A method for reducing the pitch load of aircraft propeller

Abstract

The present application discloses a method for reducing the variable pitch load of an aircraft propeller, and relates to the technical field of propeller balance. The method comprises: obtaining the operating parameters and mass distribution of the aircraft propeller, obtaining the variable pitch torque data table generated by the centrifugal force of the propeller blades through finite element analysis; judging whether the propeller operation is balanced according to the variable pitch torque data table, and obtaining the unbalanced data if it is unbalanced; obtaining the operating environment of the aircraft, determining the counterweight mass of the counterweight block; extracting the unbalanced point in the unbalanced data, and determining the counterweight position of the counterweight block; obtaining the propeller structure, and determining the counterweight shape of the counterweight block in combination with the aerodynamic efficiency; counterweighting the aircraft propeller according to the counterweight mass, counterweight position and counterweight shape, obtaining the propeller parameters after counterweighting, and obtaining the variable pitch load scheme according to the propeller parameter settings. The present application improves the response speed of reducing the variable pitch load of an aircraft propeller.

Description

Technical Field

[0001] The present application relates to the technical field of propeller balancing, and in particular to a method for reducing the pitch load of an aircraft propeller. Background Art

[0002] Propeller variable pitch load mainly refers to the load change caused by the propeller during the pitch change process. A variable pitch propeller is a propeller that can change the blade angle according to the flight speed and altitude during flight. This change is to optimize the efficiency and thrust of the propeller in different flight phases, so as to make full use of the effective power of the engine.

[0003] The variable pitch propellers used in aircraft have multiple loads when adjusting the blade angle, which puts higher requirements on the variable pitch drive system. By counterweighting the blades and optimizing the load on the blades, the power of the variable pitch drive system can be reduced to a large extent, while the variable pitch response speed can be greatly improved. However, how to counterweight the propeller to reduce the burden of the variable pitch load is still a difficult problem that bothers people. The accuracy of the counterweight still has room for improvement, and the corresponding variable pitch response speed also has room for improvement. Summary of the invention

[0004] The object of the present invention is to provide a method for reducing the pitch change load of an aircraft propeller, so as to solve the problems raised in the above background technology.

[0005] In a first aspect, the present application provides a method for reducing the pitch load of an aircraft propeller, which adopts the following technical solution:

[0006] Obtaining the operating parameters and mass distribution of the aircraft propeller, and obtaining a data table of the pitch moment generated by the centrifugal force of the propeller blades through finite element analysis based on the operating parameters and the mass distribution;

[0007] Determine whether the propeller is running in balance according to the pitch torque data table. If it is unbalanced, obtain the unbalance data.

[0008] Obtain the operating environment of the aircraft, and determine the weight of the ballast block according to the operating environment and imbalance data;

[0009] Extract the unbalanced points in the unbalanced data, and determine the counterweight position of the counterweight block according to the unbalanced points and the mass distribution;

[0010] Obtain the propeller structure and determine the weight shape of the counterweight block in combination with aerodynamic efficiency;

[0011] The aircraft propeller is counterweighted according to the counterweight mass, counterweight position and counterweight shape to obtain the propeller parameters after counterweighting, and the variable pitch load scheme is obtained according to the propeller parameter settings.

[0012] Preferably, the step of obtaining the operating parameters and mass distribution of the aircraft propeller, and obtaining the pitch moment data table generated by the centrifugal force of the propeller blades through finite element analysis according to the operating parameters and the mass distribution, is specifically:

[0013] Obtain the mass distribution of the aircraft propeller, mesh the blades using finite element software to obtain mesh regions, and then assign mass attributes to the mesh regions of the blades;

[0014] The operating parameters include the rotation speed and rotation radius of the propeller, and boundary conditions are set in the finite element software according to the operating parameters;

[0015] The variable pitch moment generated by the centrifugal force of the blades under different blade angles is calculated according to the boundary conditions to form a variable pitch moment data table.

[0016] Preferably, the step of judging whether the propeller is in balance according to the variable pitch torque data table, and obtaining the unbalance data if unbalanced, is specifically:

[0017] Obtain the pitch moment of different grid areas at the same blade angle, calculate the difference between the maximum pitch moment and the minimum pitch moment and record it as the blade moment difference;

[0018] A blade moment difference threshold is set, and if the blade moment difference reaches the blade moment difference threshold, a first balance difference is calculated;

[0019] Obtain the variable pitch moment of the grid area with different blade angles in the same grid area, generate the variable pitch moment curve, and obtain the fluctuation angle of the variable pitch moment curve;

[0020] A fluctuation angle threshold is set, and if the fluctuation angle reaches the fluctuation angle threshold, a second balance difference is calculated;

[0021] The first balance difference and the second balance difference are superimposed to obtain a total balance difference, and a balance difference range is set. If the total balance difference is within the balance difference range, it is determined that the propeller is in balance.

[0022] If the total balance difference is not within the balance difference range, it is determined that the propeller is unbalanced and the unbalance data is obtained.

[0023] Preferably, if the total balance difference is not within the balance difference range, the step of determining that the propeller is unbalanced and obtaining the unbalance data is specifically:

[0024] Set the fluctuation angle range of the unbalanced point, obtain the grid area of ​​the fluctuation angle in the fluctuation angle range according to the variable pitch moment curve and record it as the initial unbalanced point;

[0025] Obtain the distribution diagram of the initial unbalanced points, and according to the moment offset principle, screen and remove the unbalanced points that offset each other to obtain the unbalanced points to be selected;

[0026] Obtain the distribution center of the unbalanced point to be selected, and use the distribution center as the determined unbalanced point;

[0027] The vertical distance between the unbalanced point and the propeller axis is obtained, a distance-degree curve of the vertical distance and the severity of the unbalance is preset, and the corresponding severity of the unbalance is obtained according to the distance-degree curve.

[0028] Preferably, the step of obtaining the operating environment of the aircraft and determining the counterweight mass of the counterweight block according to the operating environment and the imbalance data is specifically:

[0029] Acquire the operating environment of the aircraft, where the operating environment includes a humidity value AS and air quality;

[0030] Set the degree-mass curve of the severity of imbalance and the weight mass of the counterweight block, find the corresponding counterweight mass according to the degree-mass curve and record it as the primary mass value AC;

[0031] Acquire material information of the counterweight block, wherein the material information includes a moisture absorption strength value AX and a wear resistance value AM;

[0032] Extract the corrosion degree value AF of air quality, according to the weight mass correlation function The weight mass value AZ of the counterweight block is calculated, where , is the scaling factor and is greater than 0.

[0033] Preferably, the step of extracting the unbalanced point from the unbalanced data and determining the counterweight position of the counterweight block according to the unbalanced point and the mass distribution is specifically as follows:

[0034] Obtain a root area of ​​the propeller root, divide the root area, and obtain multiple initial installation points;

[0035] The distance between the initial installation point and the determined unbalanced point is calculated and recorded as the balance distance, the balance distance range is set, and the initial installation points whose balance distances are within the balance distance range are selected as candidate installation points;

[0036] Obtain the mass distribution after the counterweight is installed at the selected installation point, and determine the mass distribution uniformity value BJ based on the mass distribution;

[0037] The aerodynamic performance impact value BQ after the counterweight is installed at the selected installation point is obtained according to the aerodynamic performance calculation;

[0038] Get the vibration frequency value BZ after the counterweight is installed at the selected installation point, and use the counterweight position correlation function Calculate the optimal weight value BY, where , , is the scale factor and is greater than 0;

[0039] Select the candidate installation point with the largest counterweight preferred value BY as the counterweight position of the counterweight block.

[0040] Preferably, the step of calculating the aerodynamic performance influence value BQ after the counterweight is installed at the selected installation point according to the aerodynamic performance is specifically as follows:

[0041] Get the distance value CZ between the installation point to be selected and the propeller rotation axis;

[0042] Obtain the installation complexity value CF and the maintenance difficulty value CN of the counterweight block at the selected installation point;

[0043] Obtain the influence value CY on the blade angle area after the counterweight block is installed at the candidate installation point;

[0044] According to the aerodynamic performance correlation function The aerodynamic performance impact value BQ is calculated, where , , , is the scaling factor and is greater than 0.

[0045] Preferably, the step of obtaining the propeller structure and determining the counterweight shape of the counterweight block in combination with the aerodynamic efficiency is specifically as follows:

[0046] Obtain all preset shapes of the counterweight block, and obtain the air resistance value DZ of the preset shape according to the rotation speed;

[0047] Obtain the contact area between the preset shape and the air, and obtain the air impact value DK according to the contact area;

[0048] Obtaining a stability value DW of the preset shape according to the structural strength of the preset shape;

[0049] Correlation function according to the weight shape The shape optimization value DX is calculated, where , , is the scale factor and is greater than 0;

[0050] A preset shape with the largest shape optimization value is selected as the counterweight shape of the counterweight block.

[0051] Preferably, the step of obtaining the stability value DW of the preset shape according to the structural strength of the preset shape is specifically:

[0052] The center of gravity of the counterweight block is obtained according to the preset shape, and the distance value EL between the center of gravity and the rotation center of the propeller is obtained;

[0053] The centrifugal force value EX borne by the counterweight is obtained according to the rotation speed;

[0054] According to the preset shape and the centrifugal force value EX, the stress distribution of the counterweight block is obtained, and the stress distribution uniformity value EJ is obtained according to the stress distribution;

[0055] According to the stable correlation function The stable value DW is calculated, where , , is the scaling factor and is greater than 0.

[0056] In summary, the present application includes at least one of the following beneficial technical effects:

[0057] 1. According to the mass distribution of aircraft propellers, the pitch moment data table generated by the centrifugal force of the blades is obtained through finite element analysis. The imbalance data of the propeller is determined according to the change of the pitch moment. Then the mass, position and shape of the counterweight are determined according to the imbalance data. Finally, the counterweight is installed and the pitch load scheme is reset, which reduces the burden of the aircraft propeller pitch load and improves the response speed of reducing the aircraft propeller pitch load.

[0058] 2. The primary mass value is obtained according to the propeller imbalance degree in the imbalance data, and then the counterweight mass of the counterweight block is obtained comprehensively according to the actual operating humidity and air quality of the aircraft, combined with the moisture absorption strength and wear resistance of the counterweight material. Balancing in combination with the actual flight conditions of the aircraft can better match the flight of the aircraft, improve the matching degree between the counterweight block and the aircraft, reduce the impact of the navigation environment on the aircraft, and improve the adaptability of reducing the pitch load of the aircraft propeller.

[0059] 3. Obtain multiple initial installation points based on the root area of ​​the propeller, and obtain the candidate installation points after preliminary screening based on the distance between the initial installation point and the imbalance point. Evaluate the preferred values ​​of different candidate installation points based on the mass distribution after the counterweight is installed at the candidate installation point, the impact on aerodynamic performance and the vibration conditions, and finally determine the counterweight position of the counterweight. The impact on aerodynamic performance not only considers the distance between the candidate installation point and the propeller rotation axis and the impact on the blade angle area, but also considers the complexity of installation and difficulty of maintenance of the counterweight. Select a more suitable installation point to minimize the negative impact of the counterweight on the propeller, while maximizing the role of the counterweight, thereby improving the comprehensiveness of reducing the pitch load of the aircraft propeller. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1It is a schematic diagram of specific steps of an embodiment of a method for reducing the pitch load of an aircraft propeller of the present invention. DETAILED DESCRIPTION

[0061] Below is a combination of the embodiments and Figure 1 The present invention is further described in detail, but the embodiments of the present invention are not limited thereto.

[0062] The present invention discloses a method for reducing the pitch load of an aircraft propeller, which specifically comprises the following steps:

[0063] Step S1, obtaining the operating parameters and mass distribution of the aircraft propeller, and obtaining a data table of the pitch torque generated by the centrifugal force of the propeller blades through finite element analysis based on the operating parameters and the mass distribution.

[0064] Step S2, judging whether the propeller is running in balance according to the pitch torque data table, and obtaining unbalance data if it is unbalanced.

[0065] Step S3, obtaining the operating environment of the aircraft, and determining the counterweight mass of the counterweight block according to the operating environment and the imbalance data.

[0066] Step S4, extracting the unbalanced point in the unbalanced data, and determining the counterweight position of the counterweight block according to the unbalanced point and the mass distribution.

[0067] Step S5, obtaining the propeller structure, and determining the counterweight shape of the counterweight block in combination with the aerodynamic efficiency.

[0068] Step S6, counterweighting the aircraft propeller according to the counterweight mass, counterweight position and counterweight shape, obtaining the propeller parameters after counterweighting, and obtaining the variable pitch load scheme according to the propeller parameter settings.

[0069] In actual use, during the flight of an aircraft, the propeller variable pitch load mainly changes the air resistance and thrust of the propeller blades by adjusting the pitch of the propeller to meet the needs of different flight stages. The pitch of the propeller refers to the angle between the propeller blades and the rotating plane. By changing this angle, the thrust characteristics and efficiency of the propeller can be adjusted. When the propeller is unbalanced and unstable, the variable pitch load needs to bear a greater adjustment task, which will not only increase the burden of the variable pitch load, but also slow down the response speed of the variable pitch load, thereby affecting the flight of the aircraft. Therefore, by counterweighting the propeller, the adjustment burden of the variable pitch load can be effectively reduced, and the effect of rapid response of the variable pitch load can be achieved. For example, before counterweighting, the propeller blades have uneven mass distribution, resulting in more inconsistent forces on the propeller during flight. At this time, it is difficult for the variable pitch load to adjust the forces on the blades to be consistent, and the calculation is difficult, so it takes more time. After the weight is counterweighted, the propeller is in a balanced state during operation. At this time, the variable pitch load adjustment no longer needs to consider the balance problem, which simplifies the calculation and achieves a faster response. According to the propeller parameters after the weight is counterweighted, a new variable pitch load scheme is set according to the actual flight requirements.

[0070] The steps of obtaining the operating parameters and mass distribution of the aircraft propeller, and obtaining the pitch moment data table generated by the centrifugal force of the propeller blades through finite element analysis according to the operating parameters and the mass distribution, are specifically as follows:

[0071] Step S11, obtaining the mass distribution of the aircraft propeller, dividing the blade into grids using finite element software to obtain grid areas, and then assigning mass attributes to the grid areas of the blades.

[0072] Step S12, the operating parameters include the rotation speed and rotation radius of the propeller, and boundary conditions are set in the finite element software according to the operating parameters.

[0073] Step S13, calculating the pitch moment generated by the centrifugal force of the blades under different blade angles according to the boundary conditions, and forming a pitch moment data table.

[0074] In practical applications, finite element analysis uses mathematical approximation methods to simulate real physical systems. By using simple and interacting elements, a finite number of unknown quantities can be used to approximate a real system with infinite unknown quantities. Therefore, the finite element software can well simulate the situation when the propeller is running, which can reduce the number of tests and obtain data more quickly and conveniently. When the blade angle changes, the pitch torque will also change, and the change in pitch torque can reflect the balance of the propeller and provide favorable data support for the counterweight. The pitch torque usually refers to the change in torque generated by the propeller when the blade angle changes, and the centrifugal force is crucial in the change in torque. The centrifugal force is the force generated by the inertia of the rotating body (such as the propeller blade) during the rotation process. Its magnitude is proportional to the mass of the rotating body, the radius of rotation and the square of the angular velocity. The partial force analysis is as follows: The torque M1 generated by the centrifugal force of the blade rotation causes the blade angle to move in the direction of decreasing. The torque M2 generated by the aerodynamic force of the blade causes the blade angle to move in the direction of increasing. The friction resistance torque M3 that needs to be overcome when the blade rotates along the blade axis is relatively small and is not considered here. The positive and negative torques are defined as follows: the torque that increases the blade angle φ is positive, and the torque that decreases it is negative. In order to minimize the load requirement of the variable pitch drive system, M2-M1=0 is required under the design state. In order to bear a smaller load, the torque balance is required to make the propeller balanced.

[0075] The steps to determine whether the propeller is balanced according to the variable pitch torque data table and obtain the unbalanced data if it is unbalanced are as follows:

[0076] Step S21, obtaining the pitch change torque of different grid areas at the same blade angle, calculating the difference between the maximum pitch change torque and the minimum pitch change torque and recording it as the blade torque difference.

[0077] Step S22, setting a blade moment difference threshold, if the blade moment difference reaches the blade moment difference threshold, then calculating and obtaining a first balance difference.

[0078] All blade moment differences that reach the blade moment difference threshold are counted, and the differences of these blade moments are calculated as the first balance difference.

[0079] Step S23, obtaining the variable pitch torque of the grid areas with different blade angles in the same grid area, generating a variable pitch torque curve, and obtaining the fluctuation angle of the variable pitch torque curve.

[0080] Step S24, setting a fluctuation angle threshold, if the fluctuation angle reaches the fluctuation angle threshold, then calculating and obtaining a second balance difference.

[0081] All fluctuation angles reaching the fluctuation angle threshold are counted, and the average value of these fluctuation angles is calculated as the second balance difference.

[0082] Step S25, superimposing the first balance difference and the second balance difference to obtain a total balance difference, setting a balance difference range, and if the total balance difference is within the balance difference range, determining that the propeller is operating in balance.

[0083] Step S26: If the total balance difference is not within the balance difference range, it is determined that the propeller is unbalanced and unbalance data is obtained.

[0084] In actual use, the counterweight mainly affects the mass distribution and balance state of the propeller. By adjusting the static balance and dynamic balance of the propeller, it affects its stability and force conditions during operation. Therefore, it is necessary to first determine whether the propeller is in an unbalanced state. If the propeller is in a balanced state, no counterweight is required. If the propeller is unbalanced, it is necessary to obtain a counterweight solution based on the actual state of the propeller imbalance. When the propeller is unbalanced, the resistance torque of different blades during rotation will change. Not only are the pitch torques of different blades different, but the pitch torques of different parts of the blades will also fluctuate. Based on the changes in the pitch torque, it is possible to determine whether the propeller is unbalanced.

[0085] If the total balance difference is not within the balance difference range, the steps of determining that the propeller is unbalanced and obtaining the unbalance data are as follows:

[0086] Step S261, setting the fluctuation angle range of the unbalanced point, obtaining the grid area of ​​the fluctuation angle in the fluctuation angle range according to the variable pitch torque curve and recording it as the initial unbalanced point.

[0087] Step S262, obtaining a distribution diagram of initial unbalanced points, and screening and removing unbalanced points that cancel each other out according to the moment cancellation principle to obtain unbalanced points to be selected.

[0088] Step S263, obtaining the distribution center of the unbalanced point to be selected, and taking the distribution center as the determined unbalanced point.

[0089] Step S264, obtaining and determining the vertical distance between the imbalance point and the propeller axis, presetting a distance-degree curve of the vertical distance and the severity of imbalance, and finding the corresponding severity of imbalance according to the distance-degree curve.

[0090] In actual use, when the propeller is unbalanced, the resistance torque of different blades during rotation will change, resulting in fluctuations in the pitch torque. This fluctuation usually reaches a peak at the blade position where the unbalance point is located, and the approximate position of the unbalance point can be preliminarily determined. If multiple unbalance points are distributed at different positions of the propeller, and the unbalance torques generated by each offset or partially offset each other, the overall degree of imbalance will be relatively low. The position of the unbalance point will also change, and will be more concentrated in the position where the unbalance point is distributed more. At the same time, if the unbalance point is close to the axis and the mass deviation is large, it will have a more direct impact on the rotational stability and overall performance of the propeller, that is, the degree of imbalance of the propeller will be more serious. Obtaining the position of the unbalance point and the severity of the imbalance is conducive to the accurate setting of the subsequent counterweight scheme.

[0091] The steps of obtaining the operating environment of the aircraft and determining the counterweight mass of the counterweight block according to the operating environment and the imbalance data are specifically as follows:

[0092] Step S31, obtaining the operating environment of the aircraft, the operating environment including the humidity value AS and the air quality.

[0093] Step S32, setting a degree-mass curve of the severity of the imbalance and the counterweight mass of the counterweight block, and finding the corresponding counterweight mass according to the degree-mass curve and recording it as the primary mass value AC.

[0094] Step S33, obtaining material information of the counterweight block, the material information including a moisture absorption strength value AX and a wear resistance value AM.

[0095] Step S34, extracting the corrosion degree value AF of the air quality, according to the weight mass correlation function The weight mass value AZ of the counterweight block is calculated, where , is the scaling factor and is greater than 0.

[0096] In actual use, some counterweight materials are hygroscopic. They will absorb moisture in a high humidity environment for a long time, causing the mass to increase, thereby changing the mass of the counterweight. Air quality, such as dust and pollutants, will cause wear or corrosion on the surface of the counterweight, and long-term accumulation will also affect the mass of the counterweight. The more severe the imbalance, the greater the difference in mass distribution, so a counterweight with a larger mass is needed for counterweighting. In order to ensure the accuracy of the counterweight, the actual flight conditions of the aircraft need to be considered. For example, if the aircraft has been flying in high humidity, the mass will increase during flight due to moisture absorption. If the mass of the counterweight required is 20 grams, it actually becomes 21 grams during flight due to hygroscopicity, then only 19 grams of counterweight is needed for counterweighting. Because when the aircraft has been running for a period of time, the mass of the counterweight will increase. Similarly, if the air quality is relatively poor, it will easily cause the counterweight to wear, and since it is difficult to replace or maintain the counterweight during the operation of the aircraft, it is necessary to consider the mass reduction during the flight and increase the mass of the counterweight in advance. The correlation function only reflects the positive and negative correlation between various parameters, and does not substitute units into the calculation. It only calculates the value based on the correlation.

[0097] The steps of extracting the unbalanced point from the unbalanced data and determining the counterweight position of the counterweight block according to the unbalanced point and the mass distribution are specifically as follows:

[0098] Step S41, obtaining a root area of ​​the propeller root, dividing the root area, and obtaining a plurality of initial installation points.

[0099] Step S42, calculating the distance between the initial installation point and the determined unbalanced point and recording it as the balance distance, setting a balance distance range, and selecting the initial installation points whose balance distances are within the balance distance range as candidate installation points.

[0100] Step S43, obtaining the mass distribution of the counterweight after the installation point to be selected is installed, and determining the mass distribution uniformity value BJ based on the mass distribution.

[0101] Step S44, obtaining the aerodynamic performance impact value BQ after the counterweight is installed at the selected installation point according to the aerodynamic performance calculation.

[0102] Step S45, obtaining the vibration frequency value BZ after the counterweight is installed at the selected installation point, and calculating the vibration frequency value BZ according to the counterweight position correlation function Calculate the optimal weight value BY, where , , is the scaling factor and is greater than 0.

[0103] Step S46, selecting the candidate installation point with the largest counterweight preferred value BY as the counterweight position of the counterweight block.

[0104] In actual use, the installation position is selected at the root of the propeller because the position of the propeller root is relatively fixed and easy to install and maintain. However, the specific position of the counterweight needs to be determined according to the position of the unbalanced point to ensure that the influence of the unbalanced mass can be effectively offset. Generally speaking, the closer to the unbalanced point, the more the imbalance can be eliminated. Therefore, in the selection process of the installation point, the installation point that exceeds the appropriate distance of the unbalanced point is preferentially selected. In addition, the installation of the counterweight will change the flow field distribution around the propeller, thereby affecting its aerodynamic performance. Therefore, when installing the counterweight, it is necessary to consider its influence on aerodynamic parameters such as propeller thrust, lift and efficiency. At the same time, the installation position of the counterweight will also affect the dynamic stability of the propeller. When selecting the position of the counterweight, it is necessary to comprehensively consider its influence on the vibration characteristics of the propeller to ensure flight safety. If the installation position of the counterweight is not good, the counterweight and the propeller cannot fit tightly, and vibration will occur during the operation of the propeller, which will bring flight hazards to the aircraft. Considering the mass distribution, aerodynamic performance and vibration characteristics, a more suitable installation point is selected to minimize the negative impact of the counterweight on the propeller and maximize the effect of the counterweight.

[0105] The steps of calculating the aerodynamic performance influence value BQ after the counterweight is installed at the candidate installation point according to the aerodynamic performance are specifically as follows:

[0106] Step S441, obtaining the distance value CZ between the installation point to be selected and the propeller rotation axis.

[0107] Step S442, obtaining the installation complexity value CF and the maintenance difficulty value CN of the counterweight block at the to-be-selected installation point.

[0108] Step S443, obtaining the influence value CY of the installation of the counterweight block on the blade angle area after the installation point to be selected.

[0109] The blade angle is selected to optimize the propeller's aerodynamic performance, including thrust, lift, drag, and efficiency. Since the circumferential speeds at the root and tip of the propeller are different during rotation, the blade angle usually changes gradually in the radial direction to adapt to different airflow conditions. When the counterweight is installed at the root of the propeller, its position should try not to affect this optimized distribution of the blade angle. If the counterweight causes a significant change in the blade angle, it will reduce the propeller's aerodynamic performance.

[0110] Step S444: according to the aerodynamic performance correlation function The aerodynamic performance impact value BQ is calculated, where , , , is the scaling factor and is greater than 0.

[0111] In actual use, when the counterweight is installed near the root of the propeller and close to the rotation axis, its direct impact on the aerodynamic performance is small. This is because the position is far from the outer edge of the blade and has limited impact on the aerodynamic shape and angle of attack distribution of the blade. When the counterweight is installed at the root of the propeller but far from the rotation axis, its impact on the aerodynamic performance may be more complicated. On the one hand, this position selection may increase the propeller's rotational inertia, affecting the acceleration performance and thrust response speed. On the other hand, if the counterweight is not designed properly or installed properly, it may generate additional drag or lift components, affecting the overall aerodynamic performance. The choice of the counterweight installation position needs to consider the blade angle. The blade angle is the angle between the propeller chord and the propeller rotation plane. It changes with the radius, and its change law is the most important factor affecting the working performance of the propeller. If the installation position of the counterweight is too close to or too far away from a specific blade angle area, it will have an adverse effect on the aerodynamic performance of the propeller, such as increasing drag, reducing efficiency or causing vibration. The impact value is evaluated based on these parameters of the blade angle area after the counterweight is installed. The installation position of the counterweight should be determined according to the specific position of the imbalance point and the change law of the blade angle to ensure that the counterweight can effectively eliminate the imbalance phenomenon and minimize the impact on the propeller's aerodynamic performance. In addition to considering the impact of the counterweight on the propeller operation, it is also necessary to consider the complexity of the installation position of the counterweight and the difficulty of maintenance. If the installation position of the counterweight is more complex and the maintenance difficulty is also greater, on the one hand, more resources will be consumed, and on the other hand, it will also affect the subsequent maintenance of the aircraft, thereby affecting the propeller pitch load.

[0112] The steps of obtaining the propeller structure and determining the weight shape of the weight block in combination with the aerodynamic efficiency are as follows:

[0113] Step S51, obtaining all preset shapes of the counterweight, and obtaining the air resistance value DZ of the preset shape according to the rotation speed.

[0114] Step S52, obtaining the contact area between the preset shape and the air, and obtaining the air impact value DK according to the contact area.

[0115] Step S53, obtaining a stability value DW of the preset shape according to the structural strength of the preset shape.

[0116] Step S54: according to the weight shape correlation function The shape optimization value DX is calculated, where , , is the scaling factor and is greater than 0.

[0117] Step S55, selecting a preset shape with the largest shape optimization value as the counterweight shape of the counterweight block.

[0118] In actual use, the design of the counterweight shape should avoid adverse effects on the aerodynamic performance of the propeller. The ideal counterweight shape should be able to reduce air resistance and avoid additional turbulence or vortices when the propeller rotates, thereby ensuring that the propeller can efficiently generate thrust. The counterweight not only needs to meet aerodynamic requirements, but also needs to have sufficient structural strength and stability to ensure that it will not fall off or be damaged under high-speed rotation and complex flight conditions. At the same time, if the contact area of ​​the counterweight with the air is too large, the counterweight will be affected by the air, thereby affecting the quality of the counterweight. For example, in high-speed propellers, streamlined or flat counterweight shapes such as sheet counterweights are usually selected. This shape can reduce air resistance, allowing airflow to flow smoothly through the counterweight and avoid unnecessary energy loss. However, although sheet counterweights may be aerodynamically superior, in some cases, if their structural strength is not enough to withstand the centrifugal force generated by high-speed rotation, it is necessary to choose a stronger block or other shape of counterweight. These counterweights have more complex internal structures or thicker materials to ensure their stability. Therefore, many aspects need to be considered when choosing the shape of the counterweight.

[0119] The step of obtaining the stability value DW of the preset shape according to the structural strength of the preset shape is specifically as follows:

[0120] Step S541, obtaining the center of gravity position of the counterweight block according to the preset shape, and obtaining the distance value EL between the center of gravity position and the rotation center of the propeller.

[0121] Step S542, obtaining the centrifugal force value EX borne by the counterweight according to the rotation speed.

[0122] Step S543, obtaining the stress distribution of the counterweight block according to the preset shape and the centrifugal force value EX, and obtaining the stress distribution uniformity value EJ according to the stress distribution.

[0123] Step S544, according to the stable correlation function The stable value DW is calculated, where , , is the scaling factor and is greater than 0.

[0124] In actual use, the shape of the counterweight determines the position of its center of gravity. The closer the center of gravity is to the center of rotation, the smaller the torque generated by the centrifugal force on the counterweight, and the more stably the counterweight can withstand the centrifugal force. On the contrary, if the center of gravity deviates far from the center of rotation, the centrifugal force will generate a large torque, causing the counterweight to loosen or be damaged. The shape of the counterweight will also affect the distribution of its internal stress. Under high-speed rotation, the centrifugal force will generate stress inside the counterweight. If the shape of the counterweight is not designed reasonably, it will cause stress concentration, causing certain areas to be damaged due to excessive stress. The propeller rotation speed will change the centrifugal force value borne by the counterweight. The greater the rotation speed, the greater the centrifugal force borne by the counterweight, and it needs to have a greater ability to withstand centrifugal force. Therefore, it is more necessary to choose a counterweight shape that can withstand centrifugal force. Choosing a more stable counterweight shape is conducive to reducing the impact of the counterweight on the operation of the aircraft propeller.

[0125] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for reducing the pitch load of an aircraft propeller, characterized in that: The following steps are involved: Obtaining the operating parameters and mass distribution of the aircraft propeller, and obtaining a data table of the pitch moment generated by the centrifugal force of the propeller blades through finite element analysis based on the operating parameters and the mass distribution; Determine whether the propeller is running in balance according to the pitch torque data table. If it is unbalanced, obtain the unbalance data. Obtain the operating environment of the aircraft, and determine the weight of the ballast block according to the operating environment and imbalance data; Extract the unbalanced points in the unbalanced data, and determine the counterweight position of the counterweight block according to the unbalanced points and the mass distribution; Obtain the propeller structure and determine the weight shape of the counterweight block in combination with aerodynamic efficiency; The aircraft propeller is counterweighted according to the counterweight mass, counterweight position and counterweight shape to obtain the propeller parameters after counterweighting, and the variable pitch load scheme is obtained according to the propeller parameter settings.

2. A method for reducing aircraft propeller pitch load according to claim 1, characterized in that: The steps of obtaining the operating parameters and mass distribution of the aircraft propeller, and obtaining the pitch moment data table generated by the centrifugal force of the propeller blades through finite element analysis according to the operating parameters and the mass distribution, are specifically: Obtain the mass distribution of the aircraft propeller, mesh the blades using finite element software to obtain mesh regions, and then assign mass attributes to the mesh regions of the blades; The operating parameters include the rotation speed and rotation radius of the propeller, and boundary conditions are set in the finite element software according to the operating parameters; The variable pitch moment generated by the centrifugal force of the blades under different blade angles is calculated according to the boundary conditions to form a variable pitch moment data table.

3. A method for reducing aircraft propeller pitch load according to claim 2, characterized in that: The step of judging whether the propeller is running in balance according to the variable pitch torque data table, and obtaining the unbalance data if it is unbalanced, is specifically as follows: Obtain the pitch moment of different grid areas at the same blade angle, calculate the difference between the maximum pitch moment and the minimum pitch moment and record it as the blade moment difference; A blade moment difference threshold is set, and if the blade moment difference reaches the blade moment difference threshold, a first balance difference is calculated; Obtain the variable pitch moment of the grid area with different blade angles in the same grid area, generate the variable pitch moment curve, and obtain the fluctuation angle of the variable pitch moment curve; A fluctuation angle threshold is set, and if the fluctuation angle reaches the fluctuation angle threshold, a second balance difference is calculated; The first balance difference and the second balance difference are superimposed to obtain a total balance difference, and a balance difference range is set. If the total balance difference is within the balance difference range, it is determined that the propeller is in balance. If the total balance difference is not within the balance difference range, it is determined that the propeller is unbalanced and the unbalance data is obtained.

4. A method for reducing aircraft propeller pitch load according to claim 3, characterized in that: If the total balance difference is not within the balance difference range, the step of determining that the propeller is unbalanced and obtaining the unbalance data is specifically as follows: Set the fluctuation angle range of the unbalanced point, obtain the grid area of ​​the fluctuation angle in the fluctuation angle range according to the variable pitch moment curve and record it as the initial unbalanced point; Obtain the distribution diagram of the initial unbalanced points, and according to the moment offset principle, screen and remove the unbalanced points that offset each other to obtain the unbalanced points to be selected; Obtain the distribution center of the unbalanced point to be selected, and use the distribution center as the determined unbalanced point; The vertical distance between the unbalanced point and the propeller axis is obtained, a distance-degree curve of the vertical distance and the severity of the unbalance is preset, and the corresponding severity of the unbalance is obtained according to the distance-degree curve.

5. A method for reducing aircraft propeller pitch load according to claim 4, characterized in that: The step of obtaining the operating environment of the aircraft and determining the counterweight mass of the counterweight block according to the operating environment and the imbalance data is specifically as follows: Acquire the operating environment of the aircraft, where the operating environment includes a humidity value AS and air quality; Set the degree-mass curve of the severity of imbalance and the weight mass of the counterweight block, find the corresponding counterweight mass according to the degree-mass curve and record it as the primary mass value AC; Acquire material information of the counterweight block, wherein the material information includes a moisture absorption strength value AX and a wear resistance value AM; Extract the corrosion degree value AF of air quality, according to the weight mass correlation function The weight mass value AZ of the counterweight block is calculated, where , is the scaling factor and is greater than 0.

6. A method for reducing aircraft propeller pitch load according to claim 5, characterized in that: The step of extracting the unbalanced point from the unbalanced data and determining the counterweight position of the counterweight block according to the unbalanced point and the mass distribution is specifically as follows: Obtain a root area of ​​the propeller root, divide the root area, and obtain multiple initial installation points; The distance between the initial installation point and the determined unbalanced point is calculated and recorded as the balance distance, the balance distance range is set, and the initial installation points whose balance distances are within the balance distance range are selected as candidate installation points; Obtain the mass distribution after the counterweight is installed at the selected installation point, and determine the mass distribution uniformity value BJ based on the mass distribution; The aerodynamic performance impact value BQ after the counterweight is installed at the selected installation point is obtained according to the aerodynamic performance calculation; Get the vibration frequency value BZ after the counterweight is installed at the selected installation point, and use the counterweight position correlation function Calculate the optimal weight value BY, where , , is the scale factor and is greater than 0; Select the candidate installation point with the largest counterweight preferred value BY as the counterweight position of the counterweight block.

7. A method for reducing aircraft propeller pitch change load according to claim 6, characterized in that: The step of calculating the aerodynamic performance impact value BQ after the counterweight is installed at the selected installation point according to the aerodynamic performance is specifically as follows: Get the distance value CZ between the installation point to be selected and the propeller rotation axis; Obtain the installation complexity value CF and the maintenance difficulty value CN of the counterweight block at the selected installation point; Obtain the influence value CY on the blade angle area after the counterweight block is installed at the candidate installation point; According to the aerodynamic performance correlation function The aerodynamic performance impact value BQ is calculated, where , , , is the scaling factor and is greater than 0.

8. A method for reducing aircraft propeller pitch change load according to claim 7, characterized in that: The step of obtaining the propeller structure and determining the weight shape of the weight block in combination with the aerodynamic efficiency is specifically as follows: Obtain all preset shapes of the counterweight block, and obtain the air resistance value DZ of the preset shape according to the rotation speed; Obtain the contact area between the preset shape and the air, and obtain the air impact value DK according to the contact area; Obtaining a stability value DW of the preset shape according to the structural strength of the preset shape; Correlation function according to the weight shape The shape optimization value DX is calculated, where , , is the scale factor and is greater than 0; A preset shape with the largest shape optimization value is selected as the counterweight shape of the counterweight block.

9. A method for reducing aircraft propeller pitch change load according to claim 8, characterized in that: The step of obtaining the stability value DW of the preset shape according to the structural strength of the preset shape is specifically as follows: The center of gravity of the counterweight block is obtained according to the preset shape, and the distance value EL between the center of gravity and the rotation center of the propeller is obtained; The centrifugal force value EX borne by the counterweight is obtained according to the rotation speed; According to the preset shape and the centrifugal force value EX, the stress distribution of the counterweight block is obtained, and the stress distribution uniformity value EJ is obtained according to the stress distribution; According to the stable correlation function The stable value DW is calculated, where , , is the scaling factor and is greater than 0.

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