Open fan components of open rotary engines, open rotary engines, and noise reduction methods

Abstract

This application relates to an open fan component of an open rotor engine, an open rotor engine, and a noise reduction method. The open fan component includes a stator with stator blades; a rotor with rotor blades, the stator blades being located downstream of the rotor blades; the rotor blades are provided with a plasma actuator array, the plasma actuator array having multiple plasma actuators; the open fan component has a standby state, a first operating state, a second operating state, and a third operating state.

Description

TECHNICAL FIELD

[0001] The present application relates to an open fan component of an open rotor engine, an open rotor engine and a noise reduction method. BACKGROUND

[0002] The open rotor engine, also known as the open fan engine, has the characteristics of low fuel consumption of turboprop engine and high flight speed of turbofan engine. Compared with the turbofan engine of the same technical level, the open fan engine has the technical advantages of high propulsion efficiency, low fuel consumption and high cycle efficiency, but at the same time, it also has the technical difficulties of difficulty in integration of fan and engine, too high noise and poor reliability. The biggest challenge is the noise problem. For the unducted open rotor engine, the noise generated by the propeller fan cannot be weakened by the way of shortening the cabin sound absorption lining as in the traditional turbofan engine, but can only be improved by aerodynamic acoustic design, which further highlights the importance of aerodynamic acoustic design technology in the design of propeller fan. The biggest noise source comes from the open fan component. The noise spectrum of a typical open fan component is shown in the figure, which is composed of single tone noise and broadband noise. It includes 1st and 2nd blade passing frequency (BPF), broadband noise and vibration shaft frequency single tone. Figure 2

[0003] The primary goal of solving the noise problem is to limit the noise regulations of airworthiness, and the regulations limit the noise radiation energy received by the microphone measuring point corresponding to the three flight conditions of approach, flyover and sideline of the aircraft during the airport landing stage. The specific noise measuring point is shown in the figure. Figure 1 The approach measuring point A, the sideline measuring point S and the flyover measuring point F are shown in the figure. In addition, since the human ear is more sensitive to high-energy single tone noise, the single tone correction penalty of the BPF single tone shown in the figure is carried out by the airworthiness regulations, highlighting the disturbing effect of single tone noise on the human ear. Whether the BPF noise of the engine can be controlled is the key for the engine to pass the airworthiness regulations. Figure 2

[0004] A comparative scheme of the structure design of the open fan engine is shown in the figure. Figure 3 ​​As shown, the open-type fan component includes a rotor and a stator. The stator may include stator blades 1, a stator fixing connection device 4, and a casing 6. The rotor may include rotor blades 2 and a rotating shaft 3. The main function of the upstream rotor blades 2 is to accelerate the air and generate thrust. Through high-speed rotation, the rotor blades can transfer energy to the airflow, causing it to accelerate backward and thus generate forward thrust. The downstream fixed blades 1 mainly function to rectify and guide the airflow. The airflow accelerated by the rotor blades 2 usually has a certain rotational component. The stator blades 2 can reduce this rotational motion, rectifying the airflow into a smoother direct current, which helps to reduce eddies and energy loss, and improve aerodynamic efficiency. The inventors discovered that... Figure 2 The BPF noise shown is mainly composed of two parts: single tones generated by individual rotor blades and single tones generated by interference from rotor-stator blade tip eddies and viscous wakes. The inventors discovered that... Figure 3 The comparative schemes shown are unlikely to meet the noise requirements of airworthiness regulations.

[0005] In one existing technology, such as the Chinese patent application with publication number CN120402189A entitled "Open fan component of open rotor engine, open rotor engine and noise reduction method", a solution is disclosed that achieves a noise reduction effect that balances the aerodynamic efficiency of rotor blades and airworthiness through a mechanical telescopic structure. However, the inventors further discovered that the above solution still requires sacrificing some aerodynamic performance, and in order not to affect aerodynamic performance too much, there is room for further improvement in its noise reduction effect.

[0006] Therefore, there is a need in the field for a new open fan component for an open rotor engine, an open rotor engine, and a noise reduction method, in order to further improve the noise reduction effect while minimizing the impact on aerodynamic performance, especially taking into account the noise reduction effect under three airworthiness conditions. Summary of the Invention

[0007] One object of this application is to provide an open fan component for an open rotor engine.

[0008] One objective of this application is to provide a noise reduction method.

[0009] One object of this application is to provide an open rotary engine.

[0010] An open fan component of an open rotor engine according to a first aspect of this application includes a stator, comprising stator blades; a rotor, comprising rotor blades, the stator blades being located downstream of the rotor blades; the rotor blades being provided with a plasma actuator array, the plasma actuator array having multiple plasma actuators; the open fan component has a standby state, a first operating state, a second operating state, and a third operating state: in the standby state, the plasma actuator array is off; in the first operating state, the plasma actuator array is on, a first portion of the plasma actuators in the plasma actuator array are on, the voltage amplitude of the plasma actuators is a first amplitude, the pulse modulation frequency is a first frequency, and the duty cycle is... In the first duty cycle; in the second operating state, the plasma actuator array is turned on, the second part of the plasma actuator array is turned on, the voltage amplitude of the plasma actuator is the second amplitude, the pulse modulation frequency is the characteristic frequency of the tip vortex corresponding to instability, the duty cycle is the second duty cycle, the second duty cycle is lower than the first duty cycle, and the second part is smaller than the first part; in the third operating state, the plasma actuator array is turned on, the voltage amplitude of the plasma actuator is the third amplitude, the pulse modulation frequency is the third frequency, the duty cycle is the third duty cycle, the third amplitude is smaller than the first amplitude and the second amplitude, the third frequency is smaller than the first frequency and the characteristic frequency, and the third duty cycle is greater than the first duty cycle and the second duty cycle.

[0011] In one or more embodiments of the open fan component, the plasma actuator array includes a wireless power transmission device, a dedicated power processing unit, and an actuator patch array; wherein, the thickness of the actuator patch of each plasma actuator is less than 1 mm, and it is attached to the rotor blade.

[0012] In one or more embodiments of the open fan component, the wireless power transmission device includes a primary coil and a secondary coil. The primary coil is disposed on a stationary part of the engine, surrounding a rotating shaft, with the rotor blades disposed on the rotating shaft. The secondary coil is disposed on a rotating portion of the rotating shaft and is coaxially aligned with the primary coil. The total power required for the entire plasma actuator array is provided through electromagnetic induction between the secondary and primary coils.

[0013] In one or more embodiments of the open fan component, the dedicated power processing unit has a distributed structure, and there are multiple dedicated power processing units, with each dedicated power processing unit corresponding to each rotor blade.

[0014] In one or more embodiments of the open fan component, each of the dedicated power processing units has a built-in microcontroller and a sensor. The sensor is capable of sensing flight altitude information and angle of attack information, and outputting the above information to the microcontroller to control the current output of the dedicated power processing unit.

[0015] In one or more embodiments of the open fan component, each rotor blade has a pre-embedded groove or conduit for setting up wires to transmit current.

[0016] In one or more embodiments of the open fan component, the wire groove or conduit is filled with epoxy resin.

[0017] In one or more embodiments of the open fan component, the plasma actuator includes: a dielectric barrier discharge plasma actuator, a sliding discharge plasma actuator, and a nanosecond pulse discharge plasma actuator.

[0018] According to a noise reduction method of the second aspect of this application, an open fan component as described in the first aspect is used. The noise reduction method includes: determining whether noise reduction is required in the engine's flight state; if the determination result is no, the open fan component is in a standby state; if the determination result is yes, further determining: if in an approach / landing flight state, the open fan component is in a first operating state; if in a flyover / climb flight state, the open fan component is in a second operating state; if in a flight state at the edge of the flight path, the open fan component is in a third operating state.

[0019] In one or more embodiments of the noise reduction method, the determination of whether the engine flight status requires noise reduction, and the further determination of whether the flight status is approaching / landing, overflying / climbing, or on the edge of the flight path, are made manually by the pilot and / or automatically by the corresponding processor.

[0020] An open rotor engine according to a third aspect of this application includes an open fan component as described in the first aspect.

[0021] The beneficial effects of this case include, but are not limited to:

[0022] By arranging plasma exciter arrays, certain local aerodynamic separation points can be affected, that is, the eddy current characteristics of key areas of the open rotor can be actively and in real time controlled. In turn, the noise can be affected by controlling the flow field, including not only controlling BPF noise, but also controlling broadband noise caused by tip vortex instability. This allows the open engine to meet the noise reduction requirements of three airworthiness conditions. Furthermore, the plasma exciter is a miniature structure, which is small in size and light in weight, and can be easily integrated into the blade structure of the open engine, with minimal negative impact on aerodynamic performance. Attached Figure Description

[0023] The above and other features, properties and advantages of this application will become more apparent from the following description taken in conjunction with the accompanying drawings and embodiments. It should be noted that the drawings are merely illustrative and are not drawn to scale, and should not be construed as limiting the scope of protection actually claimed by this application, wherein:

[0024] Figure 1 This is a schematic diagram of airworthiness noise measurement points near the airport.

[0025] Figure 2 This is a typical noise spectrum diagram of an open fan component.

[0026] Figure 3 This is a schematic diagram of the structure of an open rotary engine for comparison.

[0027] Figure 4 This is a schematic diagram of the standby state of the open fan component of an open rotor engine according to an embodiment.

[0028] Figure 5 This is a schematic diagram of the airflow near the rotor blades in the standby state of the open fan component of an open rotor engine according to an embodiment.

[0029] Figure 6 This is a schematic diagram of the working state of the open fan component of an open rotor engine according to an embodiment.

[0030] Figure 7 This is a schematic diagram of the airflow near the rotor blades in the operating state of the open fan component of an open rotor engine according to an embodiment.

[0031] Figure 8 This is a schematic diagram of the structure of a single micro plasma exciter in the open fan component of an open rotor engine according to one embodiment.

[0032] Figure 9 This is a flowchart illustrating a noise reduction method according to one embodiment. Detailed Implementation

[0033] The following discloses various implementation methods or embodiments of the described subject matter technical solutions. To simplify the disclosure, specific examples of the various elements and arrangements are described below. Of course, these are merely examples and are not intended to limit the scope of protection of this application.

[0034] Furthermore, it should be understood that terms such as "an embodiment," "one embodiment," and / or "some embodiments," or "one or more embodiments" refer to a particular feature, structure, or characteristic related to at least one embodiment of this application. Therefore, it should be emphasized and noted that "an embodiment," "one embodiment," "some embodiments," or "one or more embodiments" mentioned twice or more in different locations in this specification do not necessarily refer to the same embodiment. Moreover, certain features, structures, or characteristics in one or more embodiments of this application can be appropriately combined.

[0035] In the following description, some terms have the following meanings.

[0036] Open rotor engine: also known as an open fan engine or ductless fan engine, is a new type of aircraft engine designed to improve fuel efficiency and reduce pollutant emissions. The biggest difference between it and a traditional turbofan engine is that the open rotor engine lacks a traditional nacelle structure; the blades are exposed and generally longer and thinner. The open fan component mentioned in this application specifically refers to the combination of the rotor blade rows and stator blade rows of this engine. The open rotor engine provided in this application includes the open fan component, which will be described in detail in the following embodiments.

[0037] Stator: refers to the fixed blade downstream of the rotor blades. Its main function is to guide and regulate airflow to improve the efficiency and performance of the engine.

[0038] Blade passing frequency: The noise generated by the high-speed rotation of the rotor blades and the frequency corresponding to the number of blades is manifested as regular discrete spikes in the noise spectrum. Its generation is the result of multiple factors, such as the rotor's own rotational noise, viscous wake, and stator interference, etc., which are complex aeroacoustic phenomena.

[0039] Approach: The flight state in which the aircraft approaches the airport and prepares to land. Airworthiness noise regulations specify the arrangement of microphone measurement points for approach conditions.

[0040] Sideline: The flight state of an aircraft when it leaves the ground and accelerates at full power. Airworthiness noise regulations have specific requirements for the arrangement of microphone measuring points for sideline conditions.

[0041] Overflight: The flight state in which an aircraft moves away from the airport and climbs upward. Airworthiness noise regulations specify the arrangement of microphone measurement points for overflight conditions.

[0042] Vortex: A rotating structure generated by a fluid during motion. In open rotors, complex vortices are generated at the blade tips, blade surfaces, and wake, and these vortices are one of the main sources of noise.

[0043] Plasma exciter: An exciter used for fluid control. The principle is to apply a high-voltage AC signal between a pair of asymmetric electrodes to form a low-temperature plasma between the electrodes, thereby ionizing the air molecules around the electrodes and accelerating them through an electric field, thus generating an induced ion wind to control the flow separation point.

[0044] like Figure 4 , Figure 6 As shown, in some embodiments, the basic structure of the open fan component is similar to... Figure 3 The structure shown is similar; the open-type fan components include a rotor and a stator. The stator may include stator blades 1, a stator fixing connection device 4, a base 5, and a casing 6. The rotor may include rotor blades 2 and a rotating shaft 3. The main function of the upstream rotor blades 2 is to accelerate the air and generate thrust. Through high-speed rotation, the rotor blades can transfer energy to the airflow, causing it to accelerate backward and thus generate forward thrust. The downstream fixed blades 1 mainly function to rectify and guide the airflow. The airflow accelerated by the rotor blades 2 usually has a certain rotational component. The stator blades 2 can reduce this rotational motion, rectifying the airflow into a smoother direct current. This helps to reduce eddies and energy loss, and improve aerodynamic efficiency.

[0045] Unlike Figure 3 The illustrated scheme includes an open fan component with a plasma actuator array, which comprises multiple plasma actuators. It is understood that the force generated by a single plasma actuator is limited, and its effective range is relatively small. For the powerful tip vortex generated by the high-speed rotation of the rotor blades in an open rotor engine, the energy of a single actuator may be insufficient to produce an effective impact. The embodiment details the precise optimization of noise reduction based on the different operating parameters of the plasma actuator array for different operating conditions, thereby minimizing the impact on aerodynamic performance.

[0046] exist Figure 4 and Figure 6 In order to intuitively demonstrate the overall logic and effect of vortex control, it can be seen that... Figure 4 and Figure 7 The intensity of the airflow 11 passing over the blade tip and the vortex structure 12 are significantly different. In actual use, it does not function as a simple on / off system. Instead, the vortex generation form of the blade tip shedding will be slightly different when the aircraft is in different flight states (such as approach / landing, overflight / climb, and edge line, which are the three measurement points of airworthiness concern). This corresponds to different control methods. The structure will be explained in detail later.

[0047] contrast Figure 5 as well as Figure 7The diagram shown illustrates typical airflow control for a micro plasma actuator array. Figure 4 , Figure 5 As shown, because the plasma control system was not activated, the tip vortex structure became more complex and chaotic, resulting in significant BPF single-tone noise and broadband noise caused by the instability of the tip vortex structure. Figure 6 and Figure 7 As shown, the tip vortex structure is significantly more regular.

[0048] like Figure 4 as well as Figure 6 As shown, the plasma actuator array includes a wireless power transmission device, a dedicated power processing unit 9, and an actuator patch array 10. The current energy source for the actuator is generated by the wireless power transmission device.

[0049] The wireless power transfer device operates on the principle of a combination of a rotary transformer and inductive coupling, utilizing the principle of electromagnetic induction, specifically a combination of a primary coil 8a and a secondary coil 8b. The primary coil 8a can be mounted on a stationary component of the engine, surrounding the rotating shaft (the main shaft of the propeller hub). The secondary coil 8b can be mounted on the rotating shaft or the rotating part of the propeller hub, coaxially aligned with the primary coil 8a. The total power required by the entire system is transferred through electromagnetic induction between the two. While the primary coil 8a and secondary coil 8b appear as two lines in the schematic diagram, they are actually two electromagnetic loops. The aircraft's battery pack can power the primary coil 8a, which in turn powers the secondary coil 8b located on the rotating shaft. The secondary coil 8b then controls a dedicated power processing unit, ultimately controlling a micro-plasma exciter array and influencing vortex generation.

[0050] The primary coil 8a and secondary coil 8b can be structured, for example, as inductor coils tightly wound in turns of conductive copper wire (or aluminum wire, etc.) on a high-performance ferrite core. To reduce energy loss when operating under high-frequency alternating current, primarily due to losses caused by the "skin effect" and "proximity effect," it is preferable to use special Litz wire instead of a simple single thick copper wire. The only condition for the generation of induced current is a change in the magnetic flux through a closed coil. In this patent, passing alternating current through the primary coil generates a similarly changing (oscillating) magnetic field that passes through the adjacent secondary coil. Regardless of whether the secondary coil rotates or not, the magnetic flux passing through it changes, thereby inducing alternating current. However, it should be noted that the "raw" alternating current induced by the secondary coil 8b has parameter mismatches and lacks active control functionality compared to the "precise" alternating current required to drive the plasma exciter. Therefore, it is preferable to provide a dedicated power processing unit 9 as a "bridge" for each rotor blade 2. That is, the dedicated power processing unit 9 has a distributed structure, and there are multiple dedicated power processing units 9, each corresponding to each rotor blade 5. In some embodiments, a microcontroller and sensors can be installed in the dedicated power processing unit 9. For example, the sensors can receive flight altitude information and angle of attack information. Through this information, it can be determined which airworthiness noise measurement point the aircraft should focus on at this time. The information collected by the sensors is fed back to the built-in microcontroller for current regulation, so that the exciter patch array 10 can automatically make the most reasonable eddy current regulation response for different flight states (such as the three measurement points of airworthiness concern: near field, overflight, and edge line), and control the vortex structure 12 between the rotor blade 2 and the stator blade 1 to the greatest extent to reduce BPF noise.

[0051] For the electrical connection between the plasma actuator array, including the wireless power transmission device, the dedicated power processing unit 9, and the actuator patch array 10, in some embodiments, a groove / conduit can be pre-embedded inside each rotor blade 2 to accommodate the wires 7 for current transmission. Preferably, in some embodiments, the groove or conduit is filled with epoxy resin. The inventors have found that, due to the large vibrations of open rotor engines, filling the groove or conduit with epoxy resin can effectively resist centrifugal force and vibration, resulting in better structural reliability. It is understood that the electrical connection is not limited to the above-described wire connection structure; a wireless connection can also be used, and neither is a limitation.

[0052] like Figure 8As shown, the current control structure of a single plasma actuator corresponding to the plasma actuator array can be as follows: the plasma actuator includes electrode strips 12, a plasma gas region 13, and a dielectric 14. The plasma actuator is located at the tip 15 of the rotor blade, influencing the airflow 11. Its working principle is that a high-voltage AC signal is applied between a pair of asymmetric electrode strips 12, forming a low-temperature plasma between the electrode strips 12. This ionizes the air molecules around the electrodes and accelerates them through the electric field, thereby generating an induced ion wind, i.e., the plasma gas region 13, achieving control over the flow separation point of the airflow 11 flowing through the tip region of the rotor blade. The plasma actuator can take the form of a dielectric barrier discharge plasma actuator, a sliding discharge plasma actuator, a nanosecond pulse discharge plasma actuator, etc. These actuators have similar principles and simple structures, generating low-temperature plasma between the electrodes to apply volume force or thermal effect to the local gas. Taking the most common dielectric barrier discharge plasma actuator as an example, it mainly includes three components: an exposed electrode, which is typically a thin conductive material (such as copper foil) directly exposed to the air; and an encapsulated electrode, also a thin conductive material, but completely encapsulated inside an insulating dielectric. The insulating dielectric layer is generally a thin insulating material sandwiched between two electrodes, such as polyimide, Teflon, ceramic, or quartz glass.

[0053] The specific structure of the actuator patch array 10 can be such that the thickness of each plasma actuator patch is less than 1 mm, and it is attached to the rotor blade. Specifically, the thickness of a single plasma actuator patch should be in the micrometer range, and the thickest should not exceed 1 mm, similar to a flexible material attached to the rotor blade 2 (also called a "blade"). Depending on the specific blade size, the length and width of a single plasma actuator patch can vary from a few millimeters to a few centimeters. The single plasma actuator patch and the actuator patch array 10 can be manufactured using micro-nano manufacturing technology, and therefore can also be called a micro plasma actuator patch array. It has the advantages of low profile and lightweight, and can minimize the impact on aerodynamic performance.

[0054] The following details the working states of the plasma excitation array of the fan component corresponding to different flight conditions.

[0055] The open-type fan component has a standby state, a first working state, a second working state, and a third working state.

[0056] like Figure 4 As shown, the plasma actuator array is turned off in standby mode.

[0057] The corresponding flight state of the open rotor engine is approach or landing. The open fan component is in the first working state. At this time, the plasma exciter array is turned on, the first part of the plasma exciter array is turned on, the voltage amplitude of the plasma exciter is the first amplitude, the pulse modulation frequency is the first frequency, and the duty cycle is the first duty cycle.

[0058] Specifically, the inventors discovered that by setting multiple synergistic parameters of the plasma actuator array according to different operating conditions, it is possible to further improve the noise reduction effect while minimizing the impact on aerodynamic performance, especially considering the noise reduction effect under the three airworthiness conditions. The specific control parameters include the following.

[0059] Voltage amplitude: mainly determines the intensity of the action of a single exciter (hereinafter, a single exciter can also be called an "exciter unit"), that is, it determines the magnitude of the induced velocity.

[0060] Drive frequency: The frequency of the AC power supply for the plasma exciter, usually in the kHz range, which affects the plasma morphology and efficiency.

[0061] Pulse modulation frequency: The exciter is generally not continuously turned on, but rather switched on and off at a certain frequency (usually in the range of tens to thousands of Hz) to form a pulsed excitation. This frequency can be used to match or interfere with the characteristic frequency of the flow.

[0062] Duty cycle: The proportion of "on" time within a pulse cycle determines the total energy injected into the flow field.

[0063] Spatial activation mode: Which individual exciters in the array are activated, and whether there is a phase difference between them. This can create complex spatial perturbations.

[0064] The corresponding flight state for an open rotor engine is approach or landing. The open fan component is in its first operating state, and the flight state and vortex characteristics are low-speed flight, but the engine needs to provide a certain amount of thrust (sometimes even reverse thrust). Flaps, landing gear, and other lift-enhancing devices are deployed. The blade angle of attack is usually large, and the rotational speed is low. The tip vortex intensity is high, the vortex core size is large, and the movement speed is slow, resulting in relatively poor stability. Its strong pressure pulsation is the main source of low-frequency noise at this time, which has a significant impact on ground communities.

[0065] The inventors discovered that the following strategy for configuring the exciter array effectively addresses noise during approach or landing: Spatial activation mode activates most of the exciter units in the blade tip region, creating a large-scale, carpet-like, powerful disturbance; that is, the first part involves the majority, for example, more than 80% of the exciter units are activated. The temporal modulation strategy employs high-energy pulse modulation. The pulse modulation frequency is set relatively high, but it doesn't necessarily need to precisely match a specific flow field characteristic frequency. The purpose is to "violently" inject a large amount of disturbance, triggering rapid instability and breakup of the vortex. The voltage amplitude is a first voltage amplitude, relatively high. The pulse modulation frequency is a first frequency, which is high-frequency random or swept, for example, it can vary within the range of 500Hz-2000Hz, avoiding a "lock-in" effect of the vortex on a single frequency. The first duty cycle is also relatively high, for example, >50%, injecting as much energy as possible. This allows the originally stable, robust blade tip vortex to break up within a very short distance after leaving the blade, decomposing into many small, disordered vortex structures. Acoustically, this manifests as a significant reduction in the main low-frequency noise peaks and a decrease in the overall sound pressure level.

[0066] The corresponding flight state of the open rotor engine is either flyby or climb. The open fan component is in the second working state. The plasma exciter array is turned on. The second part of the plasma exciter array is turned on. The voltage amplitude of the plasma exciter is the second amplitude. The pulse modulation frequency is the characteristic frequency of the tip vortex corresponding to instability. The duty cycle is the second duty cycle. The second duty cycle is lower than the first duty cycle. The second part is smaller than the first part.

[0067] The corresponding flight state of the open rotor engine is either flyby or climb. The open fan component is in its second operating state. The inventors discovered that the flight state and vortex characteristics indicate that the engine is in a high-thrust state (takeoff thrust or thrust reduction), the flight speed is relatively high, and the aircraft is climbing. The blade load is extremely high, and the rotational speed is high. The tip vortex intensity is extremely strong, the vortex core is compact, and it is very stable, with a clear spiral trajectory.

[0068] The inventors discovered that the following strategy for configuring the exciter array effectively addresses noise during flyby or climb, with the spatial activation mode generally not requiring the activation of all units. Interleaved or grouped activation can be used to create specific, periodic disturbance waveforms on the blade tip surface. For example, a simulated "miniature virtual vortex generator" array can be used to introduce tiny vortices opposite to the main vortex's rotation direction. The time modulation strategy identifies the optimal mode (feature frequency) of the tip vortex most prone to instability under current operating conditions using sensors (or a preset model). The pulse modulation frequency is then precisely tuned to this frequency or its harmonics to achieve "resonance" excitation, maximizing efficiency. This allows for precise and efficient induction of vortex core instability. Utilizing the vortex's inherent vulnerability—its sensitivity to disturbances at specific frequencies—the most unstable mode is excited with minimal energy input, causing it to collapse "on its own." The voltage amplitude is a second amplitude, similar to the first, and is relatively high. The pulse modulation frequency is the second frequency, which, unlike the first frequency, is the characteristic frequency of instability corresponding to the tip vortex. The duty cycle is the second duty cycle, which is higher than the first duty cycle; the second duty cycle is medium or lower, for example, 20-40%. This is because energy utilization efficiency is high in this state, eliminating the need for continuous injection. This allows the tip vortex, after leaving the blade, to experience a "precise strike," causing its internal unstable waves to grow rapidly, leading to a spiral or symmetrical "explosion" of the vortex core within a short distance. This fundamentally eliminates this strong noise source.

[0069] The corresponding flight state of the open rotor engine is the edge state, the open fan component is in the third working state, the plasma exciter array is turned on, the voltage amplitude of the plasma exciter is the third amplitude, the pulse modulation frequency is the third frequency, the duty cycle is the third duty cycle, the third amplitude is less than the first amplitude and the second amplitude, the third frequency is less than the first frequency and the characteristic frequency, and the third duty cycle is greater than the first duty cycle and the second duty cycle.

[0070] The corresponding flight state for the open rotor engine is the edge-line state, with the open fan component in its third operating state. The inventors discovered that this corresponds to the aircraft's acceleration and initial climb phase on the runway, with the engine operating at maximum takeoff thrust. The flight speed increases from zero, and the state is non-steady and rapidly changing. In addition to the noise from the vortex itself, the interaction noise between the vortex and the ground, wings, and tail becomes extremely important.

[0071] The inventors discovered that the following strategy for configuring the actuator array effectively addresses edge-state noise: spatial activation mode is asymmetric activation, such as activating only the actuator on the tip pressure surface side, or applying different intensities of excitation at the leading and trailing edges of the tip, thereby generating a net lateral induced airflow near the tip. The time modulation strategy favors quasi-steady-state or high-duty-cycle pulse operation. This is because the goal is to generate a nearly continuous force to "deflect" the vortex, rather than introducing high-frequency instabilities. This reduces interference noise by altering the vortex trajectory. It is not necessary to completely destroy the vortex, but rather to apply a continuous, asymmetric force to slightly "push" the initial position or trajectory of the vortex, causing it to deviate from the path that would otherwise strongly interfere with the machine components. The voltage amplitude of the plasma actuator is a third amplitude, which is generally smaller than the first and second amplitudes. The pulse modulation frequency is the third frequency, which is lower than the first frequency and the characteristic frequency. The third frequency is generally low or even zero (no pulse modulation is performed, and continuous operation mode is used). The duty cycle is the third duty cycle, which is generally greater than the first duty cycle and the second duty cycle. The third duty cycle is generally greater than 80% and is set to 100%. This can cause a slight shift in the overall spiral trajectory of the blade tip vortex (for example, being pushed up or down by tens of centimeters). This seemingly small change may cause it to just "miss" the strong interference area with the wingtip or horizontal stabilizer, thereby significantly reducing the harsh interference noise.

[0072] refer to Figure 9 This application also provides a noise reduction method using an open fan component as described in the above embodiments, the noise reduction method comprising:

[0073] S100. Determine whether noise reduction is needed for the engine's flight status.

[0074] S200. If the judgment result is negative, the open fan component is in standby mode;

[0075] S300. If the judgment result is yes, then further judgment is made:

[0076] S301. If the aircraft is in the approach / landing flight state, the open fan component is in the first operating state;

[0077] S302. If the aircraft is in a flyby / climbing flight state, the open fan component is in the second operating state;

[0078] S303. If the aircraft is in flight mode on the edge of the boundary, the open fan component is in the third operating state.

[0079] In some embodiments, the judgment steps of S100, S301, S302, and S302, namely, judging whether the engine flight status needs noise reduction, and further judging whether the flight status is approaching / landing, or flying over / climbing, or flying over the edge, can be judged manually by the pilot and / or automatically by the corresponding processor. For example, the pilot or the processor can make the judgment based on flight parameters such as speed, altitude, engine power, etc., or the processor can make an automatic judgment and give a suggestion, which is then confirmed and executed by the pilot. Neither of these is a limitation.

[0080] The specific parameters corresponding to the standby state, the first working state, the second working state, and the third working state have been described in detail in the above embodiments and will not be repeated here.

[0081] As described above, the beneficial effects of the solutions presented in the above embodiments include, but are not limited to, influencing certain local aerodynamic separation points by arranging plasma exciter arrays, i.e., actively and in real-time controlling the eddy current characteristics of key areas of the open rotor, and thus affecting noise through flow field control. This includes not only controlling BPF noise, but also controlling broadband noise caused by tip vortex instability, enabling the open engine to meet the noise reduction requirements of three airworthiness conditions. Furthermore, the plasma exciter is a miniature structure, small in size and light in weight, and easily integrated into the blade structure of the open engine, with minimal negative impact on aerodynamic performance.

[0082] While this application discloses the above embodiments, it is not intended to limit the scope of this application. Any changes and modifications can be made by those skilled in the art without departing from the spirit and scope of this application. Therefore, any modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of this application without departing from the content of the technical solution of this application shall fall within the protection scope defined by the claims of this application.

Claims

1. An open fan component of an open-rotor engine, characterized by, Comprise: Stator comprising stator blades; Rotor comprising rotor blades, the stator blades being downstream of the rotor blades; The rotor blades are provided with a plasma exciter array, the plasma exciter array having a plurality of plasma exciters; The open fan component has standby state, first working state, second working state, third working state: In the standby state, the plasma exciter array is closed; In the first working state, the plasma exciter array is opened, a first part of the plasma exciter array is opened, the voltage amplitude of the plasma exciter is the first amplitude, the pulse modulation frequency is the first frequency, and the duty cycle is the first duty cycle; In the second working state, the plasma exciter array is opened, a second part of the plasma exciter array is opened, the voltage amplitude of the plasma exciter is the second amplitude, the pulse modulation frequency is the characteristic frequency corresponding to the instability of the tip vortex, and the duty cycle is the second duty cycle, the second duty cycle is lower than the first duty cycle, and the second part is smaller than the first part; In the third working state, the plasma exciter array is opened, the voltage amplitude of the plasma exciter is the third amplitude, the pulse modulation frequency is the third frequency, and the duty cycle is the third duty cycle, the third amplitude is smaller than the first amplitude and the second amplitude, the third frequency is smaller than the first frequency and the characteristic frequency, and the third duty cycle is greater than the first duty cycle and the second duty cycle.

2. The open fan component of claim 1, wherein, The plasma exciter array comprises a wireless energy transmission device, a dedicated power supply processing unit, and an exciter patch array; wherein the thickness of the exciter patch of each plasma exciter is less than or equal to 1mm, and the exciter patch is attached to the rotor blade.

3. The open fan assembly of claim 2, wherein, The wireless energy transmission device comprises a primary coil and a secondary coil, the primary coil is arranged on the stationary part of the engine, surrounds the rotating shaft, the rotor blade is arranged on the rotating shaft, the secondary coil is arranged on the rotating part of the rotating shaft, and the secondary coil is coaxially aligned with the primary coil, and the total power required by the entire plasma exciter array is provided through electromagnetic induction between the secondary coil and the primary coil.

4. The open fan assembly of claim 2, wherein, The dedicated power supply processing unit is of a distributed structure, the number of the dedicated power supply processing units is multiple, and each dedicated power supply processing unit corresponds to each rotor blade.

5. The open fan assembly of claim 4, wherein, Each dedicated power supply processing unit is internally provided with a microcontroller and a sensor, the sensor can sense the flight altitude information and the attack angle information, and output the above information to the microcontroller to control the current output of the dedicated power supply processing unit.

6. The open fan component of claim 1, wherein, Each rotor blade is internally provided with a wire slot or a wire tube for arranging the wire to transmit current.

7. The open fan assembly of claim 6, wherein, The wire slot or the wire tube is filled with epoxy resin.

8. The open fan component of claim 1, wherein, The plasma exciter comprises a dielectric barrier discharge plasma exciter, a sliding discharge plasma exciter, and a nanosecond pulse discharge plasma exciter.

9. A method of noise reduction, the method comprising: The open fan component according to any one of claims 1-8, the noise reduction method comprises: Judging whether the engine flight state needs to reduce noise; If the judgment result is no, the open fan component is in standby state; If the result of the judgment is yes, further judgment is made: If the flight state is approach / landing, the open fan component is in the first working state; If the flight state is overflight / climb, the open fan component is in the second working state; If the flight state is sideline, the open fan component is in the third working state.

10. The noise reduction method of claim 9, wherein, The judgment of whether the engine flight state needs noise reduction, and the further judgment of the approach / landing flight state, or the overflight / climb flight state, or the sideline flight state, are made by the pilot manually or by the corresponding processor automatically.

11. An open rotor engine characterized by, The open fan component as claimed in any one of claims 1-8.

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