Flow control device and method for improving propulsion efficiency of ducted fan

Abstract

The invention provides a flow control device and method for improving the propulsion efficiency of a ducted fan. The flow control device comprises a duct and a duct propeller device. The annular duct is arranged on the periphery of the duct propeller device; the duct comprises an air blowing flow channel, an air blowing port, an air suction port, an air suction flow channel and an air source device; the air blowing opening is formed in the position, close to the front edge of the duct airfoil profile, of the inner surface of the duct, namely the upper surface of the duct airfoil profile; the air suction port is formed in the position, away from the front edge of the duct airfoil profile, of the upper surface of the duct airfoil profile of the duct; according to the invention, collaborative jet active flow control is introduced to the ducted fan, so that the overall propulsion efficiency of the ducted fan is greatly improved, meanwhile, the wind resistance characteristic of the ducted fan is improved, and the controllability of the ducted fan is enhanced.

Description

Technical Field

[0001] The present invention belongs to the technical field of active flow control, and in particular relates to a flow control device and method for improving the propulsion efficiency of a ducted fan. Background Art

[0002] As a highly efficient propulsion device, ducted fans are widely used in helicopter tail rotors, airships, vertical take-off and landing vehicles, hovercraft and other vehicles. Compared with traditional propellers, ducted fans have the advantages of high propulsion efficiency, good safety and small size. As the research on ducted fan design methods gradually deepens, how to more effectively improve its aerodynamic propulsion efficiency is the focus and difficulty of current research. Summary of the invention

[0003] In view of the defects in the prior art, the present invention provides a flow control device and method for improving the propulsion efficiency of a ducted fan, which can effectively solve the above problems.

[0004] The technical solution adopted by the present invention is as follows:

[0005] The present invention provides a flow control device for improving the propulsion efficiency of a ducted fan, comprising a duct (100) and a ducted propeller device (200);

[0006] The duct (100) is provided in an annular shape on the periphery of the ducted propeller device (200); the duct (100) comprises a blowing flow channel (101), a blowing port (102), an air intake port (103), an air intake flow channel (104) and an air source device (105); the blowing port (102) is arranged on the inner surface of the duct (100), i.e., the upper surface of the duct airfoil, and close to the leading edge of the duct airfoil; the air intake port (103) is arranged on the upper surface of the duct airfoil of the duct (100) and away from the leading edge of the duct airfoil; Arranged inside the duct (100) are the blowing flow channel (101) connected to the blowing port (102), the suction flow channel (104) connected to the suction port (103), and the air source device (105) located between the blowing flow channel (101) and the suction flow channel (104); driven by the air source device (105), the air inhaled from the suction port (103) flows through the suction flow channel (104) and the blowing flow channel (101), and then is blown out from the blowing port (102), thereby forming an air flow cycle.

[0007] Preferably, the blowing flow rate of the blowing port (102) is equal to the suction flow rate of the suction port (103), thereby realizing a zero-mass jet and performing active flow control on the external flow field.

[0008] Preferably, the blowing port (102) is arranged on the upper surface of the ducted airfoil at a position 0.05c to 0.08c from the leading edge of the ducted airfoil, the blowing port (102) has a width of 0.003c to 0.008c, and the angle between the center line of the blowing port (102), i.e. the jet direction, and the chord line of the ducted airfoil is 30° to 40°;

[0009] The air intake (103) is arranged on the upper surface of the ducted airfoil at a position 0.7c to 0.9c from the leading edge of the ducted airfoil, the width of the air intake (103) is 0.008c to 0.012c, and the angle between the center line of the air intake (103), i.e., the air intake direction, and the chord line of the ducted airfoil is 15° to 30°; wherein c is the chord line of the ducted airfoil.

[0010] Preferably, the blowing ports (102) are arranged continuously or discretely on the inner surface of the duct (100), and correspondingly, the suction ports (103) are arranged continuously or discretely on the inner surface of the duct (100);

[0011] Wherein: continuous arrangement means: the inner surface of the duct (100) is provided with the blowing port (102) and the suction port (103) in a continuous 360° circular shape;

[0012] Discrete arrangement means that: the inner surface of the duct (100) is provided with a plurality of blowing ports (102) and a plurality of suction ports (103) at intervals along a circle; at the same time, when the blowing ports (102) and the suction ports (103) are discretely arranged, each blowing port (102) forms a group of blowing and suction units with a corresponding one of the suction ports (103) through an independent air flow channel and an independent air source device (105); by independently controlling the blowing and suction volume of each group of the blowing and suction units, an asymmetric thrust is generated, and then a pitch moment and a yaw moment are generated, so that the duct fan is vector-controlled.

[0013] Preferably, the ducted propeller device (200) comprises a ducted fan engine nacelle (201) and a ducted fan blade (202);

[0014] A plurality of ducted fan blades (202) are arranged in a circular divergent manner on the periphery of the ducted fan engine nacelle (201), and the ducted fan engine nacelle (201) drives each of the ducted fan blades (202) to rotate; and an annular duct (100) is arranged on the periphery of each of the ducted fan blades (202).

[0015] The present invention also provides an active flow control method of a flow control device for improving the propulsion efficiency of a ducted fan, comprising the following steps:

[0016] Simultaneously starting the air source device (105) of the duct (100) and the ducted fan engine nacelle (201) of the ducted propeller device (200);

[0017] For the ducted propeller device (200), the ducted fan engine nacelle (201) drives the ducted fan blades (202) to rotate, thereby generating aerodynamic propulsion force;

[0018] For the duct (100), an airflow is ejected from the blowing port (102), flows through the upper surface of the duct airfoil, and then sucked in from the suction port (103). Under the action of the air source device (105), an airflow is ejected again from the blowing port (102), thereby forming a CFJ jet cycle, and the blowing flow rate of the blowing port (102) and the suction flow rate of the suction port (103) are equal;

[0019] During the CFJ jet circulation process, since the blowing port (102) is arranged at the lip position of the leading edge of the ducted airfoil, the lip position becomes an airflow acceleration region due to the suction effect; since the suction port (103) is arranged at the rear side of the ducted fan blade (202), the suction port (103) is also located in the airflow acceleration region under the work action of the ducted fan blade (202);

[0020] Therefore, the air blowing port (102) and the air suction port (103) are both arranged in the high kinetic energy area of ​​the airflow, driving the CFJ jet to circulate efficiently, and cooperating with the ducted propeller device (200) to improve the overall propulsion efficiency of the ducted fan.

[0021] The flow control device and method for improving the propulsion efficiency of a ducted fan provided by the present invention have the following advantages:

[0022] The present invention significantly improves the overall propulsion efficiency of the ducted fan by introducing cooperative jet active flow control on the ducted fan, while also improving the wind resistance of the ducted fan and enhancing the controllability of the ducted fan. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A cross-sectional view of a flow control device for improving the propulsion efficiency of a ducted fan provided by the present invention;

[0024] Figure 2 A partial enlarged schematic diagram of the air outlet provided by the present invention;

[0025] Figure 3 A partial enlarged schematic diagram of the air inlet provided by the present invention;

[0026] Figure 4 A numerical simulation result diagram of a ducted fan equipped with a CFJ provided by the present invention;

[0027] Figure 5A schematic diagram of the present invention for performing vector control on a ducted fan using a discrete CFJ;

[0028] Figure 6 A three-dimensional diagram of a specific structure of a flow control device for improving the propulsion efficiency of a ducted fan provided by the present invention;

[0029] Figure 7 An internal diagram of a specific structure of a flow control device for improving the propulsion efficiency of a ducted fan provided by the present invention;

[0030] Figure 8 A cross-sectional view of a specific structure of a flow control device for improving the propulsion efficiency of a ducted fan provided by the present invention;

[0031] Fig. 9 A three-dimensional diagram of a hidden duct housing of a specific structure of a flow control device for improving the propulsion efficiency of a ducted fan provided by the present invention;

[0032] Fig.10 A partial diagram of a specific structure of a flow control device for improving the propulsion efficiency of a ducted fan provided by the present invention;

[0033] Fig.11 A cross-sectional view of an I-beam ring-rib in a specific structure of a flow control device for improving the propulsion efficiency of a ducted fan provided by the present invention;

[0034] Fig.12 A cross-sectional view of an I-beam ring-micro fan in a specific structure of a flow control device for improving the propulsion efficiency of a ducted fan provided by the present invention;

[0035] in:

[0036] 100- duct; 200- duct propeller device; 300- duct support base;

[0037] 101-blowing air duct; 102-blowing air port; 103-intake air port; 104-intake air duct; 105-air source device; 106-duct outer shell; 107-duct inner shell; 108-I-beam ring: 109-front rib; 110-rear rib; 111-micro fan; 112-rib fixing screw; 113-duct outer shell fixing countersunk screw; 114-duct inner shell fixing countersunk screw; 201-ducted fan engine nacelle; 202-ducted fan blade;

[0038] 1061-front section of duct casing; 1062-rear section of duct casing; 1081-web plate of I-beam; 1082-outer circular ring of I-beam; 1083-inner circular ring of I-beam; 1111-wiring hole of fan; 1112-installation hole of fan. DETAILED DESCRIPTION

[0039] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0040] In order to further improve the overall propulsion efficiency of the ducted fan, the present invention introduces cooperative jet active flow control on the ducted fan, which greatly improves the overall propulsion efficiency of the ducted fan, while improving the wind resistance of the ducted fan and enhancing the controllability of the ducted fan.

[0041] Specifically, the present invention controls the flow on the upper surface of the ducted airfoil by blowing air near the low-pressure area at the leading edge and sucking air near the high-pressure area at the trailing edge, namely, cooperative jet active flow control (Co-flow Jet, abbreviated as CFJ). In addition, the mass flow rates of blowing and sucking are equal, and it has the characteristics of low energy consumption and zero mass jet, and the total energy consumption is much lower than other active flow control methods.

[0042] See also Figures 1 to 12 The present invention provides a flow control device for improving the propulsion efficiency of a ducted fan, which is an efficiency-enhancing method of applying active flow control technology to a ducted fan, comprising a duct 100 and a ducted propeller device 200;

[0043] An annular duct 100 is arranged on the periphery of the ducted propeller device 200; the duct 100 includes a blowing flow channel 101, a blowing port 102, an air intake port 103, an air intake flow channel 104 and an air source device 105; the blowing port 102 is arranged on the inner surface of the duct 100, that is, the upper surface of the duct airfoil, and close to the leading edge of the duct airfoil; the air intake port 103 is arranged on the upper surface of the duct airfoil of the duct 100 and away from the leading edge of the duct airfoil; the blowing flow channel 101 connected with the blowing port 102, the air intake flow channel 104 connected with the air intake port 103, and the air source device 105 located between the blowing flow channel 101 and the air intake flow channel 104 are arranged inside the duct 100; driven by the air source device 105, the air inhaled from the air intake port 103 flows through the air intake flow channel 104 and the blowing flow channel 101, and is blown out from the blowing port 102 to form an air flow circulation.

[0044] In the present invention, when the ducted fan integrated with CFJ is in operation, the air source device 105 is started based on the rotation of the blades of the ducted propeller device 200. The air source device 105 consumes energy to drive the air in the internal flow channel to flow forward. The air flows out from the blowing port 102 and flows in from the suction port 103 to form a cycle. The blown airflow has a control effect on the external flow.

[0045] As a specific embodiment, the blowing flow rate of the blowing port 102 is equal to the suction flow rate of the suction port 103, so as to realize zero-mass jet and perform active flow control on the external flow field.

[0046] As a specific example, Figure 2 As shown, the blowing port 102 is arranged on the upper surface of the ducted airfoil at a position 0.05c to 0.08c from the leading edge of the ducted airfoil, the width of the blowing port 102 is 0.003c to 0.008c, and the angle between the center line of the blowing port 102, i.e. the jet direction and the chord line of the ducted airfoil is 30° to 40°;

[0047] like Figure 3 As shown, the air intake 103 is arranged on the upper surface of the ducted airfoil at a distance of 0.7c to 0.9c from the leading edge of the ducted airfoil. The width of the air intake 103 is 0.008c to 0.012c. The center line of the air intake 103, i.e., the air inlet direction, and the angle between the chord line of the ducted airfoil are 15° to 30°; wherein c is the chord line of the ducted airfoil. Figure 2 and Figure 3 In the figure, the airflow direction is from left to right, the left side is the leading edge of the ducted airfoil, and the right side is the trailing edge of the ducted airfoil.

[0048] In the present invention, the air source device 105 arranged in the duct 100 consumes energy to drive the airflow forward, and the air source device 105 can be a micro fan, an air pump, etc. The blowing port 102 and the suction port 103 are connected by the blowing air channel 101 and the suction air channel 104 buried in the duct 100; the flow channel shapes of the blowing air channel 101 and the suction air channel 104 are mainly determined by the duct shape and internal structure, and it is sufficient to ensure smooth airflow.

[0049] In the present invention, the blowing ports 102 are arranged continuously or discretely on the inner surface of the duct 100, and correspondingly, the suction ports 103 are arranged continuously or discretely on the inner surface of the duct 100;

[0050] Wherein: continuous arrangement means: the inner surface of the duct 100 is provided with the blowing port 102 and the suction port 103 in a continuous 360° circular shape;

[0051] Discrete arrangement means that: the inner surface of the duct 100 is provided with a plurality of blowing ports 102 and a plurality of suction ports 103 at intervals along a circle; at the same time, when the blowing ports 102 and the suction ports 103 are discretely arranged, each blowing port 102 forms a group of blowing and suction units with a corresponding suction port 103 through an independent air flow channel and an independent air source device 105; by independently controlling the blowing and suction volume of each group of blowing and suction units, asymmetric thrust is generated, and then pitch moment and yaw moment are generated, so that the duct fan is vector-controlled.

[0052] As a specific structure, the bottom of the duct 100 is supported by a duct support base 300 .

[0053] As a specific structure, the ducted propeller device 200 includes a ducted fan engine nacelle 201 and a ducted fan blade 202;

[0054] A plurality of ducted fan blades 202 are arranged in a circular divergent manner on the periphery of the ducted fan engine nacelle 201 , and the ducted fan engine nacelle 201 drives each ducted fan blade 202 to rotate; an annular duct 100 is arranged on the periphery of each ducted fan blade 202 .

[0055] The present invention provides a flow control device for improving the propulsion efficiency of a ducted fan, which has the following characteristics and advantages:

[0056] 1. Ducted thrust is effectively improved:

[0057] The numerical simulation of the ducted fan equipped with the CFJ of the present invention is carried out, and the numerical simulation results are as follows: Figure 4 As shown. Figure 4 In the figure: S1 represents the pressure cloud diagram of the symmetrical surface of the ducted fan with CFJ installed; S2 is the pressure cloud diagram of the symmetrical surface of the ducted fan without CFJ installed; S3 is the pressure distribution curve of the ducted airfoil section of the ducted fan with CFJ installed according to the present invention; S4 is the pressure distribution curve of the ducted airfoil section of the ducted fan without CFJ installed; S5 is the negative pressure increment on the inner surface of the duct after the CFJ of the present invention is installed, which is the source of the ducted thrust increment; wherein, when drawing the pressure distribution curve, the negative direction of the Y axis is upward.

[0058] from Figure 4 It can be seen that after the CFJ is added to the present invention, the CFJ jet significantly increases the negative pressure peak at the leading edge lip of the ducted airfoil, increases the area of ​​the negative pressure region, and thus increases the ducted thrust. At the same time, the CFJ jet itself generates considerable thrust. The overall propulsion efficiency of the CFJ ducted fan of the present invention can be increased by about 15% at most compared to the original ducted fan. If the jet intensity is increased, the overall propulsion efficiency of the ducted fan can be further improved.

[0059] 2. Low energy consumption:

[0060] Since the blowing port of the present invention is arranged at the leading edge lip of the ducted airfoil, the leading edge lip of the ducted fan is an airflow acceleration area due to the suction effect, and the suction port is arranged behind the blades, which is also an airflow acceleration area due to the work done by the blades. The blowing and suction ports are arranged in the high kinetic energy area of ​​the airflow, and the energy required to drive the CFJ airflow cycle is relatively low. According to the CFD numerical simulation results, when the overall propulsion efficiency of the CFJ ducted fan is improved by 15%, the total energy consumption of the blades and the air source device only increases by 5%.

[0061] 3. Ducted fan's ability to resist crosswind:

[0062] The CFJ jet of the present invention can effectively suppress the separation of the leading edge of the ducted airfoil, improve the crosswind resistance of the ducted fan, and broaden the operating range of the ducted fan.

[0063] 4. Ducted fan vector control can be achieved:

[0064] In the present invention, the air inlet and outlet can be arranged in a continuous 360° ring or in a discrete form; when a plurality of air inlet and outlet are arranged discretely, and each is equipped with an independent flow channel and air source device, the air source device can be controlled by the switch part to realize asymmetric air inlet and outlet, generate asymmetric force, and then realize vector control of the ducted fan, so that the CFJ ducted fan has the potential of vector control. Figure 7 As shown, it is a schematic diagram of vector control of the ducted fan using discrete CFJ, where F is the pitch moment and yaw moment generated by non-uniform thrust.

[0065] The present invention also provides an active flow control method of a flow control device for improving the propulsion efficiency of a ducted fan, comprising the following steps:

[0066] Simultaneously start the air source device 105 of the duct 100 and the ducted fan engine nacelle 201 of the ducted propeller device 200;

[0067] For the ducted propeller device 200, its ducted fan engine nacelle 201 drives the ducted fan blades 202 to rotate, generating aerodynamic propulsion force;

[0068] For the duct 100, the airflow is ejected from the blowing port 102, flows through the upper surface of the duct airfoil, and is sucked in from the suction port 103. Under the action of the air source device 105, the airflow is ejected again from the blowing port 102, thereby forming a CFJ jet cycle, and the blowing flow rate of the blowing port 102 is equal to the suction flow rate of the suction port 103.

[0069] In the CFJ jet cycle, since the blowing port 102 is arranged at the lip position of the leading edge of the ducted airfoil, the lip position is an airflow acceleration area due to the suction effect; since the suction port 103 is arranged at the rear side of the ducted fan blade 202, the suction port 103 is also located in the airflow acceleration area under the work action of the ducted fan blade 202;

[0070] Therefore, the air outlet 102 and the air intake 103 are both arranged in the high kinetic energy area of ​​the airflow, driving the CFJ jet to circulate efficiently, and cooperating with the ducted propeller device 200 to improve the overall propulsion efficiency of the ducted fan.

[0071] Combination Figure 6 to Figure 12 , a specific embodiment is described below:

[0072] like Figure 6 to Figure 12, which is a structural diagram of a specific flow control device for improving the propulsion efficiency of a ducted fan provided by the present invention.

[0073] In this embodiment, the bottom of the duct 100 is supported by a duct support base 300. A duct propeller device 200 is coaxially mounted inside the duct 100; wherein the duct propeller device 200 includes a ducted fan engine nacelle 201 and a ducted fan blade 202.

[0074] The duct 100 includes a duct outer shell 106, a duct inner shell 107, an I-beam ring 108, a front rib 109, a rear rib 110 and a micro fan 111;

[0075] The I-beam ring 108 includes an I-beam web 1081, an I-beam outer ring 1082 and an I-beam inner ring 1083; wherein the I-beam web 1081 is vertically arranged, and the outer end and the inner end of the I-beam web 1081 are respectively fixedly arranged with the I-beam outer ring 1082 and the I-beam inner ring 1083;

[0076] A plurality of ribs are installed on the I-beam web 1081 at intervals along the circumference; each rib includes a front rib 109 and a rear rib 110 arranged in pairs; the front rib 109 and the rear rib 110 are arranged in a straight line on the front and rear sides of the I-beam web 1081, and are assembled and fixed to the I-beam web 1081 by rib fixing screws 112; specifically, the rib fixing screws 112 can pass through the ears on both sides of the I-beam web 1081 to achieve the connection and fixation of the front rib 109, the rear rib 110 and the I-beam web 1081.

[0077] In the section of the I-beam web 1081 between every two ribs, a plurality of fan mounting holes 1112 and fan wiring holes 1111 are provided; each fan mounting hole 1112 is used to assemble and install a micro fan 111; the fan wiring holes 1111 are used for routing the cables of the micro fan 111; the fan mounting holes 1112 and the fan wiring holes 1111 are blocked with foam blocks when not in use.

[0078] The duct shell 106 is assembled and installed on the outer surface of the I-beam outer ring 1082 by means of countersunk screws 113 fixing the duct shell body; and the duct shell 106 is divided into two sections, namely, a duct shell front section 1061 and a duct shell rear section 1062 located on both sides of the I-beam web 1081;

[0079] The duct inner shell 107 is assembled and installed on the lower surface of the inner ring 1083 of the I-beam by fixing the countersunk screws 114 on the duct inner shell.

[0080] The structure of the above duct 100 is adopted, and the main load-bearing structure of the model is an I-beam ring 108, a front rib 109, a rear rib 110 and a duct support base 300. The I-beam ring 108, the front rib 109, and the rear rib 110 are all made of aluminum alloy and are formed by CNC processing; the duct support base 300 is made of 45# steel and is formed by welding.

[0081] The duct outer shell 106 and the duct inner shell 107 are formed by 3D printing. The duct outer shell 106 and the duct inner shell 107 are combined to form an airfoil, and the internal cavity is a CFJ internal flow channel. The duct outer shell front section 1061 and the duct inner shell 107 are combined to form the blowing port 102, and the duct outer shell rear section 1062 and the duct inner shell 107 are combined to form the suction port 103. The duct outer shell 106 and the duct inner shell 107 are connected and fixed with the I-beam ring 108 by countersunk screws, and the ribs are in contact with the duct outer shell 106 and the duct inner shell 107 to play a supporting role.

[0082] When used as a ducted fan wind tunnel test model, the duct 100 is connected to an external stand via a duct support base 300 .

[0083] In this embodiment, a micro fan 111 is used as the air source device 105. The diameter of the micro fan 111 is 50 mm, the rated power is 0.66 kW, and 24 fan mounting holes 1112 and 24 fan wiring holes 1111 are opened on the web 1081 of the I-beam. The micro fan 111 is fixed through the fan mounting holes 1112. In actual testing, only part of the micro fans 111 can be installed for testing. For example, 12 micro fans 111 are installed for testing. This device can install up to 24 micro fans 111. The vacant fan mounting holes 1112 and fan wiring holes 1111 are blocked with foam boards. The speed control of the micro fan 111 is controlled by PWM signal open-loop control, and the control system is realized by computer input.

[0084] The ducted fan blades 202 are made of aluminum alloy and are formed by CNC integral processing. They can realize variable pitch operation in conjunction with the hub. The rotation of the ducted fan blades 202 is driven by another motor with a maximum power of 100kW.

[0085] The above duct 100 structure has the following advantages:

[0086] The I-beam ring 108 facilitates installation of multiple micro fans 111, and facilitates installation of the duct outer shell 106 and the duct inner shell 107, which has the advantage of easy assembly; by arranging ribs at intervals along the circumference, the supporting effect on the duct outer shell 106 and the duct inner shell 107 is enhanced, thereby ensuring the structural strength of the entire duct 100.

[0087] The I-beam ring 108 and the ribs are load-bearing structures. The micro fan 111 is installed on the I-beam web 1081 of the I-beam ring 108 of the duct, which is easy to install and can ensure structural strength.

[0088] A single chip microcomputer can control a plurality of micro fans 111 at the same time, realize computer command input, and control the behaviors of all micro fans 111 in real time.

[0089] The duct 100 involved in the present invention may be a duct model used in a wind tunnel test, or may be a duct device assembled and used in an actual aircraft, but the present invention is not limited thereto.

[0090] The present invention significantly improves the overall propulsion efficiency of the ducted fan by introducing cooperative jet active flow control on the ducted fan, while also improving the wind resistance of the ducted fan and enhancing the controllability of the ducted fan.

[0091] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be considered as the scope of protection of the present invention.

Claims

1. A flow control device for improving the propulsion efficiency of a ducted fan, characterized in that: It comprises a duct (100) and a ducted propeller device (200); The duct (100) is provided in an annular shape on the periphery of the ducted propeller device (200); the duct (100) comprises a blowing flow channel (101), a blowing port (102), an air intake port (103), an air intake flow channel (104) and an air source device (105); the blowing port (102) is arranged on the inner surface of the duct (100), i.e., the upper surface of the duct airfoil, and close to the leading edge of the duct airfoil; the air intake port (103) is arranged on the upper surface of the duct airfoil of the duct (100) and away from the leading edge of the duct airfoil; Arranged inside the duct (100) are the blowing flow channel (101) connected to the blowing port (102), the suction flow channel (104) connected to the suction port (103), and the air source device (105) located between the blowing flow channel (101) and the suction flow channel (104); driven by the air source device (105), the air inhaled from the suction port (103) flows through the suction flow channel (104) and the blowing flow channel (101), and then is blown out from the blowing port (102), thereby forming an air flow cycle.

2. A flow control device for improving propulsion efficiency of a ducted fan according to claim 1, characterized in that: The blowing flow rate of the blowing port (102) is equal to the suction flow rate of the suction port (103), thereby realizing a zero-mass jet and performing active flow control on the external flow field.

3. A flow control device for improving propulsion efficiency of a ducted fan according to claim 1, characterized in that: The blowing port (102) is arranged on the upper surface of the ducted airfoil at a position 0.05c to 0.08c from the leading edge of the ducted airfoil, the blowing port (102) has a width of 0.003c to 0.008c, and the included angle between the center line of the blowing port (102), i.e. the jet direction, and the chord line of the ducted airfoil is 30° to 40°; The air intake (103) is arranged on the upper surface of the ducted airfoil at a position 0.7c to 0.9c from the leading edge of the ducted airfoil, the width of the air intake (103) is 0.008c to 0.012c, and the angle between the center line of the air intake (103), i.e., the air intake direction, and the chord line of the ducted airfoil is 15° to 30°; wherein c is the chord line of the ducted airfoil.

4. A flow control device for improving propulsion efficiency of a ducted fan according to claim 1, characterized in that: The air blowing ports (102) are arranged continuously or discretely on the inner surface of the duct (100), and correspondingly, the air suction ports (103) are arranged continuously or discretely on the inner surface of the duct (100); Wherein: continuous arrangement means: the inner surface of the duct (100) is provided with the blowing port (102) and the suction port (103) in a continuous 360° circular shape; Discrete arrangement means that: the inner surface of the duct (100) is provided with a plurality of blowing ports (102) and a plurality of suction ports (103) at intervals along a circle; at the same time, when the blowing ports (102) and the suction ports (103) are discretely arranged, each blowing port (102) forms a group of blowing and suction units with a corresponding one of the suction ports (103) through an independent air flow channel and an independent air source device (105); by independently controlling the blowing and suction volume of each group of the blowing and suction units, an asymmetric thrust is generated, and then a pitch moment and a yaw moment are generated, so that the duct fan is vector-controlled.

5. A flow control device for improving propulsion efficiency of a ducted fan according to claim 1, characterized in that: The ducted propeller device (200) comprises a ducted fan engine nacelle (201) and a ducted fan blade (202); A plurality of ducted fan blades (202) are arranged in a circular divergent manner on the periphery of the ducted fan engine nacelle (201), and the ducted fan engine nacelle (201) drives each of the ducted fan blades (202) to rotate; and an annular duct (100) is arranged on the periphery of each of the ducted fan blades (202).

6. An active flow control method of a flow control device for improving propulsion efficiency of a ducted fan according to any one of claims 1 to 5, characterized in that: The following steps are involved: Simultaneously starting the air source device (105) of the duct (100) and the ducted fan engine nacelle (201) of the ducted propeller device (200); For the ducted propeller device (200), the ducted fan engine nacelle (201) drives the ducted fan blades (202) to rotate, thereby generating aerodynamic propulsion force; For the duct (100), an airflow is ejected from the blowing port (102), flows through the upper surface of the duct airfoil, and then sucked in from the suction port (103). Under the action of the air source device (105), an airflow is ejected again from the blowing port (102), thereby forming a CFJ jet cycle, and the blowing flow rate of the blowing port (102) and the suction flow rate of the suction port (103) are equal; During the CFJ jet circulation process, since the blowing port (102) is arranged at the lip position of the leading edge of the ducted airfoil, the lip position becomes an airflow acceleration region due to the suction effect; since the suction port (103) is arranged at the rear side of the ducted fan blade (202), the suction port (103) is also located in the airflow acceleration region under the work action of the ducted fan blade (202); Therefore, the air blowing port (102) and the air suction port (103) are both arranged in the high kinetic energy area of ​​the airflow, driving the CFJ jet to circulate efficiently, and cooperating with the ducted propeller device (200) to improve the overall propulsion efficiency of the ducted fan.

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