Small low-cost turbofan engine
By introducing an external bypass duct and thrust fan structure into the turbojet engine, and adopting a reverse air intake and mixed exhaust method, the problem of insufficient thrust was solved, achieving efficient and low-cost propulsion.
Patent Information
- Application Number
- CN202511154804.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-18
- Publication Date
- 2025-10-31
AI Technical Summary
Existing small turbojet engines have low thrust and poor fuel economy, making it difficult to meet the requirements of low-cost, high thrust-to-weight ratio power plants for low-altitude economic applications.
By adding an outer bypass duct and thrust fan structure to the turbojet engine, and adopting a reverse air intake and mixed exhaust working mode, the thrust fan is driven to rotate through the guide air duct, guide wheel, and free turbine, thereby improving thrust and working efficiency.
It significantly improves thrust, reduces fuel consumption, has a simple overall structure, low cost, and is suitable for low-altitude economic applications.
Smart Images
Figure CN120867904A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of turbofan engines, and in particular to a small, low-cost turbofan engine. Background Technology
[0002] Currently, in low-altitude economic applications, a common power source for equipment such as drones, target drones, and loitering munitions is a small turbojet engine. This small, low-cost turbojet engine features an electric starter, a low-pressure turbine, a combustion chamber, a power turbine, and a tail-end converging nozzle arranged sequentially along the airflow direction. When the electric starter operates, it drives the low-pressure and power turbines to rotate. The incoming airflow is forced into the combustion chamber by the low-pressure turbine from the intake, where it mixes with fuel injected from the fuel nozzle and is ignited. The resulting gas is compressed by the power turbine, forming a high-pressure airflow that is ejected at high speed from the tail-end converging nozzle, generating forward thrust. Because the high-speed ejection of air directly generates reaction thrust, some airflow is lost outwards, resulting in low thrust, poor fuel economy, and low propulsion efficiency. This makes it difficult to meet the low-cost, high thrust-to-weight ratio requirements of low-altitude economic applications. Summary of the Invention
[0003] The present invention aims to at least solve one of the technical problems existing in the prior art. Therefore, one object of the present invention is to provide a small, low-cost turbofan engine.
[0004] The technical solution of the present invention is as follows: a small, low-cost turbofan engine, characterized in that it comprises: an outer cylinder, an inner cylinder, a gas generator, a guide wheel, a free turbine, and a thrust fan;
[0005] The outer cylinder has an air inlet and an exhaust outlet at its two axial ends, respectively. The inner cylinder is coaxially fitted inside the outer cylinder, and the cylinder walls of the two are spaced apart to form an outer duct. The end of the inner cylinder adjacent to the air inlet is open, and the end adjacent to the exhaust outlet is closed.
[0006] The gas generator is located inside the inner cylinder. The gas inlet of the gas generator faces the closed end of the inner cylinder. The gas outlet of the gas generator is provided with a guide member. The guide member is defined with a guide air passage. The end of the guide air passage is provided with an exhaust pipe. The exhaust pipe extends into the outer duct and bends toward the exhaust end.
[0007] The airflow duct is provided with a guide wheel and a free turbine arranged opposite to each other. Along the gas flow direction of the airflow duct, the guide wheel is located upstream of the free turbine. The thrust fan is located at the air inlet and connected to the free turbine. The free turbine is used to drive the thrust fan to rotate. Part of the airflow generated by the rotation of the thrust fan flows to the outer bypass duct and part flows to the inner cylinder.
[0008] Furthermore, the closed end of the inner cylinder is a tapered end.
[0009] Furthermore, the gas generator is a turbojet engine.
[0010] Furthermore, a speed reducer is provided between the free turbine shaft and the thrust fan shaft.
[0011] Furthermore, there are multiple exhaust pipes, which are arranged at intervals along the circumference of the outer bypass duct.
[0012] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0013] This device adds an external bypass duct and thrust fan structure to a conventional gas generator. By using a reverse air intake and mixed exhaust working mode, it can greatly increase the thrust generated, improve working efficiency, and reduce overall fuel consumption. The overall structure of this device is simple, easy to manufacture and process, and has low operating costs.
[0014] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description
[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention, and the drawings are only examples and not strictly drawn to scale. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort:
[0016] Figure 1 This is a half-sectional schematic diagram of the internal structure of the inner cylinder of the present invention;
[0017] Figure 2 This is a full sectional schematic diagram of the internal structure of the inner cylinder of the present invention;
[0018] Figure 3 This is a full sectional view of the outer cylinder portion of the present invention.
[0019] Figure label:
[0020] 1. Outer cylinder; 2. Inner cylinder; 3. Gas generator; 4. Guide wheel; 5. Free turbine; 6. Thrust fan; 7. Outer bypass duct; 8. Air guide duct; 9. Air guide component; 10. Exhaust pipe; 11. Reducer. Detailed Implementation
[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0022] The embodiments of the present invention are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. In the description of the present invention, it should be understood that the terms "upper," "lower," "front," "rear," "left," "right," "inner," "outer," "vertical," "circumferential," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.
[0023] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.
[0024] In the description of this invention, "first feature" and "second feature" may include one or more of the indicated features. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" and "second" may explicitly or implicitly include one or more of the indicated features.
[0025] The following is a reference appendix. Figures 1-3 A small, low-cost turbofan engine according to an embodiment of the present invention is described. The device includes: an outer cylinder 1, an inner cylinder 2, a gas generator 3, a guide wheel 4, a free turbine 5, and a thrust fan 6.
[0026] The outer cylinder 1 has an air inlet and an exhaust outlet at its two axial ends, respectively. The inner cylinder 2 is coaxially fitted inside the outer cylinder 1, with their cylinder walls spaced apart to form an outer duct 7. The end of the inner cylinder 2 adjacent to the air inlet is open, and the end adjacent to the exhaust outlet is closed. Taking the view shown in the figure as an example, the right end of the outer cylinder 1 is the air inlet, and the left end is the exhaust outlet. The right end of the inner cylinder 2 is open, and the left end is closed.
[0027] The gas generator 3 is located inside the inner cylinder 2. The gas generator 3 is a device that generates combustion gas with a certain pressure and temperature as the working fluid of the turbine. It generally consists of components such as a compressor, fuel pump, and combustion chamber, as well as their auxiliary systems. Here, the gas generator 3 can be, for example, a small, low-cost turbojet engine.
[0028] The air inlet of the gas generator 3 faces the closed end of the inner cylinder 2, and the air outlet of the gas generator 3 is equipped with a guide 9. Therefore, this device actually adopts a reverse air intake method. The airflow from the front passes through the inner cylinder 2 and reaches the closed end area, where it is drawn back into the gas generator 3 by the compressor. In some embodiments, the closed end of the inner cylinder 2 is set as a conical end, which can adjust the airflow direction, optimize the intake efficiency, and reduce energy loss.
[0029] The guide member 9 is provided with a guide air passage 8, and the end of the guide air passage 8 is provided with an exhaust pipe 10. The exhaust pipe 10 extends into the outer bypass 7 and bends towards the exhaust end. The guide member 9 is provided to guide the high-speed exhaust jet generated by the gas generator 3 into the guide air passage 8. Then the high-speed exhaust jet flows from the exhaust pipe 10 to the outer bypass 7 and is finally discharged from the exhaust end. In some embodiments, there are multiple exhaust pipes, and the multiple exhaust pipes 10 are arranged at intervals along the circumference of the outer bypass 7.
[0030] The guide air duct 8 is equipped with a guide wheel 4 and a free turbine 5 arranged opposite to each other. Along the gas flow direction of the guide air duct 8, the guide wheel 4 is located upstream of the free turbine 5. The thrust fan 6 is located at the intake end and connected to the free turbine 5. Thus, when the high-speed exhaust jet flows in the guide air duct 8, it will drive the guide wheel 4 and the free turbine 5 to rotate. After the free turbine 5 rotates, it can drive the thrust fan 6 to rotate. Part of the air flow generated by the rotation of the thrust fan 6 flows to the inner cylinder 2, and part flows to the outer bypass duct 7. In this way, it will mix with the high-speed exhaust jet that has done work through the free turbine 5 in the outer bypass duct 7, and then be discharged together to generate thrust. This can greatly improve the thrust-to-weight ratio, improve working efficiency, and reduce overall fuel consumption.
[0031] The guide wheel 4 can guide the high-speed exhaust jet to flow parallel to the blade spiral of the free turbine 5, so as to ensure that the high-speed exhaust jet can efficiently impact the free turbine 5 and complete the energy conversion.
[0032] In some embodiments, a speed reducer 11 is provided between the turbine shaft of the free turbine 5 and the fan shaft of the thrust fan 6, which can reduce the rotational speed of the output thrust fan 6, increase the torque, and thus generate a larger thrust.
[0033] In summary, this device adds an external bypass duct 7 and a thrust fan 6 to a conventional gas generator 3. By using a reverse air intake and mixed exhaust working mode, it can greatly increase the thrust generated, improve working efficiency, and reduce overall fuel consumption. The overall structure of this device is simple, easy to manufacture and process, and has low operating costs.
[0034] Although some embodiments of the present invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and variations of these embodiments without departing from the principles and spirit of the present invention are within the scope of protection of the claims of the present invention.
Claims
1. A small, low-cost turbofan engine, characterized in that, include: Outer cylinder, inner cylinder, gas generator, guide wheel, free turbine and thrust fan; The outer cylinder has an air inlet and an exhaust outlet at its two axial ends, respectively. The inner cylinder is coaxially fitted inside the outer cylinder, and the cylinder walls of the two are spaced apart to form an outer duct. The end of the inner cylinder adjacent to the air inlet is open, and the end adjacent to the exhaust outlet is closed. The gas generator is located inside the inner cylinder. The gas inlet of the gas generator faces the closed end of the inner cylinder. The gas outlet of the gas generator is provided with a guide member. The guide member is defined with a guide air passage. The end of the guide air passage is provided with an exhaust pipe. The exhaust pipe extends into the outer duct and bends toward the exhaust end. The airflow duct is provided with a guide wheel and a free turbine arranged opposite to each other. Along the gas flow direction of the airflow duct, the guide wheel is located upstream of the free turbine. The thrust fan is located at the air inlet and connected to the free turbine. The free turbine is used to drive the thrust fan to rotate. Part of the airflow generated by the rotation of the thrust fan flows to the outer bypass duct and part flows to the inner cylinder.
2. The small, low-cost turbofan engine according to claim 1, characterized in that, The closed end of the inner cylinder is a tapered end.
3. The small, low-cost turbofan engine according to claim 1, characterized in that, The gas generator is a turbojet engine.
4. The small, low-cost turbofan engine according to claim 1, characterized in that, A speed reducer is provided between the free turbine shaft and the thrust fan shaft.
5. The small, low-cost turbofan engine according to claim 1, characterized in that, The exhaust pipes are multiple, and the multiple exhaust pipes are arranged at intervals along the circumference of the outer bypass.