Fan rotor blade structure and design method thereof

Abstract

The invention belongs to the technical field of aero-engines, and particularly relates to a fan rotor blade structure and a design method thereof. The blade back side damping rib is arranged on the back side of the blade body of the basic blade; the blade basin side vibration reduction ribs are arranged on the blade body basin side of the basic blade; and the outer contour lines of the blade back side vibration reduction ribs and the blade basin side vibration reduction ribs are formed by outwards offsetting the blade body basic blade profile of the cross section of the basic blade at the same height position. According to the application, the aerodynamic performance loss caused by blade tip chamfers can be eliminated, and the structural safety risk caused by too small blade tip gaps is reduced; the problem of non-whole-order vibration of the blade tip of the fan rotor blade can be effectively solved, and the modal inherent frequency of each order of the rotor blade is improved by adjusting the structural parameters of the vibration reduction ribs on the two sides of the blade body.

Description

Technical Field

[0001] The present application belongs to the field of aero-engine technology, and in particular relates to a fan rotor blade structure and a design method thereof. Background Art

[0002] Existing technical solutions for aircraft engines, driven by multiple requirements such as lightweight structure, low aerodynamic losses, reduced parts count, and increased reliability, often utilize an integral bladed disc structure. Compared to traditional disc-and-tenon joints, integral bladed discs are more prone to vibration during engineering, and the problem of excessive vibration is particularly prominent. Furthermore, as the load of modern fans continues to increase, blade designs are becoming more radical, making airflow unpredictable. Due to the unstable nature of airflow at the blade tips and the excitation source generated by the rotating pressure waves generated by vortex shedding, fan rotor blades rotate at a speed lower than the blade speed. This results in airflow-induced non-whole-order blade vibration in the fan, which can, in severe cases, cause rotational stall of fan components or blade flutter damage.

[0003] The solutions commonly used for this type of vibration problem are: 1. The swept portion of the inlet edge of the blade tip is cut to change the airflow of the blade to improve the aerodynamic excitation source and solve the problem of high-order corner vibration; 2. Adjust the blade profile and load of adjacent stator blades and adjust the aerodynamic matching between stages to change the aerodynamic excitation source of the rotor blades; 3. When non-integral-order vibration occurs, adjust the regulation rules of the adjustable intake support plate and nozzle area at the engine operating point, and change the overall matching of the engine to avoid the fan aerodynamic excitation source; 4. Add a damping device to the fan rotor structure to suppress blade vibration and absorb vibration energy; 5. Reduce the tip clearance, improve the influence of unsteady flow at the tip, and reduce the airflow excitation energy.

[0004] The existing solutions to the non-integral-order vibration of blisks have the following technical problems: 1. The blade tip cut angle will break the blade profile integrity, reduce the blade's work capacity, significantly lead to a decrease in fan component margin and efficiency, and adversely affect the performance of the entire machine; 2. Adjusting the blade profiles of adjacent stator blades cannot completely solve the problem of non-whole-order vibration. This measure usually works only when used in conjunction with other means. It also has an adverse effect on component performance, and in engineering applications, new stator blades need to be put into production, which is costly in engineering applications.

[0005] 3. Adjusting the regulation of the adjustable air intake support plate and the nozzle area essentially adjusts the fan's aerodynamic state on the common working line of the entire machine when non-whole-order vibration occurs, thereby avoiding the problem of non-whole-order vibration within a specific speed range of the fan components. However, this method has a significant impact on the performance of the entire machine and cannot fundamentally solve the problem of non-whole-order vibration. It only actively avoids vibration from the perspective of the overall machine operation strategy, which still leaves some risks. 4. The integral blade disk structure is different from the traditional disk-tenon connection structure. Due to the lack of disk-tenon friction, the structural damping is very small. In addition, because the original disk-tenon connection space is eliminated, it is difficult to inherit the use of traditional damping structural measures (such as damping blocks placed under the blade edge plate or damping plates in the gap between the blade tenon and the disk tenon groove). The damping structure can only be placed away from the blade body and blade tip, which will reduce its vibration reduction and absorption effect. 5. Although reducing the tip clearance can reduce the airflow excitation effect, considering the steady-state and transitional state usage requirements of the entire machine envelope (the tip cannot rub against the casing body), the tip clearance cannot be reduced indefinitely, so the effect of this method is also limited. Summary of the Invention

[0006] In order to solve the above problems, the present application provides a fan rotor blade structure, comprising: Basic leaves; The back side vibration damping ribs are arranged on the back side of the blade body of the basic blade; The blade basin side vibration damping ribs are arranged on the blade basin side of the basic blade; The outer contour lines of the blade back side vibration damping ribs and the blade basin side vibration damping ribs are respectively the same as the outer contour lines of the base blades at the same positions, and meet the following conditions: The included angle αb≤γ between the vibration damping rib on the back of the blade and the flow path at the blade tip; The included angle αp≤γ between the vibration damping rib on the blade basin side and the blade tip flow path; Wherein, γ is the angle between the flow path inside the blade and the flow path at the blade tip under meridian plane projection.

[0007] A method for designing a fan rotor blade structure, for designing the fan rotor blade structure, comprises the following steps: Step 1: Set the values ​​of variables, including the radial thickness Δb of the blade back side vibration damping rib, the radial thickness Δp of the blade basin side vibration damping rib, the offset distance Hp between the blade basin side vibration damping rib and the blade basin side airfoil profile, the offset distance Hb between the blade back side vibration damping rib and the blade back side airfoil profile, the distance Cbq between the leading edge of the blade back side vibration damping rib and the air inlet edge of the blade tip profile, the distance Cbh between the trailing edge of the blade back side vibration damping rib and the exhaust edge of the blade tip profile, the distance Cpq between the leading edge of the blade basin side vibration damping rib and the air inlet edge of the blade tip profile, and the distance Cph between the trailing edge of the blade basin side vibration damping rib and the exhaust edge of the blade tip profile. Step 2: Calculate the modal mass matrix of the entire blade, the modal damping matrix of the entire blade, and the modal stiffness matrix of the entire blade according to the values ​​of the set variables; Step 3: Calculate the vibration response of the entire blade under the modal aerodynamic load based on the modal mass matrix, modal damping matrix and modal stiffness matrix of the entire blade. When the vibration response meets the preset requirements, output the value of the set variable; otherwise, reset the value of the variable and return to step 2.

[0008] Preferably, the modal mass matrix M of the entire blade is n The calculation methods include: Calculate the modal mass matrix M of the base blade 基础 , calculate the modal mass matrix M of the blade back side vibration damping rib and the blade basin side vibration damping rib as a whole 减振筋 ; Modal mass matrix M based on the basic blade 基础 , the modal mass matrix M of the blade back side vibration damping rib and the blade basin side vibration damping rib as a whole 减振筋 , calculate the modal mass matrix M of the entire blade n .

[0009] Preferably, the modal mass matrix M of the entire blade is n The calculation formula is: .

[0010] Preferably, the modal damping matrix C of the entire blade is n The calculation formula is: ; Among them, C 基础 is the modal damping matrix of the basic blade; C 减振筋 is the modal damping matrix of the blade back side vibration damping rib and the blade basin side vibration damping rib as a whole.

[0011] Preferably, the modal stiffness matrix K of the entire blade is n The calculation formula is: ; Among them, K 基础 is the modal stiffness matrix of the base blade; K 减振筋 is the modal stiffness matrix of the blade back side vibration damping rib and the blade basin side vibration damping rib as a whole.

[0012] Preferably, ; Where ρ is the system mass density, F is the volume function, Lb is the axial length of the vibration damping rib on the back of the blade, and Lp is the axial length of the vibration damping rib on the base of the blade.

[0013] Preferably, the values ​​of the set variables that meet the preset requirements are divided into multiple groups, and one group is selected as the optimal group, wherein the optimal group minimizes the radial thickness Δb of the blade back side vibration damping rib, the radial thickness Δp of the blade basin side vibration damping rib, the offset distance Hp between the blade basin side vibration damping rib and the blade basin side blade profile surface, the offset distance Hb between the blade back side vibration damping rib and the blade back side blade profile surface, the axial length Lb of the blade back side vibration damping rib, the axial length Lp of the blade basin side vibration damping rib, the angle θbq of the leading edge bevel of the blade basin side vibration damping rib relative to the X-axis of the blade profile coordinate system, the angle θpq of the leading edge bevel of the blade basin side vibration damping rib relative to the X-axis of the blade profile coordinate system, the angle θbh of the trailing edge bevel of the blade back side vibration damping rib relative to the X-axis of the blade profile coordinate system, and the angle θph of the trailing edge bevel of the blade basin side vibration damping rib relative to the X-axis of the blade profile coordinate system.

[0014] The advantages of this application include: eliminating the aerodynamic performance loss caused by the blade tip cutting angle, reducing the structural safety risk caused by the blade tip clearance, effectively solving the problem of non-integer order vibration at the blade tip of the fan rotor blade, and improving the natural frequency of each modal mode of the rotor blade by adjusting the structural parameters of the vibration damping ribs on the back side of the blade and the vibration damping ribs on the blade basin side. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic diagram of the back side structure of a fan rotor blade structure in a preferred embodiment of the present application.

[0016] Figure 2 This is a schematic diagram of the blade basin side structure of a fan rotor blade structure in a preferred embodiment of the present application.

[0017] Figure 3 It is a schematic cross-sectional view of a fan rotor blade structure according to a preferred embodiment of the present application. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solutions and advantages of the implementation of this application clearer, the technical solutions in the implementation of this application will be described in more detail below in conjunction with the drawings in the implementation of this application. In the drawings, the same or similar numbers throughout represent the same or similar elements or elements with the same or similar functions. The described implementation is a part of the implementation of this application, not all of the implementations. The implementation described below with reference to the drawings is exemplary and is intended to be used to explain this application, and should not be understood as a limitation on this application. Based on the implementation in this application, all other implementations obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. The implementation of this application is described in detail below in conjunction with the drawings.

[0019] like Figure 1-Figure 3 As shown, the present application provides a fan rotor blade structure, comprising: Basic blade 1; A blade back side vibration damping rib 3 is provided on the back side of the blade body of the basic blade 1; The blade basin side vibration damping rib 4 is provided on the blade basin side of the basic blade 1; The outer contour lines of the blade back side vibration damping rib 3 and the blade basin side vibration damping rib 4 are respectively the same as the outer contour lines of the base blade 1 at the same position, that is, the outer contour lines of the blade back side vibration damping rib 3 and the blade basin side vibration damping rib 4 are formed by the outward offset of the blade body basic airfoil of the cross section of the base blade 1 at the same height position, and meet the following conditions: The included angle αb≤γ between the vibration damping rib 3 on the back side of the blade and the flow path at the blade tip; The included angle αp≤γ between the vibration damping rib 4 on the blade basin side and the blade tip flow path; Wherein, γ is the angle between the flow path inside the blade and the flow path at the blade tip under meridian plane projection.

[0020] Based on the above technical features, without the need to adjust the airflow excitation, without adjusting the adjustment rules of the adjustable support plate IGV and nozzle area, without affecting the common working line of the entire machine, and without being limited to the disk-tenon connection structure, only the vibration damping ribs on the back of the blade and the vibration damping ribs on the blade basin, that is, the vibration damping ribs on both sides are placed directly at the high-incidence areas of the blade edge vibration, which can effectively strengthen the blade edge stiffness and resist the vibration caused by non-whole-order airflow excitation. Moreover, through the detuning design of the blade surface, it can also achieve the same vibration reduction and suppression effect as the damping structure. In addition, by adjusting the structural parameters of the vibration damping ribs on both sides of the blade, the blade mode can be further changed, eliminating or reducing the probability of non-whole-order vibration.

[0021] A method for designing a fan rotor blade structure, for designing the fan rotor blade structure, comprises the following steps: Step 1: Set the values ​​of variables, including the radial thickness Δb of the blade back side vibration damping rib, the radial thickness Δp of the blade basin side vibration damping rib, the offset distance Hp between the blade basin side vibration damping rib and the blade basin side blade profile, the offset distance Hb between the blade back side vibration damping rib and the blade back side blade profile, the distance Cbq between the leading edge of the blade back side vibration damping rib and the air inlet edge of the blade tip profile, the distance Cbh between the trailing edge of the blade back side vibration damping rib and the air outlet edge of the blade tip profile, the distance Cpq between the leading edge of the blade basin side vibration damping rib and the air inlet edge of the blade tip profile, and the distance Cph between the trailing edge of the blade basin side vibration damping rib and the air outlet edge of the blade tip; in some optional implementations, In this embodiment, other variables include: the distance Apq from the intersection of the leading edge oblique side of the blade basin side vibration damping rib and the offset line to the Y-axis of the blade profile coordinate system, the distance Bph from the intersection of the trailing edge oblique side of the blade basin side vibration damping rib and the offset line to the Y-axis of the blade profile coordinate system, the distance Abq from the intersection of the leading edge oblique side of the blade back side vibration damping rib and the offset line to the Y-axis of the blade profile coordinate system, the distance Bbh from the intersection of the trailing edge oblique side of the blade back side vibration damping rib and the offset line to the Y-axis of the blade profile coordinate system, the fillet Rb between the upper and lower surfaces of the blade back side vibration damping rib and the basic blade profile, and the fillet Rp between the upper and lower surfaces of the blade basin side vibration damping rib and the basic blade profile.

[0022] Step 2: Calculate the modal mass matrix of the entire blade, the modal damping matrix of the entire blade, and the modal stiffness matrix of the entire blade according to the values ​​of the set variables; Step 3: Calculate the vibration response of the entire blade under the modal aerodynamic load based on the modal mass matrix, modal damping matrix and modal stiffness matrix of the entire blade. When the vibration response meets the preset requirements, output the value of the set variable; otherwise, reset the value of the variable and return to step 2.

[0023] In some optional embodiments, the modal mass matrix M of the entire blade is n The calculation methods include: Calculate the modal mass matrix M of the base blade 1 基础 , calculate the modal mass matrix M of the blade back side vibration damping rib 3 and the blade basin side vibration damping rib 4 as a whole 减振筋 ; Modal mass matrix M based on base blade 1 基础 , the modal mass matrix M of the blade back side vibration damping rib 3 and the blade basin side vibration damping rib 4 as a whole 减振筋 , calculate the modal mass matrix M of the entire blade n .

[0024] In some optional embodiments, the modal mass matrix M of the entire blade is n The calculation formula is: .

[0025] In some optional embodiments, the modal damping matrix C of the entire blade is n The calculation formula is: ; Among them, C 基础 is the modal damping matrix of base blade 1; C 减振筋 is the modal damping matrix of the blade back side vibration damping rib 3 and the blade basin side vibration damping rib 4.

[0026] In some optional embodiments, the modal stiffness matrix K of the entire blade is n The calculation formula is: ; Among them, K 基础 is the modal stiffness matrix of base blade 1; K 减振筋 is the modal stiffness matrix of the blade back side vibration damping rib 3 and the blade basin side vibration damping rib 4.

[0027] In some optional embodiments, ; Where ρ is the system mass density, F is the volume function, Lb is the axial length of the vibration damping rib on the back of the blade, and Lp is the axial length of the vibration damping rib on the base of the blade.

[0028] In step 3, the vibration response of the entire blade is calculated as: ; Where x represents the modal amplitude of the entire blade; f n(t) represents the modal aerodynamic load applied to the entire blade, is the unit velocity of the vibration amplitude, The unit acceleration of the vibration amplitude.

[0029] In some optional embodiments, the values ​​of the set variables that meet the preset requirements are divided into multiple groups, and one group is selected as the optimal group, wherein the optimal group minimizes the radial thickness Δb of the blade back side vibration damping rib, the radial thickness Δp of the blade basin side vibration damping rib, the offset distance Hp between the blade basin side vibration damping rib and the blade basin side blade profile surface, the offset distance Hb between the blade back side vibration damping rib and the blade back side blade profile surface, the axial length Lb of the blade back side vibration damping rib, the axial length Lp of the blade basin side vibration damping rib, the angle θbq of the leading edge bevel of the blade basin side vibration damping rib relative to the X-axis of the blade profile coordinate system, the angle θpq of the leading edge bevel of the blade basin side vibration damping rib relative to the X-axis of the blade profile coordinate system, the angle θbh of the trailing edge bevel of the blade back side vibration damping rib relative to the X-axis of the blade profile coordinate system, and the angle θph of the trailing edge bevel of the blade basin side vibration damping rib relative to the X-axis of the blade profile coordinate system.

[0030] The advantages of this application include: eliminating the aerodynamic performance loss caused by the blade tip cutting angle, reducing the structural safety risk caused by the blade tip clearance, effectively solving the problem of non-integer order vibration at the blade tip of the fan rotor blade, and improving the natural frequency of each modal mode of the rotor blade by adjusting the structural parameters of the vibration damping ribs on the back side of the blade and the vibration damping ribs on the blade basin side.

[0031] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A fan rotor blade structure, characterized in that: include: base leaf (1); A blade back side vibration damping rib (3) provided on the back side of the blade body of the basic blade (1); Blade basin side vibration damping ribs (4) provided on the blade basin side of the base blade (1); The outer contour lines of the blade back side vibration damping rib (3) and the blade basin side vibration damping rib (4) are respectively the same as the outer contour lines of the base blade (1) at the same position thereof, and meet the following conditions: The included angle αb between the vibration damping rib (3) on the back of the blade and the flow path at the blade tip is ≤γ; The included angle αp≤γ between the vibration damping rib (4) on the blade basin side and the blade tip flow path; Wherein, γ is the angle between the flow path inside the blade and the flow path at the blade tip under meridian plane projection.

2. A method for designing a fan rotor blade structure, for designing the fan rotor blade structure according to claim 1, characterized in that: The steps include: Step 1: Set the values ​​of variables, including the radial thickness Δb of the blade back side vibration damping rib, the radial thickness Δp of the blade basin side vibration damping rib, the offset distance Hp between the blade basin side vibration damping rib and the blade basin side airfoil profile, the offset distance Hb between the blade back side vibration damping rib and the blade back side airfoil profile, the distance Cbq between the leading edge of the blade back side vibration damping rib and the air inlet edge of the blade tip profile, the distance Cbh between the trailing edge of the blade back side vibration damping rib and the exhaust edge of the blade tip profile, the distance Cpq between the leading edge of the blade basin side vibration damping rib and the air inlet edge of the blade tip profile, and the distance Cph between the trailing edge of the blade basin side vibration damping rib and the exhaust edge of the blade tip profile. Step 2: Calculate the modal mass matrix of the entire blade, the modal damping matrix of the entire blade, and the modal stiffness matrix of the entire blade according to the values ​​of the set variables; Step 3: Calculate the vibration response of the entire blade under the modal aerodynamic load based on the modal mass matrix, modal damping matrix and modal stiffness matrix of the entire blade. When the vibration response meets the preset requirements, output the value of the set variable; otherwise, reset the value of the variable and return to step 2.

3. The method for designing a fan rotor blade structure according to claim 2, wherein: The modal mass matrix M of the entire blade n The calculation methods include: Calculate the modal mass matrix M of the base blade (1) 基础 , calculate the modal mass matrix M of the blade back side vibration damping rib (3) and the blade basin side vibration damping rib (4) as a whole 减振筋 ; The modal mass matrix M of the basic blade (1) 基础 , the modal mass matrix M of the blade back side vibration damping rib (3) and the blade basin side vibration damping rib (4) as a whole 减振筋 , calculate the modal mass matrix M of the entire blade n .

4. The method for designing a fan rotor blade structure according to claim 3, wherein: The modal mass matrix M of the entire blade n The calculation formula is: 。 5. The method for designing a fan rotor blade structure according to claim 3, wherein: The modal damping matrix C of the entire blade n The calculation formula is: ； Among them, C 基础 is the modal damping matrix of the basic blade (1); C 减振筋 is the modal damping matrix of the blade back side vibration damping rib (3) and the blade basin side vibration damping rib (4) as a whole.

6. The method for designing a fan rotor blade structure according to claim 3, wherein: The modal stiffness matrix K of the entire blade n The calculation formula is: ； Among them, K 基础 is the modal stiffness matrix of the base blade (1); K 减振筋 is the modal stiffness matrix of the blade back side vibration damping rib (3) and the blade basin side vibration damping rib (4) as a whole.

7. The method for designing a fan rotor blade structure according to claim 3, wherein: ； Where ρ is the system mass density, F is the volume function, Lb is the axial length of the vibration damping rib on the back of the blade, and Lp is the axial length of the vibration damping rib on the base of the blade.

8. The method for designing a fan rotor blade structure according to claim 7, wherein: The values ​​of the set variables that meet the preset requirements are divided into multiple groups, and one group is selected as the optimal group. The optimal group minimizes the radial thickness Δb of the blade back side vibration damping rib, the radial thickness Δp of the blade basin side vibration damping rib, the offset distance Hp between the blade basin side vibration damping rib and the blade basin side blade profile surface, the offset distance Hb between the blade back side vibration damping rib and the blade back side blade profile surface, the axial length Lb of the blade back side vibration damping rib, the axial length Lp of the blade basin side vibration damping rib, the angle θbq of the leading edge bevel of the blade basin side vibration damping rib relative to the X-axis of the blade profile coordinate system, the angle θpq of the leading edge bevel of the blade basin side vibration damping rib relative to the X-axis of the blade profile coordinate system, the angle θbh of the trailing edge bevel of the blade back side vibration damping rib relative to the X-axis of the blade profile coordinate system, and the angle θph of the trailing edge bevel of the blade basin side vibration damping rib relative to the X-axis of the blade profile coordinate system.

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