Self-driven fan large-bypass-ratio turbofan engine with inner loop air turbine

Abstract

The invention relates to a self-driven fan large-bypass-ratio turbofan engine with an inner loop air turbine and a design method. The self-driven fan large-bypass-ratio turbofan engine is characterized in that an outer bypass part is provided with a self-driven fan rotor with a larger bypass ratio and with an inner loop air turbine, the rotor comprises an auxiliary bypass fan rotor (1), an air-driving turbine rotor (3) and a rotating medium casing (5); an auxiliary bypass fan stator (2) is arranged on the downstream of the auxiliary bypass fan rotor (1); an air-driving turbine stator (4) is arranged on the downstream of the air-driving turbine rotor (3). The self-driven fan large-bypass-ratio turbofan engine has advantages: (1) while the bypass ratio is increased, the problem of the large-bypass-ratio turbofan that the rotation speed of the fan is not matched with that of the low voltage rotor can be avoided; (2) compared with the scheme of a gear turbofan engine (GTF) and a three-rotor turbofan engine for solving the mismatch problem of the rotation speed, the structure is simplified; (3) the self-driven fan large-bypass-ratio turbofan engine can be improved on the basis of the existing two-rotor turbofan engine, so that the technical risk and research cost can be reduced, and the research period can be shortened.

Description

technical field [0001] The technology of the invention belongs to the field of new-concept turbofan engines, and mainly relates to the design concept, main structural arrangement and aerodynamic design method of a self-driven fan high bypass ratio turbofan engine with an inner ring air turbine. The present invention proposes to change the method of transferring work from the inner duct parts of the turbofan engine to the outer duct parts from the traditional mechanical shaft torsion to the fan self-driven by the airflow, that is, the airflow driven by the pressurized airflow at the outlet of the fan rotor of the original turbofan engine is self-driven. The fan air turbine is driven to do work, and the additional duct fan rotor fixedly connected with it is driven to rotate through the intermediary casing, thereby realizing the supercharging of the additional duct. Background technique [0002] For a long time, the development of aero-engines has been aimed at pursuing high th...

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Problems solved by technology

[0004] These methods have alleviated the speed mismatch problem of the turbofan engine with a large bypass ratio to a certain extent, but there are also some deficiencies: (1) The turbofan engine is driven by a gear, and the low-pressure turbine drives the fan after being decelerated by a gear reducer, so that The speed of the low-pressure shaft matches the speed of the fan rotor. However, due to the huge transmission power and large speed ratio of the gear reducer, its design is very difficult, and there are problems of reliability and life. It is often used as a turbofan engine with a large bypass ratio. The bottleneck of development restricts the increase of bypass ratio of this type of engine; (2) The use of three-rotor turbofan engine can more reasonably distribute power and match speed among fans, high and low pressure compressors and high, low and medium pressure turbines. The turbine only needs to drive the fan instead of the low-pressure compressor, so its speed can be further reduced

However, even though the increase in the outer diameter of the low-pressure turbine caused many problems, there is still a large rim speed difference between the diameter of the high-bypass fan rotor and the low-pressure turbine (the speed mismatch problem is only alleviated but not resolved)

In addition, the structure of the three-rotor turbofan engine is often very complex, and there are complex rotordynamic problems in the three concentric shafts. These factors make it possible for only a few engine companies to adopt and master this technology; (3) adopt the rear fan turbofan The engine, its independent low-pressure turbine drives the fan, the fan can use a lower speed, and the turbine work does not need to be forwarded through the rotating shaft, avoiding the concentric shaft system with complex structure, but its disadvantages are also significant: on the one hand, the integration of different materials The fans and turbines are difficult to process and manufacture, and require complex structures for sealing to prevent gas from leaking to the outer body; Contribute to the improvement of content economy

These shortcomings make the turbofan engine in the form of rear fan not widely used after the early development of turbofan engine, and gradually fade out of people's field of vision

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