Ducted fan

Abstract

The utility model discloses a ducted fan, which belongs to the technical field of aviation ducted fan engines, and comprises an annular duct, a plurality of blades and a plurality of blades, the fan blades are arranged in the annular duct, blade tip arc surfaces are arranged at the blade tips of the fan blades, and blowing gaps are formed in the sides, close to the suction surfaces, of the fan blades; the fan blades are fixedly connected to the outer side of the fan shaft; the driving part is used for driving the fan shaft to rotate, and the driving part is arranged on the rear side of the annular duct; the ratio of the height of the air blowing seam to the diameter of the arc surface of the blade tip is set to be 0.01-0.05; an air flow channel is formed in the fan blade and communicates with the air blowing seam. The number of the fan blades is two or more. The interior of the fan shaft is of a hollow structure. According to the utility model, the blade top clearance leakage flow is reduced by blowing at the top ends of the blades, so that the propulsion efficiency of the ducted fan is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of aviation ducted fan engines, in particular to a ducted fan. Background Art

[0002] A ducted fan is a form of aircraft engine propulsion system, consisting of a duct and a fan. The special shape of the duct generates leading edge suction and increases thrust. At the same time, the shape of the duct can adjust the incoming flow to keep the fan in the best working condition. For a turbofan engine, the duct and fan are one of its components, providing most of the thrust, while the turbine at the rear of the engine provides the power for the fan to rotate. In addition, the duct and fan can also be used as an independent propulsion system, directly driven by an electric motor, or obtain power from other engines through a drive shaft.

[0003] There is a certain gap between the inner wall of the duct and the top of the fan blade, namely the blade tip gap. The blade tip gap is about 1% to 3% of the blade height. Due to the pressure difference between the pressure side and the suction side of the blade, the blade tip gap produces leakage flow. The leakage flow causes airflow separation and leakage vortex at the tip of the blade, reducing the efficiency of the fan. The larger the blade tip gap, the lower the propulsion efficiency coefficient of the ducted fan. Due to limited manufacturing precision, the blade tip gap cannot be infinitely small, otherwise the inner wall of the duct is prone to friction with the blade tip; therefore, we propose a ducted fan to solve this problem. Utility Model Content

[0004] The utility model aims to provide a ducted fan, which reduces the leakage flow in the blade tip gap by blowing air at the blade tip, thereby improving the propulsion efficiency of the ducted fan and solving the problems raised in the above-mentioned background technology.

[0005] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0006] A ducted fan, comprising:

[0007] The annular duct is arranged in a ring shape;

[0008] A plurality of fan blades are arranged inside the annular duct, the blade tips of the fan blades are provided with blade tip arc surfaces, and a blowing slot is provided on a side of the fan blades close to the suction surface;

[0009] A fan shaft, wherein the fan blades are fixedly connected to the outer side of the fan shaft;

[0010] A driving member is used for driving the fan shaft to rotate, and the driving member is arranged on the rear side of the annular duct.

[0011] Preferably, the ratio of the height of the blowing slot to the diameter of the blade tip arc surface is set between 0.01-0.05.

[0012] Preferably, an air flow channel is provided inside the fan blade, and the air flow channel is communicated with the blowing slit.

[0013] Preferably, the number of the fan blades is set to two or more.

[0014] Preferably, the interior of the fan shaft is configured as a hollow structure, and the outer side of the fan shaft is provided with a connecting hole connected to the air flow channel.

[0015] Preferably, the driving member is configured as an engine, and a power output end of the engine is fixedly connected to one end of the fan shaft.

[0016] Preferably, the fan blades are arranged in an inclined shape, and a plurality of fan blades are distributed in a ring shape at equal intervals on the outside of the fan shaft.

[0017] Preferably, the blade top arc surface of the fan blade is a semi-cylindrical surface, and its cross-section is a semicircle or an ellipse.

[0018] In the utility model, a ducted fan is described, in which the fan shaft is driven to rotate by the power of the engine, and the fan shaft drives the fan blades to rotate to generate wind force, and at the same time, a high-pressure airflow is introduced to the fan shaft and the fan blades through the compressor of the aircraft turbine engine or an electric air pump, and the high-pressure airflow is blown out from the blowing slit through the air flow channel inside the fan blade. At this time, the high-speed airflow blown out from the blowing slit is blown toward the lower surface of the blade along the tangent direction of the circular arc surface of the blade tip and close to the circular arc surface. At this time, the curved high-speed airflow produces an induced effect, driving the surrounding airflow to blow toward the pressure surface of the blade, increasing the circulation along the airflow direction. The airflow direction is opposite to the direction of the leakage flow of the blade tip gap, which can weaken the leakage flow, thereby reducing the pressure loss caused by the separation of the airflow between the pressure surface and the suction surface, and improving the thrust;

[0019] The utility model has a reasonable structural design and reduces the leakage flow of the blade tip gap by blowing air at the blade tip, thereby improving the propulsion efficiency of the ducted fan. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a front view of a ducted fan proposed by the utility model;

[0021] Figure 2 for Figure 1 Schematic diagram of the cross-sectional structure of the AA section;

[0022] Figure 3 A three-dimensional structural schematic diagram of a ducted fan proposed by the utility model;

[0023] Figure 4It is a partial cross-sectional structural schematic diagram of a ducted fan proposed by the utility model;

[0024] Figure 5 A schematic diagram of the three-dimensional structure of a ducted fan proposed by the utility model from another perspective;

[0025] Figure 6 This is a schematic diagram of the partial cross-sectional structure of the fan blades and the fan shaft proposed by the utility model.

[0026] In the figure: 1. fan blade; 101. arc surface of blade tip; 102. air blowing slot; 103. air flow channel; 2. fan shaft; 3. annular duct; 4. driving member. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments.

[0028] Reference Figure 1-6 , a ducted fan, comprising:

[0029] The annular duct 3 is arranged in an annular shape;

[0030] A plurality of fan blades 1 are arranged inside the annular duct 3, and a blade tip arc surface 101 is arranged at the blade tip of the fan blade 1, and a blowing slot 102 is arranged on the side of the fan blade 1 close to the suction surface, so as to generate radial high-speed airflow, and the high-speed radial airflow will be close to the blade tip arc surface 101 and blow to the pressure surface of the fan blade 1 under the action of the 'Coanda' effect;

[0031] The fan shaft 2, the fan blade 1 is fixedly connected to the outer side of the fan shaft 2;

[0032] The driving member 4 is used for driving the fan shaft 2 to rotate. The driving member 4 is arranged at the rear side of the annular duct 3 .

[0033] In this embodiment, the ratio of the height of the blowing slot 102 to the diameter of the blade tip arc surface 101 is set between 0.01-0.05.

[0034] In this embodiment, an air flow channel 103 is provided inside the fan blade 1 , and the air flow channel 103 is communicated with the air blowing slot 102 .

[0035] In this embodiment, the number of the fan blades 1 is set to two or more.

[0036] In this embodiment, the interior of the fan shaft 2 is configured as a hollow structure, and a connecting hole communicating with the air flow channel 103 is opened on the outer side of the fan shaft 2 .

[0037] In this embodiment, the driving member 4 is configured as an engine, and a power output end of the engine is fixedly connected to one end of the fan shaft 2 .

[0038] In this embodiment, the fan blades 1 are arranged in an inclined shape, and a plurality of fan blades 1 are distributed in a ring-shaped manner at equal intervals on the outside of the fan shaft 2 .

[0039] Preferably, the blade top arc surface of the fan blade 1 is a semi-cylindrical surface, and its cross section is a semicircle or an ellipse.

[0040] In this embodiment, when in use, the fan shaft 2 is driven to rotate by the power of the engine, and the fan shaft 2 drives the fan blades 1 to rotate to generate wind. At the same time, a high-pressure airflow is introduced to the fan shaft 2 and the fan blades 1 through the compressor of the aircraft turbine engine or the electric air pump, and the high-pressure airflow is blown out from the blowing slit 102 through the air flow channel 103 inside the fan blade 1. At this time, the high-speed airflow blown out from the blowing slit 102 is along the tangent direction of the blade tip arc surface 101, and close to the arc surface, and blows toward the lower surface of the blade. At this time, the curved high-speed airflow produces an induced effect, driving the surrounding airflow to blow toward the pressure surface of the blade, increasing the circulation along the airflow direction. The airflow direction is opposite to the leakage flow direction of the blade tip gap, which can weaken the leakage flow, thereby reducing the pressure loss between the pressure surface and the suction surface due to airflow separation, thereby increasing the thrust.

[0041] The above is a detailed introduction to a ducted fan provided by the utility model. This article uses specific embodiments to explain the principle and implementation method of the utility model. The description of the above embodiments is only used to help understand the method and core idea of ​​the utility model. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the utility model, the utility model can also be improved and modified, and these improvements and modifications also fall within the scope of protection of the claims of the utility model.

Claims

1. A ducted fan, characterized in that: include: The annular duct (3) is arranged in an annular shape; A plurality of fan blades (1) are arranged inside the annular duct (3), the blade tips of the fan blades (1) are provided with blade tip arc surfaces (101), and a blowing slit (102) is provided on a side of the fan blades (1) close to the suction surface; A fan shaft (2), wherein the fan blades (1) are fixedly connected to the outer side of the fan shaft (2); A driving member (4) is used for driving the fan shaft (2) to rotate, and the driving member (4) is arranged on the rear side of the annular duct (3).

2. A ducted fan according to claim 1, characterized in that: The ratio of the height of the air blowing slot (102) to the diameter of the blade tip arc surface (101) is set between 0.01 and 0.

05.

3. A ducted fan according to claim 1, characterized in that: An air flow channel (103) is provided inside the fan blade (1), and the air flow channel (103) is connected to the air blowing slot (102).

4. A ducted fan according to claim 1, characterized in that: The number of the fan blades (1) is set to two or more.

5. A ducted fan according to claim 3, characterized in that: The interior of the fan shaft (2) is arranged as a hollow structure, and the outer side of the fan shaft (2) is provided with a connecting hole which is connected to the air flow channel (103).

6. A ducted fan according to claim 1, characterized in that: The driving member (4) is configured as an engine, and a power output end of the engine is fixedly connected to one end of the fan shaft (2).

7. The ducted fan according to claim 1, characterized in that: The fan blades (1) are arranged in an inclined shape, and a plurality of fan blades (1) are distributed in an annular shape at equal intervals on the outside of the fan shaft (2).

8. The ducted fan according to claim 1, characterized in that: The blade top arc surface of the fan blade (1) is a semi-cylindrical surface, and its cross section is a semi-circle or an ellipse.

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