A method for optimizing the profile design of high aspect ratio blades

Abstract

The present application belongs to the technical field of profile optimization design of large aspect ratio working blades in low-pressure turbines of high-bypass-ratio turbofan engines, and specifically relates to a profile optimization design method for large aspect ratio working blades, comprising: increasing the blade turning angle of the working blade by reducing the inlet structural angle β1k and the outlet structural angle β2k of the working blade; matching a larger trailing edge bending angle δ for the outlet structural angle β2k of the working blade; and offsetting the profile curve of the working blade basin side toward the profile curve of the blade back side by adjusting the leading edge lower wedge angle W12 and the trailing edge wedge angle W2 of the working blade, as well as the Bezier profile curve control coefficients P1 and P2 of the blade basin side.

Description

Technical Field

[0001] The present application belongs to the technical field of profile optimization design of high-aspect-ratio working blades in a low-pressure turbine of a high-bypass-ratio turbofan engine, and specifically relates to a profile optimization design method of high-aspect-ratio working blades. Background Art

[0002] In the low-pressure turbine of a turbofan engine, the aspect ratio of the working blade is the ratio of the blade height to the chord length of the blade mid-section.

[0003] The low-pressure turbine speed of small and medium bypass ratio turbofan engines is relatively high, and most of them use medium aspect ratio working blades, with the aspect ratio of the working blades being less than 5.0;

[0004] The low-pressure turbine of a high-bypass-ratio turbofan engine has a low speed and mostly uses large-aspect-ratio working blades, with the aspect ratio of the working blades being between 6.0 and 7.5.

[0005] Using the current working blade profile design method, the medium aspect ratio working blades of the low-pressure turbine of a small and medium bypass ratio turbofan engine are designed. The resulting medium aspect ratio working blades have a relatively thick blade profile, high blade density, and a small turning angle. The design of large aspect ratio working blades of the low-pressure turbine of a large bypass ratio turbofan engine will result in a large weight and pressure loss of the resulting large aspect ratio working blades, resulting in a large overall weight and low efficiency of the turbofan engine.

[0006] This application is proposed in view of the above-mentioned technical defects.

[0007] It should be noted that the disclosure of the above background technology content is only used to assist in understanding the inventive concept and technical solution of the present invention, and it does not necessarily belong to the prior art of this patent application. In the absence of clear evidence that the above content has been disclosed on the filing date of this application, the above background technology should not be used to evaluate the novelty and creativity of this application. Summary of the Invention

[0008] The purpose of this application is to provide a method for optimizing the profile design of a large aspect ratio working blade to overcome or alleviate at least one of the existing technical defects.

[0009] The technical solution of this application is:

[0010] A method for optimizing the profile design of a large aspect ratio working blade comprises:

[0011] By reducing the inlet structural angle β1k and the outlet structural angle β2k of the working blade, the blade turning angle of the working blade is increased;

[0012] The outlet construction angle β2k of the working blade matches the larger trailing edge bending angle δ;

[0013] By adjusting the leading edge lower wedge angle W12, the trailing edge wedge angle W2, and the blade basin side Bezier profile curve control coefficients P1 and P2 of the working blade, the blade basin side profile curve of the working blade is offset toward the blade back side profile curve.

[0014] According to at least one embodiment of the present application, in the above-mentioned method for optimizing the profile design of a large aspect ratio working blade, the blade profile turning angle of the working blade is 100° to 120°.

[0015] According to at least one embodiment of the present application, in the above-mentioned method for optimizing the profile design of a working blade with a large aspect ratio, the trailing edge bending angle δ of the working blade is greater than the outlet structural angle β2k, and is 0° to 5°.

[0016] According to at least one embodiment of the present application, in the above-mentioned method for optimizing the profile design of a working blade with a large aspect ratio, a small positive angle of attack is obtained by adjusting the inlet structural angle β1k of the working blade;

[0017] By increasing the wedge angle W11 on the leading edge of the working blade, the installation angle γ, and the Bezier curve control point coefficients SLE1 and SLE2 of the front half of the blade back, the curvature of the profile curve of the front part of the blade back is increased;

[0018] The curvature of the throat and the profile curve behind the throat is reduced by adjusting the installation angle γ of the working blades and the Bezier curve control coefficients STE1 and STE2 of the back of the throat blade.

[0019] According to at least one embodiment of the present application, in the above-mentioned method for optimizing the profile design of a large aspect ratio working blade, the angle of attack of the working blade is 14° to 8°.

[0020] According to at least one embodiment of the present application, in the above-mentioned method for optimizing the profile design of a large aspect ratio working blade, the blade cascade density is reduced by reducing the cascade pitch t of the working blade.

[0021] According to at least one embodiment of the present application, in the above-mentioned method for optimizing the profile design of a large aspect ratio working blade, the blade cascade consistency of the working blade is 1.0-1.2. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of a high aspect ratio blade profile optimization design method provided in an embodiment of the present application;

[0023] Figure 2 This is a schematic diagram of an embodiment of the present application, wherein the working blade basin-side profile curve is shifted toward the blade back-side profile curve by adjusting the leading edge lower wedge angle W12, the trailing edge wedge angle W2, and the blade basin-side Bezier profile curve control coefficients P1 and P2.

[0024] Figure 3This is a schematic diagram of an embodiment of the present application in which the front portion of the inscribed circle diameter of the cascade channel is appropriately expanded along the axial direction and the rear portion is converged more;

[0025] Figure 4 Schematic diagram of the change of pressure loss with angle of attack provided in an embodiment of the present application;

[0026] Figure 5 Schematic diagram of reducing the curvature of the throat and the rear-throat profile curve by adjusting the installation angle γ of the working blades and controlling the Bezier curve coefficients STE1 and STE2 of the rear-throat blade back, provided by an embodiment of the present application;

[0027] Figure 6 This is a schematic diagram of the front loading and rear loading of a working blade at a small positive attack angle provided by an embodiment of the present application;

[0028] Figure 7 Schematic diagram of a working blade obtained according to the high aspect ratio working blade profile optimization design method provided in an embodiment of the present application;

[0029] in:

[0030] t is the grid pitch;

[0031] d1 is the diameter of the small circle at the leading edge;

[0032] d2 is the diameter of the small circle at the trailing edge;

[0033] b is the chord length;

[0034] a is the throat width;

[0035] γ is the installation angle;

[0036] W11 is the upper wedge angle of the leading edge;

[0037] W12 is the lower wedge angle of the leading edge;

[0038] W2 is the trailing edge wedge angle;

[0039] δ is the trailing edge bending angle;

[0040] β1k is the inlet structural angle;

[0041] β2k is the outlet structural angle;

[0042] P1 and P2 are the control coefficients of Bezier profile curve on the blade basin side;

[0043] SLE1 and SLE2 are the Bezier curve control point coefficients of the front half of the leaf back.

[0044] STE1 and STE2 are the Bezier curve control coefficients of the posterior lobe of the laryngeal region.

[0045] In order to better illustrate this embodiment, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product. In addition, the drawings are only used for illustrative purposes and should not be understood as limitations on this patent. DETAILED DESCRIPTION

[0046] To make the technical solution and its advantages of the present application clearer, the technical solution of the present application will be described in further detail below in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only some embodiments of the present application and are only used to explain the present application, not to limit the present application. It should be noted that, for ease of description, only the parts related to the present application are shown in the accompanying drawings, and other related parts can refer to the general design. In the absence of conflict, the embodiments of the present application and the technical features in the embodiments can be combined with each other to obtain new embodiments.

[0047] In addition, unless otherwise defined, the technical or scientific terms used in the description of this application should have the ordinary meanings understood by those of ordinary skill in the art to which this application belongs. The words "upper," "lower," "left," "right," "center," "vertical," "horizontal," "inner," and "outer" used in the description of this application are only used to indicate relative directions or positional relationships, and do not imply that the device or component must have a specific orientation, be constructed, or operate in a specific orientation. When the absolute position of the described object changes, its relative positional relationship may also change accordingly. Therefore, they should not be understood as limitations on this application. The words "first," "second," "third," and similar terms used in the description of this application are used only for descriptive purposes to distinguish different components and should not be understood to indicate or imply relative importance. The words "one," "an," or "the" used in the description of this application should not be understood as absolute limitations on quantity, but should be understood as meaning the presence of at least one. The words "include" or "comprises" used in the description of this application mean that the element or object listed before the word includes the elements or objects listed after the word and their equivalents, but does not exclude other elements or objects.

[0048] In addition, it should be noted that, unless otherwise clearly stipulated and limited, the words "install", "connect", "connect" and similar terms used in the description of this application should be understood in a broad sense. For example, the connection can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, an indirect connection through an intermediate medium, or a connection between two components. Technical personnel in the field can understand their specific meanings in this application according to the specific circumstances.

[0049] The following is combined with Figures 1 to 6 This application is described in further detail.

[0050] Based on the blade profile design method, a profile optimization design method for high-aspect-ratio blades of a high-bypass-ratio turbofan engine low-pressure turbine is provided, including:

[0051] By reducing the inlet structural angle β1k and the outlet structural angle β2k of the working blade, the blade turning angle of the working blade is increased;

[0052] The outlet construction angle β2k of the working blade matches the larger trailing edge bending angle δ;

[0053] By adjusting the leading edge lower wedge angle W12, the trailing edge wedge angle W2, and the blade basin side Bezier profile curve control coefficients P1 and P2 of the working blade, the blade basin side profile curve of the working blade is offset toward the blade back side profile curve.

[0054] Regarding the large aspect ratio working blade profile optimization design method disclosed in the above embodiment, technical personnel in the field can understand that the blade profile turning angle of the working blade is numerically equal to 180°-β1k-β2k. By reducing the inlet structural angle β1k and the outlet structural angle β2k of the working blade and increasing the blade profile turning angle of the working blade, it can fully adapt to the large turning flow of the airflow in the large aspect ratio working blade cascade, reduce pressure loss, and ensure the efficiency of the turbofan engine.

[0055] Regarding the large aspect ratio working blade profile optimization design method disclosed in the above embodiment, those skilled in the art can also understand that increasing the blade turning angle of the working blade will significantly increase the working thickness and weight, resulting in an increase in the weight of the turbofan engine. If the working blade is thinned by shifting the back side profile curve toward the blade basin side profile curve to reduce the weight of the working blade, the load distribution on the working blade will be worsened, the pressure loss will increase, and the efficiency of the turbofan engine will be reduced. By adjusting the leading edge lower wedge angle W12 and the trailing edge wedge angle W2 of the working blade, as well as the blade basin side Bezier profile curve control coefficients P1 and P2, the working blade basin side profile curve is shifted toward the back side profile curve. This can achieve a thinning design of the working blade while ensuring that the back side profile curve remains unchanged. Figure 2 As shown in the figure, the weight of the working blade can be reduced, and the front part of the inscribed circle diameter of the cascade channel can be appropriately expanded along the axial direction, and the convergence degree of the rear part can be increased, as shown in the figure. Figure 3 As shown, the pressure loss can be further reduced to ensure the efficiency of the turbofan engine.

[0056] Regarding the large aspect ratio working blade profile optimization design method disclosed in the above embodiment, technical personnel in the field can also understand that the outlet structural angle β2k of the working blade is matched with a larger trailing edge bending angle δ, which can be specifically 20° to 30°, which can optimize the load distribution on the working blade, avoid the occurrence of a large pressure gradient, and thereby reduce pressure loss and ensure the efficiency of the turbofan engine.

[0057] In some optional embodiments, in the above-mentioned high aspect ratio working blade profile optimization design method, the blade turning angle of the working blade is 100° to 120°.

[0058] In some optional embodiments, in the above-mentioned method for optimizing the profile design of a working blade with a large aspect ratio, the trailing edge bending angle δ of the working blade is greater than the outlet structural angle β2k, and is 0° to 5°.

[0059] In some optional embodiments, in the above-mentioned method for optimizing the profile design of a working blade with a large aspect ratio, a small positive attack angle is obtained by adjusting the inlet structural angle β1k of the working blade;

[0060] By increasing the wedge angle W11 on the leading edge of the working blade, the installation angle γ, and the Bezier curve control point coefficients SLE1 and SLE2 of the front half of the blade back, the curvature of the profile curve of the front part of the blade back is increased;

[0061] By adjusting the installation angle γ of the working blades and the Bezier curve control coefficients STE1 and STE2 of the back of the throat blade, the curvature of the throat and the back of the throat profile curve is reduced;

[0062] The size of the installation angle γ of the working blade is adapted to the inlet structural angle β1k and the outlet structural angle β2k.

[0063] Regarding the large aspect ratio working blade profile optimization design method disclosed in the above embodiment, those skilled in the art can also understand that the angle of attack of the working blade is numerically equal to the airflow angle minus the inlet structural angle β1k. By adjusting the inlet structural angle β1k of the working blade, a small positive angle of attack is obtained, which can increase the load level of the front part of the working blade, reduce the maximum Mach number of the blade slot, and make the airflow direction shift toward the negative angle of attack direction under typical working conditions, so as to maintain a low pressure loss in the full operating range of the turbofan engine. Figure 4 As shown, the efficiency of the turbofan engine is guaranteed.

[0064] Regarding the large aspect ratio blade profile optimization design method disclosed in the above embodiment, those skilled in the art can also understand that by increasing the leading edge upper wedge angle W11 and the installation angle γ of the blade, as well as the Bezier curve control point coefficients SLE1 and SLE2 of the front half of the blade back, the curvature of the front blade back profile curve is increased, the front of the blade can be loaded, and the aerodynamic load of the blade can be increased. By adjusting the installation angle γ of the blade and the Bezier curve control coefficients STE1 and STE2 of the back of the blade behind the throat, the curvature of the throat and the back of the throat profile curve can be reduced, as shown in FIG. Figure 5 As shown, the working blades are loaded afterward.

[0065] Regarding the method for optimizing the profile design of a large aspect ratio working blade disclosed in the above embodiment, those skilled in the art can also understand that, while adopting a small positive angle of attack, the design increases the curvature of the profile curve of the front portion of the blade back and reduces the curvature of the profile curve of the throat and the rear portion of the throat, thereby achieving front loading and rear loading of the working blade, reducing the throat load, and weakening the adverse pressure gradient behind the throat. Figure 6 As shown, the pressure loss is reduced and the efficiency of the turbofan engine is ensured.

[0066] In some optional embodiments, in the above-mentioned method for optimizing the profile design of a large aspect ratio working blade, the angle of attack of the working blade is 4° to 6°.

[0067] In some optional embodiments, in the above-mentioned method for optimizing the profile design of a working blade with a large aspect ratio, the cascade density is reduced by reducing the cascade pitch t of the working blades.

[0068] Regarding the large aspect ratio working blade profile optimization design method disclosed in the above embodiment, technical personnel in the field can understand that the blade density of the working blade is numerically equal to the ratio of the chord length b to the blade pitch t. Under the large aspect ratio limitation, by reducing the blade pitch t and reducing the blade density, the number of working blades in the blade grid can be reduced, which can effectively reduce the total friction loss and trailing edge loss of the blade grid, reduce the pressure loss, ensure the efficiency of the turbofan engine, and reduce the total weight of the blade grid, thereby reducing the weight of the turbofan engine.

[0069] In some optional embodiments, in the above-mentioned large aspect ratio working blade profile optimization design method, the blade cascade density of the working blade is 1.0-1.2, which should not be too small. If it is too small, it will affect the stiffness of the blade cascade and the performance of the turbofan engine.

[0070] In a specific embodiment, according to the large aspect ratio blade profile optimization design method disclosed in the above embodiment, the following is obtained: Figure 7 The parameters of the working blades shown are shown in the table below:

[0071] t(mm) 27.2 Diameter of small circle at the front edge d1 (mm) 0.8 Diameter of small circle at the trailing edge d2 (mm) 0.5 Chord length b(mm) 31.5 Throat width a(mm) 11.1 Installation angle γ(°) 54 Leading edge upper wedge angle W11(°) 16 Leading edge lower wedge angle W12(°) 8 Trailing edge wedge angle W2 (°) 8 Trailing edge bending angle δ(°) 21 Inlet structural angle β1k(°) 40 Outlet structural angle β2k(°) 21

[0072] The various embodiments in the specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to in detail.

[0073] So far, the technical solution of the present application has been described in conjunction with the preferred embodiments shown in the accompanying drawings. Those skilled in the art should understand that the scope of protection of the present application is obviously not limited to these specific embodiments. Without departing from the principles of the present application, those skilled in the art can make equivalent changes or replacements to the relevant technical features, and the technical solutions after these changes or replacements will fall within the scope of protection of the present application.

Claims

1. A method for optimizing the profile design of a high aspect ratio blade, characterized in that: include: By reducing the inlet structural angle β1k and the outlet structural angle β2k of the working blade, the blade turning angle of the working blade is increased; The outlet construction angle β2k of the working blade matches the larger trailing edge bending angle δ; By adjusting the leading edge lower wedge angle W12, the trailing edge wedge angle W2, and the blade basin side Bezier profile curve control coefficients P1 and P2 of the working blade, the blade basin side profile curve is shifted toward the blade back side profile curve; By adjusting the inlet structural angle β1k of the working blade, a small positive attack angle is obtained; By increasing the wedge angle W11 on the leading edge of the working blade, the installation angle γ, and the Bezier curve control point coefficients SLE1 and SLE2 of the front half of the blade back, the curvature of the profile curve of the front part of the blade back is increased; The curvature of the throat and the profile curve behind the throat is reduced by adjusting the installation angle γ of the working blades and the Bezier curve control coefficients STE1 and STE2 of the back of the throat blade.

2. The high aspect ratio blade profile optimization design method according to claim 1, characterized in that: The blade turning angle of the working blade is 100°~120°.

3. The high aspect ratio blade profile optimization design method according to claim 1, characterized in that: The trailing edge bending angle δ of the working blade is greater than the outlet structural angle β2k, and is 0°~5°.

4. The high aspect ratio blade profile optimization design method according to claim 1, characterized in that: The attack angle of the working blades is 14°~8°.

5. The high aspect ratio blade profile optimization design method according to claim 1, characterized in that: By reducing the blade pitch t, ​​the blade density is reduced.

6. The high aspect ratio blade profile optimization design method according to claim 5, characterized in that: The cascade consistency of the working blades is 1.0-1.2.

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