A fan rotor blade structure and a design method thereof

Abstract

The application belongs to the technical field of aero-engines, and particularly relates to a fan rotor blade structure and a design method thereof, which comprises a basic blade, a blade back side damping rib arranged on the back side of the blade body of the basic blade, and a blade basin side damping rib arranged on the basin side of the blade body of the basic blade; and the outer contour lines of the blade back side damping rib and the blade basin side damping rib are formed by outwardly offsetting the blade body basic blade profile of the cross section of the basic blade at the same height position. The application can eliminate the aerodynamic performance loss caused by the blade tip chamfer, reduce the structural safety risk caused by too small blade tip gap, effectively solve the non-integer order vibration problem of the blade tip part of the fan rotor blade, and improve the natural frequency of each order mode of the rotor blade by adjusting the structural parameters of the damping ribs on both sides of the blade body.

Description

Technical Field

[0001] This application belongs to the field of aero-engine technology, and specifically relates to a fan rotor blade structure and its design method. Background Technology

[0002] In existing technologies, aero-engines, driven by requirements for lightweight structure, low aerodynamic losses, reduced parts quantity, and increased reliability, often employ integral bladed disk (IBD) structures for their fans. Compared to traditional disk-joint structures, IBDs are more prone to vibration during engineering, with vibration exceeding limits being a significant concern. Furthermore, with the increasing loads on modern fans, blade designs have become more aggressive, making airflow unpredictable. The unstable airflow at the blade tips, coupled with the excitation source—the rotating pressure wave generated by vortex shedding—rotates at a speed lower than the blade's rotational speed, leading to airflow-induced non-integer-order blade vibrations. In severe cases, this can cause fan component stall or blade flutter damage.

[0003] Common solutions to this type of vibration problem include:

[0004] 1. Cut the angle of the inlet edge of the blade tip of the integral bladed disk to change the airflow of the blades to improve the aerodynamic excitation source, and at the same time solve the problem of high-order edge vibration.

[0005] 2. Adjust the airfoil and load of adjacent stator blades, and adjust the interstage aerodynamic matching to change the aerodynamic excitation source of the rotor blades;

[0006] 3. Jointly adjust the adjustment rules of the intake adjustable support plate and nozzle area at the engine operating point when non-integer vibration problems occur, and change the overall engine matching to avoid the fan aerodynamic excitation source.

[0007] 4. Add a damping device to the fan rotor structure to suppress blade vibration and absorb vibration energy;

[0008] 5. Reduce the blade tip clearance to mitigate the effects of unsteady airflow at the blade tip and reduce airflow excitation energy.

[0009] Existing solutions for non-integers in integral bladed disks have the following technical problems:

[0010] 1. The blade tip cut-off angle will break the integrity of the blade shape, reduce the working capacity of the blade, significantly reduce the margin and efficiency of the fan components, and have an adverse effect on the overall performance of the machine.

[0011] 2. Adjusting the blade profile of adjacent stator blades cannot completely solve the problem of non-integer vibration. This measure usually needs to be used in conjunction with other methods to be effective. It also has an adverse effect on the performance of the components. Furthermore, it requires the production of entirely new stator blades for engineering applications, which results in high costs.

[0012] 3. Adjusting the adjustment rules of the adjustable intake support plate and the nozzle area is essentially adjusting the aerodynamic state of the fan on the common working line of the whole machine when non-integer vibration occurs, thereby avoiding the problem of non-integer vibration of the fan component within a specific speed range. However, this method has a significant impact on the overall performance of the machine and cannot fundamentally solve the problem of non-integer vibration. It only actively avoids vibration from the perspective of the overall machine usage strategy, leaving behind usage risks.

[0013] 4. The integral bladed 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. Furthermore, because it eliminates the original disk tenon connection space, it is difficult to inherit and use 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 far away from the blade body and blade tip, which will reduce its vibration reduction and vibration absorption effect.

[0014] 5. Although reducing the blade tip clearance can reduce the airflow excitation effect, considering the steady-state and transient state requirements of the entire machine envelope (the blade tip cannot rub against the casing body), the blade tip clearance cannot be reduced indefinitely. Therefore, the effect of this method is also limited. Summary of the Invention

[0015] To address the aforementioned problems, this application provides a fan rotor blade structure, comprising:

[0016] Basic blades;

[0017] Vibration damping ribs are installed on the back side of the blade of the basic blade;

[0018] Vibration damping ribs are installed on the leaf blade side of the basic blade.

[0019] The outer contour lines of the vibration damping ribs on the back side and the blade base side are the same as the outer contour lines of the base blades at the same location, and satisfy the following conditions:

[0020] The angle αb between the vibration damping rib on the back side of the blade and the flow path at the blade tip is ≤ γ;

[0021] The angle αp between the blade basin side damping rib and the blade tip flow path is ≤ γ;

[0022] Wherein, γ is the angle between the internal flow path of the blade and the flow path at the blade tip under the meridional plane projection.

[0023] A design method for a fan rotor blade structure, comprising the following steps:

[0024] Step 1: Set the values ​​of the variables, including the radial thickness Δb of the blade back side damping rib, the radial thickness Δp of the blade base side damping rib, the offset distance Hp between the blade base side damping rib and the blade base side airfoil surface, the offset distance Hb between the blade back side damping rib and the blade back side airfoil surface, the distance Cbq between the leading edge of the blade back side damping rib and the air intake edge of the blade tip surface, the distance Cbh between the trailing edge of the blade back side damping rib and the exhaust edge of the blade tip surface, the distance Cpq between the leading edge of the blade base side damping rib and the air intake edge of the blade tip surface, and the distance Cph between the trailing edge of the blade base side damping rib and the exhaust edge of the blade tip surface.

[0025] Step 2: Based on the values ​​of the set variables, calculate the modal mass matrix, modal damping matrix, and modal stiffness matrix of the entire blade.

[0026] Step 3: Calculate the vibration response of the entire blade under modal aerodynamic load based on the modal mass matrix, modal damping matrix, and modal stiffness matrix of the entire blade. If 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.

[0027] Preferably, the modal mass matrix M of the entire blade is... n The calculation methods include:

[0028] Calculate the modal mass matrix M of the basic blade. 基础 Calculate the modal mass matrix M of the entire system of the blade back-side damping ribs and the blade base-side damping ribs. 减振筋 ;

[0029] Modal mass matrix M based on the basic blade 基础 The modal mass matrix M of the entire damping ribs on the back side of the blade and the damping ribs on the base side. 减振筋 Calculate the modal mass matrix M of the entire blade. n .

[0030] Preferably, the modal mass matrix M of the entire blade is... n The calculation formula is:

[0031] .

[0032] Preferably, the modal damping matrix C of the entire blade is... n The calculation formula is:

[0033] ;

[0034] Among them, C 基础 The modal damping matrix of the basic blade; C 减振筋 The modal damping matrix is ​​the overall damping matrix of the blade back-side damping ribs and the blade base-side damping ribs.

[0035] Preferably, the modal stiffness matrix K of the entire blade is...n The calculation formula is:

[0036] ;

[0037] Among them, K 基础 The modal stiffness matrix of the basic blade; K 减振筋 This represents the modal stiffness matrix of the blade back-side damping ribs and the blade base-side damping ribs as a whole.

[0038] Preferably, ;

[0039] Where ρ is the system mass density, F is the volume function, Lb is the axial length of the damping rib on the blade back side, and Lp is the axial length of the damping rib on the blade base side.

[0040] Preferably, the values ​​of the preset 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 values ​​of the radial thickness Δb of the vibration damping rib on the back side of the blade, the radial thickness Δp of the vibration damping rib on the blade base side, the offset distance Hp between the vibration damping rib on the blade base side and the blade profile on the blade base side, the offset distance Hb between the vibration damping rib on the back side of the blade and the blade profile on the back side of the blade, the axial length Lb of the vibration damping rib on the back side of the blade, the axial length Lp of the vibration damping rib on the blade base side, the angle θbq of the leading edge of the vibration damping rib on the back side of the blade relative to the X-axis of the blade profile coordinate system, the angle θpq of the leading edge of the vibration damping rib on the blade base side relative to the X-axis of the blade profile coordinate system, the angle θbh of the trailing edge of the vibration damping rib on the back side of the blade relative to the X-axis of the blade profile coordinate system, and the angle θph of the trailing edge of the vibration damping rib on the blade base side relative to the X-axis of the blade profile coordinate system.

[0041] The advantages of this application include: it can eliminate the aerodynamic performance loss caused by the blade tip cut angle, reduce the structural safety risk caused by the blade tip clearance, effectively solve the non-integer order vibration problem at the blade tip of the fan rotor blade, and improve the natural frequencies of each mode of the rotor blade by adjusting the structural parameters of the damping ribs on the blade back side and the blade base side. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the back side structure of a fan rotor blade according to a preferred embodiment of this application.

[0043] Figure 2 This is a schematic diagram of the blade side structure of a fan rotor blade according to a preferred embodiment of this application.

[0044] Figure 3 This is a schematic cross-sectional view of a fan rotor blade structure according to a preferred embodiment of this application. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings. In the drawings, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The described embodiments are only some, not all, of the embodiments of this application. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application. The embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0046] like Figures 1-3 As shown, this application provides a fan rotor blade structure, including:

[0047] Basic blade 1;

[0048] Vibration damping rib 3 is provided on the back side of the blade of the basic blade 1;

[0049] Vibration damping rib 4 is provided on the blade basin side of the basic blade 1;

[0050] The outer contours of the blade back-side damping rib 3 and the blade base-side damping rib 4 are the same as the outer contours of the base blade 1 at the same position. That is, the outer contours of the blade back-side damping rib 3 and the blade base-side damping rib 4 are formed by the outward offset of the blade body base airfoil of the base blade 1 at the same height position, and satisfy the following conditions:

[0051] The angle αb between the vibration damping rib 3 on the back side of the blade and the flow path at the blade tip is ≤ γ;

[0052] The angle αp between the blade basin side damping rib 4 and the blade tip flow path is ≤γ;

[0053] Wherein, γ is the angle between the internal flow path of the blade and the flow path at the blade tip under the meridional plane projection.

[0054] Based on the aforementioned technical features, without requiring adjustments to the airflow excitation, the adjustable support plate IGV, or the nozzle area adjustment rules, and without affecting the overall working line of the machine or being limited to the tenon-and-palm connection structure, simply placing the damping ribs on the blade back side and blade head side—that is, the damping ribs on both sides—directly in the high-incidence areas of blade edge-angle vibration can effectively enhance the blade edge-angle stiffness and resist vibrations caused by non-integer airflow excitation. Furthermore, through the detuning design of the blade surface, it achieves the same vibration reduction and suppression effect as a damping structure. In addition, by adjusting the structural parameters of the damping ribs on both sides of the blade, the blade mode can be further altered, eliminating or reducing the probability of non-integer vibrations.

[0055] A design method for a fan rotor blade structure, comprising the following steps:

[0056] Step 1: Set the values ​​of the variables, including the radial thickness Δb of the damping rib on the blade back side, the radial thickness Δp of the damping rib on the blade tip side, the offset distance Hp between the damping rib on the blade tip side and the blade profile on the blade tip side, the offset distance Hb between the damping rib on the blade back side and the blade profile on the blade back side, the distance Cbq between the leading edge of the damping rib on the blade back side and the air intake edge of the blade tip profile, the distance Cbh between the trailing edge of the damping rib on the blade back side and the air intake edge of the blade tip profile, the distance Cpq between the leading edge of the damping rib on the blade tip side and the air intake edge of the blade tip profile, and the distance Cph between the trailing edge of the damping rib on the blade tip side and the air exhaust edge of the blade tip profile; in some optional... In the implementation method, other variables include: Apq, the distance from the intersection of the leading edge of the blade basin-side damping rib and the offset line to the Y-axis of the airfoil coordinate system; Bph, the distance from the intersection of the trailing edge of the blade basin-side damping rib and the offset line to the Y-axis of the airfoil coordinate system; Abq, the distance from the intersection of the leading edge of the blade back-side damping rib and the offset line to the Y-axis of the airfoil coordinate system; Bbh, the distance from the intersection of the trailing edge of the blade back-side damping rib and the offset line to the Y-axis of the airfoil coordinate system; Rb, the rounding between the upper and lower surfaces of the blade back-side damping rib and the base airfoil; and Rp, the rounding between the upper and lower surfaces of the blade basin-side damping rib and the base airfoil.

[0057] Step 2: Based on the values ​​of the set variables, calculate the modal mass matrix, modal damping matrix, and modal stiffness matrix of the entire blade.

[0058] Step 3: Calculate the vibration response of the entire blade under modal aerodynamic load based on the modal mass matrix, modal damping matrix, and modal stiffness matrix of the entire blade. If 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.

[0059] In some alternative implementations, the modal mass matrix M of the entire blade n The calculation methods include:

[0060] Calculate the modal mass matrix M of the basic blade 1 基础 Calculate the modal mass matrix M of the entire system of the blade back side damping rib 3 and the blade base side damping rib 4. 减振筋 ;

[0061] Modal mass matrix M based on basic blade 1 基础 The modal mass matrix M of the entire combination of blade back side damping rib 3 and blade base side damping rib 4. 减振筋 Calculate the modal mass matrix M of the entire blade. n .

[0062] In some alternative implementations, the modal mass matrix M of the entire blade n The calculation formula is:

[0063] .

[0064] In some alternative implementations, the modal damping matrix C of the entire blade n The calculation formula is:

[0065] ;

[0066] Among them, C 基础 The modal damping matrix of the basic blade 1; C 减振筋 The modal damping matrix is ​​given by 3 on the back side of the blade and 4 on the bottom side of the blade.

[0067] In some alternative implementations, the modal stiffness matrix K of the entire blade n The calculation formula is:

[0068] ;

[0069] Among them, K 基础 The modal stiffness matrix of the basic blade 1; K 减振筋 The modal stiffness matrix is ​​given by 3 for the blade back side damping rib and 4 for the blade base side damping rib.

[0070] In some alternative implementations, ;

[0071] Where ρ is the system mass density, F is the volume function, Lb is the axial length of the damping rib on the blade back side, and Lp is the axial length of the damping rib on the blade base side.

[0072] In step 3, the formula for calculating the vibration response of the entire blade is:

[0073] ;

[0074] Where x represents the modal amplitude of the entire blade; f n(t) This represents the modal aerodynamic load applied across the entire blade. The unit velocity of the vibration amplitude The unit acceleration of the vibration amplitude.

[0075] In some optional implementations, the values ​​of preset 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 values ​​of the radial thickness Δb of the blade back side damping rib, the radial thickness Δp of the blade base side damping rib, the offset distance Hp between the blade base side damping rib and the blade base side airfoil surface, the offset distance Hb between the blade back side damping rib and the blade back side airfoil surface, the axial length Lb of the blade back side damping rib, the axial length Lp of the blade base side damping rib, the angle θbq of the leading edge of the blade back side damping rib relative to the X-axis of the airfoil coordinate system, the angle θpq of the leading edge of the blade base side damping rib relative to the X-axis of the airfoil coordinate system, the angle θbh of the trailing edge of the blade back side damping rib relative to the X-axis of the airfoil coordinate system, and the angle θph of the trailing edge of the blade base side damping rib relative to the X-axis of the airfoil coordinate system.

[0076] The advantages of this application include: it can eliminate the aerodynamic performance loss caused by the blade tip cut angle, reduce the structural safety risk caused by the blade tip clearance, effectively solve the non-integer order vibration problem at the blade tip of the fan rotor blade, and improve the natural frequencies of each mode of the rotor blade by adjusting the structural parameters of the damping ribs on the blade back side and the blade base side.

[0077] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A fan rotor blade structure, characterized in that, include: Basic blade (1); Vibration damping ribs (3) are provided on the back side of the blade of the basic blade (1); A blade basin-side vibration damping rib (4) is provided on the blade basin side of the basic blade (1). The outer contours of the blade back-side damping rib (3) and the blade base-side damping rib (4) are the same as the outer contours of the base blade (1) at the same position, and satisfy the following conditions: The angle αb between the blade back side damping rib (3) and the blade tip flow path is ≤γ; The angle between the blade basin side damping rib (4) and the blade tip flow path is αp≤γ; Wherein, γ is the angle between the internal flow path of the blade and the flow path at the blade tip under the meridional plane projection.

2. A design method for a fan rotor blade structure, used to design the fan rotor blade structure as described in claim 1, characterized in that, Includes the following steps: Step 1: Set the values ​​of the variables, including the radial thickness Δb of the blade back side damping rib, the radial thickness Δp of the blade base side damping rib, the offset distance Hp between the blade base side damping rib and the blade base side airfoil surface, the offset distance Hb between the blade back side damping rib and the blade back side airfoil surface, the distance Cbq between the leading edge of the blade back side damping rib and the air intake edge of the blade tip surface, the distance Cbh between the trailing edge of the blade back side damping rib and the exhaust edge of the blade tip surface, the distance Cpq between the leading edge of the blade base side damping rib and the air intake edge of the blade tip surface, and the distance Cph between the trailing edge of the blade base side damping rib and the exhaust edge of the blade tip surface. Step 2: Based on the values ​​of the set variables, calculate the modal mass matrix, modal damping matrix, and modal stiffness matrix of the entire blade. Step 3: Calculate the vibration response of the entire blade under modal aerodynamic load based on the modal mass matrix, modal damping matrix, and modal stiffness matrix of the entire blade. If 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 design method for the fan rotor blade structure as described in claim 2, characterized in that, Modal mass matrix M of the entire blade n The calculation methods include: Calculate the modal mass matrix M of the basic blade (1) 基础 Calculate the modal mass matrix M of the entire system of the blade back side damping rib (3) and the blade base side damping rib (4). 减振筋 ; Modal mass matrix M based on the basic blade (1) 基础 The modal mass matrix M of the entire assembly of the blade back side damping rib (3) and the blade base side damping rib (4) 减振筋 Calculate the modal mass matrix M of the entire blade. n .

4. The design method for the fan rotor blade structure as described in claim 3, characterized in that, Modal mass matrix M of the entire blade n The calculation formula is: 。 5. The design method for the fan rotor blade structure as described in claim 3, characterized in that, The modal damping matrix C of the entire blade n The calculation formula is: ； Among them, C 基础 The modal damping matrix of the basic blade (1); C 减振筋 The modal damping matrix is ​​the overall structure of the blade back side damping rib (3) and the blade basin side damping rib (4).

6. The design method for the fan rotor blade structure as described in claim 3, characterized in that, Modal stiffness matrix K of the entire blade n The calculation formula is: ； Among them, K 基础 The modal stiffness matrix of the basic blade (1); K 减振筋 The modal stiffness matrix of the blade back side damping rib (3) and the blade basin side damping rib (4) as a whole.

7. The design method for the fan rotor blade structure as described in claim 3, characterized in that, ； Where ρ is the system mass density, F is the volume function, Lb is the axial length of the damping rib on the blade back side, and Lp is the axial length of the damping rib on the blade base side.

8. The design method for the fan rotor blade structure as described in claim 7, characterized in that, The values ​​of the preset 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 values ​​of the radial thickness Δb of the vibration damping rib on the back side of the blade, the radial thickness Δp of the vibration damping rib on the blade base side, the offset distance Hp between the vibration damping rib on the blade base side and the blade profile on the blade base side, the offset distance Hb between the vibration damping rib on the back side of the blade and the blade profile on the back side, the axial length Lb of the vibration damping rib on the back side of the blade, the axial length Lp of the vibration damping rib on the blade base side, the angle θbq of the leading edge of the vibration damping rib on the back side of the blade relative to the X-axis of the blade profile coordinate system, the angle θpq of the leading edge of the vibration damping rib on the blade base side relative to the X-axis of the blade profile coordinate system, the angle θbh of the trailing edge of the vibration damping rib on the back side of the blade relative to the X-axis of the blade profile coordinate system, and the angle θph of the trailing edge of the vibration damping rib on the blade base side relative to the X-axis of the blade profile coordinate system.

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