Double-rotor direct-driven coaxial reverse-propeller electric ducted fan

Abstract

The invention provides a double-rotor direct-drive coaxial reverse-propeller electric ducted fan, which is characterized in that a single motor with an inner rotor and an outer rotor directly drives two pairs of blades, an intermediate transmission device and an inner rotor excitation group to generate a rotating magnetic field, and a first-stage propulsion component and a second-stage propulsion component with the same rotational inertia are driven under the action of electromagnetic torque with the same acting force and counter-acting force; one-way rotation deflection torque is balanced, and coaxial reverse propeller movement is achieved; the rectification duct reduces the induced resistance of the blades and improves the propulsive efficiency, the convergence and expansion guide sleeve and the motor frame body dissipate heat to form circulating heat dissipation of the Brayton heat engine, meanwhile, air is heated, expanded and ejected out to generate thrust, the efficiency is high, and the thrust is large. The dual-rotor motor direct-driven coaxial reverse propeller ducted fan propulsion unit is simple in mechanism, light in structure, large in power-to-weight ratio, high in reliability, beneficial to use in a narrow space and vertical take-off and landing, especially suitable for an EVTOL (electric vertical take-off and landing aircraft), and capable of promoting popularization of small aircrafts and vertical take-off and landing urban transportation carriers.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of aviation power technology, and particularly relates to a double-rotor direct-drive coaxial counter-rotating ducted fan. BACKGROUND

[0002] The coaxial counter-rotating ducted fan arranges two propellers in a back-to-back manner in a duct, and the two-stage propeller blades are coaxial but rotate in opposite directions, so that the balance eliminates the single-rotation deflection torque, the first-stage propeller disc provides the second-stage propeller disc with "pre-compression", the second-stage propeller disc has greater "air intake / discharge" and "air flow density", and the efficiency is obviously improved. The duct's surrounding and rectifying effects reduce the impact noise, stabilize the air flow field, and reduce the induced resistance, which can further improve the efficiency and stability. Therefore, the coaxial counter-rotating ducted fan has obvious advantages: high efficiency, reduced propeller size to reduce power input, and improved system efficiency; large air flow, higher air flow density of the second-stage propeller disc under the pre-compression of the first-stage propeller disc, and high efficiency; small space, compact structure, low aerodynamic noise, and good safety in use, which is very suitable for use in urban narrow space, vertical take-off and landing, or short take-off and landing.

[0003] But the disadvantages of the coaxial contra-rotating ducted fan are also obvious, mainly in the mechanism of the coaxial and reverse of the upper and lower blades, which is complex, heavy, and deteriorates the reliability of the mechanism; the close distance between the two groups of blade groups easily causes excitation interference, reduces the propulsion efficiency, etc. For example, CN 110925364 A discloses a planetary reducer for a coaxial contra-rotating helicopter, CN 108791859 A a rotor unmanned aerial vehicle for quick approach, CN 110127043 A a new energy coaxial contra-rotating aircraft, and CN 111392049 A a coaxial contra-rotating helicopter transmission system, which adopts a two-layer two-set planetary reduction structure or differential mechanism to realize coaxial contra-rotation, with many parts, long transmission chain, heavy weight, and poor reliability; CN 2021110029228.3 a ducted fan, CN 103552686 A a combined ducted air reconnaissance robot, CN 108458892 A a rotor type Mars unmanned aerial vehicle with rock sample collection and transportation function, CN 211196609 U a tandem double-motor coaxial contra-rotating aerial electric propulsion unit, and CN 117284522 A a coaxial contra-rotating unmanned aerial vehicle structure for launching, which uses double motors to simplify the structure for realizing contra-rotating motion, but the two-stage blade disc rotation speed is not coordinated, the system reliability is poor, and the double motors are heavy; CN 2022115587786.X high thrust-to-weight ratio ducted fan, CN 2021110408978.1 a multi-stage tandem type rim-driven ducted propeller for aviation, CN 202080058186.X ducted fan, and CN 201811345417.6 dual-rotor ducted system, the ducts are generally wide and have large windward surface, large resistance, and large weight. This problem causes the coaxial contra-rotating ducted fan to have complex mechanism, heavy structure, poor reliability, large resistance, high cost, etc. For large helicopters, it is difficult to manufacture, and for small helicopters, the structure is heavy. As for military helicopters, the reliability limits their use. SUMMARY

[0004] The purpose of the present application is to provide a double-rotor direct-drive coaxial contra-rotating ducted fan to reduce the disadvantages of complex mechanism, heavy weight, and low efficiency of the coaxial contra-rotating duct, ensure high reliability and high safety of the ducted fan, facilitate use in narrow spaces and vertical take-off and landing, and be particularly suitable for EVTOL (electric vertical take-off and landing aircraft).

[0005] To achieve the above object, the application provides the following technical scheme: a double-rotor direct-drive coaxial counter-propeller ducted fan, comprising two-stage blade groups, a double-rotor motor and a rectifier duct, wherein the two-stage blade groups comprise one-stage hub, blades, blade jointers, a flow guide cone and two-stage hub, blades and blade jointers; the double-rotor motor is a motor with two rotors, comprising an inner rotor, an outer rotor, a support group and an electrical interface, the outer rotor is coaxially sleeved with the inner rotor, there is no transmission device between the inner rotor and the outer rotor, the support group comprises support bearings, a motor frame body and a motor base, the inner rotor and the outer rotor are supported by the motor frame body and the motor base, the motor frame body is installed on the motor base, so that the inner rotor and the outer rotor can rotate independently, under the electromagnetic action, the inner rotor and the outer rotor rotate in the same axis and in the opposite direction, the motor frame body is provided with heat dissipation fins on the outside, the motor base is installed on the center frame of the rectifier duct; the inner rotor is directly connected with the one-stage blade group through the jointer to form a one-stage propulsion group element, no transmission mechanism is arranged between the inner rotor and the one-stage blade group, the inner rotor directly drives the one-stage blade group; the outer rotor is directly connected with the two-stage blade group through the jointer to form a two-stage propulsion group element, no transmission mechanism is arranged between the outer rotor and the two-stage blade group, the outer rotor directly drives the two-stage blade group; the inner rotor and the outer rotor are provided with reinforced belts outside the excitation group, which can resist the centrifugal force of high-speed rotation; no transmission mechanism is arranged between the one-stage propulsion group element and the two-stage propulsion group element, the blade configuration and the number of the one-stage propulsion group element are different from those of the two-stage propulsion group element, so as to reduce and avoid excitation and noise between the two-stage blades; the flow guide cone is arranged in front of the one-stage blade; the rectifier duct is internally installed with the one-stage and two-stage propulsion units, the rectifier duct comprises a lip, a duct body, a guide plate and a converging-diffusing guide sleeve, the lip is arc-shaped and adopts a drag reduction configuration to reduce the resistance; the gap between the duct body and the one-stage and two-stage blade disc surfaces is not greater than 1mm, which reduces the induced resistance and has smooth operation and efficiency; the converging-diffusing guide sleeve is internally provided with a center frame and a flow guide fin, has three sections of converging mouth part, diffusing middle section and contraction nozzle, the diffusing middle section surrounds the motor frame body, the center frame body is a hollow structure, the flow guide fin supports the center frame body, ensures the support strength of the center frame body and stabilizes the guided diffused air flow; the converging-diffusing guide sleeve and the heat dissipation fins of the motor frame body can heat the motor, at the same time, the converging section air intake is adiabatic compression, the diffusing section air deceleration passes through the heat dissipation fins to heat at constant pressure, the contraction section adiabatic expansion heats at constant pressure to do work to the outside, so that the air passing through the heat dissipation fins from the converging mouth part is fully heated and then sprayed from the contraction section, a Brayton cycle is formed, and the backward sprayed hot air generates thrust.

[0006] Further, the one-stage propulsion group element and the two-stage propulsion group element have the same rotational inertia.

[0007] Further, the inner rotor excitation group outside the inner rotor generates a rotating magnetic field, the inner rotor is provided with an inner rotor reinforcing belt to constrain the inner rotor excitation group against the centrifugal force of high-speed rotation; the excitation group inside the outer rotor generates a rotating magnetic field, the outer rotor is provided with an outer rotor reinforcing belt to constrain the outer rotor excitation group against the centrifugal force of high-speed rotation; the inner and outer rotor excitation groups generate a rotating magnetic field, under the action of electromagnetic torque equal to the action and reaction force, bidirectional drive a two-stage propulsion group element, balance the deflection torque of unidirectional rotation, realize coaxial counter-thrust movement of the first-stage propulsion group element and the second-stage propulsion group element; the number of the outer rotor excitation group is greater than the number of the inner rotor excitation group, the number of excitation groups is generally a multiple of 3, and the number difference between the inner and outer rotor excitation groups is 1, 2 or 3, to establish a reliable and stable rotating magnetic field.

[0008] Further, the inner rotor end is provided with a continuous input and output device, preferably, the continuous input and output device is an electrical slip ring.

[0009] Further, the two-stage blade group is not provided with a variable pitch device, the blade group is a rigid rotor, and the blade is not hinged to the hub, to simplify the structure.

[0010] Further, the rotation speed of the inner and outer rotors of the double-rotor motor is precisely adjusted at 15-110% of the rated speed, preferably, the speed adjustment accuracy is not greater than 1%, the rotation speed of the inner and outer rotors is changed, and the propulsion force of the propulsion unit is accurately controlled.

[0011] Further, the number, angle of attack and type of the first-stage blades and the second-stage blades are different, to reduce the excitation between the blades, preferably, the number of the first-stage blades is 6, the number of the second-stage blades is 5, the type of the first-stage blades is a low-pressure type, and the type of the second-stage blades is a high-pressure type.

[0012] Further, the guide vane of the duct is at an angle with the airflow ejected after being compressed by the second-stage blades, to guide the airflow out of the duct in parallel.

[0013] Further, the heat dissipation fins of the motor frame body are axial, guide the air passing through and fully exchange heat, and the guide fins further constrain the air passing through, so that the air flowing out is ejected in parallel from the contraction opening.

[0014] The application has the advantages that: the application adopts a single motor with double rotors to directly drive two pairs of blades, without transmission device in the middle, and the mechanism is simple and reliable; the electromagnetic torque principle that the action force and the reaction force of the rotating magnetic field generated by the inner and outer rotor excitation groups are equal is used to balance the reverse torque generated during unidirectional rotation, so that the inner and outer rotors can rotate reversely and the unidirectional rotation deflection torque is balanced, thereby realizing the coaxial counter-propeller motion of the first and second propulsion group elements, and the structure is light and the weight is light; the increase and decrease of the single motor rotating speed of the double rotors are used to realize the change of the propulsion force; the rectification duct is used to reduce the induced resistance of the blades and improve the propulsion efficiency, the converging-diverging guide sleeve and the motor frame body are used for heat dissipation to form a Brayton heat engine cycle to dissipate heat for the motor, and at the same time, the air is heated, expanded and sprayed to generate thrust, and the efficiency is high and the thrust is large. The double-rotor motor direct-drive coaxial counter-propeller duct fan propulsion unit has the advantages of simple mechanism, light structure, large power-to-weight ratio and high reliability, and is beneficial to the rapid promotion and popularization of the coaxial counter-propeller duct on the aircraft, and especially can promote the promotion of small aircraft and vertical take-off and landing urban transport vehicles. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 It is a structural schematic front view of the application.

[0016] Figure 2 It is a structural schematic top view of the application.

[0017] Figure 3 It is a structural schematic axonometric view of the application.

[0018] Figure 4 It is a structural schematic view of the first propulsion unit of the application.

[0019] Figure 5 It is a structural schematic view of the second propulsion unit of the application.

[0020] Figure 6 It is a schematic view of the flow of air in the duct of the application.

[0021] Figure 7 It is a schematic view of the relationship between the blade angle of attack and the airflow in the duct of the application.

[0022] Figure 8 It is a structural schematic front view of the fairing duct of the application.

[0023] Figure 9 It is a structural schematic top view of the fairing duct of the application.

[0024] In the figure: 100 is a first-stage blade group, 101 is a first-stage blade, 102 is a first-stage hub, 103 is a first-stage blade group adapter, 104 is a guide cone; 200 is a second-stage blade group, 201 is a second-stage blade, 202 is a second-stage hub, 203 is a second-stage blade group adapter; 300 is a double-rotor motor, 310 is an inner rotor, 311 is an upper shaft segment of the inner rotor, 312 is an inner rotor excitation group, 313 is a lower shaft neck of the inner rotor, 314 is an inner rotor reinforcing belt, 320 is an outer rotor, 321 is an upper shaft neck of the outer rotor, 322 is an outer rotor shell, 323 is an outer rotor excitation group, 324 is an outer rotor reinforcing belt, 325 is a lower shaft neck of the outer rotor, 330 is a support group, 331 is bearing I, 332 is bearing II, 333 is bearing II, 334 is bearing IV, 335 is bearing V, 336 is a motor frame body, 337 is a heat dissipation fin, 338 is a motor base; 340 is an electrical interface, 341 is a continuous input and output device; 342 is a cable group; 400 is a rectifying tunnel, 401 is a lip, 402 is a tunnel body, 403 is a guide plate, 410 is a converging and expanding guide sleeve, 411 is a center frame body, 412 is a guide fin, 413 is a converging mouth part, 414 is an expanding middle segment, 415 is a contraction nozzle; straight arrows are the movement direction of the first-stage blades, dotted arrows are the movement direction of the second-stage blades, dash-dot arrows are the schematic flow lines and directions of the airflow inside the converging and expanding guide sleeve, double dash-dot arrows are the schematic flow lines and directions of the airflow inside the rectifying tunnel. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present application will be apparently and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application. If the specific conditions are not indicated in the embodiments, the conventional conditions or the conditions suggested by the manufacturer are adopted. If the manufacturers of the reagents or instruments are not indicated, the conventional products that can be purchased in the market are adopted.

[0026] In the description of the present application, it should be noted that the orientations or positional relationships indicated by the terms “center”, “upper”, “lower”, “left”, “right”, “vertical”, “horizontal”, “inner”, “outer” and the like are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms “first”, “second”, “third” are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0027] In the description of the application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connecting" should be understood in a broad sense, for example, can be fixedly connected, can also be detachably connected, or integrally connected; can be mechanically connected, can also be electrically connected; can be directly connected, can also be indirectly connected through an intermediate medium, can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the application can be understood according to the specific circumstances.

[0028] Example one, as shown in the accompanying drawings Figures 1-9As shown, a double-rotor direct-drive coaxial counter-propeller electric ducted fan includes a first-stage blade group 100, a second-stage blade group 200, a double-rotor motor 300 and a rectification duct 400. The first-stage blade group 100 includes a first-stage blade 101, a first-stage blade hub 102, a first-stage blade joint 103 and a flow guide cone 104, the center of which is arranged at the front end of the first-stage blade group 100 and coincides with the rotation center of the blade. The second-stage blade group 200 includes a second-stage blade 201, a second-stage blade hub 202 and a second-stage blade joint 203. The double-rotor motor 300 includes an inner rotor 310, an outer rotor 320, a support group 330 and an electrical interface 340. The outer rotor 320 is coaxially sleeved with the inner rotor 310, and there is no transmission device between them. The support group 330 includes support bearings 331-335, a motor frame body 336 and a motor base 337. The support group 330 rotatably supports the inner rotor 310 and the outer rotor 320 on the motor frame body 336 and the motor base 337. The motor frame body 336 is fixed to the motor base 337, so that the inner rotor 310 and the outer rotor 320 can independently rotate. The inner rotor 310 is directly connected to the first-stage blade joint 103 of the first-stage blade group 100 through an upper shaft segment 311 of the inner rotor 310 to form a first-stage propulsion group element. There is no transmission mechanism between the upper shaft segment 311 of the inner rotor 310 and the first-stage blade group 100. The inner rotor 310 directly drives the first-stage blade group 100. The outer rotor 320 is directly connected to the second-stage blade joint 203 of the second-stage blade group 200 through an upper shaft neck 321 of the outer rotor 320 to form a second-stage propulsion group element. There is no transmission mechanism between the outer rotor 320 and the second-stage blade group 200. The outer rotor 320 directly drives the second-stage blade group 200. The inner rotor 310 is provided with an inner rotor reinforcing belt 314 outside an inner rotor excitation group 312 to balance the centrifugal force of high-speed rotation. The outer rotor 320 is provided with an outer rotor reinforcing belt 324 outside an outer rotor excitation group 323 to balance the centrifugal force of high-speed rotation. The electrical interface 340 includes a continuous input and output device 341 and a cable group 342 to provide electrical support for the propulsion unit. The rectification duct 400 is internally installed with the first-stage and second-stage propulsion units. The rectification duct 400 includes a lip 401, a duct body 402, a flow guide plate 403 and a converging-diverging guide sleeve 410. The lip 401 is arc-shaped and adopts a drag reduction configuration to reduce resistance. The gap between the duct body 402 and the first-stage and second-stage blade disc surfaces is not greater than 1 mm to reduce induced drag and have smooth operation and efficiency. The flow guide plate 403 fixes the converging-diverging guide sleeve 410 to the center of the rectification duct 400.The convergent expansion guide sleeve 410 is internally provided with a center frame body 411 and a guide fin 412, has a convergent portion 413, an expansion middle section 414 and a contraction nozzle 415, the expansion middle section 414 surrounds the motor frame body 336, the center frame body 411 is a hollow structure, the guide fin 412 supports the center frame body 411, guarantees the support strength of the center frame body 411, and stabilizes the guide expansion airflow; the convergent expansion guide sleeve 410 and the heat dissipation fin 337 of the motor frame body 336 are used for heat dissipation of the motor, at the same time, when air is taken in through the convergent portion 413, the air is adiabatic compressed, the air in the expansion middle section 414 is decelerated and passed through the heat dissipation fin to be heated and pressurized, the air in the contraction nozzle 415 is adiabatic expanded and pressurized to release heat and do work to the outside, so that the air passing through the heat dissipation fin through the convergent portion 413 is fully heated and expanded and then sprayed out of the contraction nozzle 415, a Brayton cycle is formed, and the backward sprayed hot air generates thrust.

[0029] Further, the first propulsion group element and the second propulsion group element have the same rotational inertia.

[0030] Further, the inner rotor 310 is externally provided with an inner rotor excitation group 312 for generating a rotating magnetic field, the inner rotor is provided with an inner rotor reinforcing belt 314 for restraining the inner rotor excitation group 312 from centrifugal force caused by high-speed rotation; the outer rotor 320 is internally provided with an outer rotor excitation group 323 for generating a rotating magnetic field, the outer rotor is provided with an outer rotor reinforcing belt 324 for restraining the outer rotor excitation group 323 from centrifugal force caused by high-speed rotation; the number of the outer rotor excitation group 323 is greater than the number of the inner rotor excitation group 313, the number of excitation groups is generally a multiple of 3, and the number difference between the inner and outer rotor excitation groups is 1 or 2 or 3, so as to establish a reliable and stable rotating magnetic field.

[0031] Further, the inner rotor 310 is provided with a continuous input and output device 341 at the end, preferably, the continuous input and output device 341 is an electrical slip ring.

[0032] Further, neither the first propulsion group element nor the second propulsion group element is provided with a variable pitch device, the blade group is a rigid rotor, the blade is not hinged to the hub, and preferably, the blade and the hub are an integral structure, so as to simplify the structure.

[0033] Further, the double-rotor motor 300 controls the electrical parameters to change the rotating speed, so as to change the propulsion force of the double-motor direct-drive coaxial counter-propeller electric ducted fan.

[0034] It should be noted that, in the specification, relational terms such as first and second, and the like, can be used solely to distinguish one entity or action from another entity or action without necessarily implying any actual relationship or order between such entities or actions. Also, the terms "comprises", "comprising", or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a device or method that comprises a list of elements does not include only those elements but can also include other elements not expressly listed or inherent to such device or method. An element proceeded by "comprises a" does not, without more constraints, exclude the existence of additional identical elements in the device or method that includes the recited element.

[0035] Various embodiments are described herein with reference to particular applications. Those of ordinary skill in the art will understand that the embodiments described are merely illustrative of the principles and applications of the present application. Numerous modifications and adaptations will be readily apparent to those of ordinary skill in the art without departing from the spirit and scope of the present application. Each of the various embodiments can be implemented alone or in combination with one another.

[0036] The above description is merely illustrative of the principles of the application. Various modifications and changes can be made as would be obvious to a person of ordinary skill in the art. The disclosure is not to be limited to the details given herein, but can be modified within the scope and spirit of the application. This application is not limited in its application to the details set forth in the description contained herein or illustrated in the drawings. The application is capable of other embodiments and of being practiced or carried out in various ways.

[0037] While the application has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the scope of the application is not to be limited to the details given herein and modifications can be made within the scope and spirit of the application. Various embodiments can be implemented alone or in combination with one another. Various embodiments can be implemented only for parts of the applications. Various embodiments can be implemented only for parts of the applications. Various embodiments can be implemented only for parts of the applications. Various embodiments can be implemented only for parts of the applications. Various embodiments can be implemented only for parts of the applications. Various embodiments can be implemented only for parts of the applications. Various embodiments can be implemented only for parts of the applications. Various embodiments can be implemented only for parts of the applications. Various embodiments can be implemented only for parts of the applications. Various embodiments can be implemented only for parts of the applications. Various embodiments can be implemented only for parts of the applications. Various embodiments can be implemented only for parts of the applications. Various embodiments can be implemented only for parts of the applications. Various embodiments can be implemented only for parts of the applications. Various embodiments can be implemented only for parts of the applications. Various embodiments can be implemented only for parts of the applications. Various embodiments can be implemented only for parts of the applications. Various embodiments can be implemented only for parts of the applications. Various embodiments can be implemented only for parts of the applications. Various embodiments can be implemented only for parts of the applications. Various embodiments can be implemented only for parts of the applications. Various embodiments can be implemented only for parts of the applications. Various embodiments can be implemented only for parts of the applications. Various embodiments can be implemented only for parts of the applications. Various embodiments can be implemented only for parts of the applications. Various embodiments can be implemented only for parts of the applications. Various embodiments can be implemented only for parts of the applications. Various embodiments can be implemented only for parts of the applications.

Claims

1. A dual-rotor direct-drive coaxial counter-rotating propeller electric ducted fan, characterized in that: It comprises two-stage blade groups, a double-rotor motor and a rectifying duct; the double-rotor motor is composed of an inner rotor, an outer rotor, a support group and an electrical interface; the support group comprises support bearings, a motor frame body and a motor base; the support group rotationally supports the coaxially sleeved inner and outer rotors for coaxial reverse rotation; the inner rotor is directly connected with the first-stage blade group to form a first-stage propulsion group element; the outer rotor is directly connected with the second-stage blade group to form a second-stage propulsion group element; no transmission mechanism is arranged between the first-stage propulsion group element and the second-stage propulsion group element; the rectifying duct is internally provided with the first-stage and second-stage propulsion units.

2. A dual-rotor direct-drive co-axial counter-wash electric ducted fan according to claim 1, characterized in that: The rectifying duct comprises a lip, a duct body, a flow guide plate and a converging-dilating guide sleeve; the converging-dilating guide sleeve has three sections of a converging mouth portion, a dilating middle section and a contracting spout portion, is internally provided with a central frame and flow guide fins, and the dilating middle section surrounds the motor frame body.

3. A dual-rotor direct-drive co-axial counter-wash electric ducted fan according to claim 1, characterized in that: The inner rotor is provided with an inner rotor excitation group to generate a rotating magnetic field, and is externally provided with an inner rotor reinforcing band; the outer rotor is internally provided with an outer rotor excitation group to generate a rotating magnetic field, and is externally provided with an outer rotor reinforcing band.

4. A dual-rotor direct drive co-axial counter-prop electric ducted fan according to claim 1, characterized in that: The blade configuration and number of the first-stage propulsion group element are different from those of the second-stage propulsion group element, so as to reduce and avoid inter-stage excitation noise.

5. A dual-rotor direct-drive co-axial counter-wash electric ducted fan according to claim 1, characterized in that: The first-stage propulsion group element and the second-stage propulsion group element have the same rotational inertia.

6. A dual-rotor direct-drive co-axial counter-wash electric ducted fan according to claim 2, characterized in that: The flow guide plate of the duct is at an angle with the air flow jetted out after being compressed by the second-stage blades, so as to parallelly guide the air flow out of the duct.

7. A dual-rotor direct-drive co-axial counter-wash electric ducted fan according to claim 2, characterized in that: The converging-dilating guide sleeve guides the air flow to pass through the motor frame body heat dissipation fins to dissipate heat for the double-rotor motor; the air is adiabatically compressed when entering the converging section, is decelerated and heated at constant pressure in the dilating section, and is adiabatically expanded and heated at constant pressure in the contracting section; the fully heated air is jetted out from the contracting section to generate thrust to do work on the outside.

8. A dual-rotor direct-drive co-axial counter-wash electric ducted fan according to any of claims 2, 6, 7, characterized in that: The lip is arc-shaped for reducing resistance; the central frame body is of a hollow structure, and the flow guide fins support the central frame body.

9. A dual-rotor direct-drive co-axial counter-wash electric ducted fan as claimed in any one of claims 1, 3-5, characterized in that: The two-stage blade groups are not provided with a pitch changing device; the blade groups are rigid rotors, and the blades are not hingedly connected with the hubs.

10. A dual-rotor direct drive co-axial counter-prop electric ducted fan according to any one of claims 9, characterized in that: The rotational speed of the double-rotor motor is precisely adjusted within a range of 15-110%.

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