Low-noise open type rotor engine and rotor blade and stator blade thereof
By designing blade configurations with large forward and backward sweeps, as well as blade tip lift and large chord length design, the noise problem of open rotor engines was solved, achieving an increase in rotor-to-stationary distance and an effective reduction in noise.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- AECC COMML AIRCRAFT ENGINE CO LTD
- Filing Date
- 2024-10-15
- Publication Date
- 2026-04-17
AI Technical Summary
Existing noise reduction measures for open rotor engines have limited potential, with noise mainly originating from propeller blades, particularly the interference noise problem between rotor and stator blades.
By designing rotor blades with a large forward sweep configuration and stator blades with a large backward sweep configuration, the distance between the rotor and stator blades is increased. By optimizing the blade shape to reduce interference noise, rotor tip lift design and large tip chord design are adopted to optimize airflow and reduce tip vortex generation.
It effectively reduced blade pass frequency (BPF) single-tone noise, reduced rotor blade load noise, optimized rotor wake motion, increased rotor-to-station distance, and reduced rotor-to-station interference noise.
Smart Images
Figure CN121875832A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of aero-engines, and more particularly to an open rotor engine and its rotor blades and stator blades. Background Technology
[0002] An open rotary engine, also known as a ductless fan engine or propfan engine, is a gas turbine engine that generates thrust by using the output power of a power turbine shaft to drive a propfan. It is a new type of engine that falls between turboprop and turbofan engines, primarily composed of four main components: a gas generator, a power turbine, a transmission system, and a propfan. Open rotary engines offer advantages such as high propulsive efficiency and low fuel consumption, making them an important technological development direction for commercial aero engines.
[0003] Open rotor engines have a high bypass ratio and low jet velocity, and their noise mainly comes from the propeller blades. Furthermore, because the propeller blades lack the shielding and containment of a nacelle, the noise problem is particularly pronounced. Currently, noise reduction designs for open rotor engine propeller blades have developed measures such as increasing the number of rotor and stator blades, reducing rotor blade tip velocity, and cutting the downstream stator tip.
[0004] However, the existing noise reduction measures have limited noise reduction potential, and there is a need to continue developing noise reduction measures for open rotor engines. Summary of the Invention
[0005] The purpose of this application is to provide an open rotary engine.
[0006] Another objective of this application is to provide a rotor blade for an open rotary engine.
[0007] Another objective of this application is to provide a stator blade for an open rotary engine.
[0008] According to one aspect of this application, an open rotary engine includes: a rotor blade, including a rotor blade root and a rotor blade tip that radially define the rotor blade, and a rotor leading edge and a rotor trailing edge that axially define the rotor blade; a stator blade located axially downstream of the rotor blade, including a stator blade root and a stator blade tip that radially define the stator blade, and a stator leading edge and a stator trailing edge that axially define the stator blade; and a hub providing mounting positions for the rotor blade and the stator blade, the rotor blade and the stator blade extending radially from the hub; wherein the rotor trailing edge includes a sweep angle λ with an extreme value between 45° and 90° at a span of 50% or more, and the stator leading edge includes a sweep angle λ with an extreme value between -90° and -50° at a span of 50% or more.
[0009] The solutions provided in the above embodiments increase the rotor-to-stationary distance of the open rotor engine's propeller blades by employing large forward-swept rotor blades. This reduces the intensity of the rotor blade tip vortices and wakes acting on the stator blades axially upstream, and generates more cross-cancellation of rotor-to-stationary interference noise, achieving noise reduction, especially reducing blade passing frequency (BPF) single-tone noise. Employing large backward-swept stator blades further increases the rotor-to-stationary distance of the open rotor engine's propeller blades, achieving a noise reduction effect. Aerodynamic and noise design of the propeller blades, under the constraint of aerodynamic performance parameters such as thrust and efficiency, sufficiently increases the rotor-to-stationary distance simply by optimizing the shape of the rotor blades and stator blades, without the need for variable propeller blades or additional accessories or devices.
[0010] In one or more embodiments of the open rotor engine, the rotor blade tip includes a rise-fall angle θ with an extreme value between 5° and 15°.
[0011] The solution provided in the above embodiments adopts a rotor tip lifting design so that the rotor trailing edge is higher than the rotor leading edge in the radial direction, thereby guiding the airflow, suppressing the generation of rotor tip vortices and optimizing the motion trajectory of the rotor wake, thereby reducing the rotor-stationary interference intensity and reducing noise.
[0012] In one or more embodiments of the open rotor engine, the stator blade tip includes a rise-fall angle θ with an extreme value between -10° and -5°.
[0013] In one or more embodiments of the open rotor engine, the chord length C of the rotor blade at 100% span S is 1.2 to 1.6 times that of the chord length C at 1% span S.
[0014] The solution provided in the above embodiments adopts a large chord length design for the rotor blade tip, which increases the area of the rotor blade tip, reduces the aerodynamic load level per unit area in the blade tip region, and reduces the load noise of the rotor blade.
[0015] In one or more embodiments of the open rotary engine, the connection point between the rotor leading edge and the rotor blade tip includes a rounded corner.
[0016] According to another aspect of this application, the rotor blade of an open rotor engine includes a rotor root and a rotor tip that radially define the rotor blade, and a rotor leading edge and a rotor trailing edge that axially define the rotor blade; wherein the rotor trailing edge includes a sweep angle λ with an extreme value between 45° and 90° at a span of 50% or more.
[0017] In one or more embodiments of the rotor blades, the rotor blade tip includes the rise-fall angle θ, which has an extreme value between 5° and 15°.
[0018] In one or more embodiments of the rotor blade, the chord length C of the rotor blade at 100% span S is 1.2 to 1.6 times that of the chord length C at 1% span S.
[0019] In one or more embodiments of the rotor blade, the connection point between the rotor leading edge and the rotor blade tip includes a rounded corner.
[0020] According to another aspect of this application, the stator blade of an open rotor engine includes a stator root and a stator tip that define the stator blade radially, and a stator leading edge and a stator trailing edge that define the stator blade axially; wherein the stator leading edge includes a sweep angle λ with an extreme value between -90° and -50° at a span of 50% or more.
[0021] In one or more embodiments of the stator blade, the stator blade tip includes the rise and fall angle θ, which has an extreme value between -10° and -5°. Attached Figure Description
[0022] 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, in which the same reference numerals always denote the same features. It should be noted that these 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:
[0023] Figure 1 This is a schematic diagram of the structure of an open rotary engine in a meridional projection plane according to an embodiment.
[0024] Figure 2 The diagram schematically shows the noise reduction effect curves of rotor blades with different forward-swept configurations.
[0025] Figure 3 The diagram schematically shows the noise reduction effect curves of stator blades with different swept configurations.
[0026] Figure 4 The diagram schematically shows the noise reduction effect curves of rotor blade tips with different lifting configurations.
[0027] Explanation of reference numerals in the attached figures:
[0028] 1. Open rotary engine;
[0029] 10. Wheel hub;
[0030] 20. Rotor blade; 21. Rotor blade root; 22. Rotor blade tip; 23. Rotor leading edge; 24. Rotor trailing edge; 25. Rounded corner;
[0031] 30. Jingzi leaf blade; 31. Jingzi leaf root; 32. Jingzi leaf tip; 33. Jingzi leading edge; 34. Jingzi trailing edge. Detailed Implementation
[0032] Reference will now be made in detail to various embodiments of this application, examples of which are shown in the accompanying drawings and described below. Although this application will be described in conjunction with exemplary embodiments, it should be understood that this specification is not intended to limit this application to those exemplary embodiments. Rather, this application is intended to cover not only these exemplary embodiments, but also various alternatives, modifications, equivalents, and other embodiments that may be included within the spirit and scope of this application as defined by the appended claims.
[0033] In the specification of this application, "upstream" and "downstream", "front" and "rear" are distinguished by the general airflow direction during engine operation. That is, during engine operation, air generally flows from "upstream" to "downstream" and from "front" to "rear". This direction is also roughly the "intake" to "exhaust" direction of the engine turbine.
[0034] Furthermore, this specification uses specific terms to describe embodiments thereof. For example, "an embodiment" and / or "one embodiment" refers to a particular feature, structure, or characteristic associated with at least one embodiment of this specification. Therefore, it should be emphasized and noted that "an embodiment" or "one embodiment" mentioned twice or more in different locations in this specification do not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of this specification can be appropriately combined.
[0035] Currently, noise is a prominent issue with open rotor engines, and conventional noise reduction techniques have limited potential, necessitating further development of noise reduction measures for open rotor engines.
[0036] Through in-depth research, the inventors discovered that open rotor engines, with their high bypass ratio and low jet velocity, primarily generate noise from the propeller blades. During high-speed rotor rotation, airflow over the blade surface moves from the blade root to the blade tip. The leading edge and tip of the blades are unsteady pressure hot zones, which are the main sources of noise. The propeller blade noise of open rotor engines mainly includes rotor load noise and interference noise between the front and rear rows. The rotor-to-stationary distance has a significant impact on propeller blade noise. This distance can be significantly increased by optimizing the shape of the rotor and stator blades, without the need for variable propellers or additional accessories or devices. Based on this, the inventors have proposed a low-noise open rotor engine.
[0037] Figure 1A meridional projection plane of the open rotor engine 1 according to one embodiment is shown. Within this meridional projection plane, the open rotor engine 1 has a central axis X, the direction of which is defined as the axial direction, and the direction perpendicular to the central axis X is defined as the radial direction.
[0038] In the radial direction, the blade has a radial dimension from the leaf root to the leaf tip, i.e., a span S. A portion of the blade is positioned radially by the span S, with the leaf root at 0% span S and the leaf tip at 100% span S. "x% span S" refers to the radial position at a percentage of x% relative to the total span from the leaf root to the leaf tip. Accordingly, a range of the blade in the radial direction can also be described; for example, "within the range of x1% to x2% span S" refers to the range of the blade from x1% span S to x2% span S, and "above x% span S" refers to the range of the blade from x% span S to 100% span S.
[0039] The axial dimension of the blade is defined by the chord length C (not shown), which is the length of the meridional projection of the chord line, and the chord line is defined as the common tangent of the leading and trailing edges within the blade section at a certain span S.
[0040] The sweep profile of the leading and trailing edges of a blade is defined by the sweep angle λ, which is defined as the angle between the tangential and radial directions of the sweep curve of the blade edge on the meridional projection plane. Using a non-swept blade (i.e., a blade whose sweep curve is perpendicular to the central axis X) as a reference, an upstream deflection of the sweep curve is considered forward sweep, and a downstream deflection is considered backward sweep. The sweep angle λ is defined as positive for forward sweep and negative for backward sweep. The extreme values of the sweep angle λ, i.e., the maximum (or minimum) value of the sweep angle λ, represent the maximum degree of forward (or backward sweep) of the leading and trailing edges.
[0041] It is understood that the shape of the blade tip has a significant impact on the airflow trajectory during blade rotation, especially on the formation of tip vortices, and a blade tip lifting (or lowering) design can be adopted. This lifting (or lowering) is defined by the rise and fall angle θ, which is defined as the angle between the tangent and the axial direction of the profile curve of the blade tip on the meridional projection plane. From upstream to downstream, an increase in the radial dimension of the blade tip is considered lifting, and vice versa. The rise and fall angle θ is defined as positive when lifting and negative when lowering. The extreme value of the rise and fall angle θ, i.e., the maximum (or minimum) value of the rise and fall angle θ, represents the maximum degree of blade tip lifting (or lowering).
[0042] like Figure 1As shown, in some embodiments, the open rotary engine 1 includes: a rotor blade 20, which includes a rotor blade root 21 and a rotor blade tip 22 that radially define the rotor blade 20, and a rotor leading edge 23 and a rotor trailing edge 24 that axially define the rotor blade 20; a stator blade 30, which is located axially downstream of the rotor blade 20, including a stator blade root 31 and a stator blade tip 32 that radially define the stator blade 30, and a stator leading edge 33 and a stator trailing edge 34 that axially define the stator blade 30; a hub 10 that provides mounting positions for the rotor blade 20 and the stator blade 30, the rotor blade 20 and the stator blade 30 extending radially from the hub 10; wherein the rotor trailing edge 24 includes a sweep angle λ with an extreme value between 45° and 90° at more than 50% span S, and the stator leading edge 33 includes a sweep angle λ with an extreme value between -90° and -50° at more than 50% span S.
[0043] Adopting a large forward-sweep rotor blade configuration increases the rotor-to-stationary distance. This benefits both the attenuation of tip vortices and wakes of the upstream rotor blade 20 before they interfere with the stator blade 30, thus reducing the intensity of the rotor-to-stationary interference. It also facilitates more cross-cancellation of the rotor-to-stationary interference noise, achieving noise reduction, particularly at the blade passing frequency (BPF) single-tone noise. A large backward-sweep stator blade configuration also increases the rotor-to-stationary distance, reducing noise. Aerodynamic-noise design of the propeller blades, while meeting the constraints of thrust, efficiency, and other aerodynamic performance parameters, can significantly increase the rotor-to-stationary distance simply by optimizing the shape of the rotor blade 20 and stator blade 30, without the need for variable propeller blades or additional accessories or devices.
[0044] Figure 2 The diagram schematically illustrates the noise reduction effect of the rotor blades 20 with different forward-swept configurations at a span of 50% or more S. The horizontal axis represents the observation angle, the vertical axis represents the noise sound pressure level, and the baseline curve represents the reference noise result. Figure 2 As shown, compared to the baseline noise results, noise is effectively reduced when the rotor trailing edge 24 includes a sweep angle λ with an extreme value between 45° and 90°. However, the noise reduction effect is not significant when the extreme value of the sweep angle λ for the forward sweep is less than 45°.
[0045] Figure 3The diagram schematically illustrates the noise reduction effect of the stator blade 30 with different sweep configurations at a span of 50% or more, reflecting the noise sound pressure level at different observation angles. The baseline represents the reference noise result. Compared to the reference noise result, the stator leading edge 33 with a sweep angle λ having an extreme value between -90° and -50° effectively reduces noise. When the sweep is small, i.e., when the extreme value of the sweep angle λ is greater than -50°, the noise reduction effect is not significant.
[0046] Continue to refer to Figure 1 In some embodiments, the rotor blade tip 22 includes the rise and fall angle θ with an extreme value between 5° and 15°.
[0047] The rotor blade tip 22 is designed to be raised, so that the rotor trailing edge 24 is higher than the rotor leading edge 23 in the radial direction. This guides the airflow, suppresses the generation of rotor tip vortices, and optimizes the rotor wake trajectory, thereby reducing the intensity of rotor-to-stationary interference and noise. A large rise-fall angle θ has a significant impact on the flow field; preferably, the rise-fall angle θ is no greater than 15°.
[0048] Figure 4 The diagram schematically illustrates the noise reduction effect of the rotor blades 20 with different rise and fall angles θ. The horizontal axis represents the observation angle, the vertical axis represents the noise sound pressure level, and the baseline curve represents the reference noise result. Figure 4 As shown, compared to the baseline noise results, the rotor blade tip 22 effectively reduces noise when the lift angle θ has an extreme value between 5° and 15°. However, the noise reduction effect is not significant when the extreme value of the lift angle θ is less than 5°.
[0049] like Figure 1 As shown, in some embodiments, the stator blade tip 32 includes a rise / fall angle θ with an extreme value between -10° and -5°. The stator blade 30 adopts a descending design such that the radial dimension of the stator trailing edge 34 is smaller than the radial dimension of the stator leading edge 33, thereby reducing the area of the stator blade tip 32 and reducing the interference of the rotor blade 20 wake on the stator blade 30.
[0050] In some embodiments, the chord length C of the rotor blade 20 at 100% span S is 1.2 to 1.6 times the chord length C at 1% span S, that is, the chord length C of the rotor blade tip 22 is approximately 1.2 to 1.6 times the chord length C of the rotor blade root 21.
[0051] The rotor blade 30 adopts a large tip chord length design, thereby increasing the area of the rotor blade tip 32, reducing the aerodynamic load level per unit area of the rotor blade tip 32, and thus reducing the load noise of the rotor blade 30.
[0052] Continue to refer to Figure 1 In some embodiments, the connection point between the rotor leading edge 23 and the rotor blade tip 22 includes a fillet 25. By modifying the connection point between the rotor leading edge 23 and the rotor blade tip 22 to a fillet 25, tip vortices can be controlled. Compared to a sharp connection point, the fillet 25 can reduce the generation of tip vortices and lower rotor-to-stationary interference noise.
[0053] Building upon the foregoing, this application also provides a rotor blade for a low-noise open rotary engine. For example... Figure 1 As shown, the rotor blade 20 includes a rotor blade root 21 and a rotor blade tip 22 that radially define the rotor blade 20, and a rotor leading edge 23 and a rotor trailing edge 24 that axially define the rotor blade 20; wherein the rotor trailing edge 24 includes a sweep angle λ with an extreme value between 45° and 90° at a span of 50% or more.
[0054] In some embodiments, the rotor blade tip 22 includes the rise and fall angle θ, which has an extreme value between 5° and 15°.
[0055] In some embodiments, the chord length C at 100% span S of the rotor blade 20 is 1.2 to 1.6 times the chord length C at 1% span S, that is, the chord length C of the rotor blade tip 22 is approximately 1.2 to 1.6 times the chord length C of the rotor blade root 21.
[0056] In some embodiments, the connection position between the rotor leading edge 23 and the rotor blade tip 22 includes a rounded corner 25.
[0057] Building upon the foregoing, this application also provides a stator blade for a low-noise open rotor engine. (Continue to reference...) Figure 1 The stator blade 30 includes a stator root 31 and a stator tip 32 that define the stator blade 30 radially, and a stator leading edge 33 and a stator trailing edge 34 that define the stator blade 30 axially; wherein the stator leading edge 33 includes a sweep angle λ with an extreme value between -90° and -50° at a span of 50% or more.
[0058] In some embodiments, the stator blade tip 32 includes the rise and fall angle θ, which has an extreme value between -10° and -5°.
[0059] In summary, the low-noise open rotor engine and its rotor blades and stator blades described in the above embodiments have beneficial effects including, but not limited to, one or a combination of the following:
[0060] 1. Adopting a large forward-sweep rotor blade configuration can increase the rotor-to-stationary distance. On the one hand, this facilitates the attenuation of tip vortices and wakes of the upstream rotor blades before they interfere with the stator blades, thus reducing the intensity of rotor-to-stationary interference. On the other hand, it allows for more cross-cancellation of the acoustic waves of rotor-to-stationary interference noise. These two aspects achieve noise reduction, especially in reducing blade passing frequency (BPF) single-tone noise. Adopting a large backward-sweep stator blade configuration can also increase the rotor-to-stationary distance and reduce noise. Aerodynamic-noise design of the propeller blades, under the constraint of aerodynamic performance parameters such as thrust and efficiency, can sufficiently increase the rotor-to-stationary distance simply by optimizing the shape of the rotor and stator blades, without the need for variable propeller blades or additional accessories or devices.
[0061] 2. Optimize the rotor wake trajectory to reduce rotor-to-station interference noise. The rotor blade tip adopts a lifting design so that the rotor trailing edge is higher than the rotor leading edge in the radial direction, thereby guiding the airflow, suppressing the generation of rotor tip vortices, and optimizing the rotor wake trajectory, thus reducing the intensity of rotor-to-station interference and reducing noise.
[0062] 3. Reduce blade load noise. The rotor blades adopt a large tip chord length design, which increases the rotor blade tip area, thereby reducing the aerodynamic load level per unit area of the rotor blade tip and thus reducing the load noise of the rotor blades.
[0063] 4. Reduce tip vortex formation and lower rotor-to-station interference noise. Tip vortices can be controlled by rounding the connection between the rotor leading edge and the rotor blade tip. Compared to a sharp connection, a rounded corner reduces tip vortex generation and lowers rotor-to-station interference noise.
[0064] While this application discloses preferred embodiments as described above, 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 rotor engine (1) characterized by, include: The rotor blade (20) includes a rotor blade root (21) and a rotor blade tip (22) that radially define the rotor blade (20), and a rotor leading edge (23) and a rotor trailing edge (24) that axially define the rotor blade (20). The stator blade (30), located axially downstream of the rotor blade (20), includes a stator root (31) and a stator tip (32) that radially define the stator blade (30), and a stator leading edge (33) and a stator trailing edge (34) that axially define the stator blade (30). A hub (10) provides a mounting position for the rotor blades (20) and the stator blades (30), which extend radially from the hub (10); The rotor trailing edge (24) has a sweep angle (λ) with an extreme value between 45° and 90° when it has a span of 50% (S); the stator leading edge (33) has a sweep angle (λ) with an extreme value between -90° and -50° when it has a span of 50% (S).
2. The open rotary engine (1) as described in claim 1, characterized in that, The rotor blade tip (22) includes the rise and fall angle (θ) with an extreme value between 5° and 15°.
3. The open rotary engine (1) as described in claim 1, characterized in that, The stator leaf tip (32) includes the rise and fall angle (θ) with extreme values between -10° and -5°.
4. The open rotary engine (1) as described in claim 1, characterized in that, The chord length (C) of the rotor blade (20) at 100% span (S) is 1.2 to 1.6 times that of the chord length (C) at 1% span (S).
5. The open rotary engine (1) as described in claim 1, characterized in that, The connection between the rotor leading edge (23) and the rotor blade tip (22) includes a rounded corner (25).
6. A rotor blade (20) of an open rotary engine (1), characterized in that, It includes a rotor blade root (21) and a rotor blade tip (22) that radially define the rotor blade (20), and a rotor leading edge (23) and a rotor trailing edge (24) that axially define the rotor blade (20); The rotor trailing edge (24) includes a sweep angle (λ) with an extreme value between 45° and 90° above 50% span (S).
7. The rotor blade (20) as described in claim 6, characterized in that, The rotor blade tip (22) includes the rise and fall angle (θ) with an extreme value between 5° and 15°.
8. The rotor blade (20) as described in claim 6, characterized in that, The chord length (C) of the rotor blade (20) at 100% span (S) is 1.2 to 1.6 times that of the chord length (C) at 1% span (S).
9. The rotor blade (20) as claimed in claim 6, characterized in that, The connection between the rotor leading edge (23) and the rotor blade tip (22) includes a fillet (25).
10. A stator blade (30) of an open rotary engine (1), characterized in that, The stator blade (30) includes a stator root (31) and a stator tip (32) that radially define the stator blade (30), and a stator leading edge (33) and a stator trailing edge (34) that axially define the stator blade (30). The stator leading edge (33) includes a sweep angle (λ) with an extreme value between -90° and -50° above 50% span (S).
11. The stator blade (30) as described in claim 10, characterized in that, The stator leaf tip (32) includes the rise and fall angle (θ) with extreme values between -10° and -5°.