Turbofan engine with adjustable bypass ratio

Abstract

An adjustable bypass ratio turbofan engine comprises a subsonic speed air inlet channel and a medium or high bypass ratio turbofan engine, and an adjustable axial symmetry air inlet channel which is composed of an actuating system and an adjusting piece controlled by an adjusting machine in a sealing cover and is not connected with the turbofan engine is connected behind the subsonic speed air inlet channel. When the turbofan engine runs after being started, according to the working scene of the engine, an actuating system and an adjusting machine are controlled, and the opening degree of an adjusting piece is changed, so that the area of an opening of an adjustable axial symmetry air inlet channel is increased during low-altitude flight, the air inlet bypass ratio of the turbofan engine is increased, the turbofan engine works in a turbofan state with the maximum bypass ratio, the thrust is large, and the oil consumption rate is low; when the height is increased and the thrust is reduced, especially during high-altitude cruise, the opening area of the adjustable axial symmetry air inlet channel is reduced, the air inlet bypass ratio of the turbofan engine is reduced, the turbofan engine works in a turbofan state after the bypass ratio is reduced, the increasing and decreasing amplitude is reduced when the thrust ratio is not adjusted, the structure is not changed, and the windward resistance is reduced.

Description

Technical Field

[0001] This invention relates to an adjustable bypass ratio turbofan engine, belonging to the technical field of medium and high bypass ratio turbofan engines. Background Technology

[0002] Air density is highest at sea level and gradually decreases with increasing altitude. This causes the thrust of turbofan engines to gradually decrease with increasing altitude, especially for medium and high bypass ratio turbofan engines. High bypass ratios result in high drag, leading to a significant thrust drop at high altitudes. For example, the CFM56-7B high bypass ratio turbofan engine used in the Boeing 737 has a ground thrust of 12 tons, but only 2100 kg of thrust during high-altitude cruise, which is detrimental to increasing range and reducing fuel consumption. The "variable cycle high bypass ratio turbofan engine" patent application number 2017109246053, while able to alter the flow rate of the inner and outer bypass ducts to some extent by changing the turbine guide vane flow area and the adjustable guide vane installation angle of the booster stage compressor, will change the overall pressure ratio, affecting the engine's fuel consumption and range. Summary of the Invention

[0003] The purpose of this invention is to provide an adjustable bypass ratio turbofan engine that reduces the thrust drop at high altitudes without altering the structure of medium- and high bypass ratio turbofan engines.

[0004] This invention is implemented as follows: an adjustable bypass ratio turbofan engine, comprising a subsonic inlet and a medium-bypass or high-bypass turbofan engine, characterized in that its subsonic inlet is connected to an adjustable axisymmetric inlet, which is not connected to the turbofan engine and consists of adjustable vanes controlled by an actuation system and adjustment mechanism within a sealed casing; when the medium- or high-bypass turbofan engine with the above structure is running after startup, the actuation system and adjustment mechanism are manipulated according to the engine's operating scenario to change the opening degree of the adjustable axisymmetric inlet, so that the area of ​​the adjustable axisymmetric inlet opening increases during low-altitude flight, thereby increasing the turbofan engine's inlet bypass ratio and operating at maximum bypass ratio turbofan status, resulting in high thrust and low fuel consumption; when the flight altitude increases and the thrust decreases, especially during high-altitude cruise descent, the area of ​​the adjustable axisymmetric inlet opening decreases, thereby decreasing the turbofan engine's inlet bypass ratio and operating at the reduced bypass ratio turbofan status, resulting in increased thrust ratio when not adjusted, reduced descent amplitude, and reduced frontal drag while maintaining the same structure. Attached Figure Description

[0005] Figure 1 This is a schematic diagram of the adjustable bypass ratio turbofan engine of the present invention when the intake bypass ratio increases.

[0006] Figure 2 This is a schematic diagram of the adjustable bypass ratio turbofan engine of the present invention when the intake bypass ratio is reduced. Detailed Implementation

[0007] See attached document Figure 1 , 2 The adjustable bypass ratio turbofan engine of the present invention includes a subsonic air intake 1, a sealing cover 2, an actuation system and adjustment mechanism 3, an adjustment plate 4, and a turbofan engine 5, etc. Figure 1 , 2 These are schematic diagrams illustrating the present invention when the opening area of ​​the adjustable axisymmetric air intake is increased and decreased. The subsonic air intake 1 is a fixed air intake with a Pitot-type inlet, subsequently connected to an adjustable axisymmetric air intake consisting of an adjusting plate 4 controlled by an actuation system and adjusting mechanism 3 within a sealing cover 2. The two ends of the sealing cover 2 are connected to and sealed to the casings of the subsonic air intake 1 and the outer bypass duct of the turbofan engine 5 at both ends of the adjustable axisymmetric air intake. The actuation system and adjusting mechanism 3 can be various actuation systems and adjusting mechanisms found in currently known adjustable axisymmetric tailpipes for fighter jets, such as hydraulically driven linkage mechanisms, etc., and there are multiple such mechanisms. The adjusting plate 4 is connected to the fighter jet... The fish-scale-like plates in the adjustable axisymmetric tail nozzle of the fighter jet serve the same function. Multiple adjusting plates 4 form a movable axisymmetric air intake channel, and its axis is on the same straight line as the axis of the turbofan engine 5. The seal between the adjusting plates 4 can be any of the sealing methods between the fish-scale-like plates in the adjustable axisymmetric tail nozzle of the fighter jet, such as interlocking seals between the inner and outer adjusting plates, etc. There is no air leakage during the adjustment process. The front end of the air intake channel formed by the adjusting plates 4 is fixedly connected to the subsonic air intake 1, and the rear end is in front of the air intake of the turbofan engine 5 but is not connected to it. It is not fixed and is movable. Furthermore, the actuation system and the adjusting mechanism 3 are also connected to the adjusting plates 4. The turbofan engine 5 is a medium-bypass ratio or high-bypass ratio turbofan engine. Figure 1 , 2 The diagram in the diagram is a sectional view.

[0008] When the medium-bypass or high-bypass turbofan engine 5 with the above-described structure starts up, the actuation system and adjustment mechanism 3 are manipulated according to the engine's operating scenario to change the opening of the adjustment vane 4. This increases the area of ​​the adjustable axisymmetric air intake opening during low-altitude flight, transforming the adjustable axisymmetric air intake into a cylindrical air intake. This increases the intake bypass ratio of the turbofan engine 5, making it as large as the intake area of ​​its fan, allowing it to operate at maximum bypass ratio. This results in high thrust and low fuel consumption, comparable to current medium- and high-bypass turbofan engines at low altitudes. The situation is the same; when the flight altitude increases and the thrust decreases, especially when the thrust decreases during high-altitude cruise, the area of ​​the adjustable axisymmetric air intake opening becomes smaller, and the adjustable axisymmetric air intake becomes a convergent air intake, which reduces the bypass ratio of the turbofan engine 5. Although the bypass ratio remains unchanged, the airflow in the inner bypass increases and the airflow in the outer bypass decreases, so that the turbofan operates in a state with a reduced bypass ratio. When the thrust ratio is not adjusted, it increases, the descent rate decreases, and the structure of the turbofan engine 5 remains unchanged, and the frontal drag decreases, as described above.

[0009] Because the total outlet pressure and temperature of the compressor and the turbine inlet temperature of the turbofan engine 5 change when the flight altitude and thrust change, the bypass ratio of the turbofan engine 5 can be adjusted by adjusting the area of ​​the adjustable axisymmetric inlet opening, based on parameters such as the flight altitude, the total outlet pressure and temperature of the compressor, and the turbine inlet temperature. These parameters can be measured by relevant sensors, probes, or measuring instruments in the aircraft and the turbofan engine 5. Furthermore, during the above implementation process, the total outlet pressure and temperature of the compressor and the turbine inlet temperature of the turbofan engine 5 remain within their safe operating range.

[0010] When the technology of this invention is adopted in my country's domestically produced WS-18, Air Force Il-76 transport aircraft, and H-6K, H-6N, and H-6J bombers, the Russian-made D30-KP-2 engines and CJ1000A and WS20 medium- and high-bypass turbofan engines can reduce the bypass ratio during mid- to high-altitude cruise by adjusting the area of ​​the adjustable axisymmetric air intake opening, thereby increasing thrust and reducing fuel consumption. This invention can be applied to various medium- and high-bypass turbofan engines that use subsonic air intakes.

Claims

1. An adjustable bypass ratio turbofan engine, comprising a subsonic inlet (1) and a medium-bypass or high-bypass ratio turbofan engine (5), characterized in that the subsonic inlet (1) is connected to an adjustable axisymmetric inlet consisting of adjustable vanes (4) controlled by an actuation system and adjusting mechanisms (3) within a sealed casing (2), which is not connected to the turbofan engine (5). The two ends of the sealed casing (2) are connected to and sealed to the casings of the subsonic inlet (1) and the outer bypass duct of the turbofan engine (5) at both ends of the adjustable axisymmetric inlet. The actuation system and adjusting mechanisms (3) are multiple, and the multiple adjustable vanes (4) form an axisymmetric inlet channel. The front end of the channel is fixedly connected to the subsonic inlet (1), and the rear end is in front of the turbofan engine (5) inlet but not connected to it. Fixed and movable, and the actuation system and adjustment mechanism (3) are also connected to the adjustment plate (4); when the turbofan engine (5) is running after starting, the actuation system and adjustment mechanism (3) are manipulated according to the working scenario of the engine to change the opening of the adjustment plate (4), so that the area of ​​the adjustable axisymmetric air intake opening increases when flying at low altitude, so that the air intake bypass ratio of the turbofan engine (5) increases, and it works in the turbofan state with the maximum bypass ratio, with high thrust and low fuel consumption. When the flight altitude increases and the thrust decreases, especially during high-altitude cruise, the area of ​​the adjustable axisymmetric air intake opening decreases, so that the air intake bypass ratio of the turbofan engine (5) decreases, and it works in the turbofan state with the reduced bypass ratio. When the thrust ratio is not adjusted, it increases, the descent rate decreases, and the structure remains unchanged, and the frontal drag decreases.

Images