofan engine.

[0011] Preferably, it also includes a main shaft sleeve and a fixed shaft sleeve which are rotatably sleeved on the main shaft respectively, the wheel disc of the fan guide is fixedly connected to the fixed shaft sleeve, and the wheel disc of the compressor guide and the wheel disc of the turbine guide are respectively fixedly connected to the main shaft sleeve.

[0012] Preferably, the main shaft sleeve and the fixed shaft sleeve are rotatably engaged with the main shaft through bearings respectively.

[0013] Compared with the prior art, the present invention has achieved the following technical effects:

[0014] The centripetal turbine-driven single-shaft mixed-row micro-turbofan engine of the present invention has a simple structure and low cost.

[0015] Furthermore, in the present invention, a centripetal turbine is used to drive the main shaft to rotate. The pressure drop ratio of a single-stage centripetal turbine can reach up to about 3.0, and the structure is simple and the cost is low.

[0016] Furthermore, the present invention uses a centrifugal compressor to compress the air in the inner duct. The single-stage pressure ratio of the centrifugal compressor can reach up to 6.0 or more, which can efficiently compress the air in the inner duct, and has a simple structure and low manufacturing cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 A schematic structural diagram of a centripetal turbine-driven single-shaft hybrid micro-turbofan engine according to the present invention;

[0019] Figure 2 for Figure 1 AA section view;

[0020] Figure 3 A schematic diagram of a portion of the structure of a centripetal turbine-driven single-shaft hybrid micro-turbofan engine according to the present invention;

[0021] Among them, 1. Shell; 2. Inner duct; 3. Outer duct; 4. Main shaft; 5. Centrifugal fan; 6. Centrifugal compressor; 7. Centripetal turbine; 8. Combustion chamber; 9. Mixer; 10. Jet port; 11. Fan guide wheel; 12. Fixed sleeve; 13. Compressor guide wheel; 14. Main shaft sleeve; 15. Turbine guide wheel; 16. Fan guide; 17. Compressor guide; 18. Turbine guide. DETAILED DESCRIPTION

[0022] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0023] The purpose of the present invention is to provide a single-shaft mixed-displacement micro-turbofan engine driven by a centripetal turbine to solve the problems existing in the above-mentioned prior art, simplify the structure of the turbofan engine, and thereby reduce the cost of the turbofan engine.

[0024] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0025] like Figure 1-Figure 3As shown, this embodiment provides a single-shaft mixed-displacement micro-turbofan engine driven by a centripetal turbine, including an outer duct 3, an inner duct 2, a main shaft 4, a centrifugal fan 5, a centrifugal compressor 6, a centripetal turbine 7, a combustion chamber 8, a mixer 9 and an air jet 10.

[0026] Among them, the centrifugal fan 5, the centrifugal compressor 6 and the centripetal turbine 7 are all coaxial with the main shaft 4 and are respectively fixed to the main shaft 4; the centrifugal fan 5 is located at the air inlet of the turbofan engine, and the centrifugal fan 5 is used to send air to the outer duct 3 and the inner duct 2. The combustion chamber 8 is arranged in the inner duct 2. The centrifugal compressor 6 and the centripetal turbine 7 are both located in the inner duct 2, and the combustion chamber 8 is located between the centrifugal compressor 6 and the centripetal turbine 7; the air outlet of the outer duct 3 and the air outlet of the inner duct 2 are respectively communicated with the air inlet end of the mixer 9, and the air outlet end of the mixer 9 is communicated with the air inlet end of the jet port 10.

[0027] The centripetal turbine-driven single-axis mixed-displacement micro-turbofan engine of this embodiment also includes a fan guide 16 for guiding the airflow of the centrifugal fan 5, a compression guide 17 for guiding the airflow of the centrifugal compressor 6, and a turbine guide 18 for guiding the airflow of the centripetal turbine 7. The main shaft 4 passes through the fan guide wheel 11, the compression guide wheel 13 and the turbine guide wheel 15. The fan guide wheel 11, the compression guide wheel 13 and the turbine guide wheel 15 are respectively rotatably matched with the main shaft 4 and are respectively fixed to the casing 1 of the turbofan engine.

[0028] The main shaft sleeve 14 and the fixed shaft sleeve 12 are each rotatably mounted on the main shaft 4. The fan guide vane 11 is fixedly connected to the fixed shaft sleeve 12, while the compressor guide vane 13 and the turbine guide vane 15 are each fixedly connected to the main shaft sleeve 14. The main shaft sleeve 14 rotates with the main shaft 4 via two bearings, while the fixed shaft sleeve 12 rotates with the main shaft 4 via a single bearing. The drive shaft is configured as a stepped shaft, with steps corresponding to the three bearings to support them. The force generated by the engine is transmitted to the engine casing via the fan guide vane 16, the compressor guide vane 17, and the turbine guide vane 18.

[0029] It should be noted that the main shaft sleeve 14 also passes through the combustion chamber 8. The main shaft sleeve 14 separates the combustion chamber 8 from the main shaft 4, radially hindering heat conduction and heat radiation. On the hot end side of the turbine guide 18 bearing seat, an insulation ring made of insulation material (such as mica) is added, and an adjustment gasket is added to locate the axial position of the rotor. It is radially fixed to the main shaft sleeve 14 with capless bolts to hinder axial heat conduction and radiation.

[0030] The specific working principle of the centripetal turbine-driven single-shaft hybrid micro-turbofan engine of this embodiment is as follows:

[0031] After being pressurized by the centrifugal fan 5, the air flow is divided into two streams, one flows into the outer duct 3, and the other flows into the inner duct 2; the air flow flowing into the inner duct 2 continues to be pressurized by the centrifugal compressor 6, and then enters the combustion chamber 8, is sprayed and burned, and the hot combustion gas generated in the combustion chamber 8 enters the centrifugal turbine 7 to expand and do work. The centrifugal turbine 7 rotates and drives the main shaft 4, the centrifugal compressor 6 and the centrifugal fan 5 to rotate and do work. The expanded combustion gas enters the mixer 9 and mixes with the air flow entering the mixer 9 through the outer duct 3 to form a mixed flow. The temperature of the mixed flow is lower than that of the combustion gas. The mixed flow enters the convergent jet port 10 to generate thrust.

[0032] The static pressure of the gas entering the inlet of the mixer 9 through the outer duct 3 is equal to the static pressure of the gas entering the inlet of the mixer 9 through the inner duct 2. Since the airflow velocity at the inlet of the mixer 9 is generally lower than the Mach number of 0.3, it is approximately assumed that the total pressure of the inner and outer ducts 3 of the mixer 9 is the same. Since the airflow is divided into two streams after passing through the centrifugal fan 5, one stream flows into the outer duct 3 and the other flows into the inner duct 2. The total pressure loss of the airflow in the outer duct 3 can be considered fixed, and the airflow in the outer duct 3 directly enters the mixer 9. The airflow in the inner duct 2 is pressurized by the centrifugal compressor 6, burned in the combustion chamber 8, and depressurized by the centrifugal turbine 7. Since the total pressure loss of the combustion chamber 8 can be considered fixed, the pressure ratio of the centrifugal compressor 6 should be similar to the pressure drop ratio of the centrifugal turbine 7. The maximum pressure drop ratio of the single-stage centrifugal turbine 7 is around 2.9. The pressure ratio of the centrifugal compressor 6 is slightly higher than the maximum pressure drop ratio of 2.9 of the single-stage centrifugal turbine 7, ranging from 2.9 to 3.1.

[0033] The centrifugal turbine-driven single-axis mixed-displacement micro-turbofan engine of this embodiment uses a centrifugal turbine 7 to drive the main shaft 4 to rotate. The pressure drop ratio of the single-stage centrifugal turbine 7 can reach up to about 3.0, with a simple structure and low cost. A centrifugal compressor 6 is used to compress the air in the inner duct 2. The single-stage pressure ratio of the centrifugal compressor 6 can reach up to more than 6.0, which can efficiently compress the air in the inner duct 2, and has a simple structure and low manufacturing cost.

[0034] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A centripetal turbine driven single-shaft hybrid micro-turbofan engine, characterized in that: The invention comprises an outer duct, an inner duct, a main shaft, a centrifugal fan, a centrifugal compressor, a centripetal turbine, a combustion chamber, a mixer and an air jet; the centrifugal fan, the centrifugal compressor and the centripetal turbine are all coaxial with the main shaft and are respectively fixed to the main shaft; the centrifugal fan is located at the air inlet, and is used to send air to the outer duct and the inner duct, the combustion chamber is arranged in the inner duct, the centrifugal compressor and the centripetal turbine are both located in the inner duct, and the combustion chamber is located between the centrifugal compressor and the centripetal turbine; the air outlet of the outer duct and the air outlet of the inner duct are respectively communicated with the air inlet end of the mixer, and the air outlet end of the mixer is communicated with the air inlet end of the air jet; The engine further comprises a fan guide for guiding the airflow of the centrifugal fan, a compression guide for guiding the airflow of the centrifugal compressor, and a turbine guide for guiding the airflow of the centripetal turbine, wherein the main shaft passes through the wheel disc of the fan guide, the wheel disc of the compression guide, and the wheel disc of the turbine guide, and the wheel disc of the fan guide, the wheel disc of the compression guide, and the wheel disc of the turbine guide are respectively rotatably matched with the main shaft and are respectively fixedly connected to the casing of the turbofan engine; It also includes a main shaft sleeve and a fixed shaft sleeve which are respectively rotatably sleeved on the main shaft, the wheel disc of the fan guide device is fixedly connected to the fixed shaft sleeve, and the wheel disc of the compressor guide device and the wheel disc of the turbine guide device are respectively fixedly connected to the main shaft sleeve; the main shaft sleeve passes through the combustion chamber, and the main shaft sleeve separates the combustion chamber from the main shaft.

2. The centripetal turbine-driven single-shaft hybrid micro-turbofan engine according to claim 1, characterized in that: The static pressure of the gas entering the air inlet end of the mixer through the outer bypass is equal to the static pressure of the gas entering the air inlet end of the mixer through the inner bypass.

3. The centripetal turbine driven single-shaft hybrid micro-turbofan engine according to claim 1, characterized in that: The pressure ratio of the centrifugal compressor is greater than the pressure drop ratio of the centripetal turbine.

4. The centripetal turbine driven single-shaft hybrid micro-turbofan engine according to claim 1, characterized in that: The main shaft sleeve and the fixed shaft sleeve are respectively rotatably matched with the main shaft through bearings.

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