Open rotor engine and fan structure therefor

Abstract

The present disclosure provides a fan structure of an open rotor engine and an open rotor engine. The fan structure comprises: a hub; rotor blades and stator blades installed in sequence along an airflow direction on an outer periphery of the hub; a sound signal generator; and a control device connected to the sound signal generator and configured to cause the sound signal generator to emit a noise reduction sound wave for superimposing with a noise sound wave generated by airflow passing through the rotor blades and the stator blades, so as to reduce an amplitude of the noise sound wave, in a state that the rotor blades rotate around an axis of the hub. The open rotor engine comprises the aforementioned fan structure. The fan structure and the open rotor engine provided by the present disclosure can effectively reduce fan noise.

Description

Technical Field

[0001] This disclosure relates to the field of noise reduction in aero-engines, and in particular to an open rotor engine and its fan structure. Background Technology

[0002] Currently, with the advancement of science and technology and the increasing demands of humankind for the environment, green environmental protection is becoming a theme of the times, and reducing the environmental impact of air transport has become a new research and development goal for aero engines. Open rotor engines combine the low fuel consumption of turboprop engines with the high-speed flight characteristics of turbofan engines. Compared to conventional turbofan engines of the same thrust level, open rotor engines can reduce fuel consumption and CO2 emissions by 20% to 30%, making them suitable for powering civil airliners and military transport aircraft.

[0003] Large passenger aircraft face increasingly stringent airworthiness noise regulations, and meeting noise limits has become a prerequisite for obtaining international airworthiness certification. However, open rotor engines suffer from tip vortex and root vortex interference, as well as front and rear blade interference, which are typical nonlinear, multi-scale coupling problems. Because the fan is not enclosed by a casing, noise control of open rotor engines is extremely difficult. Summary of the Invention

[0004] In view of this, the purpose of this disclosure is to provide an open rotor engine and its fan structure that can effectively reduce fan noise.

[0005] The first aspect of this disclosure provides a fan structure for an open rotary engine, comprising:

[0006] Wheel hub;

[0007] Rotor blades and stator blades are sequentially mounted on the outer periphery of the hub along the airflow direction;

[0008] Sound signal generator; and

[0009] A control device, signal-connected to the sound signal generator, is configured to, while the rotor blades are rotating about the axis of the hub, cause the sound signal generator to emit a noise reduction wave to superimpose with the noise, based on the noise sound waves generated by the airflow passing through the rotor blades and the stator blades, so as to reduce the amplitude of the noise sound waves.

[0010] In some embodiments, the control device is configured to cause the acoustic signal generator to emit the noise-reducing wave with the same frequency and opposite phase as the noise acoustic wave.

[0011] In some embodiments, the control device is configured to determine the frequency of the noise reduction wave based on the frequency at which the rotor blades rotate about the hub and the number of rotor blades.

[0012] In some embodiments, the control device includes a memory and a processor coupled to the memory, the memory being configured to store a mathematical model required to generate the noise-reduced wave, and the processor being configured to correct the mathematical model based on the phase difference between the noise-reduced wave and the noise wave, and based on the corrected mathematical model, to cause the sound signal generator to emit the corrected noise-reduced wave until the phase difference between the corrected noise-reduced wave and the noise wave is within an allowable range.

[0013] In some embodiments, the mathematical model includes a Kalman filter model with the noise wave as the input signal, the noise-reduced wave as the output signal, and the superimposed sound wave of the noise wave and the noise-reduced wave as the feedback signal.

[0014] In some embodiments, at least one of the acoustic signal generators is disposed downstream of the rotor blades along the airflow direction.

[0015] In some embodiments, at least one of the acoustic signal generators includes:

[0016] A first sound signal generator, disposed in the hub between the rotor blades and the stator blades along the airflow direction, emits the noise-reducing wave into the region between the trailing edge of the rotor blades and the leading edge of the stator blades; and / or

[0017] A second acoustic signal generator is located at the hub downstream of the stator blade along the airflow direction to emit the noise-reducing wave toward the region where the trailing edge of the stator blade is located.

[0018] In some embodiments, the rotor blades have a sweep angle relative to the airflow direction in the radial section of the hub. α 1 and tangential angle β 1. The stator blade has a sweep angle relative to the airflow direction in the radial section of the hub. α 2 and tangential angle β 2. In some embodiments,

[0019] 50°≤ α 1≤80°; and / or

[0020] 30°≤ β 1≤50°; and / or

[0021] 45°≤ α 2≤80°; and / or

[0022] 35°≤ β 2≤60°.

[0023] In some embodiments, along the radial direction of the hub, the profile of the rotor blade tip is further away from the hub than the profile of the stator blade tip.

[0024] In some embodiments, β 1 < β 2.

[0025] A second aspect of this disclosure provides an open rotary engine including the fan structure described in the first aspect of this disclosure.

[0026] The fan structure provided in this disclosure is equipped with a sound signal generator. When the rotor blades rotate around the axis of the hub, under the action of the control device, the sound signal generator can emit noise reduction waves to the locations in the fan structure where noise is generated, such as the blade tip position, blade root position, position between two sets of blades, and downstream position of the stator blades along the airflow direction. After the noise reduction wave is superimposed with the noise sound wave, the amplitude of the noise sound wave is reduced and thus attenuated. This can achieve active noise reduction of the fan from the perspective of blocking the propagation of noise.

[0027] The open rotor engine provided in this disclosure, as an engine without a casing-enclosed fan structure, has the advantages of the fan structure provided in the embodiments of this disclosure due to the adoption of the fan structure provided in the embodiments of this disclosure, and can effectively reduce fan noise.

[0028] Other features and advantages of this disclosure will become clear from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0029] The accompanying drawings, which are included to provide a further understanding of this disclosure and form part of this application, illustrate exemplary embodiments of this disclosure and are used to explain this disclosure, but do not constitute an undue limitation of this disclosure. In the drawings:

[0030] Figure 1 This is a schematic diagram of the fan structure of some embodiments of this disclosure.

[0031] Figure 2 This is a schematic diagram illustrating the noise reduction control principle of a fan structure in some embodiments of this disclosure.

[0032] In the attached figures, the reference numerals represent:

[0033] 1. Rotor blades; 2. Stator blades; 31. First acoustic signal generator; 311. First loudspeaker; 312. First drive power supply; 32. Second acoustic signal generator; 321. Second loudspeaker; 322. Second drive power supply; 4. Hub. Detailed Implementation

[0034] The technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this disclosure or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0035] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of this disclosure. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0036] In the description of this disclosure, it should be understood that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this disclosure.

[0037] In the description of this disclosure, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings and is only for the convenience of describing this disclosure and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this disclosure; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0038] refer to Figure 1 and Figure 2 Some embodiments of this disclosure provide a fan structure for an open rotor engine, including a hub 4, rotor blades 1, stator blades 2, an acoustic signal generator, and a control device.

[0039] Rotor blade 1 and stator blade 2 are sequentially mounted on the outer periphery of hub 4 along the airflow direction. The control device is connected to the sound signal generator and is configured to, when the rotor blade 1 rotates around the axis of hub 4, generate a noise reduction wave by superimposing it on the noise generated by the airflow passing through rotor blade 1 and stator blade 2, thereby reducing the amplitude of the noise wave.

[0040] It should be noted that the "airflow direction" mentioned in this disclosure refers to the direction of airflow relative to the overall fan structure, which is along the axial direction of the hub 4, i.e. Figure 1 The direction from left to right in the middle.

[0041] Specifically, both rotor blades 1 and stator blades 2 exhibit specific spatial curved surface shapes and form a certain angle with the hub 4. The specific shape of the spatial curved surface can be determined based on the aerodynamic performance of the fan structure blades. Multiple rotor blades 1 are distributed along the outer periphery of the hub 4 and rotatably arranged around the axis of the hub 4, while multiple stator blades 2 are distributed along the outer periphery of the hub 4 and remain fixed relative to the hub 4. To avoid obscuring the concept of this disclosure, Figure 1 Only one rotor blade 1 and one stator blade 2 are shown in the figure.

[0042] The inventors discovered through research that, for open rotary engines, when the rotor blades rotate at high speed, under the action of centrifugal force, the airflow on the blade surface moves from the blade root to the blade tip, creating a tip vortex at the blade tip and a rotor wake at the blade trailing edge, such as... Figure 1 As shown, the airflow generates a steady load on the rotor blades, producing load noise. After the tip vortex and rotor wake leave the upstream front blades, they continue to move along the rotor axis. When the tip vortex and rotor wake hit the rear stator blades, they will generate rotor-stator interference noise. Similarly, hub vortices and hub wakes will be generated near the blade root trailing edge.

[0043] The fan structure provided in the embodiments of this disclosure is equipped with a sound signal generator. When the rotor blade 1 rotates around the axis of the hub 4, under the action of the control device, the sound signal generator can emit noise reduction waves to the locations in the fan structure where noise is generated, such as the blade tip position, blade root position, position between the two sets of blades, and the downstream position of the stator blade 2 along the airflow direction. After the noise reduction wave is superimposed with the noise sound wave, the amplitude of the noise sound wave is reduced and thus attenuated. Active noise reduction of the fan can be achieved from the perspective of blocking the propagation of noise.

[0044] In some embodiments, the control device is configured to cause the acoustic signal generator to emit a noise-reducing wave with the same frequency and opposite phase as the noise sound wave.

[0045] Optionally, the control device is configured to cause the sound signal generator to emit a noise sound wave with the same frequency and amplitude but opposite phase to the noise sound wave. Optionally, the fan structure includes a first sound wave measuring device, which is signal-connected to the control device and configured to detect parameters such as the frequency, phase, and amplitude of the noise sound wave.

[0046] In this embodiment, the noise wave and the noise reduction wave have the same frequency and opposite phase. When the two waves are superimposed, the peak of the noise wave is superimposed with the trough of the noise reduction wave, and the trough of the noise wave is superimposed with the peak of the noise reduction wave. This can minimize the amplitude of the superimposed wave, thereby fully attenuating the noise.

[0047] In some embodiments, the control device is configured to determine the frequency of the noise reduction wave based on the frequency at which the rotor blades 1 rotate around the hub 4 and the number of rotor blades 1.

[0048] Specifically, the frequency of the rotor-stationary interference noise generated by the interaction between rotor blade 1 and stator blade 2 is an integer multiple of the product of the frequency of rotor blade 1 rotating around hub 4 and the number of rotor blades 1. Therefore, it can be determined that the frequency of the noise reduction wave that achieves a good noise reduction effect is also an integer multiple of the product of the frequency of rotor blade 1 rotating around hub 4 and the number of rotor blades 1.

[0049] In some embodiments, the control device includes a memory and a processor coupled to the memory. The memory is configured to store a mathematical model required to generate a noise-reduced wave, and the processor is configured to correct the mathematical model based on the phase difference between the noise-reduced wave and the noise wave, and based on the corrected mathematical model, cause the acoustic signal generator to emit a corrected noise-reduced wave until the phase difference between the corrected noise-reduced wave and the noise wave is within an allowable range.

[0050] The noise reduction wave is generated in real time based on a mathematical model. However, the phase of the generated noise reduction wave may have some error compared to the noise wave propagating in the air. In this embodiment, the control device can correct the mathematical model based on the phase difference between the noise reduction wave and the noise wave, so that the phase of the generated noise reduction wave is also corrected accordingly. By controlling the phase difference between the corrected noise reduction wave and the noise wave within an allowable range, the peaks of the noise reduction wave and the troughs of the noise wave are made to coincide as much as possible, and the troughs of the noise reduction wave and the peaks of the noise wave are made to coincide as much as possible. This minimizes the amplitude of the superimposed sound wave of the noise wave and the noise reduction wave, achieving a good noise reduction effect.

[0051] Of course, the process of modifying the mathematical model is not limited to modifying the phase of the noise reduction wave it generates, but can also modify parameters such as the frequency and amplitude of the noise reduction wave to achieve a better noise reduction effect.

[0052] In some embodiments, reference Figure 2The mathematical model includes a Kalman filter model that uses noise sound waves as input signals, noise-reduced sound waves as output signals, and superimposed sound waves of noise sound waves and noise-reduced sound waves as feedback signals.

[0053] Optionally, the fan structure includes a second acoustic wave measuring device, which is signal-connected to the control device and configured to detect parameters such as the frequency, phase, and amplitude of the superimposed acoustic waves.

[0054] In this embodiment, the Kalman filter model can dynamically adjust the filter parameters according to the changes in the noise wave and the superimposed noise wave, thereby continuously reducing the phase error between the noise wave and the noise wave.

[0055] Of course, the mathematical model mentioned above can also be based on other types of adaptive filtering algorithms, as long as it can achieve the goal of reducing the phase difference between the noise wave and the noise sound wave and improving the noise reduction effect.

[0056] Considering that the noise generated by the fan structure of the open rotor engine is caused by the disturbance of the airflow by the rotor blade 1 and the impact of the airflow on the rotor blade 1 and the stator blade 2, the noise is usually generated at the rotor blade 1 and downstream of the rotor blade 1 along the airflow direction. In some embodiments, at least one sound signal generator is located downstream of the rotor blade 1 along the airflow direction.

[0057] In some embodiments, at least one acoustic signal generator includes a first acoustic signal generator 31 and / or a second acoustic signal generator 32. The first acoustic signal generator 31 is disposed in the hub 4 between the rotor blade 1 and the stator blade 2 along the airflow direction to emit a noise-reducing wave to the region between the trailing edge of the rotor blade 1 and the leading edge of the stator blade 2. The second acoustic signal generator 32 is disposed in the hub 4 downstream of the stator blade 2 along the airflow direction to emit a noise-reducing wave to the region where the trailing edge of the stator blade 2 is located.

[0058] The first acoustic signal generator 31 can be used to attenuate the load noise or rotor-to-stationary interference noise in the region between the trailing edge of the rotor blade 1 and the leading edge of the stator blade 2. The second acoustic signal generator 32 can be used to attenuate the load noise or rotor-to-stationary interference noise in the region where the trailing edge of the stator blade 2 is located.

[0059] Optionally, refer to Figure 1 At least one sound signal generator includes the aforementioned first sound signal generator 31 and second sound signal generator 32. Optionally, the first sound signal generator 31 includes one or more first speakers 311 and a first drive power supply 312 for supplying power to the first speakers 311, and the second sound signal generator 32 includes one or more second speakers 321 and a second drive power supply 322 for supplying power to the second speakers 321.

[0060] When there are multiple sound signal generators, the waveforms of the noise-reduced waves emitted by different sound signal generators can be the same or different; when the sound signal generator includes multiple loudspeakers, the waveforms of the noise-reduced waves emitted by different loudspeakers in the same sound signal generator can be the same or different.

[0061] In some embodiments, reference Figure 1 The rotor blade 1 has a sweep angle relative to the airflow direction in the radial section of the hub 4. α 1 and tangential angle β 1. The stator blade 2 has a sweep angle relative to the airflow direction in the radial section of the hub 4. α 2 and tangential angle β 2.

[0062] In this embodiment, rotor blade 1 and stator blade 2 each have a sweep angle and a tangential angle.

[0063] By matching the sweep angle and tangential angle of rotor blade 1 and stator blade 2, and controlling the shape of rotor blade 1 and stator blade 2, the three-dimensional streamline trajectory of at least a portion of the tip vortex generated by rotor blade 1 can pass over the tip of stator blade 2 without hitting stator blade 2, thereby reducing the interference of tip vortex on stator blade 2 and reducing fan noise from the perspective of suppressing noise sources.

[0064] In some embodiments, reference Figure 1 50°≤ α 1 ≤ 80°, and / or, 30° ≤ β 1 ≤ 50°, and / or, 45° ≤ α 2 ≤ 80°, and / or, 35° ≤ β 2≤60°.

[0065] Optionally, 50°≤ α 1≤80°, 30°≤ β 1≤50°, 45°≤ α 2≤80°, 35°≤ β 2≤60°.

[0066] The above range of sweep angle and tangential angle values ​​can, without affecting the aerodynamic performance of rotor blade 1 and stator blade 2, ensure that the three-dimensional streamline trajectory of the tip vortex generated by rotor blade 1 sweeps across the tip of stator blade 2 as much as possible, thereby significantly reducing the interference of the tip vortex on stator blade 2 and thus reducing fan noise.

[0067] In some embodiments, along the radial direction of the hub 4, the profile of the tip of the rotor blade 1 is further away from the hub 4 than the profile of the tip of the stator blade 2.

[0068] In some embodiments,β 1 < β 2.

[0069] Optionally, refer to Figure 1 Along the radial direction of hub 4, the profile of the rotor blade 1's tip is further away from hub 4 than the profile of the stator blade 2's tip. β 1 < β 2.

[0070] The fan structure of the above embodiment can optimize the propagation path of the tip vortex generated by the rotor blade 1 by limiting the shape and size of the rotor blade 1, so that the tip vortex is as far away from the tip of the stator blade 2 as possible. Furthermore, the positional, dimensional, and angular relationships of the stator blade 2 relative to the rotor blade 1 can also ensure that the tip of the stator blade 2 provides sufficient clearance for the propagation path of the tip vortex, thereby reducing fan noise.

[0071] Some embodiments of this disclosure also provide an open rotor engine, including the fan structure provided in the embodiments of this disclosure.

[0072] The open rotor engine provided in the embodiments of this disclosure is an engine without a casing-enclosed fan structure. Due to the adoption of the fan structure provided in the embodiments of this disclosure, it has the advantages of the fan structure provided in the embodiments of this disclosure, and can effectively reduce fan noise.

[0073] In some embodiments, the control device described above may be implemented as a general-purpose processor, a programmable logic controller (PLC), a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, or any suitable combination thereof for performing the functions described herein.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this disclosure and not to limit them; although this disclosure has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of this disclosure or equivalent substitutions can be made to some technical features, all of which should be covered within the scope of the technical solutions claimed in this disclosure.

Claims

1. A fan structure for an open rotary engine, characterized in that, include: Wheel hub (4); Rotor blades (1) and stator blades (2) are sequentially installed on the outer periphery of the hub (4) along the airflow direction; Sound signal generator; and The control device, which is connected to the sound signal generator, is configured to, in the state of the rotor blade (1) rotating about the axis of the hub (4), cause the sound signal generator to emit a noise reduction wave to superimpose the noise based on the noise sound wave generated by the airflow passing through the rotor blade (1) and the stator blade (2), so as to reduce the amplitude of the noise sound wave.

2. The fan structure according to claim 1, characterized in that, The control device is configured to cause the acoustic signal generator to emit the noise-reducing wave, which has the same frequency and opposite phase as the noise wave.

3. The fan structure according to claim 2, characterized in that, The control device is configured to determine the frequency of the noise reduction wave based on the frequency of the rotation of the rotor blades (1) around the hub (4) and the number of rotor blades (1).

4. The fan structure according to claim 1, characterized in that, The control device includes a memory and a processor coupled to the memory. The memory is configured to store a mathematical model required to generate the noise-reduced wave. The processor is configured to correct the mathematical model based on the phase difference between the noise-reduced wave and the noise wave, and based on the corrected mathematical model, to cause the sound signal generator to emit the corrected noise-reduced wave until the phase difference between the corrected noise-reduced wave and the noise wave is within an allowable range.

5. The fan structure according to claim 4, characterized in that, The mathematical model includes a Kalman filter model that uses the noise wave as the input signal, the noise-reduced wave as the output signal, and the superimposed sound wave of the noise wave and the noise-reduced wave as the feedback signal.

6. The fan structure according to claim 1, characterized in that, At least one of the acoustic signal generators is disposed downstream of the rotor blade (1) along the airflow direction.

7. The fan structure according to claim 6, characterized in that, At least one of the said acoustic signal generators includes: A first sound signal generator (31) is disposed in the hub (4) between the rotor blade (1) and the stator blade (2) along the airflow direction to emit the noise-reducing wave to the region between the trailing edge of the rotor blade (1) and the leading edge of the stator blade (2); and / or A second sound signal generator (32) is disposed at the hub (4) downstream of the stator blade (2) along the airflow direction to emit the noise reduction wave to the area where the trailing edge of the stator blade (2) is located.

8. The fan structure according to any one of claims 1 to 7, characterized in that, The rotor blade (1) has a sweep angle relative to the airflow direction in the radial section of the hub (4). α 1 and tangential angle β 1. The stator blade (2) has a sweep angle relative to the airflow direction in the radial section of the hub (4). α 2 and tangential angle β 2.

9. The fan structure according to claim 8, characterized in that, 50°≤ α 1≤80°; and / or 30°≤ β 1≤50°; and / or 45°≤ α 2≤80°; and / or 35°≤ β 2≤60°。 10. The fan structure according to claim 8, characterized in that, Along the radial direction of the hub (4), the profile of the tip of the rotor blade (1) is further away from the hub (4) than the profile of the tip of the stator blade (2).

11. The fan structure according to claim 10, characterized in that, β 1＜ β 2。 12. An open rotary engine, characterized in that, Includes the fan structure according to any one of claims 1 to 11.

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