A fan and an aeroengine

Abstract

The present application provides a fan and an aero-engine, the fan comprising blades, the blades having a profile perpendicular to the spanwise direction, the profile having a chord length, the profile comprising a first profile, the first profile having a maximum chord length of the blade, a ratio of a height of the first profile to a height of the blade being less than or equal to 0.8, wherein the height refers to a dimension along the spanwise direction.

Description

Technical Field

[0001] This invention relates to the field of engine fans, and more particularly to a fan and an aircraft engine. Background Technology

[0002] Modern gas turbine aircraft engines typically include a fan that compresses incoming air and directs at least a portion of it through a bypass duct. The remaining air flows through the engine core. Fan blades are susceptible to a known phenomenon called flutter. Blade flutter is a fluid-structure interaction instability phenomenon where a blade generates unstable aerodynamic forces when it self-excites. Under normal circumstances, these unstable aerodynamic forces can cause oscillations in the surrounding gas, which in turn do work relative to the blade. If the work done by the surrounding gas exceeds the work dissipated by mechanical damping, the blade vibration will increase; this is known as flutter.

[0003] Blade flutter is a major threat to the safe operation of aero engines. Once it occurs, it can lead to serious consequences such as blade fatigue, fracture, and failure in a very short time, severely affecting the overall safety of the engine and reducing its service life. At the same time, in order to meet the stringent requirements of low fuel consumption, the bypass ratio of aero engines is constantly being increased to improve propulsion efficiency. The continuous increase in bypass ratio leads to a corresponding increase in fan size, which increases the risk of fan blade flutter.

[0004] Therefore, during the fan design phase, it is necessary to comprehensively consider the coupling of aerodynamic performance and structural strength in blade design. It is necessary to suppress blade flutter while ensuring the aerodynamic performance of the fan to guarantee the engine's thrust and fuel consumption rate. This is a difficult point in turbomachinery research and an important challenge in the development of high bypass ratio aero engines. Summary of the Invention

[0005] The purpose of this invention is at least to provide a fan that balances aerodynamic performance and flutter suppression requirements.

[0006] The following provides a brief overview of one or more aspects to offer a basic understanding of them. This overview is not an exhaustive summary of all conceived aspects, nor is it intended to identify key or decisive elements of all aspects, nor to define the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form to prepare for the more detailed descriptions that follow.

[0007] One embodiment of the present invention provides a fan, the fan including blades, the blades having a cross section perpendicular to the spanwise direction, the cross section having a chord length, the cross section including a first cross section having the maximum chord length of the blade, the ratio of the height of the first cross section to the height of the blade being less than or equal to 0.8, wherein the height refers to the dimension along the spanwise direction.

[0008] In some embodiments, the ratio of blade height to the maximum chord length of the blade is greater than 1.2 and less than 2.2.

[0009] In some embodiments, the blade includes, from the inside to the outside along the spanwise direction, a blade root, a corresponding position of the flow divider ring, and a blade tip. The corresponding position of the flow divider ring indicates the boundary between the inner and outer bypass of the engine, and the ratio of the blade root chord length to the maximum chord length is greater than or equal to 0.65.

[0010] In some embodiments, the ratio of the chord length at the corresponding position of the shunt ring to the maximum chord length is greater than or equal to 0.75.

[0011] In some embodiments, the ratio of the minimum chord length to the tip chord length in a region on the blade is greater than or equal to 0.9, and the region is the portion of the blade whose height is greater than the height of the first profile.

[0012] In some embodiments, the blade includes, from the inside to the outside along the spanwise direction, a blade root, a corresponding position of the splitter ring, and a blade tip. The corresponding position of the splitter ring indicates the boundary between the inner and outer bypass of the engine. The ratio of the pressure ratio at the corresponding position of the splitter ring to the maximum pressure ratio along the spanwise direction of the blade is greater than or equal to 0.8. The ratio of the pressure ratio at the blade tip to the maximum pressure ratio along the spanwise direction of the blade is greater than or equal to 0.8.

[0013] In some embodiments, the difference between the height of the first profile and the height at the point on the blade where the maximum pressure ratio along the span is located is less than or equal to one-tenth of the blade height.

[0014] In some embodiments, the ratio of the maximum thickness of the first profile to the maximum chord length is greater than or equal to 0.025.

[0015] In some embodiments, the ratio of the maximum thickness at the leaf root to the leaf root chord length is greater than or equal to 0.08.

[0016] In some embodiments, the ratio of the maximum thickness at the leaf tip to the leaf tip chord length is greater than or equal to 0.02.

[0017] In some embodiments, the blade includes, from the inside to the outside along the spanwise direction, a blade root, a corresponding position of the splitter ring, and a blade tip. The corresponding position of the splitter ring indicates the boundary between the inner and outer bypass of the engine. The cross-section has a center of gravity and includes a second cross-section. The center of gravity of the second cross-section has the minimum axial dimension of the center of gravity on the blade. There is a first distance between the center of gravity of the second cross-section and the center of gravity of the blade root. The ratio of the first distance to the chord length of the blade root is less than or equal to 0.1.

[0018] In some embodiments, the profile includes a third profile, the centroid of which has a second distance between itself and the centroid of the leaf root, the ratio of the second distance to the chord length of the leaf root being less than or equal to 0.3.

[0019] In some embodiments, there is a third distance between the centroid of the leaf tip and the centroid of the leaf root, and the ratio of the third distance to the chord length of the leaf root is less than or equal to 0.3.

[0020] In some embodiments, the flow rate per unit annular area of ​​the fan is less than or equal to 230 kg / s / m³. 2 Wherein, the flow rate per unit toroidal area is the ratio of the fan flow rate to the fan toroidal area.

[0021] One embodiment of the present invention also provides an aircraft engine, which includes the fan of any of the above embodiments.

[0022] The fan involved in this invention achieves the coupling of aerodynamic performance and structural strength in the fan by setting the structural parameters of the fan blades, which are related to their aerodynamic performance and structural stiffness and strength, within an appropriate range. This balances the contradiction between the aerodynamic requirements and the flutter suppression requirements of the fan blades, improves the aerodynamic efficiency of the fan, ensures the structural strength of the fan, suppresses the occurrence of fan blade flutter, and achieves the safe operation of the fan. Attached Figure Description

[0023] The above-described features and advantages of the present invention will be better understood after reading the following detailed description of embodiments of the present disclosure in conjunction with the accompanying drawings. In the drawings, components are not necessarily drawn to scale, and components having similar related properties or features may have the same or similar reference numerals. Wherein:

[0024] Figure 1 It is a cross-sectional view of an aircraft engine according to some embodiments;

[0025] Figure 2 This is a front view of the blade according to some embodiments;

[0026] Figure 3 This is a schematic diagram of a first cross-section according to some embodiments;

[0027] Figure 4 This is a schematic diagram showing the distribution of blade chord length along the blade span according to some embodiments;

[0028] Figure 5 This is a schematic diagram showing the distribution of blade pressure ratio along the blade span, based on some embodiments;

[0029] Figure 6 This is a schematic diagram showing the distribution of the maximum blade thickness along the blade span, based on some embodiments;

[0030] Figure 7 This is a schematic diagram showing the distribution of the axial position of the blade's center of gravity along the blade span, based on some embodiments. Detailed Implementation

[0031] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. It should be noted that the aspects described below with reference to the accompanying drawings and specific embodiments are merely exemplary and should not be construed as limiting the scope of protection of the present invention in any way.

[0032] It is understood that the technical terms that may be used in the description of this specification, such as “center,” “longitudinal,” “lateral,” “front,” “rear,” “left,” “right,” “vertical,” “horizontal,” “top,” “bottom,” “inner,” and “outer,” indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the implementation method and 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. Therefore, they should not be construed as limiting the scope of protection of the invention.

[0033] It should be noted that the use of terms such as "first" and "second" to define features in this article is merely for the purpose of distinguishing the corresponding features. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0034] like Figure 1 As shown, the aircraft engine has a rotation axis 10, and the axial direction described in this specification extends along the rotation axis 10. It is understood that... Figure 1 Half of the aircraft engine profile along the rotation axis 10 is shown.

[0035] An aero-engine includes an air intake 20 and a fan 30 along its axial direction. Air enters through the air intake 20 and is accelerated by the fan 30 to generate high-pressure, high-speed gas for propelling the aircraft forward. The fan 30 is a crucial component for generating thrust, and its aerodynamic efficiency significantly impacts the engine's thrust and fuel consumption. However, while improving the aerodynamic performance of the fan 30, it is necessary to suppress fan flutter to ensure safe operation of the aero-engine. Some embodiments in this specification achieve a coupling of aerodynamic performance and structural strength on the fan by setting the structural parameters of the fan blades. This improves the fan's aerodynamic efficiency while ensuring its structural strength, suppressing fan blade flutter, and ensuring safe operation of the fan.

[0036] Flow rate per unit toroidal area refers to the flow rate per unit area at the fan inlet. It is a crucial parameter for evaluating engine propulsion performance, reflecting the amount of air passing through a unit area per unit time. Increasing the flow rate per unit toroidal area can increase the fan's flow capacity, thereby reducing the engine's diameter and weight. This is particularly important for aero-engine design, as it directly impacts engine performance, weight, and fuel efficiency. However, increasing the flow rate per unit toroidal area increases the incoming Mach number, which may intensify shock wave interactions, leading to increased fan flutter and affecting fan stability margin. Therefore, in some embodiments, limiting the flow rate per unit toroidal area of ​​fan 30 to a relatively large maximum value improves fan aerodynamic efficiency while suppressing fan flutter.

[0037] In some embodiments, the flow rate per unit annular area of ​​the fan is less than or equal to 230 kg / s / m³. 2 The flow rate per unit annular area is the ratio of fan flow rate to fan annular area. Fan flow rate, also known as inlet flow rate, refers to the amount of air passing through the fan per unit time, and fan annular area refers to the area of ​​the annular region at the fan inlet. In some embodiments, the flow rate per unit annular area... Calculated using the following formula:

[0038]

[0039] in, For fan flow rate, A au The fan toroidal area is the same as the inlet area. With the center area The difference, L1 and L2, see [link / reference]. Figure 1 .

[0040] Fan 30 includes blades 31, and the blades 31 involved in the embodiments of this specification are as follows: Figure 2 As shown. See also Figure 2 The blade 31 has a spanwise orientation (see...) Figure 2 The spanwise direction refers to the direction in which the blade 31 extends between the end closest to the axis of rotation 10 and the end furthest from the axis of rotation 10. The spanwise dimension of the blade 31 characterizes the height of the blade. The blade 31 has several cross-sections perpendicular to the spanwise direction, each cross-section having a chord length, which is the length of the straight line connecting the leading and trailing edges of the blade cross-section, characterizing the width of the blade cross-section.

[0041] In some embodiments, to enhance the structural strength of the blade 31 and reduce the possibility of blade flutter, the overall center of gravity of the blade 31 is positioned close to the blade root, which is the portion of the blade 31 closest to the rotation axis 10. The blade 31, along its spanwise direction, includes, from the inside out, the blade root, the corresponding position of the flow divider ring, and the blade tip. In some embodiments, such as... Figure 2 and Figure 3 As shown, the blade 31 has several cross-sections, including a first cross-section 311. The chord length of the first cross-section 311 is the maximum value of the chord lengths of the several cross-sections, and the chord length of the first cross-section 311 is defined as the maximum chord length L4 of the blade 31. The height of the first cross-section 311 is related to the blade height (see...). Figure 1 The ratio of the blade height L3 shown is less than or equal to 0.8 to avoid the overall center of gravity of the blade 31 being set close to the blade tip, thereby improving the structural strength of the blade 31. In some embodiments, to further improve the structural strength of the blade 31, the ratio of the height of the first section 311 to the blade height is less than or equal to 0.7.

[0042] A higher aspect ratio of blade 31 results in better aerodynamic performance, but correspondingly, a greater likelihood of flutter. Therefore, it is necessary to limit the range of the aspect ratio of blade 31 to ensure a balance between aerodynamic performance and flutter suppression. In some embodiments, the ratio of blade height to maximum chord length (i.e., aspect ratio) is greater than 1.2 and less than 2.2. In some embodiments, to improve blade aerodynamic performance, the ratio of blade height to maximum chord length is greater than 1.5 and less than 2.2. In some embodiments, to suppress flutter, the ratio of blade height to maximum chord length is greater than 1.3 and less than 2.

[0043] In some embodiments, in order to suppress flutter, the blades are made wider overall by setting the spanwise distribution of the blade aspect ratio, thereby improving the structural strength of the blades while ensuring their aerodynamic performance. Figure 4 A cross-sectional chord length of blade 31 distributed along its span is shown, with the horizontal axis representing the chord length and the vertical axis representing the blade span (i.e., blade height). In some embodiments, such as Figure 4 As shown, the ratio of the blade root chord length to the maximum chord length (at the maximum chord length 201) is greater than or equal to 0.65. For example, the ratio of the blade root chord length to the maximum chord length is 0.7 or 0.75. The blade root chord length referred to here is the chord length of the cross-section at the blade root. In some embodiments, the ratio of the chord length at the corresponding position 203 of the splitter ring to the maximum chord length is greater than or equal to 0.75. For example, the ratio of the chord length at the corresponding position 203 of the splitter ring to the maximum chord length is 0.8 or 0.85. The corresponding position 203 of the splitter ring referred to here is the position on the blade corresponding to the splitter ring. The splitter ring, as described in this specification, is a component in an engine used to separate the bypass airflow from the internal airflow. The corresponding position 203 of the splitter ring indicates the boundary between the internal and external airflow of the engine (see...). Figure 4In some embodiments, the ratio of the minimum chord length to the tip chord length within a region on the blade is greater than or equal to 0.9. For example, the ratio of the minimum chord length to the tip chord length within a region on the blade is 0.92 or 0.95. The region is the portion of the blade whose height is greater than the height of the first cross-section. Figure 4 As shown, the first cross-section corresponds to the maximum chord length 201. The region includes positions 204 and 202 on the blade. The position with the minimum chord length in the region is position 204. The blade tip chord length refers to the chord length of the cross-section at the blade tip 202.

[0044] In some embodiments, in order to adapt to the different tangential velocities and loads at different points along the span of the blades 31 when the fan 30 is rotating, a spanwise distribution of the blade boost ratio is set so that the boost ratio on the blades is adapted to the load at different points along the span, ensuring the structural strength of the blades, while maximizing the boost ratio, reducing shock wave losses, and improving the stability of the fan 3's operation. Figure 5 The diagram illustrates a pressure ratio distribution along the span of blade 31, with the horizontal axis representing the pressure ratio and the vertical axis representing the blade span. In some embodiments, such as... Figure 5 As shown, the ratio of the pressure ratio at position 303 corresponding to the splitter ring to the maximum pressure ratio along the blade span is greater than or equal to 0.8. For example, the ratio of the pressure ratio at position 303 corresponding to the splitter ring to the maximum pressure ratio along the blade span is 0.85 or 0.9. Figure 5 As shown, the position on the blade 31 with the maximum pressure ratio along the span is position 301. In some embodiments, the ratio of the pressure ratio at the blade tip 302 to the maximum pressure ratio along the span of the blade is greater than or equal to 0.8. For example, the ratio of the pressure ratio at the blade tip 302 to the maximum pressure ratio along the span of the blade is 0.83 or 0.88.

[0045] In some embodiments, the difference between the height of the first profile 311 and the height of the blade at the point 301 with the maximum spanwise pressure ratio (i.e., position 301) is less than or equal to one-tenth of the blade height. For example, the ratio of the difference between the height of the first profile 311 and the height of the blade at the point 301 with the maximum spanwise pressure ratio to the blade height is 0.08 or 0.06. By limiting the height of the first profile 311 to be close to the height of the blade at the point 301 with the maximum spanwise pressure ratio, the spanwise distribution of the chord length, aerodynamic load, and pressure ratio of the blade 31 is matched to balance the conflict between aerodynamic pressure ratio and flutter suppression.

[0046] By rationally setting the thickness distribution of the blades along the spanwise direction based on the load distribution along the blades, the contradiction between the aerodynamic efficiency and the structural stiffness of the fan can be balanced. Figure 6The diagram illustrates the maximum thickness of a blade 31 distributed along its span, with the horizontal axis representing the maximum thickness and the vertical axis representing the blade span. The thickness described in this specification refers to the straight-line distance between the two surfaces of the blade, located between the leading and trailing edges. The maximum thickness refers to the maximum thickness on a given blade cross-section. In some embodiments, the ratio of the maximum thickness to the maximum chord length of the first cross-section 311 is greater than or equal to 0.025. For example, the ratio of the maximum thickness to the maximum chord length of the first cross-section 311 is 0.03 or 0.035. The first cross-section 311 and... Figure 6 This corresponds to position 402. In some embodiments, the ratio of the maximum thickness at the leaf root 403 to the leaf root chord length is greater than or equal to 0.08. For example, the ratio of the maximum thickness at the leaf root 403 to the leaf root chord length is 0.09 or 0.1. Here, the maximum thickness at the leaf root 403 refers to the maximum thickness of the cross-section at the leaf root 403. In some embodiments, the ratio of the maximum thickness at the leaf tip 401 to the leaf tip chord length is greater than or equal to 0.02. For example, the ratio of the maximum thickness at the leaf tip 401 to the leaf tip chord length is 0.03 or 0.04. Here, the maximum thickness at the leaf tip 401 refers to the maximum thickness of the cross-section at the leaf tip 401.

[0047] Several cross-sections of blade 31 have centers of gravity, which can be considered as the center of the cross-section. By setting the axial position of the centers of gravity of several cross-sections distributed along the spanwise direction, the sweep shape of the blade can be restricted, ensuring that the sweep shape meets the aerodynamic requirements of the blade and improving its aerodynamic performance. Simultaneously, it prevents the center of gravity of the blade from deviating excessively from the blade root, which would affect the structural stiffness of the blade and increase the possibility of flutter. The axial position referred to here is the position of the center of gravity of the cross-section along the engine axis, expressed as an axial dimension. Figure 7 The diagram shows the axial position of the centroid of several cross-sections of a blade 31 distributed along its span, with the horizontal axis representing the axial position of the centroid and the vertical axis representing the blade span.

[0048] In some embodiments, such as Figure 7 As shown, the centroid of the second section has a first distance L6 between it and the centroid of the blade root. The ratio of the first distance L6 to the blade root chord length is less than or equal to 0.1. The centroid of the second section has the smallest axial dimension among the centroids of several sections distributed along the spanwise direction on the blade. In other words, the second section on the blade is located at the very tip of the blade in the engine axial direction. Figure 7 The position 502 shown refers to the centroid of the section at the leaf root 503. For example, the ratio of the first distance L6 to the leaf root chord length is 0.08 or 0.06. In some embodiments, such as Figure 7As shown, the centroid of the third section has a second distance L7 between it and the centroid of the blade root. The ratio of the second distance L7 to the blade root chord length is less than or equal to 0.3. The centroid of the third section has the largest axial dimension among the centroids of several sections distributed along the spanwise direction above half the blade height. In other words, the third section on the blade is located at the rearmost end of the blade portion above half the blade height in the engine axial direction. The third section corresponds to... Figure 7 Position 504 is shown. For example, the ratio of the second distance L7 to the leaf root chord length is 0.28 or 0.25. In some embodiments, such as Figure 7 As shown, there is a third distance L5 between the centroid of the leaf tip and the centroid of the leaf root, and the ratio of the third distance L5 to the chord length of the leaf root is less than or equal to 0.3. The centroid of the leaf tip refers to the centroid of the section 501 at the leaf tip. For example, the ratio of the third distance L5 to the chord length of the leaf root is 0.24 or 0.2.

[0049] By setting the blade structure parameters according to the above embodiments, the resulting blades can achieve a relatively large flutter margin without significantly reducing aerodynamic performance. For example, a flutter margin of more than 15% can be achieved while maintaining a fan rotor aerodynamic efficiency of 90%.

[0050] The basic concepts have been described above. It is clear that the detailed disclosure above is merely illustrative and does not constitute a limitation of this specification, especially for those skilled in the art. Furthermore, unless expressly stated in the claims, the order of elements and sequences, the use of numbers and letters, or other names in this specification are not intended to limit the order of the processes and methods described herein. Although various examples of currently considered useful embodiments of the invention have been discussed in the foregoing disclosure, it should be understood that such details are for illustrative purposes only, and the appended claims are not limited to the disclosed embodiments. Rather, the claims are intended to cover all modifications and equivalent combinations that conform to the substance and scope of the embodiments described herein.

Claims

1. A fan, characterized in that, The fan includes blades having a cross-section perpendicular to the spanwise direction, the cross-section having a chord length, the cross-section including a first cross-section having the maximum chord length of the blade, the ratio of the height of the first cross-section to the height of the blade being less than or equal to 0.8, wherein the height refers to the dimension along the spanwise direction.

2. The fan according to claim 1, characterized in that, The ratio of the blade height to the maximum chord length of the blade is greater than 1.2 and less than 2.

2.

3. The fan according to claim 1, characterized in that, The blade includes, from the inside to the outside along the spanwise direction, a blade root, a corresponding position of the flow divider ring, and a blade tip. The corresponding position of the flow divider ring indicates the boundary between the inner and outer bypass of the engine. The ratio of the blade root chord length to the maximum chord length is greater than or equal to 0.

65.

4. The fan according to claim 3, characterized in that, The ratio of the chord length at the corresponding position of the shunt ring to the maximum chord length is greater than or equal to 0.

75.

5. The fan according to claim 3, characterized in that, The ratio of the minimum chord length in a region on the blade to the chord length at the blade tip is greater than or equal to 0.9, and the region is the portion of the blade whose height is greater than the height of the first cross-section.

6. The fan according to claim 1, characterized in that, The blade, from the inside to the outside along the spanwise direction, includes a blade root, a corresponding position of the splitter ring, and a blade tip. The corresponding position of the splitter ring indicates the boundary between the inner and outer bypass of the engine. The ratio of the pressure ratio at the corresponding position of the splitter ring to the maximum pressure ratio of the blade along the spanwise direction is greater than or equal to 0.

8. The ratio of the pressure ratio at the blade tip to the maximum pressure ratio along the blade's span is greater than or equal to 0.

8.

7. The fan according to claim 6, characterized in that, The difference between the height of the first profile and the height on the blade at the point where the maximum pressure ratio is along the span is less than or equal to one-tenth of the blade height.

8. The fan according to claim 3, characterized in that, The ratio of the maximum thickness of the first profile to the maximum chord length is greater than or equal to 0.

025.

9. The fan according to claim 8, characterized in that, The ratio of the maximum thickness at the leaf root to the chord length of the leaf root is greater than or equal to 0.

08.

10. The fan according to claim 8 or 9, characterized in that, The ratio of the maximum thickness at the leaf tip to the chord length of the leaf tip is greater than or equal to 0.

02.

11. The fan according to claim 1, characterized in that, The blade, along the spanwise direction, includes, from the inside to the outside, a blade root, a corresponding position of the flow divider ring, and a blade tip. The corresponding position of the flow divider ring indicates the boundary between the inner and outer bypass of the engine. The cross-section has a center of gravity, and the cross-section includes a second cross-section, the center of gravity of the second cross-section having the minimum axial dimension of the center of gravity on the blade, and the center of gravity of the second cross-section having a first distance from the center of gravity of the blade root, the ratio of the first distance to the chord length of the blade root being less than or equal to 0.

1.

12. The fan according to claim 11, characterized in that, The cross-section includes a third cross-section, wherein the centroid of the third cross-section is at a second distance from the centroid of the leaf root, and the ratio of the second distance to the chord length of the leaf root is less than or equal to 0.

3.

13. The fan according to claim 11 or 12, characterized in that, There is a third distance between the center of gravity of the leaf tip and the center of gravity of the leaf root, and the ratio of the third distance to the chord length of the leaf root is less than or equal to 0.

3.

14. The fan according to claim 1, characterized in that, The fan's flow rate per unit annular area is less than or equal to 230 kg / s / m³. 2 The unit toroidal area flow rate is the ratio of fan flow rate to fan toroidal area.

15. An aircraft engine, characterized in that, The aircraft engine includes the fan as described in any one of claims 1-14.

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