A real-time variable speed rotor for high-speed forward flight

Abstract

The invention discloses a real-time variable speed rotor for high-speed forward flight, which relates to the technical field of helicopters, and comprises a first transmission link, a second transmission link and a controller; the first transmission link is provided with a first blade, a first rotor shaft, a first gear, a second gear, a first bevel gear, a second bevel gear and a first motor in sequence; the second transmission link is provided with a second blade, a second rotor shaft, a third gear, a fourth gear, a third bevel gear, a fourth bevel gear and a second motor in sequence; the controller determines the rotation speed of the first blade according to the azimuth angle of the first blade sent by a first angle sensor, and determines the rotation speed of the second blade according to the azimuth angle of the second blade sent by a second angle sensor; the first motor drives the first blade to rotate according to the rotation speed of the first blade; the second motor drives the second blade to rotate according to the rotation speed of the second blade. The variable speed rotor disclosed by the invention can improve the maximum forward flight speed of the helicopter.

Description

Technical Field

[0001] The invention relates to the technical field of helicopters, in particular to a real-time variable speed rotor for high-speed forward flight. Background Art

[0002] Since Sikorsky launched the first practical helicopter VS-300 in 1939, the overall performance of helicopters has been greatly improved as helicopter technology has made great progress in design, manufacturing, control and power. Compared with general fixed-wing aircraft, helicopters are irreplaceable. Helicopters can easily achieve vertical take-off and landing, hover in the air, operate at low altitude and low speed, and have fewer restrictions on landing sites. In addition, the safety brought by its excellent maneuverability and autorotation and gliding ability also makes it play a huge role in both military and civilian fields.

[0003] However, with the complexity and variety of modern helicopter missions, the maximum flight speed of helicopters can no longer fully meet people's needs. The forward flight speed of a helicopter is mainly limited by the shock wave of the forward blades and the airflow separation of the backward blades, such as Figure 1 As shown, Figure 1 This is a schematic diagram of the helicopter level flight speed envelope, quoted from helicopter aerodynamics.

[0004] like Figure 2 As shown, Figure 2 This is a schematic diagram of the speed distribution of the rotor disc plane when the helicopter is flying forward, quoted from helicopter aerodynamics. At 0°~90°~180°, the blades rotate against the wind, and the forward blades will add the forward flight speed. The forward flight speed increases, which is easy to generate shock waves on the forward blades. At 180°~270°~360°, it is just the opposite. The blades are rotating with the wind. Due to the influence of the forward flight speed, there will be a reflow zone at the root of the backward blades. The airflow flows from the leading edge of the blade to the trailing edge. Therefore, the blades in this area are prone to abnormal air characteristics. Due to these two main reasons, the maximum cruising speed of conventional single-rotor helicopters with tail rotors is generally within 300km / h.

[0005] In response to the shortcomings of helicopter speed, countries have been committed to exploring new technical paths and have conducted test flights to verify helicopters that use new technologies to increase speed. At present, there are two main mainstream high-speed helicopter research and development ideas: one is a convertible high-speed helicopter, which can realize the conversion between helicopter mode and fixed-wing mode during flight, so as to better adapt to mission requirements, but the transition state control is complex. Its main representative is the V-22 tilt-rotor aircraft jointly developed by Bell Helicopter and Boeing in the United States. However, the tilt-rotor aircraft cannot achieve speed changes. In order to increase the forward flight speed of the helicopter, there are currently only two types of helicopters: tilt-rotor aircraft and coaxial helicopters. The other is to add auxiliary lift devices or auxiliary thrust devices to conventional configuration helicopters to obtain higher speeds, but the power required is high. This type of helicopter is also called a compound helicopter.

[0006] In summary, the art urgently needs a real-time variable speed rotor for high-speed forward flight, which can improve the flow environment of the blades at different azimuth angles in the rotor disc plane through real-time speed changes, so as to achieve the purpose of increasing the maximum forward flight speed of the helicopter. Summary of the invention

[0007] The purpose of the present invention is to provide a real-time variable speed rotor for high-speed forward flight, so as to improve the maximum forward flight speed of a helicopter.

[0008] To achieve the above object, the present invention provides the following solutions:

[0009] A real-time variable speed rotor for high-speed forward flight, the rotor comprising a first transmission link, a second transmission link and a controller;

[0010] The first transmission chain is provided with a first blade, a first rotor shaft, a first gear, a second gear, a first bevel gear, a second bevel gear and a first motor in sequence;

[0011] The second transmission chain is provided with a second blade, a second rotor shaft, a third gear, a fourth gear, a third bevel gear, a fourth bevel gear and a second motor in sequence;

[0012] The first blade is vertically fixed to one end of the first rotor shaft; the first gear is vertically fixed to the other end of the first rotor shaft; the second gear is meshed with the first gear; the first bevel gear is fixed to the second gear; the second bevel gear is meshed with the first bevel gear; the first motor is connected to the second bevel gear; the first motor drives the second bevel gear to rotate, the second bevel gear cooperates with the first bevel gear to achieve steering and first-stage reduction, and the second gear and the first bevel gear have the same rotation axis and rotation speed; the second gear drives the first gear to achieve second-stage reduction; the first gear drives the first rotor shaft to rotate; the first rotor shaft drives the first blade to rotate;

[0013] The second rotor shaft is a hollow shaft, and the second rotor shaft is sleeved in the middle part of the first rotor shaft; the second blade is vertically fixed to one end of the second rotor shaft; the third gear is vertically fixed to the other end of the second rotor shaft; the fourth gear is meshed with the third gear; the third bevel gear and the fourth gear are fixed together; the fourth bevel gear is meshed with the third bevel gear; the second motor is connected to the fourth bevel gear; the second motor drives the fourth bevel gear to rotate, and the fourth bevel gear cooperates with the third bevel gear to achieve steering and first-stage deceleration, and the fourth gear and the third bevel gear have the same rotation axis and rotation speed; the fourth gear drives the third gear to achieve second-stage deceleration; the third gear drives the second rotor shaft to rotate; the second rotor shaft drives the second blade to rotate;

[0014] A first angle sensor is arranged on the first rotor shaft; the first angle sensor is used to obtain the total angle and number of rotations of the first blade, and send the total angle and number of rotations of the first blade to the controller; a second angle sensor is arranged on the second rotor shaft; the second angle sensor is used to obtain the total angle and number of rotations of the second blade, and send the total angle and number of rotations of the second blade to the controller; the controller determines the rotation speed of the first blade according to the total angle and number of rotations of the first blade, and determines the rotation speed of the second blade according to the total angle and number of rotations of the second blade; the controller is connected to the first motor and the second motor respectively; the first motor drives the first blade to rotate according to the rotation speed of the first blade; the second motor drives the second blade to rotate according to the rotation speed of the second blade.

[0015] Optionally, the second bevel gear has a different tooth ratio to the first bevel gear; the fourth bevel gear has a different tooth ratio to the third bevel gear.

[0016] Optionally, the second gear has a different gear ratio than the first gear; and the fourth gear has a different gear ratio than the third gear.

[0017] Optionally, the rotor further comprises a first mass block and a second mass block;

[0018] The first mass block is connected to the first rotor shaft; the mass of the first mass block is equal to that of the first blade; the first mass block is used to balance the centrifugal force on the first rotor shaft when the first blade rotates;

[0019] The second mass block is connected to the second rotor shaft; the mass of the second mass block is equal to that of the second blade; and the second mass block is used to balance the centrifugal force on the second rotor shaft when the second blade rotates.

[0020] Optionally, the rotor further comprises a first thrust bearing and a second thrust bearing;

[0021] The first thrust bearing and the second thrust bearing are both arranged between the first rotor shaft and the second rotor shaft, and the first thrust bearing and the second thrust bearing are used to make the first rotor shaft and the second rotor shaft coaxial.

[0022] Optionally, the controller is based on the formula φ=α z -360°×n calculates the azimuth of the first blade or the second blade; where φ represents the azimuth of the first blade or the second blade, α z represents the total angle of rotation of the first blade or the total angle of rotation of the second blade, and n represents the number of revolutions of the first blade or the number of revolutions of the second blade.

[0023] Optionally, the controller calculates the rotational speed of the first blade and the rotational speed of the second blade according to the formula Ω'=Ω-Asin(φ); wherein Ω' represents the rotational speed of the first blade or the second blade, Ω represents the design speed of the rotor, Ω is a constant value, A represents the amplitude of the change in the rotor speed, A=(0.5-0.8)μΩR, μ represents the advance ratio, R represents the rotor radius, and φ represents the azimuth angle of the first blade or the azimuth angle of the second blade.

[0024] Optionally, the controller is based on the formula Calculate the rotational speed of the first blade and the rotational speed of the second blade; wherein Ω' represents the rotational speed of the first blade or the second blade, Ω represents the design rotational speed of the rotor, Ω is a constant value, A represents the amplitude of the rotor speed change, A = (0.5-0.8) μΩR, μ represents the advance ratio, R represents the rotor radius, and φ represents the azimuth angle of the first blade or the azimuth angle of the second blade.

[0025] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0026] The real-time variable speed rotor for high-speed forward flight disclosed by the present invention enables two blades to rotate independently by setting a first transmission link and a second transmission link. Since the azimuth angles of the two blades at any moment during the rotation process are different, the rotation speed of each blade is calculated according to the azimuth angle of each blade, and the different rotation speeds of the two blades are achieved respectively through the first transmission link and the second transmission link. Through real-time rotation speed changes, the blade flow environment at different azimuth angles in the rotor disc plane is improved, thereby achieving the purpose of increasing the maximum forward flight speed of the helicopter. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] 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 labor.

[0028] Figure 1 This is a schematic diagram of the helicopter's level flight speed envelope;

[0029] Figure 2 This is a schematic diagram of the speed distribution of the rotor disc plane when the helicopter is flying forward;

[0030] Figure 3 It is a structural diagram of an embodiment of a real-time variable speed rotor for high-speed forward flight of the present invention;

[0031] Figure 4 It is a schematic diagram of the internal structure of the rotor shaft in the embodiment of the real-time variable speed rotor for high-speed forward flight of the present invention;

[0032] Figure 5 It is a schematic diagram of the change of blade flow velocity with angle of attack at radius 0.7R without speed change;

[0033] Figure 6 It is a schematic diagram of the change of the blade flow velocity at the radius 0.7R with the angle of attack when the rotation speed changes;

[0034] Figure 7 It is a schematic diagram of the distribution of the incoming flow velocity at each azimuth angle of the propeller disk without speed change;

[0035] Figure 8 It is a schematic diagram of the distribution of the incoming flow velocity at each azimuth angle of the propeller disk when the rotation speed changes;

[0036] Fig. 9 It is a schematic diagram of the rotor speed change law;

[0037] Fig.10 It is a schematic diagram of the curve of the incoming flow velocity changing with azimuth at different radii;

[0038] Fig.11 It is a schematic diagram of the actual change of rotor speed with azimuth angle;

[0039] Fig.12 It is a schematic diagram of the actual change of rotor speed over time;

[0040] Fig.13 It is a schematic diagram of the distribution of aerodynamic angle of attack in the front disc plane when the rotor speed changes;

[0041] Fig.14 It is a schematic diagram of the distribution of aerodynamic angle of attack in the disc plane after the rotor speed changes;

[0042] Fig.15 This is the maximum pressure cloud diagram when the incoming flow velocity is 266.4245m / s;

[0043] Fig.16 This is the maximum pressure cloud diagram when the incoming flow velocity is 322.5833m / s;

[0044] Fig.17 It is another schematic diagram of the law of rotor speed change;

[0045] Fig.18 The graph of the blade flow velocity changing with azimuth at typical different relative radius positions of the propeller disk before the speed changes;

[0046] Fig.19 This is a curve of the blade flow velocity changing with azimuth at different typical relative radius positions of the impeller disk after the speed changes. DETAILED DESCRIPTION

[0047] 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.

[0048] The purpose of the present invention is to provide a real-time variable speed rotor for high-speed forward flight, so as to improve the maximum forward flight speed of a helicopter.

[0049] 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.

[0050] Figure 3The present invention is a structural diagram of an embodiment of a real-time variable speed rotor for high-speed forward flight. Figure 4 Schematic diagram of the internal structure of the rotor shaft in the embodiment of the real-time variable speed rotor for high-speed forward flight of the present invention. Figure 3 and Figure 4 The real-time variable speed rotor for high-speed forward flight includes a first transmission link, a second transmission link and a controller (not shown in the figure).

[0051] The first transmission chain is provided with a first blade 1, a first rotor shaft 3, a first gear 14, a second gear 13, a first bevel gear 12, a second bevel gear 11 and a first motor 10 in sequence.

[0052] The second transmission chain is provided with a second blade 2, a second rotor shaft 4, a third gear 9, a fourth gear 8, a third bevel gear 7, a fourth bevel gear 6 and a second motor 5 in sequence.

[0053] The first blade 1 is vertically fixed to one end of the first rotor shaft 3; the first gear 14 is vertically fixed to the other end of the first rotor shaft 3; the second gear 13 is meshed with the first gear 14; the first bevel gear 12 is fixed together with the second gear 13 and has the same rotation axis and rotation speed; the second bevel gear 11 is meshed with the first bevel gear 12; the first motor 10 is connected to the second bevel gear 11; the first motor 10 drives the second bevel gear 11 to rotate, and the second bevel gear 11 cooperates with the first bevel gear 12 to achieve steering and first-stage deceleration, and the second gear 13 has the same rotation axis and rotation speed as the first bevel gear 12; the second gear 13 drives the first gear 14 to achieve secondary deceleration; the first gear 14 drives the first rotor shaft 3 to rotate; the first rotor shaft 3 drives the first blade 1 to rotate.

[0054] The second rotor shaft 4 is a hollow shaft, and the second rotor shaft 4 is sleeved on the middle part of the first rotor shaft 3; the second blade 2 is vertically fixed to one end of the second rotor shaft 4; the third gear 9 is vertically fixed to the other end of the second rotor shaft 4; the fourth gear 8 is meshed with the third gear 9; the third bevel gear 7 is solidified with the fourth gear 8 and has the same rotation axis and rotation speed; the fourth bevel gear 6 is meshed with the third bevel gear 7; the second motor 5 is connected with the fourth bevel gear 6; the second motor 5 drives the fourth bevel gear 6 to rotate, and the fourth bevel gear 6 cooperates with the third bevel gear 7 to achieve steering and first-stage deceleration, and the fourth gear 8 has the same rotation axis and rotation speed as the third bevel gear 7; the fourth gear 8 drives the third gear 9 to achieve second-stage deceleration; the third gear 9 drives the second rotor shaft 4 to rotate; the second rotor shaft 4 drives the second blade 2 to rotate.

[0055] The first rotor shaft 3 is provided with a first angle sensor 20; the first angle sensor 20 is used to obtain the total angle and number of revolutions of the first blade 1, and send the total angle and number of revolutions of the first blade 1 to the controller; the second rotor shaft 4 is provided with a second angle sensor 17; the second angle sensor 17 is used to obtain the total angle and number of revolutions of the second blade 2, and send the total angle and number of revolutions of the second blade 2 to the controller; the controller determines the rotation speed of the first blade 1 according to the total angle and number of revolutions of the first blade 1, and determines the rotation speed of the second blade 2 according to the total angle and number of revolutions of the second blade 2; the controller is connected to the first motor 10 and the second motor 5 respectively; the first motor 10 drives the first blade 1 to rotate according to the rotation speed of the first blade 1; the second motor 5 drives the second blade 2 to rotate according to the rotation speed of the second blade 2. The first blade 1 and the second blade 2 rotate independently, and the two blades have independent power sources, namely the first motor 10 and the second motor 5.

[0056] Among them, the second bevel gear 11 matches the first bevel gear 12 and has different gear ratios; the fourth bevel gear 6 matches the third bevel gear 7 and has different gear ratios; the second gear 13 matches the first gear 14 and has different gear ratios; the fourth gear 8 matches the third gear 9 and has different gear ratios. The first-stage deceleration achieved by the cooperation of the second bevel gear 11 and the first bevel gear 12, and the first-stage deceleration and the second-stage deceleration achieved by the second gear 13 driving the first gear 14 are the same as the first-stage deceleration and the second-stage deceleration achieved by the cooperation of the fourth bevel gear 6 and the third bevel gear 7, and the fourth gear 8 drives the third gear 9. The different speeds of the first blade 1 and the second blade 2 are based on the different output speeds of the motor 10 and the motor 5.

[0057] The controller determines the rotation speed of the first blade 1 according to the total angle and number of revolutions of the first blade 1, and determines the rotation speed of the second blade 2 according to the total angle and number of revolutions of the second blade 2, specifically:

[0058] The controller is based on the formula φ=α z -360°×n calculates the azimuth angle of the first blade 1 or the azimuth angle of the second blade 2; where φ represents the azimuth angle of the first blade 1 or the azimuth angle of the second blade 2, α z represents the total angle of rotation of the first blade 1 or the total angle of rotation of the second blade 2, and n represents the number of revolutions of the first blade 1 or the number of revolutions of the second blade 2.

[0059] The controller calculates the rotational speed of the first blade 1 and the rotational speed of the second blade 2 according to the formula Ω'=Ω-Asin(φ); wherein Ω' represents the rotational speed of the first blade 1 or the second blade 2, Ω represents the design rotational speed of the rotor, Ω is a constant value, A represents the amplitude of the rotor speed change, A=(0.5-0.8)μΩR, μ represents the advance ratio, R represents the rotor radius, and φ represents the azimuth angle of the first blade 1 or the azimuth angle of the second blade 2.

[0060] The controller is based on the formula Calculate the rotational speed of the first blade 1 and the rotational speed of the second blade 2; wherein Ω' represents the rotational speed of the first blade 1 or the second blade 2, Ω represents the design rotational speed of the rotor, Ω is a constant value, A represents the amplitude of the rotor speed change, A = (0.5-0.8) μΩR, μ represents the advance ratio, R represents the rotor radius, and φ represents the azimuth angle of the first blade 1 or the azimuth angle of the second blade 2.

[0061] The real-time variable speed rotor for high-speed forward flight also includes a first mass block 18 and a second mass block 19. The first mass block 18 is connected to the first rotor shaft 3; the first mass block 18 has the same mass as the first blade 1; the first mass block 18 is used to balance the centrifugal force on the first rotor shaft 3 when the first blade 1 rotates. The second mass block 19 is connected to the second rotor shaft 4; the second mass block 19 has the same mass as the second blade 2; the second mass block 19 is used to balance the centrifugal force on the second rotor shaft 4 when the second blade 2 rotates.

[0062] The real-time variable speed rotor for high-speed forward flight also includes a first thrust bearing 15 and a second thrust bearing 16. The first thrust bearing 15 and the second thrust bearing 16 are both arranged between the first rotor shaft 3 and the second rotor shaft 4. The first thrust bearing 15 and the second thrust bearing 16 are used to make the first rotor shaft 3 and the second rotor shaft 4 coaxial, ensure the coaxiality of the first rotor shaft 3 and the second rotor shaft 4, and play a role of fixed support.

[0063] During the operation of the real-time variable speed rotor for high-speed forward flight, the total angle and number of rotations of the first blade 1 and the second blade 2 can be obtained respectively through the first angle sensor 20 and the second angle sensor 17. The purpose of obtaining the total angle and number of rotations is to calculate the azimuth angle of the first blade 1 and the azimuth angle of the second blade 2 in the controller. The azimuth angle is fed back to the controller as an input quantity, and the speed of the rotor is calculated through a pre-designed speed change scheme, and then the real-time output speeds of the first motor 10 and the second motor 5 are changed through electrical signals, thereby finally achieving the effect of the rotor moving according to the pre-designed speed change scheme.

[0064] The specific speed change scheme design is as follows:

[0065] Table 1 gives the main parameters of the reference rotor (without considering variable speed):

[0066] Table 1 Reference rotor parameters

[0067]

[0068] Without considering the rotor downwash and speed change, V qf The forward flight speed of the rotor is a constant. When Ω is a constant, V qf =μΩR, so the incoming flow velocity of each blade element at different azimuth angles is:

[0069] V(r,φ)=Ωr+V qf sin(φ)=Ωr+μΩRsin(φ)

[0070] Among them, V is the incoming flow velocity of each blade element at different azimuth angles when no speed change is added, Ω is the design speed of the rotor, which refers to the speed of the rotor when the speed is not changed. It is a design parameter of the rotor and is a constant value, μ is the advance ratio, φ is the azimuth angle of the blade element, R is the rotor radius, and r is the radial position of the current blade element.

[0071] The incoming flow velocity refers to any small section of the blade along the span direction, namely the blade element. Taking hovering as an example, when the blade speed is determined, the incoming flow velocities at different positions on the blade are different, and the incoming flow velocity of each blade element is: rΩ / R; r represents the position of the blade element, R represents the rotor radius, which is a constant value, and Ω is the rotation speed at this moment, which is also a constant value and a fixed constant value at any time.

[0072] Take μ=0.5,R=2.5m,Ω=88.4rad / s=800rpm, and the blade element at radius 0.7R as an example. At this time, r=0.7R=1.75m, so V(1.75,φ)=88.4·1.75+0.5·88.4·2.5sin(φ). At this time, the blade element flow velocity changes with the angle of attack as follows: Figure 5 As shown. Figure 5 It can be seen that when the blade turns to an azimuth angle of 90°, that is, on the forward side, the incoming flow velocity for the blade element at 0.7R is the largest, reaching 250m / s. Because when the incoming flow velocity is too large, the resistance of the blade element at this location will increase sharply. Therefore, it is necessary to make the incoming flow velocity of the blade element on the forward side not too large. Therefore, it is considered to change the rotation speed so that Ω is no longer a constant, but a curve that changes with the azimuth angle.

[0073] Introduce a new speed: Ω' = Ω-Asin(φ), where Ω is the speed when the speed is constant, that is, 88.4rad / s. At this time, the speed Ω' changes with the azimuth angle. After considering the change in rotor speed, replace Ω' with V(r,φ) = Ωr+V qf By replacing the Ω in sin(φ), we can get the new incoming flow velocity V' of each blade element at different azimuth angles:

[0074] V'(r,φ)=Ω'r+V qf sin(φ)=(Ω-A sin(φ))r+V qf sin(φ)

[0075] =Ωr-Ar sin(φ)+μΩR sin(φ)

[0076] Among them, A is the amplitude of the rotor speed change. The rotor speed before the speed change is a constant Ω. The value of A cannot be too large, otherwise it will cause the rotation speed of the rear side to be too small, and the blade will be on the rear side for too long. The value of A cannot be too small, otherwise the effect of reducing the incoming flow velocity of the leading side blade element is not obvious. Generally, the empirical value A=(0.5-0.8)μΩR is taken, among which 0.5-0.8 is the empirical value, Ω is the constant value, Ω' is the rotor speed after the speed change. At this time, the rotor speed is not a constant Ω, and Ω' is related to the azimuth angle.

[0077] Under the same conditions of μ=0.5,R=2.5m,Ω=88.4rad / s,the blade element at radius 0.7R is compared. At this time, A=0.5μΩR=0.5·0.5·88.4·2.5=55.25, so: V'(1.75,φ)=88.4·1.75-55.25·1.75sin(φ)+0.5·88.4·2.5sin(φ). At this time, the blade element flow velocity changes with the angle of attack as shown in the following figure: Figure 6 As shown, it can be seen that when the azimuth angle is 90°, the incoming flow velocity of the blade element at a radius of 0.7R decreases to 180m / s, while at an azimuth angle of 270°, that is, the incoming flow velocity on the rear side increases from 50m / s to about 110m / s. By analyzing the case where the forward ratio is 0.5 and the speed change amplitude is 0.5μΩR, Figure 7 and Figure 8 The distribution of incoming flow velocity at various azimuth angles of the impeller disc is given respectively when there is no speed change and when there is a speed change. It can be seen that the area of ​​the rotor regurgitation zone is reduced. On the forward side of the rotor, the incoming flow velocity of the blade element at any position from 0° to 180° is lower than that when there is no speed change, especially the decrease in incoming flow velocity near the blade tip is more obvious.

[0078] The following gives the law of rotor speed change, and the control law is:

[0079] Ω'=Ω-Asin(φ)

[0080] Take A = 0.5μΩR, and the law of rotor speed change can be obtained through formula V', such as Fig. 9 shown.

[0081] Fig.10 The schematic diagram of the curve of the incoming flow velocity changing with azimuth at different radii is shown in Figure 2. Fig.10A comparison of the curves of the blade element incoming flow velocity versus azimuth angle is given with and without considering the change in rotor speed. The relative radius of 0.1 represents the blade element at 0.1R, which is closer to the blade root, and the relative radius of 1.0 represents the blade element at 1R, which is closer to the blade tip. At the same time, when the azimuth angle is 90°, the corresponding blade is on the forward side, and when the azimuth angle is 270°, the corresponding blade is on the backward side. When the blade is on the forward side, its incoming flow velocity is the rotor rotation speed superimposed on the forward flight speed. The incoming flow velocity is often large, which can easily cause shock waves to form on the blade element on the blade; when the blade is on the backward side, its incoming flow velocity is the rotor rotation speed minus the forward flight speed. In the area close to the blade root, a reversal area is often formed because the rotation speed is less than the forward flight speed, causing the blade element at the blade root to stall.

[0082] Compare the incoming flow velocity of the blade element with a relative radius of 0.1 with and without the change of rotor speed, that is, Fig.10 From the two curves in the middle and lower part, we can see that the difference between the two is small. After adding the speed change, the incoming flow velocity of the blade element near the rear side is only slightly increased, which means that the area of ​​the reversal area is reduced, that is, the negative incoming flow velocity is reduced, and the rotor performance is improved. Compare the incoming flow velocity of the blade element with a relative radius of 1 with and without the rotor speed change, that is Fig.10 From the two curves in the middle and upper part, we can see that the improvement of the airflow environment after adding the speed change is extremely obvious. When the blade is on the forward side, the blade element flow velocity is greatly reduced compared with the case without adding the speed change, making the flow velocity less than the critical Mach number, thereby weakening the effect of the shock wave and improving the aerodynamic performance. When the flow velocity is less than a certain value, the aerodynamic performance of the blade element increases with the increase of speed. When it is greater than this value, the blade element will produce a shock wave, and as the speed increases, the shock wave intensity increases, resulting in a sharp deterioration of the aerodynamic performance of the blade element. This value is called the critical Mach number. In addition, when the blade is on the rearward side, the blade element flow velocity is greatly increased compared with the case without adding the speed change, but it does not exceed the critical Mach number. Therefore, due to the increase in the flow velocity, the speed on the rearward side is also greatly improved.

[0083] In actual operation of the rotor, the lift is often borne by the blades at 0.6R-1R. Improving the flow environment of the blade element at this location is extremely important for improving rotor performance.

[0084] Discrete change of speed: In the actual process, in order to simplify the design of the speed control law of the rotor, the method of discretizing the speed to the azimuth angle is adopted, specifically:

[0085] When the rotor is at 0°-30°, the design speed when the blade is at an azimuth angle of 15° is used. Similarly, when the azimuth angle is 30°-60°, the design speed when the blade is at an azimuth angle of 45° is used, and so on. Fig.11 and Fig.12The actual rotor speed changes with azimuth and time (discrete changes) are given respectively. Due to the different rotor speeds, the time to rotate the same angle is also different. In engineering applications, the angle and number of rotations of the blades are often measured by pre-arranged angle sensors to obtain the azimuth of the blades, and then the flight control system (controller) is used to calculate the rotation angle of the blades. Fig.11 and Fig.12 The rotor speed is obtained according to the law of the curve of rotor speed changing with azimuth angle, and then converted into the speed ratio of the motor. Finally, the output speed of the motor is controlled to realize the change of rotor speed.

[0086] Fig.13 and Fig.14 The distribution of aerodynamic angle of attack in the disc plane before and after the rotor speed changes are given respectively. The induced speed adopts the uniform induced speed model. It can be seen that after the rotor speed changes, the area of ​​the negative aerodynamic angle of attack of the blade on the trailing side is significantly reduced, which is beneficial to improving the aerodynamic performance on the trailing side.

[0087] In addition, the variable rotor speed has a more obvious improvement on the aerodynamic performance when the blade is on the forward side. The distribution of the incoming flow velocity at each azimuth angle of the blade disc shows that the maximum incoming flow velocity on the forward side of the blade is 322.5833m / s when the rotor speed is constant, and when the rotor speed changes, the maximum incoming flow velocity on the forward side of the blade is 266.4245m / s. The aerodynamic characteristics of the NACA0012 airfoil at the same incoming flow angle of 8° are calculated, and the calculation results are shown in Table 2:

[0088] Table 2 Calculation results of aerodynamic characteristics of airfoil

[0089] Speed ​​(m / s) Lift(N) Resistance (N) Lift coefficient Drag coefficient 266.4245 2179.6729 4406.8806 0.0501 0.1014 322.5833 156.6123 13399.0885 0.0025 0.2102

[0090] It can be seen that the aerodynamic characteristics of the airfoil when the incoming flow velocity is 266.4245 m / s are far superior to those when the incoming flow velocity is 322.5833 m / s, which is not only reflected in the larger lift coefficient, but also in the smaller drag coefficient, where the force coefficient is defined as divided by the far-field dynamic pressure.

[0091] Fig.15 and Fig.16 The pressure cloud diagrams when the incoming flow velocity is 266.4245m / s and 322.5833m / s are respectively given. It can be seen that when the incoming flow velocity is 322.5833m / s, the pressure changes dramatically, which is also the reason for the surge in resistance. The aerodynamic characteristics of the blade element often determine the performance of the rotor. The simulation shows that the rotor speed change strategy established in this embodiment is of great benefit to improving the rotor performance at high speed.

[0092] Other speed change strategies:

[0093] Fig.17 Another rotor speed variation law is given. When designing this control law, Ω'=Ω-Asin(φ) is used as a reference and three straight line fitting is adopted:

[0094]

[0095] Taking the reference rotor described in Table 1 as an example, taking A = 0.5 μΩR, the rotor speed variation law can be obtained as follows: Fig.17 shown.

[0096] Fig.18 and Fig.19 The following are the curves of blade element incoming flow velocity versus azimuth angle at typical different relative radius positions of the impeller disc before and after the speed change. By comparing the incoming flow velocity of the blade element before and after the speed change, it can be seen that when the blade is located on the forward side, that is, at an azimuth of 90°, the incoming flow velocity of the blade element near the root of the blade, that is, at a relative radius of 0.1, does not change much. However, as the blade element position gets closer to the blade tip, the larger the relative radius, indicating that the closer the blade element is to the blade tip, the more obvious the decrease in incoming flow velocity. This indicates that the use of this rotor speed change can reduce the incoming flow velocity of the blade element near the tip area of ​​the blade on the forward side, reduce the shock wave intensity, and improve the aerodynamics of the blade on the forward side. Performance; when the blade is located on the rearward side, that is, when the azimuth angle is 270°, the incoming flow velocity of the blade element near the root of the blade, that is, at the relative radius of 0.1, increases slightly, indicating that the area of ​​the regurgitation zone formed on the rearward side of the rotor is reduced to a certain extent, and as the position of the blade element gets closer and closer to the tip of the blade, the incoming flow velocity gradually increases. When the blade moves to the rearward side, the incoming flow velocity of the blade element near the tip area does not reach the critical Mach number, so the aerodynamic performance of the blade element at this location increases with the increase of the incoming flow velocity, ultimately improving the aerodynamic performance of the rotor on the rearward side.

[0097] The present invention combines electric rotor technology, that is, uses a motor as a power source to drive the rotor, and proposes a design concept based on real-time variable speed, so as to realize a rotor that reduces the Mach number of the incoming flow of the forward blade and delays the separation of the airflow of the backward blade when the helicopter flies at a high speed. When the blade moves to the forward side, due to the superposition of the forward flight speed, the incoming flow speed of each blade element on the blade is relatively large. At this time, the rotation speed of the rotor is reduced, the incoming flow Mach number of the blade is reduced, and the generation of shock waves is slowed down or even avoided; when the blade moves to the backward side, due to the subtraction of the forward flight speed, the incoming flow speed of each blade element on the blade is reduced, and even a reflow zone appears in the area near the blade root. At this time, the rotor rotation speed is appropriately increased, which can reduce the area of ​​the reflow zone to a certain extent and improve the aerodynamic performance of the rotor; combining these two aspects, the rotor working environment of the helicopter under high-speed forward flight is finally improved, and the maximum forward speed of the helicopter is increased.

[0098] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0099] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea 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 real-time variable speed rotor for high-speed forward flight, characterized in that: The rotor includes a first transmission link, a second transmission link and a controller; The first transmission chain is provided with a first blade, a first rotor shaft, a first gear, a second gear, a first bevel gear, a second bevel gear and a first motor in sequence; The second transmission chain is provided with a second blade, a second rotor shaft, a third gear, a fourth gear, a third bevel gear, a fourth bevel gear and a second motor in sequence; The first blade is vertically fixed to one end of the first rotor shaft; the first gear is vertically fixed to the other end of the first rotor shaft; The second gear is meshed with the first gear; the first bevel gear and the second gear are fixed together; the second bevel gear is meshed with the first bevel gear; The first motor is connected to the second bevel gear; the first motor drives the second bevel gear to rotate, the second bevel gear cooperates with the first bevel gear to achieve steering and primary reduction, the second gear and the first bevel gear have the same rotation axis and rotation speed; the second gear drives the first gear to achieve secondary reduction; the first gear drives the first rotor shaft to rotate; the first rotor shaft drives the first blade to rotate; The second rotor shaft is a hollow shaft, and the second rotor shaft is sleeved in the middle of the first rotor shaft; the second blade is vertically fixed to one end of the second rotor shaft; the third gear is vertically fixed to the other end of the second rotor shaft; the fourth gear is meshed with the third gear; the third bevel gear is fixed with the fourth gear; the fourth bevel gear is meshed with the third bevel gear; The second motor is connected to the fourth bevel gear; the second motor drives the fourth bevel gear to rotate, the fourth bevel gear cooperates with the third bevel gear to achieve steering and primary reduction, the fourth gear and the third bevel gear have the same rotation axis and rotation speed; the fourth gear drives the third gear to achieve secondary reduction; the third gear drives the second rotor shaft to rotate; the second rotor shaft drives the second blade to rotate; A first angle sensor is provided on the first rotor shaft; the first angle sensor is used to obtain the total angle and number of revolutions of the first blade, and send the total angle and number of revolutions of the first blade to the controller; a second angle sensor is provided on the second rotor shaft; the second angle sensor is used to obtain the total angle and number of revolutions of the second blade, and send the total angle and number of revolutions of the second blade to the controller; the controller determines the rotation speed of the first blade according to the total angle and number of revolutions of the first blade, and determines the rotation speed of the second blade according to the total angle and number of revolutions of the second blade; the controller is connected to the first motor and the second motor respectively; the first motor drives the first blade to rotate according to the rotation speed of the first blade; the second motor drives the second blade to rotate according to the rotation speed of the second blade; The second bevel gear has a different gear ratio than the first bevel gear; the fourth bevel gear has a different gear ratio than the third bevel gear; The rotor also includes a first mass and a second mass; The first mass block is connected to the first rotor shaft; the mass of the first mass block is equal to that of the first blade; the first mass block is used to balance the centrifugal force on the first rotor shaft when the first blade rotates; The second mass block is connected to the second rotor shaft; the mass of the second mass block is equal to that of the second blade; and the second mass block is used to balance the centrifugal force on the second rotor shaft when the second blade rotates.

2. The real-time variable speed rotor for high-speed forward flight according to claim 1, characterized in that: The second gear has a different gear ratio than the first gear; and the fourth gear has a different gear ratio than the third gear.

3. The real-time variable speed rotor for high-speed forward flight according to claim 1, characterized in that: The rotor also includes a first thrust bearing and a second thrust bearing; The first thrust bearing and the second thrust bearing are both arranged between the first rotor shaft and the second rotor shaft, and the first thrust bearing and the second thrust bearing are used to make the first rotor shaft and the second rotor shaft coaxial.

4. The real-time variable speed rotor for high-speed forward flight according to claim 1, characterized in that: The controller is based on the formula φ=α z -360o×n calculates the azimuth angle of the first blade or the azimuth angle of the second blade; Where φ represents the azimuth angle of the first blade or the azimuth angle of the second blade, α z represents the total angle of rotation of the first blade or the total angle of rotation of the second blade, and n represents the number of revolutions of the first blade or the number of revolutions of the second blade.

5. The real-time variable speed rotor for high-speed forward flight according to claim 1, characterized in that: The controller calculates the rotational speed of the first blade and the rotational speed of the second blade according to the formula Ω'=Ω-Asin(φ); wherein Ω' represents the rotational speed of the first blade or the second blade, Ω represents the design rotational speed of the rotor, Ω is a constant value, A represents the amplitude of the rotor speed change, A=(0.5-0.8)μΩR, μ represents the advance ratio, R represents the rotor radius, and φ represents the azimuth angle of the first blade or the azimuth angle of the second blade.

6. The real-time variable speed rotor for high-speed forward flight according to claim 1, characterized in that: The controller is based on the formula Calculate the rotational speed of the first blade and the rotational speed of the second blade; wherein Ω' represents the rotational speed of the first blade or the second blade, Ω represents the design rotational speed of the rotor, Ω is a constant value, A represents the amplitude of the rotor speed change, A = (0.5-0.8) μΩR, μ represents the advance ratio, R represents the rotor radius, and φ represents the azimuth angle of the first blade or the azimuth angle of the second blade.

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