Rotor and aircraft

Abstract

The present invention provides a rotor, which relates to the field of aircraft technology, including a duct and at least two blades, one end of each blade is fixedly connected to the inner wall of the duct and each blade is arranged inside the duct, the speed direction of the connection point where each blade and the duct are connected is a first speed direction, each blade extends from the inner wall of the duct to a direction away from the inner wall of the duct, and the angle between the extension direction of each blade and each first speed direction is an obtuse angle. The present invention also provides an aircraft, which is provided with at least one of the above-mentioned rotors. The rotor and aircraft provided by the present invention can maximize the maximum forward flight speed.

Description

Technical Field

[0001] The present invention relates to the technical field of aircraft, and in particular to a rotor and an aircraft. Background Art

[0002] The ducted propeller system has high aerodynamic efficiency, low aerodynamic noise, and high safety. It has been widely used in military and civilian fields such as ships, special aircraft, and submarines. For rotorcraft, improving the maximum forward flight speed has always been an important research direction. However, the aerodynamic environment of the rotor limits the improvement of the forward flight speed. Due to the asymmetry of the airflow between the forward and rearward blades of the rotor, when flying forward, the relative airflow speed of the forward blade of the rotor is the superposition of the blade rotation speed and the forward flight speed, while the relative airflow speed of the rearward blade is the blade rotation speed minus the forward flight speed. Therefore, the speed of the tip of the forward blade is greater, and shock waves will appear at the tip of the forward blade when flying forward at a high speed. The shock wave resistance generated will cause the rotor torque to rise suddenly. Therefore, in order to avoid such a phenomenon, the flight speed must be limited to a very low level. Taking a conventional helicopter as an example, the speed of one end of its rotor is about 200m / s, and the maximum forward flight speed usually does not exceed 100m / s.

[0003] The specific design method of the existing one-end swept rotor is to, on the basis of a rectangular blade, deflect the blade axis toward the trailing edge of the blade at the blade tip according to a certain rule, that is, only a swept section is provided at one end of the blade. From the aerodynamic point of view, the one-end sweep can indeed improve the rotor performance, but from the perspective of structural design, the center of gravity of the swept section is offset backward relative to the center line of other parts of the blade, which will affect the dynamic characteristics of the blade and even cause uncontrollable dynamic stability problems. Therefore, for the existing one-end swept rotor, in order to prevent the center of gravity of the blade section from shifting too much, the length of the swept section and the sweep angle are usually relatively small, the sweep angle is generally around 20°, and the length of the swept section is approximately 10% to 20% of the blade extension, which can only increase the maximum forward flight speed to a limited extent. Summary of the invention

[0004] The purpose of the present invention is to provide a rotor and an aircraft to solve the problems existing in the above-mentioned prior art and to maximize the maximum forward flight speed.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] The present invention provides a rotor, comprising a duct and at least two blades, one end of each blade being fixedly connected to the inner wall of the duct and each blade being arranged inside the duct, the speed direction of the connection point between each blade and the duct being a first speed direction, each blade extending from the inner wall of the duct in a direction away from the inner wall of the duct, and the angle between the extension direction of each blade and each first speed direction is an obtuse angle.

[0007] Preferably, the angle between the extension direction of each of the blades and each of the first speed directions is less than 140°.

[0008] Preferably, the angle between the extension direction of each of the blades and each of the first speed directions is 135°.

[0009] Preferably, there are multiple blades, and the multiple blades are distributed along the circumference of the inner wall of the duct.

[0010] Preferably, there are a plurality of blades, and the plurality of blades are arranged in layers along the axial direction of the duct, each layer of the blades includes at least two blades, and the plurality of blades in each layer are distributed circumferentially along the inner wall of the duct.

[0011] Preferably, the length of each of the blades is 0.4 times the inner diameter of the duct.

[0012] Preferably, the rotor provided by the present invention further includes a driving mechanism, wherein the driving mechanism is connected to the duct, and the driving mechanism can drive the duct to rotate around its own axis.

[0013] Preferably, the driving mechanism includes a gear, a plurality of gear teeth are provided on the outer wall of the duct, the gear is meshingly connected with the outer wall of the duct, the gear is used to connect with a power device, the power device can drive the gear to rotate around its own axis, and the gear can drive the duct to rotate around its own axis.

[0014] The present invention also provides an aircraft provided with at least one rotor as described above.

[0015] Compared with the prior art, the present invention has achieved the following technical effects:

[0016] Each blade in the rotor and aircraft provided by the present invention extends from the inner wall of the duct in a direction away from the inner wall of the duct, and the angle between the extension direction of the blade and the first speed direction is an obtuse angle, which can effectively delay shock wave stall and overcome the problem of unstable center of gravity caused by only setting a swept section at the blade tip. Therefore, the rotor and aircraft provided by the present invention can have a larger swept section length and swept angle, thereby maximizing the maximum forward flight speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 is a schematic diagram of the structure of the rotor in Example 1;

[0019] Figure 2 Schematic diagram of the structure of the blade in Example 1 (single layer);

[0020] Figure 3 A schematic diagram of the structure of the blade in Example 1 (double layer);

[0021] Figure 4 A schematic diagram of the sweep angle in Example 1;

[0022] Figure 5 Schematic diagram of the distribution of the blades in Example 1 (single layer);

[0023] Figure 6 Schematic diagram of the distribution of the blades in Example 1 (double layer);

[0024] Figure 7 A schematic diagram of the maximum forward flight speed in Example 1;

[0025] Figure 8 It is a schematic diagram of the structure of the existing rotor;

[0026] Fig. 9 is the pressure coefficient curve of the section at 0.85R of the existing rotor blade when the relative incoming flow velocity is 297.5 m / s;

[0027] Fig.10 is the pressure coefficient curve of the section at 0.85R of the rotor blade in Example 1 when the relative incoming flow velocity is 297.5 m / s;

[0028] Fig.11 is a pressure coefficient curve of the section at 0.85R of the rotor blade of Example 1 under the condition of a relative incoming flow velocity of 425 m / s;

[0029] Fig.12 It is a pressure distribution cloud diagram near the blade tip of the existing rotor when the forward flight speed is 100m / s;

[0030] Fig.13 is a pressure distribution cloud diagram near the blade tip of the rotor in Example 1 when the forward flight speed is 100 m / s;

[0031] Fig.14The pressure distribution cloud diagram of the rotor blade near the blade tip when the forward flight speed is 227.5 m / s in Example 1;

[0032] In the figure: 100, rotor; 1, duct; 101, gear teeth; 2, blades; 3, driving mechanism; 301, gear; 4, existing blades; V, first speed direction; γ, sweep angle. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] The purpose of the present invention is to provide a rotor and an aircraft to solve the problems existing in the above-mentioned prior art and to maximize the maximum forward flight speed.

[0035] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] Example 1

[0037] like Figure 1-14 As shown, this embodiment provides a rotor 100, including a duct 1 and at least two blades 2, the blades 2 are preferably typical rectangular blades 2, one end of each blade 2 is fixedly connected to the inner wall of the duct 1 and each blade 2 is arranged inside the duct 1, the speed direction of the connection point where each blade 2 and the duct 1 are connected is the first speed direction V, each blade 2 extends from the inner wall of the duct 1 to the direction away from the inner wall of the duct 1, and the angle between the extension direction of each blade 2 and each first speed direction V is an obtuse angle, that is, the blade 2 is a swept blade 2 as a whole. It should be noted that the connection point where each blade 2 and the duct 1 are connected is obtained on the basis of approximately regarding the blade 2 as a straight line as a whole, that is, ignoring the thickness of the blade tip of the blade 2, and regarding the connection between the blade 2 and the duct 1 as a point, which is the connection point. Since the speed direction of a particle doing curved motion at a point on the curve is the tangent direction of the point, the first speed direction V is the tangent direction of the duct 1 at the connection point. In the rotor 100 provided in the present embodiment, each blade 2 extends from the inner wall of the duct 1 in a direction away from the inner wall of the duct 1, and the angle between the extension direction of the blade 2 and the first speed direction V is an obtuse angle, which can effectively delay the shock wave stall and overcome the problem of unstable center of gravity caused by only setting a swept section at the blade tip. Therefore, the rotor 100 provided in the present embodiment can have a larger swept section length and swept angle, thereby maximizing the maximum forward flight speed.

[0038] The principle that sweeping the blade 2 can increase the maximum forward flight speed is that when the forward flight speed of the aircraft is high, the leading tip (blade tip) of the blade 2 of the rotor 100 will generate a local shock wave, and the corresponding Mach number at this time is called the critical Mach number. The use of the sweep angle γ can effectively delay the shock wave stall, such as Figure 6 As shown, assuming that the incoming current is V ∞ , the corresponding incoming flow Mach number (the ratio of velocity to the speed of sound) is M∞. When M∞ exceeds the critical Mach number, due to the existence of the sweep angle γ, the effective velocity V perpendicular to the leading edge of blade 2 ∞ cosγ is still lower than the critical speed corresponding to the critical Mach number of the unswept design, so shock waves will not be generated prematurely, thereby increasing the maximum forward flight speed. From theoretical derivation, it can be seen that when the sweep angle γ is larger, the corresponding effective speed is smaller, the ability to delay the generation of shock waves is stronger, and the maximum forward flight speed can be further increased.

[0039] The angle between the extension direction of each blade 2 and each first speed direction V is less than 140°. That is, the deviation angle of each blade 2 away from each first speed direction V on the basis of the corresponding radial direction is less than 50°, that is, the sweep angle γ is less than 50°.

[0040] As a preferred embodiment, the angle between the extension direction of each blade 2 and each first speed direction V is 135°, that is, the sweep angle γ is 45°.

[0041] As a preferred embodiment, there are multiple blades 2, and the multiple blades 2 are distributed along the circumference of the inner wall of the duct 1. Preferably, the multiple blades 2 are evenly distributed along the circumference of the inner wall of the duct 1. This is a single-layer design of the blades 2. In a multi-layer design, there may be aerodynamic interference between the layers of blades 2, which may reduce the aerodynamic performance of the rotor 100. The single-layer design can effectively avoid this problem.

[0042] The length of each blade 2 is 0.4 times the inner diameter of the duct 1 , and the radius of the duct 1 is defined as R, and the radial extent of the blade 2 is 0.4R.

[0043] As a preferred embodiment, there are multiple blades 2, and the multiple blades 2 are arranged in layers along the axial direction of the duct 1, each layer of blades 2 includes at least two blades 2, and the multiple blades 2 in each layer are distributed along the circumference of the inner wall of the duct 1. Preferably, the multiple blades 2 in each layer are evenly distributed along the circumference of the inner wall of the duct 1. It should be noted that the geometric shapes of the blades 2 of each layer may be different, and the length and number of the blades 2 may also be different. For example, the blades 2 can be designed as three layers, and the propeller planes of each layer of blades 2 are parallel to each other. This is a multi-layer design of the blades 2. The magnitude of the rotor thrust (lift) is related to the number and length of the blades 2. Increasing the number of blades 2 or increasing the length can increase the rotor thrust. In the present embodiment, the blades 2 of the rotor 100 are overall swept back in design to avoid interference between the blades 2 and adjacent blades 2 or duct 1. Therefore, the span is smaller than the span of the existing blades 4. If the number of blades 2 is the same as the number of blades of the existing rotor, smaller pulling force will inevitably be generated. Therefore, a multi-layer design can be used to increase the number of blades 2, thereby ensuring a larger rotor pulling force.

[0044] The rotor 100 provided in this embodiment further includes a driving mechanism 3 , which is connected to the duct 1 , and the driving mechanism 3 can drive the duct 1 to rotate around its own axis.

[0045] As a preferred embodiment, the driving mechanism 3 includes a gear 301, a plurality of gear teeth 101 are provided on the outer wall of the duct 1, the gear 301 is meshed and connected with the outer wall of the duct 1, and the gear 301 is used to connect with the power device, the power device can drive the gear 301 to rotate around its own axis, and the gear 301 can drive the duct 1 to rotate around its own axis. Preferably, the power device is an engine of an aircraft, the engine output power is transmitted to the driving mechanism 3 through a transmission and a transmission mechanism, the driving mechanism 3 drives the duct 1 to rotate, and the duct 1 drives the blades 2 to rotate, and the blades 2 will generate centrifugal force when rotating at high speed, and the centrifugal force of the blades 2 will generate pressure on the duct 1, and the centrifugal force generated when the existing blades 2 rotate will generate tension on the hub. Since the compressive strength of most materials is greater than the tensile strength, the way in which the hub drives the existing blades 2 requires the hub to meet higher design requirements such as structural strength, and the general structure is more complex; and the way in which the duct 1 drives the blades 2 to rotate makes the design of the rotor 100 easier to meet the required structural strength requirements. It should be noted that the driving method of the duct 1 in this embodiment is not limited to the above method. For example, the duct 1 can also be driven by an ultrasonic motor or the like.

[0046] The rotor flow field is numerically simulated, and the shock wave generation of the existing rotor and the rotor 100 provided in this embodiment is compared by flow field simulation to verify the effect of the rotor 100 on improving the maximum forward flight speed. Among them, the blade of the existing rotor (the existing blade 4) is as described in the background technology, and the blade root of the existing blade 4 is connected to the hub, and the existing blade 4 is driven by the hub, see Figure 8 The specific scheme of flow field simulation is as follows:

[0047] (1) Establishing physical models of the existing rotor and the rotor 100 provided in this embodiment respectively; preferably, the modeling is performed using CATIA 3D modeling software;

[0048] (2) Compare and analyze the aerodynamic environment of the forward side blade surface of the two at the same speed, and monitor whether shock waves are generated; preferably, the two physical models in step 1 are simulated by the fluid simulation software Fluent. According to the flow field simulation results, the pressure distribution on the blade surface can be obtained. The shock wave can be monitored by using the characteristic that the pressure will rise sharply after the airflow passes through the shock wave, that is, if the pressure rises sharply at a certain place, a shock wave is generated near this place. The monitoring point is 0.85*R on the airfoil section of the two at a vertical distance from the rotation center. The blade at this monitoring point has a larger relative velocity to the incoming flow, and shock waves are more likely to occur. In addition, the vicinity of this monitoring point is the main blade section that generates lift, and the aerodynamic characteristics analysis of this part is more meaningful for reference.

[0049] (3) Compare the maximum forward flight speeds of the two rotors when they each generate shock waves:

[0050] in, Fig. 9 and Fig.10 The pressure coefficient curves of the existing blade 4 and the blade 2 of the rotor 100 in this embodiment at the 0.85R section are shown respectively. The horizontal axis represents the relative spanwise position of the points on the blade section, Y / b=0 represents the leading edge point, and Y / b=1 represents the trailing edge point; the vertical axis represents the pressure coefficient, which is the result of non-dimensionalization of the pressure. The relative incoming flow velocity at the 0.85R section of both is 297.5m / s. By comparison, it can be seen that Fig. 9 The pressure coefficient gradient is very large at the marked area (the part encircled by the dotted line), indicating that the pressure changes drastically near 0.4 in the chord direction of the blade section, where a shock wave appears. Fig.10 As shown, the cross-sectional pressure of the blade 2 of the rotor 100 in this embodiment at the same speed changes smoothly, and no shock wave is generated, which indicates that the rotor 100 in this embodiment has the function of delaying the generation of shock waves.

[0051] Fig.11 This is the pressure coefficient curve of the section at 0.85R of the blade 2 of the rotor 100 in this embodiment under the condition of a relative incoming flow velocity of 425 m / s. It can be seen that the pressure changes rapidly near 0.6 in the chord direction of the blade 2 section, indicating that a shock wave has occurred there. The speed at this time has obviously exceeded the maximum forward flight speed of the existing rotor, indicating that the rotor 100 in this embodiment can increase the maximum forward flight speed.

[0052] Fig.12 and Fig.13The pressure distribution cloud diagram near the blade tip of the existing rotor and the rotor 100 in this embodiment when the forward flight speed is 100m / s (P in the pressure distribution cloud diagram represents relative pressure, which is the pressure relative to atmospheric pressure). The pressure distribution cloud diagram on the blade surface can be obtained by importing the calculation results of the fluid simulation software Fluent into the post-processing software Tecplot for processing. Fig.12 It can be seen that at this forward flight speed, the surface pressure contours of the existing blade 4 are densely distributed, indicating that the pressure gradient is large. In the area where the contours are densely distributed (the part surrounded by the dotted circle), the pressure changes dramatically. It can be seen that shock waves are generated here, so the maximum forward flight speed of the existing rotor does not exceed 100m / s. In contrast, Fig.13 The distribution of contour lines on the surface of blade 2 is sparse, which shows that at this forward flight speed, rotor 100 in this embodiment does not generate obvious shock waves, indicating that its maximum forward flight speed is greater than 100 m / s. Fig.14 The pressure distribution cloud diagram near the blade tip of the rotor 100 in this embodiment when the forward flight speed increases to 227.5 m / s, at this time, a shock wave appears on the surface of the blade 2 of the rotor 100, so the maximum forward flight speed of the rotor 100 in this embodiment does not exceed 227.5 m / s, which is much greater than the maximum forward flight speed of the existing rotor. Therefore, the rotor 100 in this embodiment can delay the generation of shock waves, thereby increasing the maximum forward flight speed of the rotor 100.

[0053] Example 2

[0054] This embodiment provides an aircraft, which is provided with at least one rotor 100 in Embodiment 1. The aircraft mainly refers to a rotor aircraft, such as a helicopter, a quad (or multi) rotor drone, and a new configuration rotor aircraft.

[0055] As a preferred implementation, the aircraft provided in this embodiment can adopt a variety of layouts, such as a coaxial twin-rotor layout, a transverse twin-rotor layout, or a longitudinal twin-rotor layout.

[0056] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A rotor, characterized in that: It includes a duct and at least two blades, one end of each blade is fixedly connected to the inner wall of the duct and each blade is arranged inside the duct, the speed direction of the connection point between each blade and the duct is a first speed direction, each blade extends from the inner wall of the duct to a direction away from the inner wall of the duct, and the angle between the extension direction of each blade and each first speed direction is an obtuse angle.

2. The rotor according to claim 1, characterized in that: The included angle between the extension direction of each of the blades and each of the first speed directions is less than 140°.

3. The rotor according to claim 2, characterized in that: The included angle between the extension direction of each of the blades and each of the first speed directions is 135°.

4. The rotor according to claim 1, characterized in that: There are multiple blades, and the multiple blades are distributed along the circumference of the inner wall of the duct.

5. The rotor according to claim 1, characterized in that: There are multiple blades, and the multiple blades are arranged in layers along the axial direction of the duct. Each layer of the blades includes at least two blades, and the multiple blades in each layer are distributed along the circumference of the inner wall of the duct.

6. The rotor according to claim 1, characterized in that: The length of each blade is 0.4 times the inner diameter of the duct.

7. The rotor according to claim 1, characterized in that: It also includes a driving mechanism, which is connected to the duct and can drive the duct to rotate around its own axis.

8. The rotor according to claim 7, characterized in that: The driving mechanism includes a gear, and a plurality of gear teeth are provided on the outer wall of the duct. The gear is meshed and connected with the outer wall of the duct. The gear is used to connect with a power device. The power device can drive the gear to rotate around its own axis, and the gear can drive the duct to rotate around its own axis.

9. An aircraft, characterized in that: At least one rotor as claimed in any one of claims 1 to 8 is provided.

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