Propeller performance calculation method, device and equipment in negative advance ratio state and medium

Abstract

This application discloses a method, apparatus, device, and medium for calculating the performance of a propeller under negative advance conditions. The method includes: acquiring the incoming flow velocity, target values ​​of the axial induced velocity coefficient at the propeller disk, and target values ​​of the circumferential induced velocity coefficient at the propeller disk, wherein the target propeller is in a negative advance state; determining the target value of the actual airflow velocity angle of the target propeller based on the incoming flow velocity, the target values ​​of the axial induced velocity coefficient at the propeller disk, and the target values ​​of the circumferential induced velocity coefficient at the propeller disk; determining the blade element parameters of the target propeller based on the target value of the actual airflow velocity angle and the drag angle of the blade element of the target propeller; and determining the values ​​of the performance parameters of the target propeller based on the blade element parameters, the total number of blades of the target propeller, and the propeller radius. This application embodiment can accurately calculate the propeller performance under negative advance conditions based on target values ​​applicable to negative advance conditions.

Description

Technical Field

[0001] This application relates to the field of propeller technology, and in particular to a method, apparatus, equipment and medium for calculating the performance of a propeller under negative advance conditions. Background Technology

[0002] When the direction of the incoming airflow is opposite to the direction of the slipstream of the propeller in the absence of airflow, the propeller is in a negative advance state. At this time, the traditional propeller performance theory based on the normal propulsion state fails, and the traditional momentum theory, blade element theory and other classical theories cannot effectively calculate the propeller performance in the negative advance state. Summary of the Invention

[0003] This application provides a method, apparatus, device, and medium for calculating the performance of a propeller under negative advance conditions, which can accurately calculate the propeller performance under negative advance conditions.

[0004] In a first aspect, embodiments of this application provide a method for calculating the performance of a propeller under negative advance conditions, the method comprising: The target values ​​of the incoming flow velocity, the axial induced velocity coefficient at the disk of the target propeller, and the circumferential induced velocity coefficient at the disk are obtained. The target propeller is in a negative advance state, which means that the incoming flow direction of the airflow is opposite to the slip flow direction of the target propeller when there is no airflow. Based on the incoming flow velocity, the target value of the axial induced velocity coefficient at the propeller disk, and the target value of the circumferential induced velocity coefficient at the propeller disk, the target value of the actual airflow velocity angle of the target propeller is determined. The actual airflow velocity angle is used to characterize the angle between the direction of the actual airflow velocity at the propeller disk of the target propeller and the plane of rotation of the target propeller. Based on the target value of the actual airflow velocity angle and the drag angle of the blade element of the target propeller, the blade element parameters of the target propeller are determined, and the blade element parameters include at least one of blade element thrust, blade element circumferential force and blade element torque. Based on the blade element parameters, the total number of blades of the target propeller, and the propeller radius, the values ​​of the performance parameters of the target propeller are determined. The performance parameters include at least one of the propeller thrust, circumferential force, and torque.

[0005] The above technical solution enables accurate calculation of propeller performance under negative advance conditions based on target values ​​applicable to negative advance conditions. First, by obtaining the target values ​​for the incoming flow velocity, the axial induced velocity coefficient at the propeller disk, and the circumferential induced velocity coefficient at the propeller disk under negative advance conditions, the target value for the actual airflow velocity angle is determined accordingly. Then, based on the target value for the actual airflow velocity angle and the blade element's drag angle, blade element parameters (at least one of blade element thrust, blade element torque, and blade element circumferential force) are determined. Based on the relevant parameters under negative advance conditions, calculations are sequentially derived, effectively determining the blade element parameters of the target propeller under negative advance conditions. Finally, based on the blade element parameters, the total number of blades, and the propeller radius, the values ​​of performance parameters are determined, enabling accurate calculation of the target propeller's thrust, circumferential force, and torque, solving the problem that traditional theories cannot calculate propeller performance under negative advance conditions.

[0006] In some embodiments, obtaining the target values ​​of the axial induced velocity coefficient at the propeller disk and the target values ​​of the circumferential induced velocity coefficient at the propeller disk includes: Based on the first initial value, the second initial value, and multiple mapping relationships, iterative calculations are performed until the difference between the output value of the current iteration and the output value of the previous iteration satisfies the target condition. Then, the output value of the current iteration is determined as the target value of the axial induced velocity coefficient at the propeller disk and the target value of the circumferential induced velocity coefficient at the propeller disk. The multiple mapping relationships include angle mapping relationship, blade element thrust mapping relationship, first velocity coefficient mapping relationship, blade element torque mapping relationship, and second velocity coefficient mapping relationship. The angle mapping relationship is used to characterize the relationship between the axial induced velocity coefficient at the propeller disk, the circumferential induced velocity coefficient at the propeller disk, the incoming flow velocity, and the actual airflow velocity angle. The blade element thrust mapping relationship is used to characterize the relationship between the actual airflow velocity angle, the axial induced velocity coefficient at the propeller disk, the incoming flow velocity, and the blade element thrust. The first velocity coefficient mapping relationship is used to characterize the relationship between the blade element thrust and the axial induced velocity coefficient at the propeller disk. The blade element torque mapping relationship is used to characterize the relationship between the actual airflow velocity angle, the axial induced velocity coefficient at the propeller disk, the incoming flow velocity, and the blade element torque. The second velocity coefficient mapping relationship is used to characterize the relationship between the blade element torque and the axial induced velocity coefficient at the propeller disk and the circumferential induced velocity coefficient at the propeller disk.

[0007] In the above technical solution, the target values ​​of the axial induced velocity coefficient and the circumferential induced velocity coefficient at the propeller disk can be determined through iterative calculation. First, based on the first initial value and the second initial value, iterative calculation is carried out in combination with the angle mapping relationship, the blade element thrust mapping relationship, the first velocity coefficient mapping relationship, the blade element torque mapping relationship, and the second velocity coefficient mapping relationship. The iteration is terminated by judging whether the difference between the current iteration output value and the previous iteration output value meets the target condition. The current iteration output value is determined as the target value of the axial induced velocity coefficient and the target value of the circumferential induced velocity coefficient at the propeller disk. The above mapping relationships can accurately characterize the correlation between the corresponding parameters, so that the iterative calculation process for determining the axial induced velocity coefficient and the circumferential induced velocity coefficient at the propeller disk conforms to the inherent correlation logic of parameters under negative advance state, thereby improving the accuracy and reliability of the target values.

[0008] In some embodiments, the iterative calculation based on the first initial value, the second initial value, and multiple mapping relationships includes: For the first iteration calculation, the first initial value is used as the initial value of the axial induced velocity coefficient at the propeller disk in the angle mapping relationship, and the second initial value is used as the initial value of the circumferential induced velocity coefficient at the propeller disk in the angle mapping relationship. Based on the first set of mapping relationships, the input value for the next iteration calculation of the axial induced velocity coefficient at the propeller disk is obtained; the first set of mapping relationships includes the angle mapping relationship, the blade element thrust mapping relationship, and the first velocity coefficient mapping relationship; The first initial value is used as the initial value of the axial induced velocity coefficient at the propeller disk in the angle mapping relationship, and the second initial value is used as the initial value of the circumferential induced velocity coefficient at the propeller disk in the angle mapping relationship. According to the second set of mapping relationships, the input value for the next iteration calculation of the circumferential induced velocity coefficient at the propeller disk is obtained. The second set of mapping relationships includes the angle mapping relationship, the blade element torque mapping relationship, and the second velocity coefficient mapping relationship. For other iterations, the iterative calculation is performed based on the input values ​​of the axial induced velocity coefficient at the propeller disk for the next iteration, the input values ​​of the circumferential induced velocity coefficient at the propeller disk for the next iteration, and multiple mapping relationships.

[0009] The above technical solution clarifies the specific process of iterative calculation, achieving synchronous and independent updates of the axial induced velocity coefficient and the circumferential induced velocity coefficient at the propeller disk. In the first iteration, the first and second initial values ​​are used as the initial values ​​for the axial and circumferential induced velocity coefficients at the propeller disk, respectively. The first set of mapping relationships (angle mapping relationship, blade element thrust mapping relationship, and first velocity coefficient mapping relationship) is used to obtain the input value for the next iteration of the axial induced velocity coefficient at the propeller disk. Simultaneously, the second set of mapping relationships (angle mapping relationship, blade element torque mapping relationship, and second velocity coefficient mapping relationship) is used to obtain the input value for the next iteration of the circumferential induced velocity coefficient at the propeller disk. In subsequent iterations, the iteration continues based on these two new input values. This process allows the axial and circumferential induced velocity coefficients at the propeller disk to collaboratively approximate the target value through their respective related physical mapping relationships (thrust-related and torque-related), ensuring the convergence accuracy and computational efficiency of the target value.

[0010] In some embodiments, the step of using the first initial value as the initial value of the axial induced velocity coefficient at the propeller disk in the angle mapping relationship, and using the second initial value as the initial value of the circumferential induced velocity coefficient at the propeller disk in the angle mapping relationship, and obtaining the input value for the next iteration calculation of the axial induced velocity coefficient at the propeller disk according to the first set of mapping relationships, includes: The first calculated value of the actual airflow velocity angle is obtained based on the first initial value, the second initial value, and the angle mapping relationship; Substituting the first initial value and the first calculated value into the leaf element thrust mapping relationship, a second calculated value of the leaf element thrust is obtained; Substituting the first initial value and the second calculated value into the first velocity coefficient mapping relationship, the first iterative output value of the axial induced velocity coefficient at the propeller disk is obtained. The first iterative output value of the axial induced velocity coefficient at the propeller disk is the input value for the next iterative calculation of the axial induced velocity coefficient at the propeller disk.

[0011] In the above technical solution, the specific generation process of the input value of the axial induced velocity coefficient at the propeller disk in the first iteration calculation is clarified. First, based on the first initial value and the second initial value, the first calculated value of the actual airflow velocity angle is obtained through the angle mapping relationship. Then, the first initial value and the first calculated value of the actual airflow velocity angle are substituted into the blade element thrust mapping relationship to obtain the second calculated value of the blade element thrust. Finally, the first initial value and the second calculated value of the blade element thrust are substituted into the first velocity coefficient mapping relationship to generate the first iteration output value of the axial induced velocity coefficient at the propeller disk, which is the input value for the next iteration calculation. The above solution back-calculates and updates the axial induced velocity coefficient at the propeller disk based on the blade element thrust, ensuring the continuity and rationality of the iterative calculation process.

[0012] The step of using the first initial value as the initial value of the axial induced velocity coefficient at the propeller disk in the angle mapping relationship, and using the second initial value as the initial value of the circumferential induced velocity coefficient at the propeller disk in the angle mapping relationship, and obtaining the input value for the next iteration calculation of the circumferential induced velocity coefficient at the propeller disk according to the second set of mapping relationships, includes: The first calculated value of the actual airflow velocity angle is obtained based on the first initial value, the second initial value, and the angle mapping relationship; Substituting the first initial value and the first calculated value into the blade element torque mapping relationship, a third calculated value of the blade element torque is obtained; Substituting the first initial value and the third calculated value into the second velocity coefficient mapping relationship, the first iteration output value of the circumferential induced velocity coefficient at the propeller disk is obtained. The first iteration output value of the circumferential induced velocity coefficient at the propeller disk is the input value for the next iteration calculation of the circumferential induced velocity coefficient at the propeller disk.

[0013] The above technical solution clarifies the specific generation process of the input value of the circumferential induced velocity coefficient at the propeller disk in the first iteration calculation. First, based on the first initial value and the second initial value, the first calculated value of the actual airflow velocity angle is obtained through the angle mapping relationship. Then, the first initial value and the first calculated value are substituted into the blade element torque mapping relationship to obtain the third calculated value of the blade element torque. Finally, the first initial value and the third calculated value are substituted into the second velocity coefficient mapping relationship to generate the first iteration output value of the circumferential induced velocity coefficient at the propeller disk, which is the input value for the next iteration calculation. The above solution back-calculates and updates the circumferential induced velocity coefficient at the propeller disk based on the blade element torque, ensuring the continuity and rationality of the iterative calculation process.

[0014] In some embodiments, the target condition includes the number of iterations required for the iterative calculation satisfying a threshold; or, The difference between the output value of the axial induced velocity coefficient at the propeller disk in the current iteration and the output value in the previous iteration is less than the difference threshold, and the difference between the output value of the circumferential induced velocity coefficient at the propeller disk in the current iteration and the output value in the previous iteration is less than the difference threshold.

[0015] In the above technical solution, setting the number of iterations to meet a threshold as the target condition effectively controls the overall iterative calculation process and avoids the waste of computational resources caused by unlimited iteration. Setting the difference between the current iteration output value and the previous iteration output value of the axial and circumferential induced velocity coefficients at the propeller disk as a target condition ensures the convergence of the iterations for both velocity coefficients and guarantees that the final target values ​​meet the accuracy requirements. These target conditions ensure the standardization and controllability of the iterative calculation process, ensuring that the target values ​​of the axial and circumferential induced velocity coefficients at the propeller disk can be obtained efficiently and accurately.

[0016] In some embodiments, the first velocity coefficient mapping relationship is determined based on the derived relationship between the axial induced velocity coefficient at the disk of the target propeller and the axial induced velocity coefficient in the slipstream region of the target propeller under the negative advance state, and the derived relationship satisfies the following expression: , Where a is the axial induced velocity coefficient at the propeller disk, and b is the axial induced velocity coefficient of the slipstream region.

[0017] In the above technical solution, firstly, a mathematical relationship is established between the axial induced velocity coefficient at the propeller disk and the axial induced velocity coefficient in the slipstream region under negative advance conditions. This provides a parameter correlation basis for the first velocity coefficient mapping relationship that conforms to the negative advance condition, solving the problem of the failure of traditional theory under negative advance conditions. Secondly, the first velocity coefficient mapping relationship determined based on this derivation relationship can accurately characterize the correlation between blade element thrust and the axial induced velocity coefficient at the propeller disk, thereby ensuring the accuracy and reliability of the target value of the axial induced velocity coefficient at the propeller disk under negative advance conditions.

[0018] Secondly, embodiments of this application provide a performance calculation device for a propeller under negative advance conditions, the device comprising: The data acquisition module acquires the incoming flow velocity, the target value of the axial induced velocity coefficient at the disk of the target propeller, and the target value of the circumferential induced velocity coefficient at the disk. The target propeller is in a negative advance state, which means that the incoming flow direction of the airflow is opposite to the slip flow direction of the target propeller when there is no airflow. The first determining module determines the target value of the actual airflow velocity angle of the target propeller based on the incoming flow velocity, the target value of the axial induced velocity coefficient at the propeller disk, and the target value of the circumferential induced velocity coefficient at the propeller disk. The actual airflow velocity angle is used to characterize the angle between the direction of the actual airflow velocity at the propeller disk of the target propeller and the rotation plane of the target propeller. The second determining module determines the blade element parameters of the target propeller based on the target value of the actual airflow velocity angle and the drag angle of the blade element of the target propeller. The blade element parameters include at least one of blade element thrust, blade element circumferential force, and blade element torque. The third determining module determines the values ​​of the performance parameters of the target propeller based on the blade element parameters, the total number of blades of the target propeller, and the propeller radius. The performance parameters include at least one of the propeller thrust, circumferential force, and torque.

[0019] Thirdly, embodiments of this application provide an electronic device, including a processor and a memory, wherein the memory stores a computer program, and the processor executes the program to implement the method described in embodiments of this application.

[0020] Fourthly, embodiments of this application provide a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the methods described in embodiments of this application.

[0021] Fifthly, the computer program product provided in the embodiments of this application includes a computer program that, when executed by a processor, implements the methods described in the embodiments of this application. Attached Figure Description

[0022] Figure 1 This is a flowchart illustrating a propeller performance calculation method under negative advance conditions disclosed in an embodiment of this application; Figure 2 This is a schematic diagram of the flow field distribution of a propeller disclosed in an embodiment of this application; Figure 3 This is a schematic diagram of a propeller disclosed in an embodiment of this application; Figure 4 This is a flowchart illustrating an iterative calculation method disclosed in an embodiment of this application; Figure 5 This is a flowchart illustrating another iterative calculation method disclosed in an embodiment of this application; Figure 6 This is a schematic diagram of the structure of a performance calculation device for a propeller under negative advance state disclosed in an embodiment of this application. Detailed Implementation

[0023] The technical solutions in this application will now be described with reference to the accompanying drawings.

[0024] To facilitate a clear description of the technical solutions in the embodiments of this application, the terms "first" and "second" are used in the embodiments of this application to distinguish identical or similar items with essentially the same function and effect. For example, "first instruction" and "second instruction" are used to distinguish different user instructions and do not limit their order. Those skilled in the art will understand that the terms "first" and "second" do not limit the quantity or execution order, and the terms "first" and "second" are not necessarily different.

[0025] It should be noted that, in this application, the words "exemplarily" or "for example" are used to indicate examples, illustrations, or explanations. Any embodiment or design described as "exemplarily" or "for example" in this application should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of words such as "exemplarily" or "for example" is intended to present the relevant concepts in a specific manner.

[0026] Furthermore, "at least one" refers to one or more, while "more than one" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can mean: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, and c can mean: a, or b, or c, or a and b, or a and c, or b and c, or a, b, and c, where a, b, and c can be single or multiple.

[0027] Furthermore, the terms "comprising" and "having," and any variations thereof, in the embodiments and drawings of this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or devices.

[0028] As a core propulsion component in aviation, shipbuilding and other fields, the accurate calculation of the propeller's performance parameters is the key to the design and optimization of the equipment's power system. At present, classical performance theories such as momentum theory and blade element theory are generally used to carry out propeller performance calculations. The above theories are all based on the positive pitch condition of normal propulsion of the propeller, and the working condition in which the direction of the incoming airflow is consistent with the direction of the propeller's slip flow without airflow.

[0029] However, when the incoming airflow direction is opposite to the slipstream direction of the propeller in the absence of airflow, the propeller is in a negative advance state. Negative advance states are common in certain special flight phases of aircraft, such as helicopter descent, fixed-wing propeller braking, or headwind hovering. In this situation, the velocity distribution, pressure gradient, and other characteristics of the flow field around the propeller differ significantly from those under positive advance conditions. Traditional propeller performance theories do not fully consider negative advance states, rendering theories based on positive advance conditions ineffective and preventing effective calculations of propeller performance under negative advance conditions.

[0030] Based on this, embodiments of this application provide a method, apparatus, device, and medium for calculating the performance of a propeller under negative advance conditions. The method includes: acquiring the incoming flow velocity, target values ​​of the axial induced velocity coefficient at the propeller disk, and target values ​​of the circumferential induced velocity coefficient at the propeller disk, wherein the target propeller is in a negative advance state; determining the target value of the actual airflow velocity angle of the target propeller based on the incoming flow velocity, the target values ​​of the axial induced velocity coefficient at the propeller disk, and the target values ​​of the circumferential induced velocity coefficient at the propeller disk; determining the blade element parameters of the target propeller based on the target value of the actual airflow velocity angle and the drag angle of the blade element of the target propeller; and determining the values ​​of the performance parameters of the target propeller based on the blade element parameters, the total number of blades of the target propeller, and the propeller radius. Embodiments of this application can accurately calculate the propeller performance under negative advance conditions based on target values ​​applicable to negative advance conditions.

[0031] To make the purpose and technical solution of this application clearer and more intuitive, the performance calculation method of the propeller under negative advance state disclosed in this application is described below with reference to the accompanying drawings.

[0032] Please see Figure 1 , Figure 1 This is a flowchart illustrating a propeller performance calculation method under negative advance conditions disclosed in an embodiment of this application. Figure 1 The method shown may include the following steps: Step 101: The controller acquires the target values ​​of the incoming flow velocity, the axial induced velocity coefficient at the propeller disk of the target propeller, and the circumferential induced velocity coefficient at the propeller disk.

[0033] In this embodiment of the application, the target propeller is in a negative advance state, which means that the direction of the incoming airflow is opposite to the slipstream direction of the target propeller when there is no airflow.

[0034] It should be noted that the negative advance state can be divided into two situations: the incoming velocity of the reverse airflow is low and fails to penetrate the propeller disk; the incoming velocity of the reverse airflow is high and penetrates the propeller disk. This application is applicable to calculating propeller performance when the incoming velocity of the reverse airflow is low and fails to penetrate the propeller disk.

[0035] Please see Figure 2 , Figure 2 This is a schematic diagram of the flow field distribution of a propeller disclosed in an embodiment of this application. The expansion section on the left is the incoming flow region, the propeller disk in the middle is the circular plane formed by the rotation of the propeller, the slip flow region on the right is the airflow region behind the propeller disk after being disturbed and accelerated by the propeller, and the dashed line is the axis of rotation of the propeller.

[0036] It should be understood that, under negative advance conditions, the direction of the incoming airflow is different from the natural flow direction of the airflow in the slip zone. Figure 2 The direction of the slip flow (from left to right) is opposite, that is, in the negative advance state, the direction of the airflow is from right to left.

[0037] Optionally, the incoming airflow velocity at the propeller disk of the target propeller can be measured using sensors. It should be understood that under negative advance conditions, the incoming airflow velocity at the propeller disk is negative.

[0038] It should be noted that the incoming airflow velocity at the propeller disk can also be understood as the incoming airflow velocity at the circular plane formed by the propeller's rotation, where the circular plane formed by the propeller's rotation is as follows: Figure 2 The propeller disk shown.

[0039] Optionally, the target values ​​of the axial induced velocity coefficient and the circumferential induced velocity coefficient of the target propeller disk can be obtained through iterative calculation.

[0040] Step 102: The controller determines the target value of the actual airflow velocity angle of the target propeller based on the incoming flow velocity, the target value of the axial induced velocity coefficient at the propeller disk, and the target value of the circumferential induced velocity coefficient at the propeller disk.

[0041] In this embodiment, the actual airflow velocity angle is used to characterize the angle between the direction of the actual airflow velocity at the disk of the target propeller and the plane of rotation of the target propeller. The plane of rotation of the target propeller is the plane perpendicular to the axis of rotation of the propeller, and can also be understood as... Figure 2 The plane in which the propeller disk is shown.

[0042] In some embodiments, the formula for calculating the target value of the actual airflow velocity angle can be expressed as: ,in, This represents the actual airflow velocity angle. Let be the incoming flow velocity, and 'a' be the axial induced velocity coefficient at the propeller disk. The circumferential induced velocity coefficient at the propeller disk. This indicates the tangential velocity within the propeller disk surface.

[0043] Specifically, the calculation formula for the target value of the actual airflow velocity angle is based on the following formula: ,as well as , Of those obtained, It is the induced axial velocity at the propeller disk. It is the circumferential induced velocity at the propeller disk.

[0044] Step 103: The controller determines the blade element parameters of the target propeller based on the target value of the actual airflow velocity angle and the drag angle of the blade element of the target propeller.

[0045] It should be understood that the blade element of a propeller refers to an infinitely thin micro-segment of the propeller blade taken along the spanwise (radial) direction. In blade element theory, each blade element is regarded as a two-dimensional airfoil working under specific incoming flow conditions, thus establishing a bridge connecting the characteristics of the two-dimensional airfoil with the overall performance of the three-dimensional propeller.

[0046] In this embodiment, the lift angle of the blade element is used to characterize the angle between the airflow direction relative to the airfoil and the airfoil chord. The lift angle is obtained based on the airfoil lift coefficient and airfoil drag coefficient, and the formula for calculating the lift angle of the blade element is expressed as: = arctan(C D / C L ),in, C is the angle of hindrance for leaf element. L C is the airfoil lift coefficient. D This represents the airfoil drag coefficient.

[0047] Optionally, the airfoil aerodynamic coefficients can be determined by querying the aerodynamic characteristic data of the corresponding airfoil based on the actual state parameters of the blade element. The actual state parameters of the blade element include the actual angle of attack, Reynolds number, and Mach number, while the airfoil aerodynamic coefficients include the airfoil lift coefficient and the airfoil drag coefficient. For example, the actual state parameters of the blade element can be input into an airfoil analysis tool (such as XFOIL) for calculation to determine the airfoil aerodynamic coefficients; alternatively, the airfoil aerodynamic coefficients can be determined from a database (such as Profili) that stores the aerodynamic characteristic curves of the corresponding airfoil based on the actual state parameters of the blade element.

[0048] In the embodiments of this application, the blade element parameters include at least one of blade element thrust, blade element circumferential force, and blade element torque.

[0049] The formula for calculating leaf element thrust can be expressed as: ,in, Let ρ be the incoming flow velocity, ρ be the air density, and Tc be the tensile coefficient; the formula for calculating Tc can be expressed as: K is the proportionality coefficient; its calculation formula can be expressed as: , where C L denoted as airfoil lift coefficient, a as axial induced velocity coefficient at the rotor disk, and B as blade element chord length.

[0050] The formula for calculating the circumferential force of leaf elements can be expressed as: .

[0051] The formula for calculating blade element torque can be expressed as: Where Qc is the torque coefficient, its calculation formula can be expressed as: .

[0052] Step 104: The controller determines the values ​​of the performance parameters of the target propeller based on the blade element parameters, the total number of blades of the target propeller, and the propeller radius.

[0053] In the embodiments of this application, the performance parameters include at least one of the propeller's thrust, circumferential force, and torque. For example, the performance parameters of the target propeller may be one or two of the propeller's thrust, circumferential force, and torque, or the performance parameters of the target propeller may be the propeller's thrust, circumferential force, and torque.

[0054] For example, the performance parameters of the target propeller can be obtained by integrating and summing the blade element thrust or blade element torque based on the total number of blades and the propeller radius.

[0055] The formula for calculating the thrust of a propeller can be expressed as: Where T is the propeller thrust, and N is the thrust. B Let r0 be the total number of blades of the target propeller, r0 be the blade initial radius (hub radius), and R be the propeller radius. It should be understood that the hub radius refers to the distance from the propeller's rotation center to the blade initiation point; please refer to [link to relevant documentation]. Figure 3 , Figure 3 This is a schematic diagram of a propeller disclosed in an embodiment of this application, where the hub radius r0 is... Figure 3 The distance from the center of rotation to the beginning of the blade.

[0056] The formula for calculating the circumferential force of a propeller can be expressed as: , where F is the circumferential force of the propeller.

[0057] The formula for calculating propeller torque can be expressed as: Where M is the torque of the propeller.

[0058] As can be seen, implementing the above embodiments enables accurate calculation of propeller performance under negative advance conditions based on target values ​​applicable to negative advance conditions. First, by obtaining the target values ​​for the incoming flow velocity, the axial induced velocity coefficient at the propeller disk, and the circumferential induced velocity coefficient at the propeller disk under negative advance conditions, the target value for the actual airflow velocity angle is determined accordingly. Then, based on the target value for the actual airflow velocity angle and the blade element's drag angle, blade element parameters (at least one of blade element thrust, blade element torque, and blade element circumferential force) are determined. Based on the relevant parameters under negative advance conditions, calculations are sequentially derived, effectively determining the blade element parameters of the target propeller under negative advance conditions. Finally, based on the blade element parameters, the total number of blades, and the propeller radius, the values ​​of performance parameters are determined, enabling accurate calculation of the target propeller's thrust, circumferential force, and torque, solving the problem that traditional theories cannot calculate propeller performance under negative advance conditions.

[0059] Regarding the target values ​​of the axial induced velocity coefficient and the circumferential induced velocity coefficient at the propeller disk of the target propeller, in some embodiments, the controller can perform iterative calculations based on a first initial value, a second initial value, and multiple mapping relationships until the difference between the output value of the current iteration and the output value of the previous iteration satisfies the target conditions. Then, the output value of the current iteration is determined as the target values ​​of the axial induced velocity coefficient and the circumferential induced velocity coefficient at the propeller disk.

[0060] The multiple mapping relationships include angle mapping relationship, blade element thrust mapping relationship, first velocity coefficient mapping relationship, blade element torque mapping relationship, and second velocity coefficient mapping relationship. The angle mapping relationship is used to characterize the relationship between the axial induced velocity coefficient at the propeller disk, the circumferential induced velocity coefficient at the propeller disk, the incoming flow velocity, and the actual airflow velocity angle. The blade element thrust mapping relationship is used to characterize the relationship between the actual airflow velocity angle, the axial induced velocity coefficient at the propeller disk, the incoming flow velocity, and the blade element thrust. The first velocity coefficient mapping relationship is used to characterize the relationship between the blade element thrust and the axial induced velocity coefficient at the propeller disk. The blade element torque mapping relationship is used to characterize the relationship between the actual airflow velocity angle, the axial induced velocity coefficient at the propeller disk, the incoming flow velocity, and the blade element torque. The second velocity coefficient mapping relationship is used to characterize the relationship between the blade element torque and the axial induced velocity coefficient at the propeller disk and the circumferential induced velocity coefficient at the propeller disk.

[0061] Optionally, the first and second initial values ​​are preset values. It should be understood that the first and second initial values ​​are the iterative initial values ​​for the axial induced velocity coefficient and the circumferential induced velocity coefficient at the propeller disk, respectively.

[0062] For a detailed description of the angle mapping relationship, blade element thrust mapping relationship, first velocity coefficient mapping relationship, blade element torque mapping relationship, and second velocity coefficient mapping relationship, please refer to the relevant steps below (see steps 401, 402, 403, 501, 502, and 503).

[0063] As can be seen, by implementing the above embodiments, the target values ​​of the axial induced velocity coefficient and the circumferential induced velocity coefficient at the propeller disk can be determined through iterative calculation. First, based on the first initial value and the second initial value, iterative calculation is carried out in combination with the angle mapping relationship, the blade element thrust mapping relationship, the first velocity coefficient mapping relationship, the blade element torque mapping relationship, and the second velocity coefficient mapping relationship. The iteration is terminated by judging whether the difference between the current iteration output value and the previous iteration output value meets the target condition. The current iteration output value is determined as the target value of the axial induced velocity coefficient and the target value of the circumferential induced velocity coefficient at the propeller disk. The above mapping relationships can accurately characterize the correlation between the corresponding parameters, so that the iterative calculation process for determining the axial induced velocity coefficient and the circumferential induced velocity coefficient at the propeller disk conforms to the inherent correlation logic of parameters under negative advance state, thereby improving the accuracy and reliability of the target values.

[0064] Regarding the target conditions, in some embodiments, the target conditions include the number of iterations for the iterative calculation meeting a threshold; or, the difference between the output value of the current iteration of the axial induced velocity coefficient at the propeller disk and the output value of the previous iteration is less than a difference threshold, and the difference between the output value of the current iteration of the circumferential induced velocity coefficient at the propeller disk and the output value of the previous iteration is less than a difference threshold.

[0065] For example, the target condition is that the number of iterations for the iterative calculation is greater than or equal to a threshold number. The threshold number is a preset fixed value, such as 100.

[0066] For example, the target condition is that the difference between the output value of the axial induced velocity coefficient at the propeller disk in the current iteration and the output value in the previous iteration is less than a difference threshold, and the difference between the output value of the circumferential induced velocity coefficient at the propeller disk in the current iteration and the output value in the previous iteration is less than a difference threshold. Here, the difference threshold is a preset fixed value, such as a difference threshold of 10. -5 .

[0067] As can be seen, implementing the above embodiments and using the iteration count meeting a threshold as the target condition effectively controls the overall iterative calculation process and avoids the waste of computational resources caused by unlimited iteration. Using the difference between the current iteration output value and the previous iteration output value of the axial and circumferential induced velocity coefficients at the propeller disk being less than a difference threshold as the target condition ensures the convergence of the iterations for both velocity coefficients and guarantees that the final target values ​​meet the accuracy requirements. Through these target conditions, the standardization and controllability of the iterative calculation process are guaranteed, ensuring that the target values ​​of the axial and circumferential induced velocity coefficients at the propeller disk can be obtained efficiently and accurately.

[0068] Regarding iterative calculations based on a first initial value, a second initial value, and multiple mapping relationships, in some embodiments, it can be divided into a first iterative calculation and other subsequent iterative calculations.

[0069] 1. First iteration calculation.

[0070] In some embodiments, for the first iteration calculation, the controller uses a first initial value as the initial value of the axial induced velocity coefficient at the propeller disk in the angle mapping relationship, and a second initial value as the initial value of the circumferential induced velocity coefficient at the propeller disk in the angle mapping relationship. Based on the first set of mapping relationships, the controller obtains the input value for the next iteration calculation of the axial induced velocity coefficient at the propeller disk. The first set of mapping relationships includes the angle mapping relationship, the blade element thrust mapping relationship, and the first velocity coefficient mapping relationship.

[0071] For details on the implementation method of obtaining the input value for the next iteration of the axial induced velocity coefficient at the propeller disk, please refer to [link to relevant documentation]. Figure 4 , Figure 4 This is a flowchart illustrating an iterative calculation method disclosed in an embodiment of this application. Figure 4 The method shown may include the following steps: Step 401: The controller calculates the first calculated value of the actual airflow velocity angle based on the first initial value, the second initial value, and the angle mapping relationship.

[0072] In the application embodiment, the angle mapping relationship is used to characterize the relationship between the axial induced velocity coefficient at the propeller disk, the circumferential induced velocity coefficient at the propeller disk, the incoming flow velocity, and the actual airflow velocity angle. Specifically, the angle mapping relationship can be expressed as the calculation formula for the target value of the actual airflow velocity angle in step 102 above: ,in, This represents the actual airflow velocity angle. Let be the incoming flow velocity, and 'a' be the axial induced velocity coefficient at the propeller disk. The circumferential induced velocity coefficient at the propeller disk. This indicates the tangential velocity within the propeller disk surface.

[0073] It should be understood that the first initial value is the initial value of the axial induced velocity coefficient at the propeller disk, and the second initial value is the initial value of the circumferential induced velocity coefficient at the propeller disk. Based on the first initial value, the second initial value, and the angle mapping relationship, the first calculated value of the actual airflow velocity angle is obtained, i.e. The value of .

[0074] Step 402: The controller substitutes the first initial value and the first calculated value into the blade element thrust mapping relationship to obtain the second calculated value of the blade element thrust.

[0075] In the embodiments of the application, the blade element thrust mapping relationship is used to characterize the relationship between the actual airflow velocity angle, the axial induced velocity coefficient at the propeller disk, the incoming flow velocity, and the blade element thrust. Specifically, the blade element thrust mapping relationship can be expressed as a calculation formula: , in, The angle of hindrance for leaf pigment. This represents the actual airflow velocity angle. Let dT be the incoming flow velocity, dT be the blade element thrust, and a be the axial induced velocity coefficient at the propeller disk. K is the proportionality coefficient.

[0076] It should be understood that by substituting the first initial value of the axial induced velocity coefficient at the propeller disk and the first calculated value of the actual airflow velocity angle into the blade element thrust mapping relationship, the second calculated value of the blade element thrust, i.e., the value of dT, is obtained.

[0077] Step 403: The controller substitutes the first initial value and the second calculated value into the first velocity coefficient mapping relationship to obtain the first iterative output value of the axial induced velocity coefficient at the propeller disk.

[0078] In the embodiments of the application, the first velocity coefficient mapping relationship is used to characterize the relationship between blade element thrust and the axial induced velocity coefficient at the propeller disk. Specifically, the first velocity coefficient mapping relationship can be expressed as a calculation formula: Where dT is the blade element thrust and a is the axial induced velocity coefficient at the propeller disk.

[0079] It should be understood that by substituting the first initial value of the axial induced velocity coefficient at the propeller disk and the second calculated value of the blade element thrust into the first velocity coefficient mapping relationship, the first iterative output value of the axial induced velocity coefficient at the propeller disk is obtained, which is the value of 'a' on the right side of the calculation formula, thereby realizing the updating of the value of the axial induced velocity coefficient at the propeller disk.

[0080] In some embodiments, the first iteration output value of the axial induced velocity coefficient at the propeller disk is the input value for the next iteration calculation of the axial induced velocity coefficient at the propeller disk.

[0081] In other embodiments, the input value for the next iteration calculation of the axial induced velocity coefficient at the propeller disk can be obtained based on the first iteration output value and the first initial value of the axial induced velocity coefficient at the propeller disk.

[0082] For example, the formula for calculating the input value of the axial induced velocity coefficient at the propeller disk in the next iteration can be expressed as: ,in, This is the input value for the next iteration calculation of the axial induced velocity coefficient at the propeller disk. The input values ​​(including the first initial value) are used for the calculation of the current iteration. This is the output value calculated in the current iteration.

[0083] As can be seen, by implementing the above embodiments, the specific generation process of the axial induced velocity coefficient input value at the propeller disk in the first iteration calculation is clarified. First, based on the first initial value and the second initial value, the first calculated value of the actual airflow velocity angle is obtained through the angle mapping relationship. Then, the first initial value and the first calculated value of the actual airflow velocity angle are substituted into the blade element thrust mapping relationship to obtain the second calculated value of the blade element thrust. Finally, the first initial value and the second calculated value of the blade element thrust are substituted into the first velocity coefficient mapping relationship to generate the first iteration output value of the axial induced velocity coefficient at the propeller disk, which is the input value for the next iteration calculation. The above scheme back-calculates and updates the axial induced velocity coefficient at the propeller disk based on the blade element thrust, ensuring the continuity and rationality of the iterative calculation process.

[0084] In some embodiments, for the first iteration calculation, the controller uses a first initial value as the initial value of the axial induced velocity coefficient at the propeller disk in the angle mapping relationship, and a second initial value as the initial value of the circumferential induced velocity coefficient at the propeller disk in the angle mapping relationship. Based on the second set of mapping relationships, the controller obtains the input value for the next iteration calculation of the circumferential induced velocity coefficient at the propeller disk. The second set of mapping relationships includes the angle mapping relationship, the blade element torque mapping relationship, and the second velocity coefficient mapping relationship.

[0085] For details on the implementation method of obtaining the input value for the next iteration of the circumferential induced velocity coefficient at the propeller disk, please refer to [link to implementation details]. Figure 5 , Figure 5 This is a flowchart illustrating another iterative calculation method disclosed in an embodiment of this application. Figure 5 The method shown may include the following steps: Step 501: The controller calculates the first calculated value of the actual airflow velocity angle based on the first initial value, the second initial value, and the angle mapping relationship.

[0086] For the specific implementation of the angle mapping relationship in step 501, please refer to the content in step 401 above, which will not be repeated here.

[0087] Step 502: The controller substitutes the first initial value and the first calculated value into the blade element torque mapping relationship to obtain the third calculated value of the blade element torque.

[0088] In the embodiments of the application, the blade element torque mapping relationship is used to characterize the relationship between the actual airflow velocity angle, the axial induced velocity coefficient at the propeller disk, the incoming flow velocity, and the blade element torque. Specifically, the blade element torque mapping relationship can be expressed as a calculation formula: , in, The angle of hindrance for leaf pigment. denoted as the actual airflow velocity angle, V0 as the incoming flow velocity, dM as the blade element torque, and a as the axial induced velocity coefficient at the propeller disk.

[0089] It should be understood that by substituting the first initial value of the axial induced velocity coefficient at the propeller disk and the first calculated value of the actual airflow velocity angle into the blade element torque mapping relationship, the third calculated value of the blade element torque, i.e., the value of dM, is obtained.

[0090] Step 503: The controller substitutes the first initial value and the third calculated value into the second velocity coefficient mapping relationship to obtain the first iterative output value of the circumferential induced velocity coefficient at the propeller disk.

[0091] In the embodiments of the application, the second velocity coefficient mapping relationship is used to characterize the relationship between the blade element torque and the axial induced velocity coefficient at the propeller disk and the circumferential induced velocity coefficient at the propeller disk. Specifically, the second velocity coefficient mapping relationship can be expressed as a calculation formula: Where dM is the blade element torque and a is the axial induced velocity coefficient at the propeller disk. is the circumferential induced velocity coefficient at the propeller disk.

[0092] It should be understood that substituting the first initial value of the axial induced velocity coefficient at the propeller disk and the third calculated value of the blade element torque into the second velocity coefficient mapping relationship yields the first iterative output value of the circumferential induced velocity coefficient at the propeller disk, i.e., the value on the right side of the calculation formula. The value of is thus obtained, thereby enabling the updating of the circumferential induced velocity coefficient at the propeller disk.

[0093] In some embodiments, the first iteration output value of the circumferential induced velocity coefficient at the propeller disk is the input value for the next iteration calculation of the circumferential induced velocity coefficient at the propeller disk.

[0094] In other embodiments, the input value for the next iteration calculation of the circumferential induced velocity coefficient at the propeller disk can be obtained based on the first iteration output value and the second initial value of the circumferential induced velocity coefficient at the propeller disk.

[0095] For example, the formula for calculating the input value of the circumferential induced velocity coefficient at the propeller disk in the next iteration is as follows: ,in, This is the input value for the next iteration calculation of the circumferential induced velocity coefficient at the propeller disk. The input values ​​(including the second initial value) are used for the calculation of the current iteration. This is the output value calculated in the current iteration.

[0096] As can be seen, by implementing the above embodiments, the specific generation process of the input value of the circumferential induced velocity coefficient at the propeller disk in the first iteration calculation is clarified. First, based on the first initial value and the second initial value, the first calculated value of the actual airflow velocity angle is obtained through the angle mapping relationship. Then, the first initial value and the first calculated value are substituted into the blade element torque mapping relationship to obtain the third calculated value of the blade element torque. Finally, the first initial value and the third calculated value are substituted into the second velocity coefficient mapping relationship to generate the first iteration output value of the circumferential induced velocity coefficient at the propeller disk, which is the input value for the next iteration calculation. The above scheme back-calculates and updates the circumferential induced velocity coefficient at the propeller disk based on the blade element torque, ensuring the continuity and rationality of the iterative calculation process.

[0097] 2. Other iterations of calculation.

[0098] In some embodiments, the controller performs iterative calculations for other iterations based on the input values ​​of the axial induced velocity coefficient at the propeller disk for the next iteration, the input values ​​of the circumferential induced velocity coefficient at the propeller disk for the next iteration, and multiple mapping relationships.

[0099] It is understandable that other iterations refer to any iteration other than the first iteration, that is, the second, the third, and every iteration until the target condition is met.

[0100] For example, by performing iterative calculations based on the input values ​​of the third iteration of the axial induced velocity coefficient at the propeller disk, the third iteration of the circumferential induced velocity coefficient at the propeller disk, and multiple mapping relationships, the input values ​​of the fourth iteration of the axial induced velocity coefficient at the propeller disk and the fourth iteration of the circumferential induced velocity coefficient at the propeller disk can be obtained.

[0101] As can be seen, implementing the above embodiments clarifies the specific process of iterative calculation, achieving synchronous and independent updates of the axial induced velocity coefficient and the circumferential induced velocity coefficient at the propeller disk. In the first iteration, the first and second initial values ​​are used as the initial values ​​for the axial and circumferential induced velocity coefficients at the propeller disk, respectively. The first set of mapping relationships (angle mapping relationship, blade element thrust mapping relationship, and first velocity coefficient mapping relationship) is used to obtain the input value for the next iteration of the axial induced velocity coefficient at the propeller disk. Simultaneously, the second set of mapping relationships (angle mapping relationship, blade element torque mapping relationship, and second velocity coefficient mapping relationship) is used to obtain the input value for the next iteration of the circumferential induced velocity coefficient at the propeller disk. In other iterations, the iteration continues based on these two new input values. This process enables the axial and circumferential induced velocity coefficients at the propeller disk to collaboratively approximate the target value through their respective related physical mapping relationships (thrust-related and torque-related), ensuring the convergence accuracy and computational efficiency of the target value.

[0102] It should be noted that the specific implementation method for the first iteration calculation described above is also applicable to other iteration calculations. The only difference between the first iteration calculation and other iteration calculations is the input: the input for the first iteration calculation is the first initial value and the second initial value, while the input for other iteration calculations is the output value of the previous iteration calculation.

[0103] Regarding the mapping relationship of the first velocity coefficient, in some embodiments, the mapping relationship of the first velocity coefficient is determined based on the derivation relationship of the axial induced velocity coefficient at the disk of the target propeller and the axial induced velocity coefficient of the slipstream region of the target propeller under negative advance conditions. The derivation relationship satisfies the following expression: , where a is the axial induced velocity coefficient at the propeller disk and b is the axial induced velocity coefficient in the slipstream region.

[0104] It should be noted that the above derivation formulas are derived based on the modified propeller disk in-flight energy equation and the modified propeller disk out-of-flight energy equation. The modified propeller disk in-flight energy equation represents the total pressure in front of the propeller disk, which includes the incoming static pressure and the negative incoming kinetic pressure. The modified propeller disk out-of-flight energy equation represents the total pressure behind the propeller disk, which includes the incoming static pressure, the positive incoming kinetic pressure, and the dynamic pressure of the airflow in the slipstream region.

[0105] It should be understood that when the airflow approaches the propeller, the speed increases and the pressure decreases, resulting in a pressure of [pressure value missing] in front of the propeller disk. After the airflow passes through the propeller disk, the pressure increases by ΔP, and the axial velocity increases to V0(1+a). When the airflow approaches the slip zone, the axial velocity further increases to V0(1+b), but the pressure decreases to the incoming static pressure P.

[0106] The energy equation in front of the propeller disk is expressed as: .

[0107] The energy equation behind the propeller disk is: .

[0108] It should be noted that the propeller disk energy equation describes the energy conservation relationship during the process of airflow moving from far in front to directly in front of the propeller disk. In the negative advance state, if we assume the positive direction is the direction of propeller thrust, and the incoming flow direction is opposite to the direction of propeller thrust, then in the total pressure calculation, the kinetic energy opposite to the direction of propeller thrust should be regarded as a negative contribution, hence the minus sign, i.e., negative incoming kinetic pressure.

[0109] Specifically, the modified propeller disk inlet energy equation can be expressed as: Where P is the incoming static pressure. P* is the incoming flow pressure, and P* is the total pressure in front of the propeller disk. This represents the pressure in front of the propeller disk.

[0110] It should be understood that the energy equation behind the propeller disk describes the energy conservation relationship during the process of airflow moving from directly behind the propeller disk to far behind it. Under negative advance conditions, the static pressure behind the propeller disk increases due to the deceleration of the incoming flow. This pressure can be expressed as the pressure converted from the deceleration of the incoming flow. Therefore, in the total pressure calculation, the incoming dynamic pressure is added to the static pressure of the incoming flow and the dynamic pressure of the airflow in the slip zone. Specifically, the modified energy equation behind the propeller disk can be expressed as: Where ΔP is the pressure difference across the propeller disk. This represents the dynamic pressure of the airflow in the slipstream region.

[0111] Based on the modified energy equations for the propeller disk in front and behind, the pressure difference across the propeller disk can be obtained. Specifically, the formula for calculating the pressure difference across the propeller disk can be expressed as: .

[0112] The tension of the propeller disk can be obtained from the pressure difference across it. Specifically, the formula for calculating the tension of the propeller disk can be expressed as: T1 = AΔP, where A is the area of ​​the propeller disk and ΔP is the pressure difference across it.

[0113] According to the momentum theorem, the force exerted by the propeller on the airflow (equal in magnitude and opposite in direction to the propeller thrust T1) should be equal to the increase in momentum passing through the propeller disk per unit time. Here, the direction of the propeller's force on the airflow is the same as the direction of the airflow, while the propeller thrust T1 (the force exerted by the airflow on the propeller) is opposite to the direction of the airflow, that is: .

[0114] Since T1=T2, we can establish equations for the force equation of the propeller on the airflow and the propeller thrust calculation equation. Based on these equations, we can obtain the derivation relationship between the axial induced velocity coefficient at the propeller disk and the axial induced velocity coefficient of the slipstream region of the target propeller under negative advance conditions.

[0115] As can be seen, by implementing the above embodiments, firstly, a mathematical relationship is established between the axial induced velocity coefficient at the propeller disk and the axial induced velocity coefficient in the slipstream region under negative advance conditions. This provides a parameter correlation basis for the first velocity coefficient mapping relationship that conforms to the negative advance condition, solving the problem of the failure of traditional theory under negative advance conditions. Secondly, the first velocity coefficient mapping relationship determined based on this derivation relationship can accurately characterize the correlation between blade element thrust and the axial induced velocity coefficient at the propeller disk, thereby ensuring the accuracy and reliability of the target value of the axial induced velocity coefficient at the propeller disk under negative advance conditions.

[0116] The above combination Figures 1-5 This application provides a detailed description of a propeller performance calculation method under negative pitch conditions. It should be understood that although the steps in the flowcharts are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps; they can be executed in other orders. Furthermore, at least some steps in the flowcharts may include multiple sub-steps or stages. These sub-steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least a portion of the sub-steps or stages of other steps. Additionally, the above embodiments can be implemented independently or in combination with each other, without limitation.

[0117] Based on the foregoing embodiments, this application provides a performance calculation device for a propeller in negative advance state. The device includes various modules and units included in each module, which can be implemented by a processor; of course, it can also be implemented by specific logic circuits. In the implementation process, the processor can be a central processing unit (CPU), microprocessor (MPU), digital signal processor (DSP), or field programmable gate array (FPGA), etc.

[0118] Please see Figure 6 , Figure 6 This is a schematic diagram of the structure of a propeller performance calculation device under negative advance state disclosed in an embodiment of this application, as shown below. Figure 6 The device shown includes a data acquisition module 601, a first determination module 602, a second determination module 603, and a third determination module 604.

[0119] The data acquisition module 601 acquires the incoming flow velocity, the target value of the axial induced velocity coefficient at the disk of the target propeller, and the target value of the circumferential induced velocity coefficient at the disk. The target propeller is in a negative advance state, which means that the incoming flow direction of the airflow is opposite to the slip flow direction of the target propeller when there is no airflow. The first determining module 602 determines the target value of the actual airflow velocity angle of the target propeller based on the incoming flow velocity, the target value of the axial induced velocity coefficient at the propeller disk, and the target value of the circumferential induced velocity coefficient at the propeller disk. The actual airflow velocity angle is used to characterize the angle between the direction of the actual airflow velocity at the propeller disk of the target propeller and the rotation plane of the target propeller. The second determining module 603 determines the blade element parameters of the target propeller based on the target value of the actual airflow velocity angle and the drag angle of the blade element of the target propeller. The blade element parameters include at least one of blade element thrust, blade element circumferential force and blade element torque. The third determining module 604 determines the values ​​of the performance parameters of the target propeller based on the blade element parameters, the total number of blades of the target propeller, and the propeller radius. The performance parameters include at least one of the propeller thrust, circumferential force, and torque.

[0120] In some embodiments, the data acquisition module 601 is specifically used to perform iterative calculations based on a first initial value, a second initial value, and multiple mapping relationships until the difference between the output value of the current iteration and the output value of the previous iteration satisfies the target condition. Then, the output value of the current iteration is determined as the target value of the axial induced velocity coefficient and the target value of the circumferential induced velocity coefficient at the propeller disk. The multiple mapping relationships include an angle mapping relationship, a blade element thrust mapping relationship, a first velocity coefficient mapping relationship, a blade element torque mapping relationship, and a second velocity coefficient mapping relationship. The angle mapping relationship is used to characterize the axial induced velocity at the propeller disk. The relationships between the velocity coefficient, the circumferential induced velocity coefficient at the propeller disk, the incoming flow velocity and the actual airflow velocity angle are described. The blade element thrust mapping relationship is used to characterize the relationship between the actual airflow velocity angle, the axial induced velocity coefficient at the propeller disk, the incoming flow velocity and the blade element thrust. The first velocity coefficient mapping relationship is used to characterize the relationship between the blade element thrust and the axial induced velocity coefficient at the propeller disk. The blade element torque mapping relationship is used to characterize the relationship between the actual airflow velocity angle, the axial induced velocity coefficient at the propeller disk, the incoming flow velocity and the blade element torque. The second velocity coefficient mapping relationship is used to characterize the relationship between the blade element torque and the axial induced velocity coefficient at the propeller disk and the circumferential induced velocity coefficient at the propeller disk.

[0121] In some embodiments, the data acquisition module 601 is specifically used for the first iteration calculation, taking a first initial value as the initial value of the axial induced velocity coefficient at the propeller disk in the angle mapping relationship, and taking a second initial value as the initial value of the circumferential induced velocity coefficient at the propeller disk in the angle mapping relationship, and obtaining the input value for the next iteration calculation of the axial induced velocity coefficient at the propeller disk according to the first set of mapping relationships; the first set of mapping relationships includes angle mapping relationship, blade element thrust mapping relationship, and first velocity coefficient mapping relationship; taking the first initial value as the initial value of the axial induced velocity coefficient at the propeller disk in the angle mapping relationship, and taking a second initial value as the initial value of the circumferential induced velocity coefficient at the propeller disk in the angle mapping relationship, and obtaining the input value for the next iteration calculation of the circumferential induced velocity coefficient at the propeller disk according to the second set of mapping relationships; the second set of mapping relationships includes angle mapping relationship, blade element torque mapping relationship, and second velocity coefficient mapping relationship; for other iteration calculations, iterative calculations are performed according to the input value for the next iteration calculation of the axial induced velocity coefficient at the propeller disk, the input value for the next iteration calculation of the circumferential induced velocity coefficient at the propeller disk, and multiple mapping relationships.

[0122] In some embodiments, the data acquisition module 601 is specifically used to calculate a first calculated value of the actual airflow velocity angle based on a first initial value, a second initial value, and an angle mapping relationship; substitute the first initial value and the first calculated value into the blade element thrust mapping relationship to obtain a second calculated value of the blade element thrust; substitute the first initial value and the second calculated value into the first velocity coefficient mapping relationship to obtain the first iterative output value of the axial induced velocity coefficient at the propeller disk, and the first iterative output value of the axial induced velocity coefficient at the propeller disk is the input value for the next iterative calculation of the axial induced velocity coefficient at the propeller disk.

[0123] In some embodiments, the data acquisition module 601 is specifically used to calculate a first calculated value of the actual airflow velocity angle based on a first initial value, a second initial value, and an angle mapping relationship; substitute the first initial value and the first calculated value into the blade element torque mapping relationship to obtain a third calculated value of the blade element torque; substitute the first initial value and the third calculated value into the second velocity coefficient mapping relationship to obtain the first iterative output value of the circumferential induced velocity coefficient at the propeller disk, and the first iterative output value of the circumferential induced velocity coefficient at the propeller disk is the input value for the next iterative calculation of the circumferential induced velocity coefficient at the propeller disk.

[0124] In some embodiments, the data acquisition module 601 is specifically used for target conditions including the number of iterations for iterative calculations satisfying a number threshold; or, the difference between the output value of the current iteration of the axial induced velocity coefficient at the propeller disk and the output value of the previous iteration is less than a difference threshold, and the difference between the output value of the current iteration of the circumferential induced velocity coefficient at the propeller disk and the output value of the previous iteration is less than a difference threshold.

[0125] In some embodiments, the data acquisition module 601 is specifically used to determine the first velocity coefficient mapping relationship based on the derived relationship of the axial induced velocity coefficient at the disk of the target propeller and the axial induced velocity coefficient of the slipstream region of the target propeller under negative advance conditions. The derived relationship satisfies the following expression: , Where a is the axial induced velocity coefficient at the propeller disk and b is the axial induced velocity coefficient in the slipstream region.

[0126] It should be noted that the module division of the performance calculation device under the negative advance state of the propeller shown in the embodiments of this application is illustrative and is only a logical functional division. In actual implementation, there may be other division methods.

[0127] This application provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the steps of the method provided in the above embodiments.

[0128] This application provides a computer program product containing instructions that, when run on a computer, cause the computer to perform the steps in the method provided in the above-described method embodiments.

[0129] It should be noted that the descriptions of the above embodiments of the apparatus, electronic devices, and computer-readable storage media are similar to the descriptions of the above method embodiments, and have similar beneficial effects. For technical details not disclosed in the embodiments of the apparatus, electronic devices, and computer-readable storage media of this application, please refer to the descriptions of the method embodiments of this application for understanding.

[0130] It should be understood that the phrases "one embodiment," "an embodiment," or "some embodiments" mentioned throughout the specification mean that a specific feature, structure, or characteristic related to an embodiment is included in at least one embodiment of this application. Therefore, "in one embodiment," "in one embodiment," or "in some embodiments" appearing throughout the specification do not necessarily refer to the same embodiment. Furthermore, these specific features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. It should be understood that in the various embodiments of this application, the sequence numbers of the above-described processes do not imply a sequential order of execution; the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application. The sequence numbers of the above-described embodiments are merely for descriptive purposes and do not represent the superiority or inferiority of the embodiments. The descriptions of the various embodiments above tend to emphasize the differences between the various embodiments; their similarities or commonalities can be referred to mutually, and for the sake of brevity, they will not be repeated here.

[0131] In this article, the term "and / or" is merely a description of the relationship between related objects, indicating that there can be three kinds of relationships. For example, object A and / or object B can represent three situations: object A exists alone, object A and object B exist simultaneously, and object B exists alone.

[0132] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0133] In the several embodiments provided in this application, it should be understood that the disclosed methods, apparatus, and electronic devices can be implemented in other ways. The embodiments described above are merely illustrative. For example, the division of modules above is only a logical functional division, and in actual implementation, there may be other division methods, such as: multiple modules or components can be combined, or integrated into another system, or some features can be ignored or not executed. In addition, the coupling, direct coupling, or communication connection between the various components shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or modules, and can be electrical, mechanical, or other forms.

[0134] Those skilled in the art will understand that all or part of the steps of the above method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When the program is executed, it performs the steps of the above method embodiments. The aforementioned storage medium includes various media that can store program code, such as mobile storage devices, read-only memory (ROM), magnetic disks, or optical disks.

[0135] The methods disclosed in the several method embodiments provided in this application can be arbitrarily combined without conflict to obtain new method embodiments.

[0136] The features disclosed in the several device embodiments provided in this application can be arbitrarily combined without conflict to obtain new device embodiments.

[0137] The above description is merely an embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for calculating the performance of a propeller under negative advance conditions, characterized in that, The method includes: The target values ​​of the incoming flow velocity, the axial induced velocity coefficient at the disk of the target propeller, and the circumferential induced velocity coefficient at the disk are obtained. The target propeller is in a negative advance state, which means that the incoming flow direction of the airflow is opposite to the slip flow direction of the target propeller when there is no airflow. Based on the incoming flow velocity, the target value of the axial induced velocity coefficient at the propeller disk, and the target value of the circumferential induced velocity coefficient at the propeller disk, the target value of the actual airflow velocity angle of the target propeller is determined. The actual airflow velocity angle is used to characterize the angle between the direction of the actual airflow velocity at the propeller disk of the target propeller and the plane of rotation of the target propeller. Based on the target value of the actual airflow velocity angle and the drag angle of the blade element of the target propeller, the blade element parameters of the target propeller are determined, and the blade element parameters include at least one of blade element thrust, blade element circumferential force and blade element torque. Based on the blade element parameters, the total number of blades of the target propeller, and the propeller radius, the values ​​of the performance parameters of the target propeller are determined. The performance parameters include at least one of the propeller thrust, circumferential force, and torque.

2. The method according to claim 1, characterized in that, The target values ​​for the axial induced velocity coefficient at the propeller disk and the circumferential induced velocity coefficient at the propeller disk are obtained, including: Based on the first initial value, the second initial value, and multiple mapping relationships, iterative calculations are performed until the difference between the output value of the current iteration and the output value of the previous iteration satisfies the target condition. Then, the output value of the current iteration is determined as the target value of the axial induced velocity coefficient at the propeller disk and the target value of the circumferential induced velocity coefficient at the propeller disk. The multiple mapping relationships include angle mapping relationship, blade element thrust mapping relationship, first velocity coefficient mapping relationship, blade element torque mapping relationship, and second velocity coefficient mapping relationship. The angle mapping relationship is used to characterize the relationship between the axial induced velocity coefficient at the propeller disk, the circumferential induced velocity coefficient at the propeller disk, the incoming flow velocity, and the actual airflow velocity angle. The blade element thrust mapping relationship is used to characterize the relationship between the actual airflow velocity angle, the axial induced velocity coefficient at the propeller disk, the incoming flow velocity, and the blade element thrust. The first velocity coefficient mapping relationship is used to characterize the relationship between the blade element thrust and the axial induced velocity coefficient at the propeller disk. The blade element torque mapping relationship is used to characterize the relationship between the actual airflow velocity angle, the axial induced velocity coefficient at the propeller disk, the incoming flow velocity, and the blade element torque. The second velocity coefficient mapping relationship is used to characterize the relationship between the blade element torque and the axial induced velocity coefficient at the propeller disk and the circumferential induced velocity coefficient at the propeller disk.

3. The method according to claim 2, characterized in that, The iterative calculation based on the first initial value, the second initial value, and multiple mapping relationships includes: For the first iteration calculation, the first initial value is used as the initial value of the axial induced velocity coefficient at the propeller disk in the angle mapping relationship, and the second initial value is used as the initial value of the circumferential induced velocity coefficient at the propeller disk in the angle mapping relationship. Based on the first set of mapping relationships, the input value for the next iteration calculation of the axial induced velocity coefficient at the propeller disk is obtained; the first set of mapping relationships includes the angle mapping relationship, the blade element thrust mapping relationship, and the first velocity coefficient mapping relationship; The first initial value is used as the initial value of the axial induced velocity coefficient at the propeller disk in the angle mapping relationship, and the second initial value is used as the initial value of the circumferential induced velocity coefficient at the propeller disk in the angle mapping relationship. According to the second set of mapping relationships, the input value for the next iteration calculation of the circumferential induced velocity coefficient at the propeller disk is obtained. The second set of mapping relationships includes the angle mapping relationship, the blade element torque mapping relationship, and the second velocity coefficient mapping relationship. For other iterations, the iterative calculation is performed based on the input values ​​of the axial induced velocity coefficient at the propeller disk for the next iteration, the input values ​​of the circumferential induced velocity coefficient at the propeller disk for the next iteration, and multiple mapping relationships.

4. The method according to claim 3, characterized in that, The step of using the first initial value as the initial value of the axial induced velocity coefficient at the propeller disk in the angle mapping relationship, and using the second initial value as the initial value of the circumferential induced velocity coefficient at the propeller disk in the angle mapping relationship, to obtain the input value for the next iteration calculation of the axial induced velocity coefficient at the propeller disk according to the first set of mapping relationships, includes: The first calculated value of the actual airflow velocity angle is obtained based on the first initial value, the second initial value, and the angle mapping relationship; Substituting the first initial value and the first calculated value into the leaf element thrust mapping relationship, a second calculated value of the leaf element thrust is obtained; Substituting the first initial value and the second calculated value into the first velocity coefficient mapping relationship, the first iterative output value of the axial induced velocity coefficient at the propeller disk is obtained. The first iterative output value of the axial induced velocity coefficient at the propeller disk is the input value for the next iterative calculation of the axial induced velocity coefficient at the propeller disk.

5. The method according to claim 3, characterized in that, The step of using the first initial value as the initial value of the axial induced velocity coefficient at the propeller disk in the angle mapping relationship, and using the second initial value as the initial value of the circumferential induced velocity coefficient at the propeller disk in the angle mapping relationship, and obtaining the input value for the next iteration calculation of the circumferential induced velocity coefficient at the propeller disk according to the second set of mapping relationships, includes: The first calculated value of the actual airflow velocity angle is obtained based on the first initial value, the second initial value, and the angle mapping relationship; Substituting the first initial value and the first calculated value into the blade element torque mapping relationship, a third calculated value of the blade element torque is obtained; Substituting the first initial value and the third calculated value into the second velocity coefficient mapping relationship, the first iteration output value of the circumferential induced velocity coefficient at the propeller disk is obtained. The first iteration output value of the circumferential induced velocity coefficient at the propeller disk is the input value for the next iteration calculation of the circumferential induced velocity coefficient at the propeller disk.

6. The method according to any one of claims 3-5, characterized in that, The target condition includes that the number of iterations for the iterative calculation meets a threshold; or, The difference between the output value of the axial induced velocity coefficient at the propeller disk in the current iteration and the output value in the previous iteration is less than the difference threshold, and the difference between the output value of the circumferential induced velocity coefficient at the propeller disk in the current iteration and the output value in the previous iteration is less than the difference threshold.

7. The method according to claim 2, characterized in that, The first velocity coefficient mapping relationship is determined based on the derived relationship between the axial induced velocity coefficient at the disk of the target propeller and the axial induced velocity coefficient in the slipstream region of the target propeller under the negative advance state. The derived relationship satisfies the following expression: ， Where a is the axial induced velocity coefficient at the propeller disk, and b is the axial induced velocity coefficient of the slipstream region.

8. A performance calculation device for a propeller under negative advance conditions, characterized in that, The device includes: The data acquisition module acquires the incoming flow velocity, the target value of the axial induced velocity coefficient at the disk of the target propeller, and the target value of the circumferential induced velocity coefficient at the disk. The target propeller is in a negative advance state, which means that the incoming flow direction of the airflow is opposite to the slip flow direction of the target propeller when there is no airflow. The first determining module determines the target value of the actual airflow velocity angle of the target propeller based on the incoming flow velocity, the target value of the axial induced velocity coefficient at the propeller disk, and the target value of the circumferential induced velocity coefficient at the propeller disk. The actual airflow velocity angle is used to characterize the angle between the direction of the actual airflow velocity at the propeller disk of the target propeller and the rotation plane of the target propeller. The second determining module determines the blade element parameters of the target propeller based on the target value of the actual airflow velocity angle and the drag angle of the blade element of the target propeller. The blade element parameters include at least one of blade element thrust, blade element circumferential force, and blade element torque. The third determining module determines the values ​​of the performance parameters of the target propeller based on the blade element parameters, the total number of blades of the target propeller, and the propeller radius. The performance parameters include at least one of the propeller thrust, circumferential force, and torque.

9. A computer device comprising a memory and a processor, the memory storing a computer program executable on the processor, characterized in that, When the processor executes the program, it implements the steps of the method according to any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the method as described in any one of claims 1 to 7.

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