Self-adaptive deformation rotor wing capable of flying at high speed and large advance ratio and control method of self-adaptive deformation rotor wing

Abstract

The invention provides a high-speed large-advance-ratio flight self-adaptive deformation rotor wing which comprises a blade inner section, a blade outer section, a blade inner section and a blade outer section. The actuating system is arranged at the inner section of the blade, and the actuating system adjusts the actuating amplitude according to the rotating speed of the rotor wing and the forward flying speed and changes the bending degree of the blade in the reflux area; meanwhile, the invention further provides a control method of the self-adaptive deformation rotor wing for high-speed large-advance-ratio flight. Through the application of the deformable rotor wing, the front edge sags down, the rear edge is reversed down, the wing profile camber is increased, the negative lift force of a reflux area is reduced, the loss is reduced, the rotor wing performance of the reflux area is improved, and meanwhile the rotor wing control load is reduced.

Description

Technical Field

[0001] The present application belongs to the technical field of active flow control of rotors, and in particular relates to an adaptive deformable rotor capable of high-speed and high-advance-ratio flight and a control method thereof. Background Art

[0002] During the forward flight of a helicopter rotor, the rotor rotates one circle, and the difference in aerodynamic environment experienced by the forward and rearward blades of the rotor increases. The relative airflow speed of the forward blade is the resultant speed of the rotor speed and the forward flight speed. As the relative speed increases, the dynamic pressure increases, the lift increases, and the airflow flows from the leading edge to the trailing edge of the blade; the relative airflow speed of the rearward blade is the difference between the rotor speed and the forward flight speed. As the relative speed decreases, the dynamic pressure decreases, and the lift decreases. In order to maintain the balance of lift between the leading and trailing sides, the angle of attack of the rearward blade is increased and the angle of attack of the forward blade is reduced through cyclic pitch control. At this time, the rearward blade is in a large angle of attack state, and large-scale flow separation occurs, which in turn causes a complex unsteady dynamic stall phenomenon. The dynamic stall of the rotor causes a sharp increase in resistance.

[0003] At the same time, the airflow in the inner section of the trailing side flows from the trailing edge to the leading edge of the blade, forming a reversal area. The upper surface of the blade is the windward side, and the lower surface is the leeward side. The pressure on the upper surface increases, generating negative lift, increasing resistance, and significantly increasing power demand. As the speed increases, the reversal range of the inner section of the trailing blade increases, the rotor reversal area increases, the resistance increases, the negative lift increases, and the power consumption further increases, causing the performance of the trailing rotor to drop sharply. The larger the reversal area, the greater the difference in lift between the front and rear sides, the greater the rolling moment, and the greater the lateral cyclic pitch change, resulting in a large control load. When the control cannot meet the left and right balance, it may cause a certain lift bias phenomenon, thereby restricting the further improvement of the helicopter's aerodynamic performance.

[0004] While a superior airfoil and aerodynamic layout can improve the rotor's overall aerodynamic performance, they cannot guarantee optimal rotor performance at all phases at high advance ratios. Nor can they address the unsteady flow effects of the large reverse flow zone on the trailing side of a high-speed, high-advance-ratio rotor. The increased drag, negative lift, and high torque caused by the reverse flow result in significant control loads.

[0005] Therefore, how to improve the aerodynamic performance of the rotor in the large reversal area at high speed and large forward ratio is of great significance. Summary of the Invention

[0006] Purpose of the invention: In order to improve the reversal zone performance of a high-speed, high-advance ratio rotor, the present application provides an adaptive deformable rotor for high-speed, high-advance ratio flight and a control method thereof.

[0007] In a first aspect, the present application provides an adaptive morphing rotor capable of high-speed and high-advance-ratio flight, comprising:

[0008] an inner section of the blade, wherein the inner section of the blade is located in a counterflow area;

[0009] The actuation system is arranged in the inner section of the blade. The actuation system adjusts the actuation amplitude according to the rotor rotation speed and the forward flight speed to change the blade curvature in the regurgitation area.

[0010] Preferably, the inner blade section comprises:

[0011] a middle wing section, for installing the actuation system;

[0012] Leading edge ribs, connected to the middle wing section and the actuation system respectively;

[0013] The trailing edge ribs are connected to the middle wing section and the actuation system respectively; wherein the leading edge ribs and the trailing edge ribs are located at both ends of the middle wing section.

[0014] Preferably, the actuation system comprises:

[0015] a first actuation system, disposed on the middle wing section near the leading edge rib, the first actuation system being connected to the leading edge rib;

[0016] The second actuation system is arranged at a position on the middle wing section close to the trailing edge rib, and the second actuation system is connected to the trailing edge rib.

[0017] Preferably, the leading edge rib comprises:

[0018] a first leading edge rib connected to the first actuation system;

[0019] A second leading edge rib, one side of the second leading edge rib is connected to the first leading edge rib through a first deflection axis, the other side of the second leading edge rib is connected to one side of the middle wing section through a second deflection axis, and the other side of the second leading edge rib is connected to the first actuation system.

[0020] Preferably, the trailing edge rib comprises:

[0021] a first trailing edge rib connected to the second actuation system;

[0022] A second trailing edge rib, one side of the second trailing edge rib is connected to the first trailing edge rib through a first deflection axis, the other side of the second trailing edge rib is connected to one side of the middle wing section through a second deflection axis, and the other side of the second trailing edge rib is connected to the second actuation system.

[0023] Preferably, the first actuation system comprises:

[0024] a first micro motor, disposed on the middle wing section near the second leading edge rib;

[0025] a first gear located on one side of the first micromotor, the first gear being engaged with the first micromotor, and the first gear being connected to the first leading edge rib via a first crank connecting rod;

[0026] The second gear is located on the other side of the first micro motor, is engaged with the first micro motor, and is connected to the second leading edge rib through a second crank connecting rod.

[0027] Preferably, the first actuation system comprises:

[0028] a second micro motor, disposed on the middle wing section near the second trailing edge rib;

[0029] a third gear located on one side of the second micromotor, the third gear meshing with the second micromotor, and the third gear connected to the first trailing edge rib via a third crank connecting rod;

[0030] The fourth gear is located on the other side of the second micro motor, the fourth gear is engaged with the second micro motor, and the fourth gear is connected to the second trailing edge rib through a fourth crank connecting rod.

[0031] In a second aspect, the present application further provides a method for controlling an adaptive morphing rotor for high-speed and high-advance-ratio flight, the method comprising:

[0032] When the helicopter is in high-speed forward flight, the micro motors on the leading and trailing edges of the blades are simultaneously activated when the blades are at a 90° azimuth angle on the forward side.

[0033] The micro motor drives the crank-connecting rod mechanism through gears to actuate the leading edge ribs and trailing edge ribs, causing the blade profile to change in curvature.

[0034] The curvature of the inner section of the blade changes synchronously and continuously along the span direction until it reaches the connection with the outer section. A micro motor is used to coaxially connect the variable curvature ribs of each section of the inner section of the blade. A set of crank-connecting rod mechanisms are synchronously arranged on the ribs of each section, and the gear transmission on each section is used to drive the curvature change of each section. The curvature change amplitude of each section can be adjusted by adjusting the length of the crank-connecting rod mechanism, that is, adjusting the nodes of the leading edge ribs and the trailing edge ribs with the connecting rod mechanism.

[0035] Beneficial technical effects of this application:

[0036] The present application provides an adaptive deformable rotor suitable for high-speed and high-advance-ratio flight. Through the use of the rotor, the leading edge droops and the trailing edge reverses downward, increasing the camber of the airfoil, reducing the negative lift in the regurgitation zone, reducing losses, improving the rotor performance in the regurgitation zone, and reducing the rotor control load. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Schematic diagram of the relative velocity distribution of the blades in the rotation plane provided by an embodiment of the present invention;

[0038] Figure 2 is a schematic diagram of a deformable rotor model provided by an embodiment of the present invention;

[0039] Figure 3 This is a structural diagram of a movable rib provided by an embodiment of the present invention;

[0040] Figure 4 This is a diagram showing the effect of adjusting the camber of the movable rib structure provided by an embodiment of the present invention;

[0041] Figure 5 is an assembly diagram of ribs and blades provided by an embodiment of the present invention;

[0042] Figure 6 This is a diagram of the assembly of the rib and the blade after deformation provided by an embodiment of the present invention;

[0043] Figure 7 is a comparison diagram of a reference airfoil and a variable camber airfoil provided by an embodiment of the present invention;

[0044] Figure 8 is a flow field diagram of the airfoil surface in the reverse flow area of a reference airfoil provided by an embodiment of the present invention;

[0045] Figure 9 This is a flow field diagram of the airfoil surface in the reverse flow area of a variable camber airfoil provided by an embodiment of the present invention;

[0046] Figure 10 1. A comparison diagram of the surface Mach numbers in the reverse flow region of a reference airfoil and a variable camber airfoil provided in an embodiment of the present invention;

[0047] Figure 11 This is a comparison diagram of the surface pressure in the reverse flow area of a reference airfoil and a variable camber airfoil provided in an embodiment of the present invention;

[0048] Figure 12 1 is a comparison diagram of the drag coefficients of a reference airfoil and a variable camber airfoil at different reverse flow angles of attack provided by an embodiment of the present invention;

[0049] Figure 13 1. A comparison diagram of lift coefficients of a reference airfoil and a variable camber airfoil at different reverse flow angles of attack provided by an embodiment of the present invention;

[0050] Figure 14 1 is a comparison diagram of lift-to-drag ratios of a reference airfoil and a variable camber airfoil at different reverse flow angles of attack provided by an embodiment of the present invention;

[0051] Figure 15This is a graph of the chordwise component of the Mach number of a 0.3R airfoil section (400 km / h, 85% Ω0) after one rotation, provided by an embodiment of the present invention;

[0052] Figure 16 1. This is a graph showing the deformation deflection of the leading edge 1 and 2 sections and the trailing edge 1 and 2 sections of the initial section of the deformable rotor provided by an embodiment of the present invention;

[0053] Figure 17 This is a lift comparison curve diagram of the reference airfoil and the initial section deflected airfoil provided by an embodiment of the present invention after one rotation;

[0054] Among them: 1-reverse flow area; 2-adjustable rib; 3-inner section of the blade; 4-outer end of the blade; 5-first leading edge rib; 6-second leading edge rib; 7-first deflection axis; 8-second deflection axis; 9-first crank-connecting rod mechanism; 10-second crank-connecting rod structure; 11-first gear; 12-second gear; 13-first micro motor; 14-first trailing edge rib; 15-second trailing edge rib; 16-third deflection axis; 17-fourth deflection axis; 18-third crank-connecting rod mechanism; 19-fourth crank-connecting rod structure; 20-third gear; 21-fourth gear; 22-second micro motor. DETAILED DESCRIPTION

[0055] This application implements active flow control on the rotor, increasing the camber of the blade surface in the reverse flow zone, effectively compensating for the performance degradation caused by negative lift in the reverse flow zone. This can further improve the flow in the rotor reverse flow zone, reduce upper surface pressure, lower negative lift in the reverse flow zone, and reduce control loads, thereby improving the aerodynamic performance of the entire rotor.

[0056] This application utilizes a micro motor, a gear set, and a crank-connecting rod mechanism to form an actuation system, which intelligently adjusts the micro motor speed and the actuation amplitude of the crank-connecting rod mechanism according to the rotor speed and forward flight speed, thereby changing the curvature of the blades in the regurgitation zone.

[0057] The present application provides an adaptive deformable rotor suitable for high-speed and high-advance-ratio flight. Through the use of the rotor, the leading edge droops and the trailing edge reverses downward, increasing the camber of the airfoil, reducing the negative lift in the regurgitation zone, reducing losses, improving the rotor performance in the regurgitation zone, and reducing the rotor control load.

[0058] See also Figures 1-17 In other embodiments of the present application, the present invention is further described in detail as follows.

[0059] Based on the naca23012 airfoil, the conventional rectangular blade layout is used. The blade is radially divided into an inner section and an outer section by the regurgitation zone. The outer section is the original blade structure, and the aerodynamic shape and structure do not change. The inner section in the regurgitation zone is divided into 5 sections according to the chord direction. Before 25%C, it is divided into leading edge sections 1 and 2 as active parts that deflect around 25%C, of which the leading edge section 1 also deflects around 12.5%C; after 75%C, it is divided into trailing edge sections 1 and 2 as active parts that deflect around 75%C, of which the trailing edge section also deflects around 87.5%C; the middle wing section is fixed with the outer blade and only performs pitch variation movement, and the inner section blade adjusts the curvature by the deflection movement of the leading and trailing edges.

[0060] Divide the inner blade into several small sections and adjust the curvature successively. Figure 2 The blade surface camber adjustment uses active ribs and mechanical control and elastic materials to perform blade variant movement, causing the leading edge to deflect downward and the trailing edge to deflect downward in the opposite direction. The mechanical control consists of a micro motor installed on the rib, a transmission gear set, and a crank-connecting rod mechanism. The micro motor speed and the crank-connecting rod mechanism's actuation amplitude are intelligently adjusted according to the rotor speed and forward flight speed. The micro motor speed frequency is consistent with the rotor rotation frequency. Figure 3 、 Figure 4 The gaps between moving parts are made of high-performance rubber, which makes it resistant to expansion and compression, and makes the blade surface smooth and changeable. This can increase the curvature of the airfoil, improve the rotor performance in the backflow area, and reduce the rotor control load.

[0061] The radial deflection amplitude of the inner deformed blade gradually decreases backward from the starting section of the airfoil, which is achieved through a deflection axis. The deflection axis has a control node on each deflection section. A micro motor is configured on the first control node to drive the crank-connecting rod mechanism of the section to move, and then the crank-connecting rod mechanisms of the remaining sections are connected through the deflection axis to move synchronously. The deflection amplitude of each section can be reduced step by step by adjusting the length of the crank-connecting rod.

[0062] The present invention aims at a forward flight speed of 400 km / h. In order to reduce the shock wave drag at the blade tip on the forward side, the rotor speed is reduced to 85% Ω0 (Ω0 corresponds to the rotor blade tip Mach number Ma = 0.65 m / s). At this time, the reverse flow area on the backward side of the rotor reaches 59% R, and the circumferential phase is 210° to 330° as the range of the reverse flow area. Figure 15 , which has a certain impact on the rotor performance.

[0063] The blades in the large reverse flow area on the trailing side are divided into several small sections. The closer to the rotor rotation center in the reverse flow area, the greater the reverse flow. Generally, there is no significant aerodynamic surface in the transition area from the hub arm to the starting section of the airfoil, so it can be ignored. From the starting section of the airfoil to the reverse flow boundary, the reverse flow speed gradually decays. Therefore, the curvature of the airfoil section at different radial positions gradually decreases from the starting section of the airfoil to the reverse flow boundary. Figure 5 、 Figure 6 , gradual and continuous changes also take into account factors such as dynamics.

[0064] The deformation of the blade starts at the forward side azimuth angle Ψ = 90°, reaches the maximum camber at the backward side Ψ = 270°, returns to the forward side Ψ = 90° and reaches the original position, completing the deformation of one rotor rotation cycle. β 2n The leading edge of the blade at the corresponding azimuth angle is deflected around the 25% chord to the upper and lower airfoil mid-axis, β 1n is the angle of deflection of the leading edge of the blade at the corresponding azimuth angle around the upper and lower wing axis at 12.5% of the chord direction. Similarly, the angle deflection of the trailing edge 1 and 2 is the same as Figure 8 As shown. 1n and A 2n The adjustment range of the camber of the leading and trailing edges of the blade is defined as N, which represents the number of segmented rib sections of the blade in the backflow area. n represents the sequence number of the deformation of the starting section section, indicating that the starting section section n = 0, the next deformation section n = 1, and so on, according to the linear change rule of the camber A 11 and A 21 It can be adjusted adaptively according to the size of the forward ratio. This paper follows A 11 =20°, A 21 =10° to design as Figure 16 .

[0065] Comparison between the baseline airfoil and the camber deformed airfoil in the backflow area Figure 7 , the flow at a large angle of attack is as follows Figure 8 、 Figure 9 . When the incoming flow is reversed and flows toward the trailing edge, the airflow separates at the wingtip, and the downward airflow separates under the leeward airfoil to form a separation vortex, and a negative pressure area is formed on the lower surface. Therefore, the change in the curvature of the airfoil has little effect on the lower surface. After the airflow separates at the wingtip, the upper airflow adheres to the upper surface of the airfoil and flows to the leading edge. The relative angle of attack of the trailing edge of the deflected airfoil is larger, and the Mach number on the boundary layer of the airfoil increases faster. The angle of attack at the transition point decreases, and the Mach number on the airfoil decreases accordingly. The relative angle of attack of the second section of the trailing edge is greater than that of the reference airfoil, and the Mach number on the airfoil increases rapidly again. Although it decreases again at the transition point, the flow velocity of the entire airfoil is increased. The leading edge of the airfoil is deflected downward, and the velocity decreases rapidly. The upper surface of the deflected airfoil increases the flow velocity. Figure 10 , the upper surface pressure decreases as Figure 11 , due to the negative lift generated by the reverse flow, the negative lift is reduced. Although the drag of the deflected camber airfoil increases, the overall lift-to-drag ratio increases significantly. Figures 12-14 , thereby improving the aerodynamic performance of the airfoil under reverse flow.

[0066] Through numerical analysis, the rotor rotates one circle, and the corresponding station has better lift than the straight airfoil. Although the drag increases, the lift increase is more significant. In general, this way of increasing the camber can significantly improve the performance of the rotor. Figure 17 shown.

[0067] Based on a conventional rectangular blade, this application divides the blade into two sections, an inner section and an outer section, separated by the reverse flow zone. The outer section retains the original blade structure and its aerodynamic shape remains unchanged. The inner section, located in the reverse flow zone, is designed separately, using elastic materials and mechanical control methods to modify the blade. This increases the airfoil camber, improves rotor performance in the reverse flow zone, and reduces rotor control loads.

Claims

1. An adaptive morphing rotor capable of high-speed and high-speed flight, characterized in that: include: an inner section of the blade, wherein the inner section of the blade is located in a counterflow area; The actuation system is arranged in the inner section of the blade. The actuation system adjusts the actuation amplitude according to the rotor rotation speed and the forward flight speed to change the blade curvature in the regurgitation area.

2. The adaptive morphing rotor for high-speed and high-advance-ratio flight according to claim 1, characterized in that: The inner section of the blade comprises: a middle wing section, for installing the actuation system; Leading edge ribs, connected to the middle wing section and the actuation system respectively; The trailing edge ribs are connected to the middle wing section and the actuation system respectively; wherein the leading edge ribs and the trailing edge ribs are located at both ends of the middle wing section.

3. The adaptive morphing rotor for high-speed and high-advance-ratio flight according to claim 2, characterized in that: The actuation system comprises: a first actuation system, disposed on the middle wing section near the leading edge rib, the first actuation system being connected to the leading edge rib; The second actuation system is arranged at a position on the middle wing section close to the trailing edge rib, and the second actuation system is connected to the trailing edge rib.

4. The adaptive morphing rotor for high-speed and high-advance-ratio flight according to claim 3, characterized in that: The leading edge rib comprises: a first leading edge rib connected to the first actuation system; A second leading edge rib, one side of the second leading edge rib is connected to the first leading edge rib through a first deflection axis, the other side of the second leading edge rib is connected to one side of the middle wing section through a second deflection axis, and the other side of the second leading edge rib is connected to the first actuation system.

5. The adaptive morphing rotor for high-speed and high-advance-ratio flight according to claim 3, characterized in that: The trailing edge rib comprises: a first trailing edge rib connected to the second actuation system; A second trailing edge rib, one side of the second trailing edge rib is connected to the first trailing edge rib through a first deflection axis, the other side of the second trailing edge rib is connected to one side of the middle wing section through a second deflection axis, and the other side of the second trailing edge rib is connected to the second actuation system.

6. The adaptive morphing rotor for high-speed and high-advance-ratio flight according to claim 4, characterized in that: The first actuation system comprises: a first micro motor, disposed on the middle wing section near the second leading edge rib; a first gear located on one side of the first micromotor, the first gear being engaged with the first micromotor, and the first gear being connected to the first leading edge rib via a first crank connecting rod; The second gear is located on the other side of the first micro motor, is engaged with the first micro motor, and is connected to the second leading edge rib through a second crank connecting rod.

7. The adaptive morphing rotor for high-speed and high-advance-ratio flight according to claim 5, characterized in that: The first actuation system comprises: a second micro motor, disposed on the middle wing section near the second trailing edge rib; a third gear located on one side of the second micromotor, the third gear meshing with the second micromotor, and the third gear connected to the first trailing edge rib via a third crank connecting rod; The fourth gear is located on the other side of the second micro motor, the fourth gear is engaged with the second micro motor, and the fourth gear is connected to the second trailing edge rib through a fourth crank connecting rod.

8. An adaptive morphing rotor control method for high-speed and high-advance-ratio flight, characterized in that: The method comprises: When the helicopter is in high-speed forward flight, the micro motors on the leading and trailing edges of the blades are simultaneously activated when the blades are at a 90° azimuth angle on the forward side. The micro motor drives the crank-connecting rod mechanism through gears to actuate the leading edge ribs and trailing edge ribs, causing the blade profile to change in curvature. The curvature of the inner section of the blade changes synchronously and continuously along the span direction until it reaches the connection with the outer section. A micro motor is used to coaxially connect the variable curvature ribs of each section of the inner section of the blade. A set of crank-connecting rod mechanisms are synchronously arranged on the ribs of each section, and the gear transmission on each section is used to drive the curvature change of each section. The curvature change amplitude of each section can be adjusted by adjusting the length of the crank-connecting rod mechanism, that is, adjusting the nodes of the leading edge ribs and the trailing edge ribs with the connecting rod mechanism.

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