Drag reduction device, boundary layer suction fan, and aircraft

Abstract

The present invention discloses a loss reduction device, a boundary layer suction fan and an aircraft. The loss reduction device is applied to the fan, and the fan includes: a nacelle, an inner casing and fan blades. The nacelle is sleeved outside the inner casing and forms a gap. The loss reduction device includes: a root loss reduction body, which extends radially outward from the outer wall of the inner casing into the gap and rotates around the inner casing; a top loss reduction body, which extends radially inward from the inner wall of the nacelle into the gap and rotates around the inner casing; there is a second gap between the extending end of the root loss reduction body and the extending end of the top loss reduction body; the air flows through the loss reduction device and then flows to the fan blades. This loss reduction device can effectively reduce the accumulation of low-energy flow in the boundary layer near the top and root of the fan blades, improve the inlet air flow quality and aerodynamic efficiency of the fan, and effectively solve the problem of low working efficiency of the boundary layer suction fan.

Description

Technical Field

[0001] The present invention relates to a drag reduction device, a boundary layer ingestion fan and an aircraft. Background Art

[0002] The International Civil Aviation Organization and relevant scientific research institutions have increasingly strict requirements for indicators such as fuel consumption and environmental protection of future aircraft. According to reports, NASA and the European Union hope that by 2035 (N+3 time frame), the fuel consumption of aircraft will be reduced by 70%. However, conventional fuel-configured aeroengines have been unable to meet this requirement. In recent years, major advanced aviation countries in Europe and America have respectively put forward concepts of new aircraft / engine propulsion systems from new perspectives such as aircraft configuration and energy usage methods. Among these new aircraft configurations, the boundary layer ingestion propulsion system (referred to as the propulsive fuselage concept in Europe and America) with a boundary layer ingestion electric fan (BLI fan, boundary layer ingestion fan) installed at the tail of the aircraft has currently become a research hotspot.

[0003] The basic idea of this configuration is to add a fan at the tail of a traditional aircraft, which is usually directly driven by the electricity generated by the operation of a conventional gas turbine engine. When the tail fan operates, it can effectively suck in the gas boundary layer that gradually accumulates on the fuselage surface due to viscous action, thereby reducing the accumulation of the fuselage boundary layer, effectively reducing the drag of the aircraft, and ultimately achieving the purpose of reducing the fuel consumption during the flight. Due to the boundary layer ingestion effect of the tail fan, the fan is usually referred to as the boundary layer ingestion fan (boundary layer ingestion fan, BLI fan) abroad. On the other hand, the boundary layer ingestion fan also provides approximately 20% - 30% of the thrust. Therefore, when the total thrust requirement of the aircraft remains unchanged, the thrust requirement of the conventional gas turbine engine decreases, so its fan diameter can also be reduced, making it easier to meet the size constraint limits under the maximum nacelle diameter.

[0004] Foreign aircraft and engine companies such as GE and Airbus have all proposed relevant patents for boundary layer ingestion fans installed at the tail of the aircraft along this line of thought. Due to the boundary layer suction effect of the boundary layer ingestion fan, it is equivalent to indirectly increasing the bypass ratio of the traditional gas turbine engine. According to data, compared with ordinary aircraft configurations under the same technical conditions, the aircraft configuration equipped with a boundary layer ingestion fan can save approximately 9 - 14% of fuel consumption, and the economic efficiency is very remarkable.

[0005] Although the boundary layer suction fan has considerable economic benefits in reducing fuel consumption, there is still room for improvement in engineering applications. The most typical aspect is that, due to the interference of the fuselage and vertical tail boundary layers upstream, the inlet airflow of the boundary layer suction fan will continuously have radial distortion around the blade root for a week and low-energy fluid in the boundary layer in some areas, that is, it continuously operates in an environment of radial distortion and circumferential distortion. According to the evaluation of relevant data, the efficiency of the tail boundary layer suction fan drops by about 4 percentage points compared with the case of uniform inlet air conditions. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a loss reduction device, a boundary layer suction fan and an aircraft in order to overcome the defect of low working efficiency of the boundary layer suction fan in the prior art.

[0007] The present invention solves the above technical problem through the following technical solutions:

[0008] A loss reduction device, the loss reduction device is applied to a fan, and the fan includes: a nacelle, an inner casing and fan blades. The nacelle is sleeved outside the inner casing and forms a gap. The feature is that the loss reduction device includes: a root loss reduction body, the root loss reduction body extends radially outward from the outer wall of the inner casing into the gap and rotates around the inner casing; a top loss reduction body, the top loss reduction body extends radially inward from the inner wall of the nacelle into the gap and rotates around the inner casing; there is a second gap between the extending ends of the root loss reduction body and the top loss reduction body; the air flows through the loss reduction device and then flows to the fan blades.

[0009] In this solution, adopting the above structural form, the loss reduction device not only has a relatively low cost and is easy to disassemble and assemble, but also can effectively reduce the accumulation of low-energy fluid in the boundary layer near the top and root of the fan blades, improve the inlet airflow quality and aerodynamic efficiency of the fan, effectively solve the problem of low working efficiency of the boundary layer suction fan, is beneficial to reducing engine fuel consumption, reducing carbon emissions, and improving the economy of the aircraft.

[0010] Preferably, the loss reduction device further includes a first driving part and a second driving part; the first driving part is fixedly connected to the nacelle, and the first driving part makes the top loss reduction body rotate around the inner casing; the second driving part is fixedly connected to the inner casing, and the second driving part makes the root loss reduction body rotate around the inner casing.

[0011] In this solution, adopting the above structural form, the relatively independent drive design of the root loss reduction body and the top loss reduction body on the loss reduction device makes the adjustment methods for the root loss reduction body and the top loss reduction body more flexible in the actual process, which is beneficial to obtaining the best matching effect when the loss reduction device works in cooperation with the fan blade.

[0012] Preferably, the first drive part surrounds and is fixed to the inner wall of the nacelle. The top loss reduction body is fixedly installed on the inner wall of the first drive part. The first drive part makes the protruding end of the top loss reduction body rotate around the root loss reduction body.

[0013] Preferably, the first drive part includes a motor stator and a motor rotor. The motor stator is surrounded and fixed to the inner wall of the nacelle. The motor rotor is arranged around the inner wall of the motor stator. The motor rotor can rotate within the motor stator. A plurality of the top loss reduction bodies are evenly fixed to the inner wall of the motor rotor along the circumferential direction thereof. The motor rotor makes the protruding end of the top loss reduction body rotate around the inner casing.

[0014] In this solution, adopting the above structural form, the first drive part adopts an annular motor and is arranged and installed on the inner wall of the nacelle, which simplifies the structural form and layout form of the first drive part. At the same time, the first drive part will not interfere with the air intake condition of the fan.

[0015] Preferably, the second drive part includes a first motor and a first transmission shaft. The first motor is fixedly installed in the inner casing. The end of the first transmission shaft is fixedly connected to the first motor. A plurality of the root loss reduction bodies are evenly fixedly installed on the outer wall of the first transmission shaft along the circumferential direction. The protruding end of the root loss reduction body rotates around the inner casing.

[0016] In this solution, adopting the above structural form, the root loss reduction body can increase the kinetic energy of the boundary layer near the inner casing and reduce the boundary layer thickness, which is beneficial to improving the aerodynamic efficiency of the fan. And the root loss reduction body has an independent second drive part to drive it, which is beneficial to making the adjustment method for the root loss reduction body more flexible.

[0017] Preferably, the loss reduction device further includes a second motor and a second transmission shaft. The second motor makes the fan blade rotate between the intervals through the second transmission shaft.

[0018] In this solution, adopting the above structural form, the fan blade plays a role in sucking the boundary layer of the fuselage and generating forward thrust. And the fan blade has an independent second motor to drive it, which is convenient for flexibly configuring the working state of the fan blade according to the results of experiments or calculations and the thrust requirements.

[0019] Preferably, the loss reduction device further includes a second transmission shaft sleeved outside the first transmission shaft. One end of the second transmission shaft is fixedly connected to the first motor, and the other end of the second transmission shaft extends towards the root loss reduction body. A plurality of the fan blades are fixedly installed on the outer wall of the protruding end of the second transmission shaft along the circumferential direction, and the second transmission shaft rotates the fan blades between the intervals.

[0020] Preferably, the second transmission shaft is coaxially sleeved outside the first transmission shaft.

[0021] In this solution, adopting the above structural form can reduce the number of motors, save space inside the inner casing, and is beneficial to achieving better integration between the loss reduction device and the fan.

[0022] Preferably, the fan further includes a speed reduction part. The first transmission shaft includes a first shaft and a second shaft. One end of the first shaft is fixedly connected to the first motor, the other end of the first shaft is fixedly connected to the input end of the speed reduction part, the output end of the speed reduction part is fixedly connected to one end of the second shaft, and a plurality of the root loss reduction bodies are evenly fixedly installed on the outer wall of the second shaft along the circumferential direction. The protruding ends of the root loss reduction bodies rotate around the inner casing.

[0023] In this solution, adopting the above structural form, the speed reduction part plays a role in regulating the speed of the root loss reduction body, which is beneficial to enabling the root loss reduction body and the fan blades to obtain their respective required rotational speeds.

[0024] A boundary layer suction fan, characterized in that the boundary layer suction fan adopts the above-mentioned loss reduction device.

[0025] In this solution, the boundary layer suction fan adopting the loss reduction device with such a structural form not only has a relatively low cost and is easy to disassemble and assemble, but also this loss reduction device can effectively reduce the accumulation of low-energy flow in the boundary layer near the top and root of the fan blades, improve the inlet air flow quality and aerodynamic efficiency of the fan, effectively solve the problem of low working efficiency of the boundary layer suction fan, and is beneficial to reducing engine fuel consumption, reducing carbon emissions, and improving the economy of the aircraft.

[0026] An aircraft, characterized in that the aircraft adopts the above-mentioned boundary layer suction fan.

[0027] In this solution, the boundary layer suction fan at the tail of the aircraft adopting the loss reduction device with such a structural form not only has a relatively low cost and is easy to disassemble and assemble, but also this loss reduction device can effectively reduce the accumulation of low-energy flow in the boundary layer near the top and root of the fan blades, improve the inlet air flow quality and aerodynamic efficiency of the fan, effectively solve the problem of low working efficiency of the boundary layer suction fan, and is beneficial to reducing engine fuel consumption, reducing carbon emissions, and improving the economy of the aircraft.

[0028] On the basis of conforming to the common knowledge in the art, the above preferred conditions can be combined arbitrarily to obtain various preferred examples of the present invention.

[0029] The positive and progressive effects of the present invention are as follows:

[0030] A loss reduction device is designed and installed in the space formed between the inner wall of the nacelle of the boundary layer suction fan and the outer wall of the inner casing. Such a structural form of the loss reduction device not only has a relatively low cost and is easy to disassemble and assemble, but also the loss reduction device can effectively reduce the accumulation of low-energy flow in the boundary layer near the top and root of the fan blade, improve the inlet air flow quality and aerodynamic efficiency of the fan, effectively solve the problem of low working efficiency of the boundary layer suction fan, is beneficial to reducing the fuel consumption of the engine, reducing carbon emissions, and improving the economy of the aircraft. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic structural diagram of a boundary layer suction fan equipped with a loss reduction device according to an embodiment of the present invention.

[0032] Figure 2 It is a schematic structural diagram of a first driving part according to an embodiment of the present invention.

[0033] Figure 3 It is a schematic structural diagram of a boundary layer suction fan according to other embodiments of the present invention.

[0034] Figure 4 It is a schematic structural diagram of an aircraft according to an embodiment of the present invention.

[0035] DESCRIPTION OF THE REFERENCE NUMERALS:

[0036] Loss reduction device 1

[0037] Root loss reduction body 11

[0038] Top loss reduction body 12

[0039] First driving part 13

[0040] Motor stator 131

[0041] Motor rotor 132

[0042] Second driving part 14

[0043] First motor 141

[0044] First transmission shaft 142

[0045] First shaft 1421

[0046] Second shaft 1422

[0047] Second motor 15

[0048] Second drive shaft 16

[0049] Reduction section 17

[0050] Boundary layer suction fan 2

[0051] Nacelle 21

[0052] Inner casing 22

[0053] Fan blade 23

[0054] Aircraft 3

[0055] Right engine 31

[0056] Right generator 32

[0057] Right engine cable 33

[0058] Left engine 34

[0059] Left generator 35

[0060] Left engine cable 36 Specific implementation mode

[0061] The present invention will be more clearly and completely described below by way of examples in conjunction with the accompanying drawings, but the present invention is not limited to the scope of the examples thereby.

[0062] An embodiment of the present invention provides a loss reduction device 1, as Figures 1-4 shown, the loss reduction device 1 is applied to a fan, and the fan includes: a nacelle 21, an inner casing 22 and a fan blade 23. The nacelle 21 is sleeved outside the inner casing 22 and forms a gap. The loss reduction device 1 includes: a root loss reduction body 11, the root loss reduction body 11 extends radially outward from the outer wall of the inner casing 22 into the gap and rotates around the inner casing 22; a top loss reduction body 12, the top loss reduction body 12 extends radially inward from the inner wall of the nacelle 21 into the gap and rotates around the inner casing 22; there is a second gap between the extended end of the root loss reduction body 11 and the extended end of the top loss reduction body 12; the air flows to the fan blade 23 after flowing through the loss reduction device 1.

[0063] Adopting the above structural form, a loss reduction device 1 is designed and installed in the gap formed between the inner wall of the nacelle 21 and the outer wall of the inner casing 22 of the boundary layer suction fan 2. The loss reduction device 1 includes a plurality of root loss reduction bodies 11 that are evenly distributed along the circumferential direction of the inner casing 22 and extend radially outward from the outer wall of the inner casing 22 into the gap, and a plurality of top loss reduction bodies 12 that are evenly distributed along the circumferential direction of the nacelle 21 and extend radially inward from the inner wall of the nacelle 21 into the gap.

[0064] When the loss reduction device 1 is working, a plurality of root loss reduction bodies 11 rotate around the inner casing 22, and a plurality of top loss reduction bodies 12 are located on the outer ring of the root loss reduction bodies 11 and rotate around the inner casing 22; in the actual working state of the boundary layer suction fan 2, due to the interference of the airframe and the vertical tail boundary layer upstream, there will be continuous radial distortion around the root of the fan blade 23 of the boundary layer suction fan 2 and low-energy fluid in the boundary layer in some areas. Therefore, the loss reduction device 1 is arranged in front of the fan blade 23 of the boundary layer suction fan 2, that is, the air flows through the loss reduction device 1 before flowing to the fan blade 23.

[0065] For the problem of the accumulation of low-energy boundary layer fluid near the root of the fan blade 23, the height range of the root loss reduction body 11 can be controlled to account for 0% - 20% of the height of the fan blade 23 of the boundary layer suction fan 2. For the problem of the accumulation of low-energy boundary layer fluid near the top of the fan blade 23, the height range of the top loss reduction body 12 can be controlled to account for 0% - 20% of the height of the fan blade 23 of the boundary layer suction fan 2. At the same time, the specific shapes and height values of the root loss reduction body 11 and the top loss reduction body 12 can be optimized and adjusted according to the boundary layer thickness distribution obtained by experiments or calculations. The rotation directions and speeds of the root loss reduction body 11 and the top loss reduction body 12 are optimally matched according to the experimental and CFD numerical calculation results to make the aerodynamic efficiency of the boundary layer suction fan 2 reach the best.

[0066] Such a structural form of the loss reduction device 1 not only has a relatively low cost and is easy to disassemble and assemble, but also the loss reduction device 1 can effectively reduce the accumulation of low-energy boundary layer fluid near the top and root of the fan blade 23, improve the inlet air flow quality and aerodynamic efficiency of the fan, effectively solve the problem of low working efficiency of the boundary layer suction fan 2, and is beneficial to reducing the fuel consumption of the engine, reducing carbon emissions, and improving the economy of the aircraft 3.

[0067] As a preferred embodiment, as Figure 1 shown, the loss reduction device 1 further includes a first driving part 13 and a second driving part 14; the first driving part 13 is fixedly connected to the nacelle 21, and the first driving part 13 makes the top loss reduction body 12 rotate around the inner casing 22; the second driving part 14 is fixedly connected to the inner casing 22, and the second driving part 14 makes the root loss reduction body 11 rotate around the inner casing 22.

[0068] The root loss reduction body 11 and the top loss reduction body 12 have their respective independent drive parts. The first drive part 13 is installed on the upper part inside the nacelle 21 and fixedly connected to the inner wall of the nacelle 21. The second drive part 14 is fixedly installed inside the inner casing 22. When the loss reduction device 1 works, several top loss reduction bodies 12 located on the outer circle of the root loss reduction body 11 rotate around the inner casing 22 under the drive of the first drive part 13, and the root loss reduction body 11 located outside the inner casing 22 rotates around the inner casing 22 under the drive of the second drive part 14. At the same time, the rotation directions and speeds of the root loss reduction body 11 and the top loss reduction body 12 can be optimally matched according to the experimental and CFD numerical calculation results, so that the low-loss areas of the roots and tops of the fan blades 23 of the boundary layer suction fan 2 are relatively minimized, and the aerodynamic efficiency of the boundary layer suction fan 2 reaches the best. The relatively independent drive design of the root loss reduction body 11 and the top loss reduction body 12 on the loss reduction device 1 makes the adjustment methods for the root loss reduction body 11 and the top loss reduction body 12 more flexible in the actual process, which is beneficial to obtaining the best matching effect when the loss reduction device 1 and the fan blades 23 work together.

[0069] As a preferred embodiment, as Figure 1 , Figure 2 shown, the first drive part 13 surrounds and is fixed to the inner wall of the nacelle 21. The inner wall of the first drive part 13 is fixedly installed with the top loss reduction body 12. The first drive part 13 makes the extended end of the top loss reduction body 12 rotate around the root loss reduction body 11. The first drive part 13 includes a motor stator 131 and a motor rotor 132. The inner wall of the nacelle 21 surrounds and is fixed with the motor stator . The inner wall of the motor stator 131 is provided with a motor rotor 132 around it. The motor rotor 132 can rotate inside the motor stator 131. A plurality of top loss reduction bodies 12 are uniformly fixed along the circumferential direction of the inner wall of the motor rotor 132. The motor rotor 132 makes the extended end of the top loss reduction body 12 rotate around the inner casing 22.

[0070] The first driving part 13 adopts a ring-shaped motor. The motor stator 131 on the ring-shaped motor is fixedly connected to the nacelle 21. The motor rotor 132 on the ring-shaped motor is installed in the motor stator 131. A plurality of top loss-reducing bodies 12 are evenly installed along the circumferential direction of the inner wall of the motor rotor 132. The plurality of top loss-reducing bodies 12 extend radially inward along the motor rotor 132. When the ring-shaped motor works, the motor stator 131 drives the motor rotor 132 to drive the plurality of top loss-reducing bodies 12 to rotate around the inner casing 22. At the same time, the height range of the top loss-reducing bodies 12 can be controlled to account for 0% - 20% of the height of the fan blades 23 of the boundary layer suction fan 2. The specific shape and height value of the top loss-reducing bodies 12 can be adjusted accordingly according to the boundary layer thickness distribution obtained by experiments or calculations. The rotation direction and speed of the top loss-reducing bodies 12 are optimized and matched according to the experimental and CFD numerical calculation results. The first driving part 13 adopts a ring-shaped motor and is installed on the inner wall of the nacelle 21, which simplifies the structural form and layout form of the first driving part 13. At the same time, the first driving part 13 will not interfere with the air intake of the fan.

[0071] As a preferred embodiment, as Figure 1 shown, the second driving part 14 includes a first motor 141 and a first transmission shaft 142. The first motor 141 is fixedly installed in the inner casing 22. The end of the first transmission shaft 142 is fixedly connected to the first motor 141. A plurality of root loss-reducing bodies 11 are evenly and fixedly installed along the circumferential direction of the outer wall of the first transmission shaft 142. The extending ends of the root loss-reducing bodies 11 rotate around the inner casing 22.

[0072] The root loss-reducing bodies 11 move through the second driving part 14. The first motor 141 in the second driving part 14 is fixedly installed in the inner casing 22. A first transmission shaft 142 is connected to the power output end of the first motor 141. The first transmission shaft 142 is coaxial with the inner casing 22. The outer wall of the first transmission shaft 142 is fixedly connected to the ends of a plurality of root loss-reducing bodies 11 evenly distributed along its circumferential direction. When the first motor 141 works, it drives the extending ends of the root loss-reducing bodies 11 to rotate around the inner casing 22 in the interval through the first transmission shaft 142. At the same time, the height range of the root loss-reducing bodies 11 can be controlled to account for 0% - 20% of the height of the fan blades 23 of the boundary layer suction fan 2. The specific shape and height value of the root loss-reducing bodies 11 can be adjusted accordingly according to the boundary layer thickness distribution obtained by experiments or calculations. The rotation direction and speed of the root loss-reducing bodies 11 are optimized and matched according to the experimental and CFD numerical calculation results. The root loss-reducing bodies 11 can increase the kinetic energy of the boundary layer near the inner casing 22 and reduce the boundary layer thickness, which is beneficial to improving the aerodynamic efficiency of the fan. And the root loss-reducing bodies 11 have an independent second driving part 14 to drive them, which is beneficial to making the adjustment method for the root loss-reducing bodies 11 more flexible.

[0073] As a preferred embodiment, as Figure 1 shown, the loss reduction device 1 further includes a second motor 15 and a second transmission shaft 16. The second motor 15 rotates the fan blades 23 between the intervals through the second transmission shaft 16.

[0074] After the air flows through the loss reduction device 1, it flows to the fan blades 23. The fan blades 23 perform a rotational motion through the second motor 15 and the second transmission shaft 16. The second motor 15 is fixedly connected inside the inner casing 22. One end of the second transmission shaft 16 is fixedly connected to the power output end of the second motor 15. The other end of the second transmission shaft 16 is coaxially and fixedly connected with a blade disc. The blade disc is fixedly connected with a plurality of fan blades 23 uniformly arranged along its circumferential direction. When the second motor 15 works, it drives the fan blades 23 to perform a rotational motion in the interval between the nacelle 21 and the inner casing 22 through the second transmission shaft 16. The fan blades 23 play a role in sucking the boundary layer of the fuselage and generating forward thrust. And the fan blades 23 have an independent second motor 15 to drive them, so that it is convenient to flexibly configure the working state of the fan blades 23 according to the experimental or calculated results and the thrust requirements.

[0075] As a preferred embodiment, as Figure 3 shown, the loss reduction device 1 further includes a second transmission shaft 16. The second transmission shaft 16 is sleeved outside the first transmission shaft 142. One end of the second transmission shaft 16 is fixedly connected to the first motor 141. The other end of the second transmission shaft 16 extends towards the root loss reduction body 11. A plurality of fan blades 23 are fixedly installed on the outer wall of the extended end of the second transmission shaft 16 along the circumferential direction. The second transmission shaft 16 rotates the fan blades 23 between the intervals and the second transmission shaft 16 is coaxial with the first transmission shaft 142.

[0076] In other embodiments, an arrangement may be adopted in which the first motor 141 drives the fan blades 23 and the root loss reduction device 1 simultaneously. The first transmission shaft 142 and the second transmission shaft 16 are both fixedly connected to the power output end of the first motor 141 in a coaxial sleeved manner. The second transmission shaft 16 is sleeved outside the first transmission shaft 142, and there is a gap between the inner wall of the second transmission shaft 16 and the outer wall of the first transmission shaft 142. The protruding end of the second transmission shaft 16 is coaxially and fixedly connected with a blade disc, and the blade disc is fixedly connected with a plurality of fan blades 23 uniformly arranged along its circumferential direction. The outer wall of the protruding end of the first transmission shaft 142 is fixedly connected with the ends of a plurality of root loss reduction bodies 11 uniformly distributed along its circumferential direction. When the first motor 141 operates, the root loss reduction bodies 11 and the fan blades 23 are respectively driven by the first transmission shaft 142 and the second transmission shaft 16 to perform rotational motion in the gap between the nacelle 21 and the inner casing 22. Such a design can reduce the number of motors, save space inside the inner casing 22, and is beneficial to achieving better integration between the loss reduction device 1 and the fan.

[0077] As a preferred embodiment, as Figure 3 shown, the fan further includes a reduction part 17. The first transmission shaft 142 includes a first shaft 1421 and a second shaft 1422. One end of the first shaft 1421 is fixedly connected to the first motor 141, and the other end of the first shaft 1421 is fixedly connected to the input end of the reduction part 17. The output end of the reduction part 17 is fixedly connected to one end of the second shaft 1422. A plurality of root loss reduction bodies 11 are uniformly and fixedly installed on the outer wall of the second shaft 1422 along the circumferential direction, and the protruding ends of the root loss reduction bodies 11 rotate around the inner casing 22.

[0078] In other embodiments, since the arrangement of using the first motor 141 to drive the fan blades 23 and the root loss reduction device 1 simultaneously is adopted, the reduction part 17 is also used in this scheme. At the same time, the first transmission shaft 142 is divided into a first shaft 1421 and a second shaft 1422. The first shaft 1421 transmits the power of the first motor 141 to the reduction part 17. After the speed is adjusted by the reduction part 17, it is transmitted to the root loss reduction bodies 11 through the second transmission shaft 16. The reduction part 17 plays a role in adjusting the speed of the root loss reduction bodies 11, which is beneficial to enabling the root loss reduction bodies 11 and the fan blades 23 to obtain the rotational speeds required by each.

[0079] An embodiment of the present invention provides a boundary layer suction fan 2, as Figure 1 、 Figure 3 shown, the boundary layer suction fan 2 adopts the above-mentioned loss reduction device 1.

[0080] With the above structural form, a loss reduction device 1 is designed and installed in the space formed between the inner wall of the nacelle 21 of the boundary layer suction fan 2 and the outer wall of the inner casing 22. The loss reduction device 1 includes a number of root loss reduction bodies 11 that are evenly distributed along the circumferential direction of the inner casing 22 and extend radially outward from the outer wall of the inner casing 22 into the space, and a number of top loss reduction bodies 12 that are evenly distributed along the circumferential direction of the nacelle 21 and extend radially inward from the inner wall of the nacelle 21 into the space. When the loss reduction device 1 is working, a number of root loss reduction bodies 11 rotate around the inner casing 22, and a number of top loss reduction bodies 12 are located outside the root loss reduction bodies 11 and rotate around the inner casing 22. The loss reduction device 1 of the boundary layer suction fan 2 with such a structural form not only has a relatively low cost and is easy to disassemble and assemble, but also can effectively reduce the accumulation of low-energy flow volume in the boundary layer near the top and root of the fan blade 23, improve the inlet air flow quality and aerodynamic efficiency of the fan, effectively solve the problem of low working efficiency of the boundary layer suction fan 2, and is beneficial to reducing the fuel consumption of the engine, reducing carbon emissions, and improving the economy of the aircraft 3.

[0081] An embodiment of the present invention provides an aircraft 3, as Figure 4 shown, the aircraft 3 adopts the above-mentioned boundary layer suction fan 2.

[0082] With the above structural form, a loss reduction device 1 is designed and installed in the space formed between the inner wall of the nacelle 21 of the boundary layer suction fan 2 at the tail of the aircraft 3 and the outer wall of the inner casing 22. The loss reduction device 1 includes a number of root loss reduction bodies 11 that are evenly distributed along the circumferential direction of the inner casing 22 and extend radially outward from the outer wall of the inner casing 22 into the space, and a number of top loss reduction bodies 12 that are evenly distributed along the circumferential direction of the nacelle 21 and extend radially inward from the inner wall of the nacelle 21 into the space. When the loss reduction device 1 is working, a number of root loss reduction bodies 11 rotate around the inner casing 22, and a number of top loss reduction bodies 12 are located outside the root loss reduction bodies 11 and rotate around the inner casing 22.

[0083] The left engine 34 and the right engine 31 on both sides of the aircraft 3 adopt conventional gas turbine engines. The low-pressure shafts or high-pressure shafts of the two engines are respectively connected to the left generator 35 and the right generator 32 through mechanisms such as reduction gearboxes to generate electricity. The electric energy generated by the left generator 35 and the right generator 32 is respectively transmitted to the boundary layer suction fan 2 at the tail through the left engine cable 36 and the right engine cable 33. The thrust generated by the electric power extracted from the left engine 34 and the right engine 31 acting on the boundary layer suction fan 2 accounts for 10-25% of the total thrust.

[0084] The drag reduction device 1 with such a structural form is adopted for the boundary layer suction fan 2 at the tail of the aircraft 3. This drag reduction device 1 not only has a relatively low cost and is easy to disassemble and assemble, but also can effectively reduce the accumulation of low-energy flow volume in the boundary layer near the top and the blade root of the fan blade 23, improve the inlet air flow quality and aerodynamic efficiency of the fan, effectively solve the problem of low working efficiency of the boundary layer suction fan 2, is beneficial to reducing the fuel consumption of the engine, reducing carbon emissions, and improving the economy of the aircraft 3.

[0085] Although the specific embodiments of the present invention have been described above, those skilled in the art should understand that this is only an example. The protection scope of the present invention is defined by the appended claims. Without departing from the principle and essence of the present invention, those skilled in the art can make various changes or modifications to these embodiments, but these changes and modifications all fall within the protection scope of the present invention.

Claims

1. A loss reduction device, the loss reduction device is applied to a fan, and the fan includes: A nacelle, an inner casing, and fan blades, the nacelle being sleeved outside the inner casing and forming a gap, characterized in that the loss reduction device comprises: A root loss reduction body extending radially outward from the outer wall of the inner casing into the gap and rotating around the inner casing; A top loss reduction body extending radially inward from the inner wall of the nacelle into the gap and rotating around the inner casing; There is a second gap between the extending ends of the root loss reduction body and the top loss reduction body; after air flows through the loss reduction device, it flows towards the fan blades.

2. The impairment device according to claim 1, characterized in that, The loss reduction device further comprises a first driving part and a second driving part; The first driving part is fixedly connected to the nacelle, and the first driving part causes the top loss reduction body to rotate around the inner casing; The second driving part is fixedly connected to the inner casing, and the second driving part causes the root loss reduction body to rotate around the inner casing.

3. The impairment device according to claim 2, characterized in that, The first driving part surrounds and is fixed to the inner wall of the nacelle, the top loss reduction body is fixedly installed on the inner wall of the first driving part, and the first driving part causes the extending end of the top loss reduction body to rotate around the root loss reduction body.

4. The impairment device according to claim 3, characterized in that, The first driving part comprises a motor stator and a motor rotor, the motor stator is surrounded and fixed to the inner wall of the nacelle, the motor rotor is surrounded and arranged on the inner wall of the motor stator, the motor rotor can rotate in the motor stator, and a plurality of the top loss reduction bodies are uniformly fixedly arranged on the inner wall of the motor rotor along the circumferential direction thereof, and the motor rotor causes the extending end of the top loss reduction body to rotate around the inner casing.

5. The impairment device according to claim 2, characterized in that, The second driving part comprises a first motor and a first transmission shaft, the first motor is fixedly installed in the inner casing, one end of the first transmission shaft is fixedly connected to the first motor, a plurality of the root loss reduction bodies are uniformly fixedly installed on the outer wall of the first transmission shaft along the circumferential direction, and the extending end of the root loss reduction body rotates around the inner casing.

6. The impairment device according to claim 5, wherein The loss reduction device further comprises a second motor and a second transmission shaft, and the second motor causes the fan blades to rotate between the gaps through the second transmission shaft.

7. The impairment device according to claim 5, characterized in that The loss reduction device further comprises a second transmission shaft, the second transmission shaft is sleeved outside the first transmission shaft, one end of the second transmission shaft is fixedly connected to the first motor, the other end of the second transmission shaft extends towards the root loss reduction body, and a plurality of the fan blades are fixedly installed on the outer wall of the extending end of the second transmission shaft along the circumferential direction, and the second transmission shaft causes the fan blades to rotate between the gaps.

8. The impairment device according to claim 7, characterized in that The second transmission shaft is coaxially sleeved outside the first transmission shaft.

9. The impairment device according to claim 8, characterized in that, The fan further comprises a reduction part, the first transmission shaft comprises a first shaft and a second shaft, one end of the first shaft is fixedly connected to the first motor, the other end of the first shaft is fixedly connected to the input end of the reduction part, the output end of the reduction part is fixedly connected to one end of the second shaft, and a plurality of the root loss reduction bodies are uniformly fixedly installed on the outer wall of the second shaft along the circumferential direction, and the extending end of the root loss reduction body rotates around the inner casing.

10. A boundary layer suction fan, characterized in that, The boundary layer suction fan includes a loss reduction device as described in any one of claims 1-9.

11. An aircraft, characterized in that, The aircraft includes a fan as described in any one of claims 1-9.

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