Stator blade and open rotor engine comprising stator blade

Abstract

The invention relates to a stator blade and an open rotor engine comprising the stator blade. The stator blade is used for the rear row of the open rotor engine. The stator blade extends from the blade root part to the blade tip part, so that the noise of the open type rotor fan can be effectively reduced. A tip portion of the stator blade has a tip surface, a leading edge of the stator blade at the tip surface extending a distance from a root portion of the blade is farther than a trailing edge of the stator blade at the tip surface extending a distance from the root portion of the blade such that the tip surface is an inclined surface with a higher leading edge and a lower trailing edge when viewed from a side view.

Description

Technical Field

[0001] The present invention relates to a stator vane for the rear row of an open rotor engine, and more particularly to reducing the blade noise of an open rotor engine. The present invention belongs to the field of engine design. Background Art

[0002] In recent years, open rotor engines have become one of the potential power alternatives for next-generation civil aircraft due to their advantages of high propulsion efficiency and low fuel consumption rate. The most significant feature of an open rotor engine is that it can achieve an ultra-high bypass ratio. Since the engine nacelle is removed, the drag is reduced, thus fuel consumption can be saved.

[0003] While the open rotor engine has great opportunities in the future, it also faces technical challenges. The noise control of a passenger aircraft involves multiple aspects such as the airworthiness, comfort, and safety of the aircraft. Ensuring that the takeoff, sideline, and approach noise levels of a civil aircraft during takeoff and landing do not exceed the external noise limits of the airworthiness regulations CCAR36 / FAR36 is a necessary condition for the aircraft to obtain an international airworthiness certificate.

[0004] Although the open rotor engine has great fuel-saving potential, its noise problem is prominent because there is no nacelle shielding and containment outside the propeller fan. The open rotor structure makes it have no casing wrapping, and the casing treatment noise reduction method of traditional turbofan engines cannot be applied.

[0005] Since it adopts a two-row rotor contra-rotating form, the flow and noise mechanisms are very complex; the noise of an open rotor engine comes from multiple aspects, such as the thickness of the blade, whether the tip speed of the blade is faster than the speed of sound, etc. The open rotor engine has a large bypass ratio and a low jet velocity, and its maximum noise mainly comes from the open fan blades.

[0006] Regarding the noise reduction of open rotor engines, a large amount of research work has been done at home and abroad, and a series of noise reduction measures have been developed. For example, the noise problem is solved by increasing the number of rotor blades, blade sweep and skew design, reducing the tip speed of rotor blades, the distance between the front row rotor and the rear row stator, reducing the strength of the wing tip vortex of the front row rotor, and changing its shape from the traditional long strip to short and wide type. It should be noted that when applying noise reduction measures, it must be on the premise of not significantly affecting the aerodynamic performance of the fan.

[0007] In order to effectively reduce the noise of open rotor fans, there is still a need to further improve the structure of existing open rotor engines. Summary of the Invention

[0008] Aiming at the above problems of the prior art, the purpose of the present invention is to provide a stator vane for the rear row of an open rotor engine. The stator vane extends from the blade root to the blade tip and can effectively reduce the noise of the open rotor fan.

[0009] In a first example of the stator vane, the tip portion of the stator vane has a tip surface, and the leading edge of the stator vane at the tip surface extends a greater distance from the root portion than the trailing edge of the stator vane at the tip surface extends from the root portion, such that the tip surface is an inclined surface that is higher at the leading edge and lower at the trailing edge when viewed from a side view.

[0010] In a second example of the stator vane, optionally including the first example, the tip surface of the stator vane forms a first angle with the leading edge of the stator vane, and the first angle is 90 degrees.

[0011] In a third example of the stator vane, optionally including the first example, the tip surface of the stator vane forms a first angle with the leading edge of the stator vane, and the first angle is less than 90 degrees:

[0012] In a fourth example of the stator vane, optionally including one or more of the first to third examples, the tip surface of the stator vane has a sharp portion protruding from the tip surface at the leading edge of the stator vane.

[0013] In a fifth example of the stator vane, optionally including one or more of the first to fourth examples, the leading edge of the sharp portion of the stator vane extends along the leading edge of the stator vane.

[0014] In a sixth example of the stator vane, optionally including one or more of the first to fifth examples, the leading edge of the stator vane has a gradually shrinking cross-sectional shape at the tip portion, such that the thickness of the leading edge of the stator vane is thinner at the tip portion than at other positions.

[0015] In a seventh example of the stator vane, optionally including one or more of the first to sixth examples, a plurality of noise reduction holes are provided on the tip surface of the stator vane.

[0016] In an eighth example of the stator vane, optionally including one or more of the first to seventh examples, the plurality of noise reduction holes are arranged facing the oncoming flow direction of the airflow shed from the rotor blades in the front row of an open rotor engine.

[0017] The present invention provides an open rotor engine, which includes a stator vane according to any one of the above aspects.

[0018] Different from the conventional method of increasing the distance between the front and rear row blades, in order to reduce the impact on the aerodynamic performance of the open rotor, the present invention redesigns the rear row blades: (1) The tip of the rear row blade is designed as an inclined curved surface that is higher on the left and lower on the right. (2) The leading edge of the tip of the rear row blade is designed to be sharp. (3) The tip surface of the rear stator blade and the leading edge are designed to be at a right angle. (4) A large number of noise reduction holes are opened on the tip surface of the rear row blade. The beneficial effects obtained are:

[0019] (1) The tip inclined surface of the rear row of blades not only reduces the probability of the front row of vortices and / or wakes colliding with the rear half of the blade tips of the rear row of blades, reducing the interference effect between the front and rear rows of blades. Additionally, it reduces the average diameter of the rear row of blades in the radial direction of the blades, reducing the probability of the front row of blade vortices or wakes colliding with the rear row of blades;

[0020] (2) Micro-flow control is performed on the tip region. The pointed tip at the leading edge of the rear row of blades reduces the contact area, and can break the front row of vortices into smaller vortices, reducing the interference noise component between the front and rear rows of blades;

[0021] (3) The leading edge is designed with a right angle, which allows some of the front row of blade vortices or wakes to flow out along the inclined surface, reducing the probability of the front row of blade vortices and / or wakes colliding with the blade tips of the rear row of blades.

[0022] (4) A large number of noise reduction holes are designed on the tip surface of the rear row of blades. The front row of blade vortices and / or wakes enter the interior through the noise reduction holes on the tip surface of the rear row of blades, and the sound energy is dissipated by the viscous effect of the hole walls.

[0023] The noise reduction design does not modify the external shape geometry of the front row of rotor blades 10, but only modifies the tips of the stator blades. Therefore, the noise is reduced on the premise of having little impact on the overall aerodynamic performance.

[0024] In summary, the present design performs micro-flow control on the tip region on the premise of having little impact on the aerodynamic performance, and can effectively reduce noise. Description of the Drawings

[0025] To describe the above and other features of the present invention in an embodiment, a more specific description of the present invention briefly described above will be presented with reference to the exemplary embodiments of the present invention shown in the drawings. It can be understood that these drawings only depict the exemplary embodiments of the present invention and should not be considered as limiting its scope. The present invention will be described and explained by using the drawings and additional features and details. In the drawings:

[0026] Figure 1 is a schematic side view of a part of an open rotor engine according to an embodiment of the present invention;

[0027] Figure 2 is a schematic side perspective view of a part of an open rotor engine according to another embodiment of the present invention;

[0028] Figure 1 、 2 are drawn approximately to scale. However, the dimensions in the drawings are only schematic and do not have to be drawn to scale, but are intended to be more clearly illustrated. In other embodiments, other relative dimensions may be used.

[0029] Herein and throughout the following, the same features appearing in different figures are denoted by the same or similar reference numerals.

[0030] List of reference numerals:

[0031] 1 Open rotor engine

[0032] 10 Rotor blade

[0033] 20 Stator blade

[0034] 20a Root part of the blade

[0035] 20b Tip part of the blade

[0036] 21 Tip surface

[0037] 22 Sharp part

[0038] 23 Noise reduction hole Detailed implementation manners

[0039] First of all, the present invention mainly relates to the field of open rotor engines. In particular, the present invention relates to the process related to the stator blades at the rear row of an open rotor engine, but is not limited to the blades at this position.

[0040] The term "heading direction" used herein is intended to describe the flight direction of an aircraft having an open rotor engine.

[0041] The terms "front row" and "rear row" used herein are intended to describe that the rotor blades of an open rotor engine are located in the front in the heading direction, and the stator blades are located in the rear in the heading direction. Therefore, there is a possibility that the airflow detached from the rotor blades impacts the stator blades.

[0042] The term "leading edge" used herein is intended to describe the blade part of a blade at the front end in the blade rotation direction, and the term "trailing edge" is intended to describe the blade part of a blade at the rear end in the blade rotation direction.

[0043] The term "extend" used herein is intended to describe that a component has a certain length in the extension direction from the starting position to the terminal position.

[0044] The term "thickness of the blade" used herein is intended to describe the width of the blade in the direction perpendicular to the heading direction in a cross-sectional plane parallel to the heading direction and perpendicular to the extension direction of the blade from the root part to the tip part of the blade.

[0045] Directional terms used in this document, such as "vertical", "horizontal", "top", "bottom", "upper", "lower", "inner", "inward", "outer", and "outward", are used to assist in describing the present invention according to the directions of the embodiments shown in the drawings. The directional terms are not absolute up, down, horizontal, vertical, etc., and should not be construed as limiting the present invention to any specific direction.

[0046] The terms "comprising", "having", "including", and their variants used in this document are intended to be open transitional phrases, terms, or words that require the presence of the specified components / steps and also allow the presence of other components / steps.

[0047] In the present invention, unless explicitly stated to the contrary, the terms "first", "second", etc. are not intended to indicate any difference in order, position, quantity, or importance, but are merely used as labels to distinguish different positions and components.

[0048] The terms "about" and "substantially" can be used to include any value that can vary without changing the basic function of that value. Generally, the terms "about" and "substantially" can refer to plus or minus 10% of the indicated number. When used with a range, "about" and "substantially" also disclose the range defined by the absolute values of the two endpoints. For example, "about 2 to about 4" also discloses the range "from 2 to 4".

[0049] All ranges disclosed in this document include the recited endpoints and can be combined independently (e.g., the range "from 2 to 4" includes the endpoints 2 and 4 and all intermediate values).

[0050] The numerical values used in this document should be understood to include the same values when rounded to the same number of significant digits, as well as values that differ from the said values by less than the experimental error determined by conventional measurement techniques of the type described in this application.

[0051] Finally, the numerical values given in each embodiment are only examples and do not limit the scope of the present invention.

[0052] The open rotor engine 1 of the present invention may have rotor blades 10 in the front row and stator blades 20 in the rear row. The shape of the rotor blades 10 is not specifically limited herein. The stator blades 20 will be described in detail below.

[0053] Tilted tip surface of the stator vane

[0054] In a non-limiting example, the stator blades 20 of the present invention extend from the blade root 20a to the blade tip 20b. The blade tip 20b of the stator blade 20 has a blade top surface 21.

[0055] In a non - restrictive example, the leading edge of the stator vane 20 at the tip surface 21 extends a greater distance from the root 20a than the trailing edge of the stator vane 20 at the tip surface 21, such that the tip surface 21 is an inclined surface with a higher leading edge and a lower trailing edge when viewed from a side view.

[0056] Here, it can be understood that based on the initial stator vane 20, a part of the trailing edge of the initial tip 20b is cut off in a direction staggered from the extension direction from the root 20a to the tip 20b.

[0057] In the prior art, the tip of the rear - row stator vane 20 is usually cut parallel to the engine axial direction to shorten the length of the stator vane. However, the inclined surface of the tip of the stator vane in the present invention means that less of the blade is cut off, the blade area is larger, the working ability of the blade is better, which can provide greater thrust and has little impact on the aerodynamic performance.

[0058] This allows the probability of the vortices shed at the tips of the front - row rotor blades 10 and / or the wakes of the rotor blades 10 colliding with the rear - half part (i.e., the part near the trailing edge) of the tip surface 21 of the rear - row stator vane 20 to be reduced, and can reduce the interference between the front - row rotor blades 10 and the rear - row stator vane 20.

[0059] In addition, after cutting off a part of the trailing edge of the initial tip 20b, it is equivalent to cutting the diameter of the rear - row stator vane 20, and the average diameter of the rear - row blades in the blade radial direction is reduced, which will reduce the probability of the wakes of the front - row rotor blades 10 colliding with the rear - row stator vane 20, so as to reduce the interference noise between the front - row and rear - row stator vanes 20.

[0060] Thin leading edge of the stator vane

[0061] In a non - restrictive example, the leading edge of the stator vane 20 of the present invention has a gradually shrinking cross - sectional shape at the tip 20b, such that the thickness of the leading edge of the stator vane 20 is thinner at the tip 20b than at other positions.

[0062] The thin cross - section of the leading edge can reduce the contact area when the vortices and / or wakes of the front - row rotor blades 10 collide with the tip of the rear - row stator vane 20. The overall intensity of the impact is small, so the noise is reduced. And the thin leading edge can easily decompose large vortices into small vortices, which is beneficial to noise reduction.

[0063] Sharp portion of the stator vane

[0064] In a non - restrictive example, the tip surface 21 of the stator vane 20 of the present invention has a sharp portion 22 protruding from the tip surface 21 at the leading edge of the stator vane 20, which is used for micro - flow control in the tip region to reduce noise.

[0065] After the vortex and / or wake of the front-row rotor blade 10 collide with the tip 22 of the rear-row stator blade 20, the tip of the tip 22 can break the vortex into smaller vortices, reducing the interference noise component between the front-row and rear-row stator blades 20 and the front-row rotor blade 10.

[0066] Multiple noise reduction holes on the tip surface of the stator vane

[0067] In a non-limiting example, a plurality of noise reduction holes 23 are provided on the tip surface 21 of the stator blade 20 of the present invention. Specifically, a large number of noise reduction holes 23 are opened on the tip surface 21 of the rear-row stator blade 20, so that the tip surface 21 of the rear-row stator blade 20 forms an inclined surface perforated plate.

[0068] When the vortex and / or wake of the front-row rotor blade 10 pass through the noise reduction holes 23 on the tip surface 21 of the rear-row stator blade 20, they enter the blade interior, and the sound energy is dissipated and absorbed through the wall viscous effect of the noise reduction holes 23, attenuating the noise without significantly affecting the aerodynamic performance.

[0069] Preferably, the noise reduction holes 23 are arranged facing the oncoming flow direction of the air flow shed from the front-row rotor blade 10 of the open rotor engine 10, which allows softening the tip surface 21 of the stator blade 20, so that the impact force is reduced when the vortex and / or wake collide with the tip surface 21.

[0070] The design of the stator blade 20 of the present invention reduces the probability of the tip vortex and / or wake of the front-row rotor blade 10 colliding with the rear row. The tip region of the rear-row stator blade 20 is designed as an inclined surface that is higher on the left and lower on the right, reducing the average diameter of the rear-row stator blade 20 and lowering the probability of the tip vortex or wake of the front-row rotor blade 10 colliding with the rear half of the tip of the rear-row stator blade 20; the designed inclined surface of the rear-row stator blade 20 forms a right angle with the tip leading edge, and part of the vortex or wake of the front-row rotor blade 10 can flow out along the inclined surface, reducing the probability of the vortex and / or wake of the front-row rotor blade 10 colliding with the tip of the rear-row stator blade 20.

[0071] The design of the stator blade 20 of the present invention reduces the problem of large interference between the front-row and rear-row stator blades 20 in the existing solution. A special tip shape is designed at the leading edge of the rear-row stator blade 20, reducing the contact area when the tip shedding vortex and / or wake of the front-row rotor blade 10 collide with the tip of the rear-row stator blade 20; the tip of the leading edge of the rear-row stator blade 20 can break the front-row tip vortex into smaller vortices, reducing the interference between the front-row and rear-row stator blades 20;

[0072] The design of the stator blade 20 of the present invention attenuates noise without significantly affecting the aerodynamic performance. Compared with the conventional design that obtains noise reduction benefits by affecting the flow characteristics, the present invention only opens a large number of noise reduction holes on the surface of the rear row of stator blades 20. The noise enters the blade interior through the upper surface of the rear row of stator blades 20 and is dissipated and absorbed.

[0073] The present invention will be further described below in conjunction with specific embodiments and the accompanying drawings. More details are set forth in the following description to facilitate a full understanding of the present invention. However, the present invention is clearly capable of being implemented in many other ways different from this description. Those skilled in the art can make similar generalizations and deductions according to the actual application situation without departing from the connotation of the present invention. Therefore, the protection scope of the present invention should not be limited by the content of this specific embodiment.

[0074] Figure 1 A side view schematically shows a part of an open rotor engine according to an embodiment of the present invention.

[0075] From the side view angle, the leading edge of the tip portion 20b of the conventional rear row of stator blades 20 forms an obtuse angle with the top blade chord length, that is, the same as the tip portion of the front row of rotor blades 10. When the vortex shed from the tip of the front row of rotor blades 10 or the wake of the rotor blade 10 collides with the tip of the rear row of stator blades 20, the contact area is large and the interaction distance is long.

[0076] Cut off Figure 1 the shaded part, the average diameter of the rear row of stator blades 20 is reduced, and the probability of the vortex or wake of the front row of rotor blades 10 colliding with the rear row of stator blades 20 is reduced.

[0077] In this embodiment, the top surface 21 of the stator blade 20 forms a first angle A with the leading edge of the stator blade 20, and the first angle A is approximately 90 degrees.

[0078] From the side view angle, considering the streamline trajectory of the front row of rotor blades 10, the designed inclined top surface 21 of the rear row of stator blades 20 forms a right angle with the leading edge of the stator blade 20 at the tip portion 20, as Figure 1 shown by the angle A, which can enable a part of the vortex and / or wake of the front row of rotor blades 10 to flow out along this inclined surface, reducing the probability of the vortex and / or wake of the front row of rotor blades 10 colliding with the tip portion 20b of the rear row of stator blades 20.

[0079] In Figure 1 it, the sharp portion 22 is schematically shown as a right triangle extending along the leading edge of the stator blade 20, and the leading edge of the sharp portion 22 extends along the leading edge of the stator blade 20.

[0080] Figure 2A side perspective view schematically showing a part of an open rotor engine according to an embodiment of the present invention is shown. In Figure 2 In the perspective view, different from Figure 1 In the side view, a detailed arrangement on the tip surface 21 of the stator vane 20 can be further observed.

[0081] In this embodiment, the tip surface 21 of the stator vane 20 forms a first angle A with the leading edge of the stator vane 20, and the first angle A is an acute angle less than 90 degrees, preferably less than 85 degrees, and more preferably less than 80 degrees. A smaller acute angle makes the probability of collision lower.

[0082] Furthermore, in this embodiment, the tip surface 21 of the stator vane 20 has a curved shape, and the line connecting the outermost end of the trailing edge at the tip portion 20b of the stator vane 20 and the outermost end of the leading edge at the tip portion 20b of the stator vane 20 forms a second angle with the leading edge of the stator vane 20, and the second angle is preferably an acute angle less than 80 degrees, preferably less than 75 degrees, and more preferably less than 70 degrees.

[0083] Therefore, a part of the vortex and / or wake of the front row of rotor blades 10 can flow out along the curved inclined surface, reducing the probability that the vortex and / or wake of the front row of rotor blades 10 collide with the tip portion 20b of the stator vane 20 in the rear row.

[0084] In Figure 2 , the sharp portion 22 is schematically shown as a sharp corner extending along the leading edge of the stator vane 20, and the leading edge of the sharp portion 22 extends along the leading edge of the stator vane 20, and the trailing edge has a curved shape and is smoothly connected to the curved shape of the tip surface 21.

[0085] Above, in order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution of the present invention has been clearly and completely described in combination with the specific embodiments of the present invention and the drawings.

[0086] Although various embodiments have been described above, it should be understood that the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments, and they are presented by way of example rather than limitation. It is obvious to those skilled in the relevant art that the disclosed subject matter can be implemented in other specific forms without departing from its spirit and essential features.

[0087] During this process, various elements important to the present invention or elements beneficial to the further development of the present invention will be mentioned in the content of specific examples, but some of these elements can also be used for the further development of the present invention when separated from the content of the corresponding examples and other features of the corresponding examples. Therefore, the embodiments described above are considered to be exemplary rather than restrictive in all aspects and do not serve as a basis for any limitation to the present invention.

[0088] Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of the present invention to be protected. This disclosure also includes various variations and variations within the equivalent scope. In addition, various combinations, methods, and further include other combinations and methods with only one element, more than one, or less than one, which also fall within the scope and ideological scope of this disclosure.

Claims

1. A stator vane for the rear row of an open rotor engine, the stator vane (20) extending from a blade root portion (20a) to a blade tip portion (20b). Characterized in that, The blade tip portion (20b) of the stator vane (20) has a blade tip surface (21), and the leading edge of the stator vane (20) at the blade tip surface (21) extends a farther distance from the blade root portion (20a) than the trailing edge of the stator vane (20) at the blade tip surface (21) extends from the blade root portion (20a), such that the blade tip surface (21) is an inclined surface with a higher leading edge and a lower trailing edge when observed from a side view.

2. The stator vane according to claim 1, Characterized in that, The blade tip surface (21) of the stator vane (20) forms a first angle (A) with the leading edge of the stator vane (20), and the first angle (A) is 90 degrees.

3. The stator vane according to claim 1, Characterized in that, The blade tip surface (21) of the stator vane (20) forms a first angle (A) with the leading edge of the stator vane (20), and the first angle (A) is less than 90 degrees.

4. The stator vane according to claim 1, Characterized in that, The blade tip surface (21) of the stator vane (20) has a sharp portion (22) protruding from the blade tip surface (21) at the leading edge of the stator vane (20).

5. The stator vane according to claim 4, Characterized in that, The leading edge of the sharp portion (22) of the stator vane (20) extends along the leading edge of the stator vane (20).

6. The stator vane according to claim 1, Characterized in that, The leading edge of the stator vane (20) has a gradually contracting cross-sectional shape at the blade tip portion (20b), such that the thickness of the leading edge of the stator vane (20) is thinner at the blade tip portion (20b) than at other positions.

7. The stator vane according to claim 1, Characterized in that, A plurality of noise reduction holes (23) are provided on the blade tip surface (21) of the stator vane (20).

8. The stator vane according to claim 7, Characterized in that, The plurality of noise reduction holes are arranged facing the oncoming flow direction of the airflow shed from the rotor blades (10) of the front row of the open rotor engine (10).

9. An open rotor engine, Characterized in that, The open rotor engine (1) includes the stator vane (20) according to any one of claims 1-8.

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