Method for optimizing the position of the paddle-fan shaft of an open-rotor engine

Abstract

The application provides a position optimization method of a paddle fan shaft handle of an open rotor engine, comprising the following steps: S1, inputting the position of the paddle fan shaft handle, paddle fan pitch angles and aerodynamic loads of all working condition points, and inputting parameters of the paddle fan; S2, taking a paddle fan translation vector under a pitch angle beta0 and a paddle fan rotation angle as optimization variables, constructing a fitness function, constructing a constraint condition, and establishing an optimization function; S3, adopting a single-target or multi-target optimization algorithm to carry out optimization calculation, and outputting an optimal paddle fan position; S4, setting a moving position of the shaft handle under the pitch angle, and substituting into an aerodynamic finite element calculation model to calculate paddle fan aerodynamic loads of all working condition points; and S5, judging whether errors between the aerodynamic loads and the aerodynamic loads adopted in the optimization calculation process meet requirements or not. The paddle fan shaft handle position optimization method based on paddle fan aerodynamic load, centrifugal load and friction load calculation formulas effectively reduces the calculation times of the aerodynamic loads in the optimization process, and improves the position optimization efficiency of the paddle fan shaft handle.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of open rotor engine, in particular to a method for optimizing the position of the paddle fan shaft of an open rotor engine. BACKGROUND

[0002] In the prior art, the open rotor engine relies on the variable pitch system to adjust the pitch angle of the paddle fan, so that the paddle blades work at the appropriate angle of attack under different working conditions, thereby improving the working efficiency. During the adjustment of the pitch angle, the variable pitch system needs to overcome the torque generated by the aerodynamic load, centrifugal load and friction load of the paddle fan. On the other hand, the aerodynamic and centrifugal loads will also generate a bending moment perpendicular to the shaft direction, which will bring a large load to the supporting bearing of the paddle fan.

[0003] However, the size of these torque and bending moment loads is related to the position of the paddle fan shaft. Therefore, by optimizing the position of the paddle fan shaft, the adjusting load of the variable pitch system and the load of the supporting bearing of the paddle fan shaft can be effectively reduced.

[0004] In fact, the paddle fan load under different flight conditions is affected by many factors such as rotational speed, pitch angle and incoming flow speed, which brings challenges to the optimization efficiency of the shaft position. Therefore, it is of great significance to establish an efficient method for optimizing the position of the paddle fan shaft by comprehensively considering the paddle fan load under various flight conditions, so as to improve the load of the variable pitch system and the supporting bearing of the paddle fan shaft.

[0005] The optimization goal of the paddle fan shaft position of the open rotor engine is mainly to reduce the adjusting load of the variable pitch system and the load of the supporting bearing of the paddle fan shaft. However, these loads are not only related to the position of the paddle fan shaft, but also affected by factors such as rotational speed, pitch angle and incoming flow speed under flight conditions. After modifying the position of the paddle fan shaft, it is usually necessary to recalculate using finite element software or dynamics software, which seriously restricts the optimization efficiency of the paddle fan shaft position.

[0006] Therefore, the present application provides a method for optimizing the position of the paddle fan shaft of an open rotor engine to overcome the above technical problems. SUMMARY

[0007] The present application solves the technical problem that the load of the paddle fan shaft of the open rotor engine in the prior art is affected by factors such as rotational speed, pitch angle and incoming flow speed under flight conditions, and needs to be recalculated using finite element software or dynamics software, which seriously restricts the optimization efficiency of the paddle fan shaft position, and provides a method for optimizing the position of the paddle fan shaft of an open rotor engine.

[0008] The present application solves the above technical problems by the following technical scheme:

[0009] A method for optimizing the position of the propeller shaft of an open rotor engine, characterized in that the optimization method includes the following steps:

[0010] S1. Input the position of the propeller shaft, as well as the propeller pitch angle and aerodynamic load F at all operating points. a (β), M a (β); Input propeller parameters;

[0011] S2, with the propeller fan translation vector P under the propeller pitch angle β0 d (β0), the angle of rotation of the propeller fan about the Ox axis at the pitch angle β0. To optimize the variables, a fitness function f(F) is constructed. t (β),M t (β)), construct constraints and establish optimization functions;

[0012] S3. Perform optimization calculations using a single-objective or multi-objective optimization algorithm on the optimization function established in step S2, and output the propeller translation vector P at the optimal propeller position with a propeller pitch angle β0. d (β0), the angle of rotation of the propeller around the Ox axis

[0013] S4. Set the movement position of the shaft at the pitch angle β0 to -P. d (β0) Substitute the values ​​into the aerodynamic finite element model to calculate the propeller aerodynamic load F′ at all operating points. a (β), M′ a (β);

[0014] S5. Determine the aerodynamic load F′ a (β), M′ a (β) and the aerodynamic load F used in the optimization calculation process a (β), M a Does the error between (β) meet the requirements?

[0015] If the requirements are not met, then the aerodynamic load used in the optimization calculation process is set to F′. a (β), M′ a (β), then proceed to step S2;

[0016] If the requirements are met, the optimal propeller shaft position will be output as -P. d (β0)

[0017] Where β represents the pitch angle under other non-design point operating conditions; β0 represents the pitch angle under design point operating conditions; P d (β0) is the propeller fan translation vector under the propeller pitch angle β0.

[0018] According to one embodiment of the present application, the parameters of the fan in step S1 include: mass of the fan, mass center, product of inertia, moment of inertia.

[0019] According to one embodiment of the present application, the position optimization method further includes calculation of aerodynamic load.

[0020] The aerodynamic pressure of the fan is obtained by flow field calculation at the design operating point, and the aerodynamic force and the aerodynamic moment of the aerodynamic integral point under the action of the aerodynamic pressure are obtained by integrating the blade aerodynamic pressure, i.e., F a (β0), M a (β0).

[0021] The aerodynamic integral point is selected as the center point of the shaft bearing of the current designed fan, and the aerodynamic integral point is located on the z-axis.

[0022] After the fan is translated along the vector P d (β0), it is assumed that the aerodynamic pressure distribution on the surface of the fan is unchanged, and the aerodynamic force and the aerodynamic moment of the point P' are still F a (β0), M a (β0).

[0023] The load on the bearing support center point is calculated by the following formula:

[0024]

[0025] For the pitch angle β of the non-design point operating condition, the translated fan is still rotated around the original bearing center Ox from the pitch angle β0 to β, and the translation vector P d (β0) is changed to P d (β), and the load on the bearing support center point is calculated by the following formula:

[0026]

[0027] Wherein, P d (β) is the translation vector of the fan at the pitch angle β, i.e., the vector P d (β0) is rotated around the original bearing center Ox by (β-β0), and is calculated by the following formula:

[0028]

[0029] According to one embodiment of the present application, the position optimization method further includes calculation of centrifugal load.

[0030]

[0031]

[0032]

[0033]

[0034] wherein the inertia product I xz , I yz and the inertia moment I yy , I xx are solved in the state that the center of mass of the paddle fan is moved to the Oz axis; denotes that the center of mass of the paddle fan is moved to the Oz axis along the Ox and Oy directions when the pitch angle of the paddle fan is β0, and then moved along the vector P d (β0), and the components of the translation vector of the entire process along the Ox, Oy and Oz directions; M cx , M cy , M cz denote the centrifugal moments of the paddle fan about the initial bearing center point B along the Ox, Oy and Oz directions in the Oxyz inertial coordinate system.

[0035] According to one embodiment of the present application, the position optimization method further comprises calculation of the friction torque:

[0036]

[0037] wherein μ is the bearing friction coefficient, d p is the average diameter of the bearing, and F c is the centrifugal force borne by a mass point on the paddle fan or blade.

[0038] According to one embodiment of the present application, the total load borne by the bearing center B of the paddle fan shaft support is:

[0039]

[0040] According to one embodiment of the present application, the position optimization method further comprises adjustment of the circumferential position:

[0041] A rotating coordinate system Ox'y'z' is established, with the Oz' axis always coinciding with the bearing B' axis;

[0042] The bearing B' is initially coincident with the bearing B, and when the paddle fan rotates along the Ox axis direction, the bearing B' will rotate together with the paddle fan;

[0043] The load F t (β)', M t (β)' borne by the bearing B' in the rotating coordinate system Ox'y'z' will always remain unchanged, and the load borne by the bearing B can be obtained by first converting the load borne by the bearing B' to the inertial coordinate system Oxyz, and then calculating through force translation.

[0044] The positive progress effect of the present application is that:

[0045] The paddle fan shaft position optimization method of the open rotor engine has the following advantages:

[0046] I. The calculation model of the paddle fan aerodynamic load, centrifugal load and friction load changing with the paddle fan position is established, which effectively shortens the load calculation time required for paddle fan shaft optimization.

[0047] II. The paddle fan shaft position optimization method based on the paddle fan aerodynamic load, centrifugal load and friction load calculation formula can effectively reduce the calculation times of aerodynamic load in the optimization process and improve the position optimization efficiency of the paddle fan shaft. BRIEF DESCRIPTION OF DRAWINGS

[0048] The above and other features, properties and advantages of the present application will become more apparent by the following description with reference to the accompanying drawings and embodiments, in which the same reference numerals are used throughout the drawings and represent the same features and in which:

[0049] Figure 1 The flowchart of the paddle fan shaft position optimization method of the open rotor engine.

[0050] Figure 2 In the paddle fan shaft position optimization method of the open rotor engine, the paddle fan position adjustment along the Ox and Oy directions is shown in the schematic diagram.

[0051] Figure 3 In the paddle fan shaft position optimization method of the open rotor engine, the paddle fan circumferential position adjustment is shown in the schematic diagram.

[0052] Figure 4 In the paddle fan shaft position optimization method of the open rotor engine, the schematic diagram of the paddle fan translation vector under non-design condition is shown.

[0053] Figure 5 In the paddle fan shaft position optimization method of the open rotor engine, the schematic diagram of the paddle fan centrifugal load is shown. DETAILED DESCRIPTION

[0054] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0055] The embodiments of the present application will now be described in detail with reference to the accompanying drawings. The preferred embodiments of the present application will now be described in detail with reference to the accompanying drawings. In all the drawings, the same reference numerals will be used to represent the same or similar parts.

[0056] Furthermore, although the terms used in the present application are selected from publicly known and used terms, some of the terms mentioned in the description of the present application can be created by the applicant in his or her own judgment, and the detailed meanings thereof are described in relevant parts of the description herein.

[0057] Furthermore, the present application is to be understood based on its meaning, not only by the actual terms used, but also by the meanings implied by each term.

[0058] As Figures 1 to 5 shown in the figure, the present application discloses a position optimization method for a paddle fan shaft of an open rotor engine, aiming at the position optimization requirement of the paddle fan shaft of the open rotor engine, based on the calculation model of the paddle fan aerodynamic load, centrifugal load and friction load varying with the paddle fan position, which comprises the following steps:

[0059] Step S1, input the position of the paddle fan shaft, and the paddle fan pitch angle and aerodynamic load F of all working condition points a (β), M a (β); input the parameters of the paddle fan.

[0060] Among them, the parameters of the paddle fan in the step S1 include: paddle fan mass, mass center, inertia product, inertia moment and other parameters.

[0061] Step S2, the paddle fan translation vector P d (β0) and the angle of the paddle fan rotating around the Ox axis direction at the pitch angle β0 are input as optimization variables, a fitness function f(F t (β), M t (β)) is constructed, a constraint condition is constructed, and an optimization function is established.

[0062] Preferably, here the fitness function f(F t (β), M t (β)) is constructed according to the variable pitch system load, paddle fan shaft bearing load requirement, etc., the constraint condition is constructed in combination with the position moving range, and thus the optimization function is established.

[0063] Among them, F t (β), M t (β) can be calculated by the following formula:

[0064]

[0065] Step S3, a single-objective or multi-objective optimization algorithm is used to carry out optimization calculation for the optimization function established in the step S2, and the paddle fan translation vector P d (β0) and the angle of the paddle fan rotating around the Ox axis direction at the pitch angle β0 are output

[0066] Step S4: Set the movement position of the shaft at the pitch angle β0 to -P d (β0) Substitute the values ​​into the aerodynamic finite element model to calculate the propeller aerodynamic load F′ at all operating points. a (β), M′ a (β).

[0067] Step S5: Determine the aerodynamic load F′ a (β), M′ a (β) and the aerodynamic load F used in the optimization calculation process a (β), M a Does the error between (β) meet the requirements?

[0068] If the requirements are not met, then the aerodynamic load used in the optimization calculation process is set to F′. a (β), M′ a (β), then proceed to step S2;

[0069] If the requirements are met, the optimal propeller shaft position will be output as -P. d (β0) In other words, the optimization result is that the propeller shaft shank position is first adjusted along the Ox and Oy directions by -r. xd -r yd Then adjust the angle along the circumferential position.

[0070] Where β represents the pitch angle under other non-design point operating conditions; β0 represents the pitch angle under design point operating conditions; P d (β0) is the propeller fan translation vector under the propeller pitch angle β0.

[0071] Based on the steps described above, the following is a further detailed explanation with reference to the accompanying drawings:

[0072] Given the initial position of the propeller shaft at the design operating point, the optimization variables for the propeller shaft position include adjustments to the circumferential, axial, and tangential positions of the shaft at the design operating point. However, propeller shaft position optimization actually involves changing the relative position between the shaft and the propeller; therefore, it can be assumed that the shaft position remains stationary while the propeller position changes during the calculation.

[0073] like Figure 2 As shown, the Oxyz inertial coordinate system is established with the engine axis as the x-axis and the propeller shaft bearing axis as the z-axis, based on the right-hand rule. Figure 2 Adjust the position of the propeller along the Ox and Oy directions, corresponding to the axial and tangential positions of the shaft. Figure 3 To adjust the circumferential position of the propeller, adjust the circumferential position of the corresponding shaft.

[0074] Figure 2and Figure 3 B represents the bearing support center point; F a represents the aerodynamic resultant force acting on point P; represents the aerodynamic resultant force acting on point B; M a represents the aerodynamic moment acting on point P; represents the aerodynamic moment acting on point B; M z represents the centrifugal torque acting on point B; M x represents the centrifugal bending moment acting on point B in the Ox direction; M y represents the centrifugal bending moment acting on point B in the Oy direction; P represents the aerodynamic integration point, which does not change with the rotation of the paddle fan; P d (β0) represents the paddle fan movement vector at the pitch angle β0.

[0075] The paddle fan load calculation under different position adjustments will be described in detail as follows:

[0076] As shown in Figure 2 , the paddle fan is adjusted in the Ox and Oy directions.

[0077] I. Aerodynamic load calculation

[0078] As shown in Figure 2 , at the design working point (the pitch angle, incoming flow velocity, and other factors are known), the paddle fan aerodynamic pressure is calculated through the flow field, the blade aerodynamic pressure is integrated to point P, and the aerodynamic force and aerodynamic moment of the aerodynamic pressure acting on the point are F a (β0) and M a (β0), respectively. Point P is fixed in the inertial coordinate system Oxyz and does not change with the rotation of the paddle fan.

[0079] Generally, point P is selected as the current designed paddle fan shaft support bearing center point, and at this time, point P is located on the z-axis. After the paddle fan is translated along the vector P d (β0), it can be assumed that the aerodynamic pressure distribution on the surface of the paddle fan does not change, and the aerodynamic force and aerodynamic moment acting on point P' are still F a (β0) and M a (β0), respectively.

[0080] At this time, the load acting on point B can be calculated by the following formula 1:

[0081]

[0082] For the pitch angle β of the non-design point working condition, the translated paddle fan still rotates around the original support bearing center Oz axis from the pitch angle β0 to β, as shown in Figure 3 , the translation vector P d (β0) of the paddle fan changes to P d(β), then the load on the bearing support center point at this time is calculated by the following formula 2:

[0083]

[0084] Among them, P d (β) is the propeller fan movement vector under the propeller pitch angle β, i.e., P d The vector (β0) after rotating (β-β0) around the original bearing center Oz axis is calculated using the following formula 3:

[0085]

[0086] II. Centrifugal Load Calculation

[0087] like Figure 4 As shown, for a mass point m on the blade i When the engine rotates along Ox, it will be subjected to centrifugal force along the Oy and Oz directions, thus generating centrifugal force, centrifugal torque and centrifugal bending moment on the bearing support point B.

[0088] Centrifugal force can be calculated using the following formula 4:

[0089]

[0090] Note the center r of the propeller shaft support bearing xB =r yB If the value is 0, then the centrifugal torque at point B is calculated using the following formula 5:

[0091]

[0092] At the design operating point, the propeller moves along vector P. d (β0)=[r xd r yd r zd ] T After translation, when the propeller rotates around the original support bearing center to the pitch angle β, the mass point m i position r i (β) is calculated using the following formula 6:

[0093]

[0094] Where, β * =β-β0,r i (β0)=[r xi r yi r zi ] T R z (β * ) is the coordinate transformation matrix for rotation around the Oz axis.

[0095]

[0096] Substitute equation 6 into equation 4, considering a fan-blade with mass m and center of mass at [r xc r yc r zc ] T , the centrifugal force of the fan-blade when it is rotated to a pitch angle β can be obtained as:

[0097]

[0098] Similarly, substitute equation 6 into equation 5, the centrifugal moment M c (β) of the fan-blade shaft support bearing center B when the fan-blade is rotated to a pitch angle β can be obtained as:

[0099]

[0100]

[0101]

[0102] where, I xz =∑m i r xi r zi , I yz =∑m i r yi r zi .

[0103] In order to further simplify equation 9, the following changes are made. When the fan-blade pitch angle is β0, first translate the center of mass of the fan-blade along the Ox, Oy directions to the Oz axis as the initial state position of the pitch angle β0, at this time the center of mass , then the movement vector of the fan-blade at the pitch angle β0 relative to the initial state position can be calculated as:

[0104]

[0105] Considering that the fan-blade only moves along the Ox, Oy directions when optimizing the fan-blade shaft, r zd =0 in equation 10. At this time, equation 8, equation 9 are simplified as:

[0106]

[0107]

[0108]

[0109] ​

[0110] At this time, the inertia product I xz , I yz and the inertia moment I yy , I xx in formula 11 should be solved in the state that the center of mass of the paddle fan is moved to the Oz axis, and these variables can be obtained by assigning mass in the three-dimensional model and then measuring.

[0111] III. Friction torque calculation

[0112] Because of the centrifugal force and the aerodynamic force, the paddle fan generates positive pressure on the bearing, so the paddle fan will be affected by the bearing friction torque during the adjustment process. Considering that the load of the centrifugal force is much greater than the aerodynamic force, the bearing friction torque is calculated according to the centrifugal force, and the calculation method is as follows:

[0113]

[0114] Where μ is the bearing friction coefficient, d p is the average diameter of the bearing.

[0115] IV. Total load calculation

[0116] The aerodynamic load, centrifugal load, and friction load are summed up to obtain the total load on the bearing center B point of the paddle fan shaft support, as shown in the following formula 13:

[0117]

[0118] Where sign() is a sign function, which extracts the sign of the value in the parentheses.

[0119] As shown in FIG. 6, the circumferential position of the paddle fan is adjusted: Figure 3

[0120] A rotating coordinate system Ox'y'z' is established, and its Oz' axis always coincides with the axis of the bearing B'. The bearing B' initially coincides with the bearing B. When the paddle fan rotates along the Ox axis, the bearing B' will rotate with the paddle fan.

[0121] Therefore, the load F t (β)' and the moment M j (β)' of the bearing B' in the rotating coordinate system Ox'y'z' will always remain unchanged, i.e., F t (β) and M t (β), respectively.

[0122] At this time, the load of the bearing B can be obtained by first converting the load of the bearing B' to the inertia coordinate system Oxyz and then calculating it through force translation. The detailed calculation formula 14 is as follows:

[0123] ​

[0124] where F is the load of bearing B' in the rotating coordinate system t (β)', M t (β)' can be calculated by formula 13.

[0125] In the above entire calculation process, the fan blade is first translated along the Oxy plane, and then rotated along the Ox axis direction. is the angle of the fan blade rotating along the Ox axis direction, is the coordinate transformation matrix of rotating along the Ox axis direction, which can be calculated by formula 15:

[0126]

[0127] BB' can be calculated as

[0128]

[0129] where I is the unit matrix.

[0130] According to the above content, the fan blade shaft position optimization method can quickly calculate the fan blade first adjusting the positions r xd , r yd along the Ox and Oy directions respectively according to formula 14, and then adjusting the circumferential position angle After that, the resultant force and the resultant moment of the aerodynamic, centrifugal and friction loads on the original supporting bearing, wherein the moment along the Oz direction is the load that needs to be overcome by the variable pitch system, and the resultant force and the moment in other directions are the loads of the fan blade shaft supporting bearing.

[0131] Considering the relative relationship between the fan blade and the shaft position, the load calculated by formula 12 and formula 13 is the load of the original fan blade on the fan blade shaft supporting bearing and the variable pitch system after adjusting the positions of the fan blade shaft along the Ox and Oy directions respectively by r xd , r yd and then adjusting the circumferential position angle .

[0132] Therefore, according to formula 14, the load of the fan blade shaft supporting bearing and the variable pitch system after adjusting the position of the fan blade shaft can be quickly calculated, so that the optimized position of the fan blade shaft can be quickly obtained according to the optimization target of the load of the fan blade shaft supporting bearing and the variable pitch system by using a multi-objective or single-objective optimization algorithm.

[0133] Then, the aerodynamic load of all the working points is recalculated under the current position and is corrected, if the optimization target is met, the optimized position of the propeller-fan shaft is output, if the target is not met, the position of the propeller-fan shaft is re-optimized according to the corrected aerodynamic load. The method can effectively reduce the number of times of calculating the aerodynamic load in the optimization process, and can directly calculate the centrifugal load, thereby improving the optimization efficiency of the position of the propeller-fan shaft.

[0134] According to the above description, the parameters involved in the open rotor engine propeller-fan shaft position optimization method of the application are listed as follows:

[0135] The meaning of the parameter is shown in the following table:

[0136] B: initial bearing center point

[0137] B': bearing center point, coincides with B at the beginning, and then rotates along the Ox axis direction with the propeller-fan

[0138] BB': vector of the bearing center point B' relative to the initial bearing center point B

[0139] d p : average diameter of the bearing

[0140] F a : aerodynamic resultant force acting on the P point

[0141] aerodynamic resultant force acting on the B point

[0142] F c : centrifugal force on a mass point on the propeller-fan

[0143] F t : total force on the bearing center B of the propeller-fan shaft support considering the translation of the propeller-fan at the initial pitch angle β0, including aerodynamic force, friction force and centrifugal force

[0144] F t (β)': total force on the bearing B' in the coordinate system Ox'y'Z' when the pitch angle is β, including aerodynamic force, friction force and centrifugal force

[0145] total force on the bearing center B of the propeller-fan shaft support considering the translation and adjustment of the circumferential position of the propeller-fan at the initial pitch angle β0, including aerodynamic force, friction force and centrifugal force

[0146] I yz , I xz , I xy inertia products of the propeller-fan about the mass center along the Ox, Oy and Oz directions in the Oxyz inertial coordinate system

[0147] I xx 、I yy 、I zz Inertia moment of the paddle about the mass center along Ox, Oy, Oz directions in the inertial coordinate system Oxyz

[0148] m i Mass of a mass point on the blade

[0149] M a Aerodynamic resultant moment acting on point P

[0150] Aerodynamic resultant moment acting on point B

[0151] M c Centrifugal moment of a mass point on the paddle or blade about the initial bearing center point B

[0152] M f Bearing friction moment

[0153] M t Total moment acting on the bearing center point B of the paddle shaft support bearing, including aerodynamic moment, friction moment, centrifugal moment, considering the translation of the paddle at the initial pitch angle β0

[0154] M t (β)′ Total moment acting on the bearing B′ in the coordinate system Ox′y′z′, including aerodynamic moment, friction moment, centrifugal moment, when the pitch angle is β

[0155] Total moment acting on the bearing center point B of the paddle shaft support bearing, including aerodynamic moment, friction moment, centrifugal moment, considering the translation and adjustment of the circumferential position of the paddle at the initial pitch angle β0

[0156] M cx 、M cy 、M cz Centrifugal moment of the paddle about the initial bearing center point B along Ox, Oy, Oz directions in the inertial coordinate system Oxyz

[0157] M x Centrifugal bending moment acting on point B along Ox direction

[0158] M y Centrifugal bending moment acting on point B along Oy direction

[0159] M z Centrifugal torsional moment acting on point B along Oz direction

[0160] OB Position vector of the initial bearing center point

[0161] OP Position vector of the aerodynamic integration point

[0162] Oxyz inertial coordinate system

[0163] Ox'y'z' coordinate system rotating with bearing B', its Oz' axis always coinciding with the bearing B' axis

[0164] P aerodynamic integration point, not changing with the blade rotation

[0165] P d translation vector of the impeller

[0166] P d (β) translation vector of the impeller at the pitch angle β, i.e. P d (β0) vector after rotating (β-β0) around the original bearing center Oz axis

[0167] P d (β0) translation vector of the impeller at the pitch angle β0

[0168] translation vector of the impeller at the pitch angle β0, the impeller mass center is translated to the Oz axis along the Ox and Oy directions, and then along the vector P d (β0), the translation vector of the whole process

[0169] r i position vector of a mass point on the blade

[0170] r xB , r yB , r zB coordinates of the initial bearing center in the Oxyz inertial coordinate system along the Ox, Oy and Oz directions

[0171] r xc , r yc , r zc coordinates of the impeller mass center in the Oxyz inertial coordinate system along the Ox, Oy and Oz directions

[0172] translation vector of the impeller at the pitch angle β0, the impeller mass center is translated to the Oz axis along the Ox and Oy directions, and the coordinates of the impeller mass center along the Ox, Oy and Oz directions at this time are

[0173] r xd , r yd , r zd translation vector of the impeller at the pitch angle β0 d (β0) components along the Ox, Oy and Oz directions

[0174] translation vector of the impeller at the pitch angle β0, the impeller mass center is translated to the Oz axis along the Ox and Oy directions, and then along the vector P d(β0), the component of the translation vector of the entire process along the Ox, Oy, Oz directions

[0175] r xi , r yi , r zi The coordinates of a certain mass point on the blade in the Oxyz inertial coordinate system along the Ox, Oy, Oz directions

[0176] R x , R y , R z Coordinate transformation matrix for rotation around the Ox, Oy, Oz axes

[0177] β Other non-design point operating pitch angle

[0178] β0 Design point operating pitch angle

[0179] β * Pitch angle increment of other non-design point operating condition relative to the design point operating condition

[0180] μ Bearing friction coefficient

[0181] ω Rotation angular velocity of the fan around the engine axis

[0182] Angle of rotation of the fan around the Ox axis direction at the pitch angle β0

[0183] For the open rotor engine fan shaft position optimization problem, the present application has the following innovations:

[0184] I. Through derivation, the calculation formula of the centrifugal load of the fan on the resultant force and moment acting on the center point of the bearing supporting the fan shaft is obtained, which can quickly calculate the centrifugal load of the fan on the variable pitch system and the fan supporting bearing under different rotation speeds and pitch angles, improving the calculation efficiency of the centrifugal load after shaft position optimization.

[0185] II. Under the assumption that the aerodynamic pressure distribution does not change with the adjustment of the fan shaft position, through derivation, the calculation formula of the resultant force and moment of the centrifugal, aerodynamic and friction load of the fan on the center point of the fan shaft support after the optimization of the fan shaft position is obtained. The fan shaft position optimization variables include axial, tangential and circumferential position adjustment, which improves the calculation efficiency of the resultant force and moment of the center point of the fan shaft support after the optimization of the fan shaft position.

[0186] Third, a method for optimizing the position of the propeller shaft is proposed. Based on the centrifugal load theory formula and the calculation formulas for the resultant force and resultant torque at the support center point of the propeller shaft after the shaft position is optimized, the method can quickly calculate the load optimization target of the propeller shaft support bearing and variable pitch system corresponding to the optimized shaft position, and correct the aerodynamic load corresponding to the optimized output shaft position. This method can effectively improve the efficiency and accuracy of the propeller shaft position optimization.

[0187] Therefore, this invention proposes a method for optimizing the position of the propeller shaft of an open rotor engine. This method can quickly calculate the variable pitch system adjustment load and the propeller shaft support bearing load under different flight conditions, corresponding to the rotational speed, pitch angle, and incoming flow velocity, thereby improving the efficiency of propeller shaft position optimization.

[0188] In summary, the method for optimizing the position of the propeller shaft of the open rotor engine of the present invention has the following advantages:

[0189] I. The established calculation model for the aerodynamic load, centrifugal load, and friction load of the propeller fan as a function of the propeller fan position effectively shortens the load calculation time required for propeller fan shaft optimization.

[0190] II. The propeller shaft position optimization method proposed based on the calculation formulas of propeller aerodynamic load, centrifugal load, and friction load can effectively reduce the number of calculations of aerodynamic load in the optimization process and improve the efficiency of propeller shaft position optimization.

[0191] For those skilled in the art, the above disclosure is merely illustrative and does not constitute a limitation of this application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements, and corrections to this application. Such modifications, improvements, and corrections are suggested in this application and therefore remain within the spirit and scope of the exemplary embodiments of this application.

[0192] Furthermore, this application uses specific terms to describe embodiments of the application. For example, "an embodiment," "one embodiment," and / or "some embodiments" refer to a particular feature, structure, or characteristic related to at least one embodiment of the application. Therefore, it should be emphasized and noted that "an embodiment," "one embodiment," or "an alternative embodiment" mentioned twice or more in different locations in this specification do not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of the application can be appropriately combined.

[0193] For simplicity and to facilitate understanding of one or more embodiments of the application, a number of features of the application are sometimes grouped together in a single embodiment, figure or description of an embodiment. This method of disclosure, however, is not to be interpreted as limiting of the scope of the application to the features described in connection with these embodiments. Indeed, the applicant regards his application as having a wide applicability and the scope of his application only being limited by the claims.

[0194] Although the foregoing application has been described in some detail for purposes of clarity and example, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the principles and scope of the application.

Claims

1. A method of optimizing the position of a paddle fan shaft of an open rotor engine, characterized in that, The position optimization method comprises the following steps: S1, input the position of the propeller-fan shaft handle, and the propeller-fan pitch angle and aerodynamic load F of all working points a (β), M a (β); input the parameters of the propeller-fan; S2, translating the fan with the pitch angle β0with the fan translation vector P d (β0), the angle of rotation of the fan around the Ox axis for the optimization variables, constructing a fitness function f(F t (β), M t (β)), constructing a constraint condition, and establishing an optimization function; S3, the optimization function established in step S2 is subjected to single-objective or multi-objective optimization algorithm to carry out optimization calculation, and a propeller pitch angle β0 of an optimal propeller and fan position is outputted d (β0), an angle of rotation of the propeller and fan around the Ox axis direction at the propeller pitch angle β0 S4, set the moving position of the shaft under the pitch angle β0 as -P d (β0), Substitute the aerodynamic finite element calculation model to calculate the fan aerodynamic load F′ of all working points a (β), M′ a (β); S5, judging aerodynamic load F' a (β), M' a (β) and whether the error between (β) and aerodynamic load F a (β), M a (β) meets the requirement; If the requirement is not satisfied, the aerodynamic load used in the optimization calculation process is set as F' a (β), M' a (β), and the process jumps to step S2. If the requirements are met, the optimal paddle fan shaft handle position is output as -P d (β0), where β represents other non-design point operating pitch angles; β0represents a design point operating pitch angle; P d (β0) the fan translation vector at pitch angle β0.

2. The method of position optimization of a paddle fan shaft of an open-rotor engine according to claim 1, characterized in that, The parameters of the fan blade in the step S1 include: mass, centroid, inertia product and inertia moment.

3. The method of optimizing the position of a paddle fan shaft of an open-rotor engine according to claim 1, characterized in that, The position optimization method further comprises calculation of aerodynamic load: The aerodynamic pressure acting on the point is obtained by integrating the blade aerodynamic pressure on the aerodynamic integral point, and the aerodynamic force and the aerodynamic moment of the aerodynamic pressure acting on the point are F a (β0), M a (β0); The aerodynamic integral point is selected as the center point of the bearing of the current designed fan blade shaft, and the aerodynamic integral point is located on the z-axis; At the paddle-fan along the vector P d After the translation of (β0), it can be assumed that the aerodynamic pressure distribution on the surface of the paddle-fan is unchanged, so the aerodynamic force and the aerodynamic moment on the point P' are still F a (β0), M a (β0); The load borne by the bearing center point is calculated by the following formula: where F a represents the aerodynamic resultant force acting on point P; represents the aerodynamic resultant force acting on point B; M a represents the aerodynamic moment acting on point P; represents the aerodynamic moment acting on point B; OP represents the position vector of the initial bearing center point; OB represents the position vector of the aerodynamic integration point; P d (β0) represents the propeller movement vector at the pitch angle β0; For a non-design point condition of the pitch angle β, the translated propfan still rotates about the original bearing center Oz axis from the pitch angle β0 to β, and the propfan translation vector P d (β0) is converted to P d (β), at which time the load on the bearing support center point is calculated by the following formula: where F a represents the aerodynamic resultant force acting on point P; represents the aerodynamic resultant force acting on point B; M a represents the aerodynamic moment acting on point P; represents the aerodynamic moment acting on point B; OP represents the position vector of the initial bearing center point; OB represents the position vector of the aerodynamic integration point; P d (β) is the propeller movement vector at the pitch angle β, i.e. P d (β0) is the vector after rotating (β-β0) around the original bearing center axis Oz, which is calculated by the following formula: Among them, P d (β0) represents the propeller fan movement vector at the propeller pitch angle β0.

4. The method of optimizing the position of a paddle fan shaft of an open-rotor engine according to claim 1, characterized in that, The position optimization method further comprises calculation of centrifugal load: wherein the inertia product I xz , yz and the inertia moment I yy , xx should be solved in the state that the center of mass of the fan is translated to the Oz axis; represents the translation of the center of mass of the fan along the Ox, Oy directions to the Oz axis, and then along the vector P d (β0) in the state that the pitch angle of the fan is β0, and the translation vector of the whole process along the Ox, Oy, Oz directions; M cx , cy , cz represents the centrifugal moment of the fan about the initial bearing center point B along the Ox, Oy, Oz directions in the Oxyz inertial coordinate system; β * represents the pitch increment of other non-design point working conditions relative to the design point working condition; and ω represents the rotation angular velocity of the fan about the engine axis.

5. The method of optimizing the position of a paddle fan shaft of an open- rotor engine as set forth in claim 1, wherein, The position optimization method further comprises calculation of friction torque: where μ is the bearing friction coefficient, d p is the average diameter of the bearing, F c is the centrifugal force experienced by a mass point on the paddle fan or blade.

6. The method of position optimization of a paddle fan shaft of an open-rotor engine according to claim 1, characterized in that, The total load borne by the bearing center B of the fan blade shaft is: wherein F t is the total force acting on the center B of the bearing of the shaft of the impeller after the impeller is translated from the initial pitch angle β0, including aerodynamic force, friction force, centrifugal force; M t is the total moment acting on the center B of the bearing of the shaft of the impeller after the impeller is translated from the initial pitch angle β0, including aerodynamic moment, friction moment, centrifugal moment; represents the aerodynamic resultant force acting on the point B; represents the aerodynamic resultant moment acting on the point B; F c represents the centrifugal force acting on the impeller; M c represents the centrifugal moment of the impeller about the initial bearing center point B; M f represents the bearing friction moment; sign() is a sign function.

7. The method of optimizing the position of a paddle fan shaft of an open- rotor engine as set forth in claim 1, wherein, The position optimization method further comprises adjustment of circumferential position: A rotating coordinate system Ox'y'z' is established, and the Oz' axis always coincides with the bearing B' axis; The bearing B' is initially coincided with the bearing B, and when the fan blade rotates along the Ox axis direction, the bearing B' rotates with the fan blade. The load F experienced by bearing B' in the rotating coordinate system Ox'y'z' t (β)', M t (β)' will always remain constant, the load of bearing B can be calculated by first converting the load of bearing B' to the inertial coordinate system Oxyz, and then through the translation of force.

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