Bearingless tail rotor aeroelastic dynamics multi-component coupling modeling method

Abstract

The invention discloses a bearingless tail rotor aeroelastic dynamics multi-component coupling modeling method, which comprises the following steps of: performing tail rotor pneumatic coupling modeling under the action of rotor interference airflow, performing tail beam / tail rotor structure coupling modeling, and coupling a tail rotor pneumatic model and a tail beam elastic support tail rotor structure model considering rotor interference; and dynamic modeling and analysis of the tail rotor gas bomb in a complex dynamic environment are realized. The tail rotor blade aerodynamic modeling adopts an unsteady surface element method and a free wake model, the rotor interference modeling calculates the induction influence of the space where the tail rotor and the tail rotor wake are located based on the rotor wake, and a tail rotor / tail beam coupling structure model is established based on tail rotor hub freedom degree coordination. According to the method, coupling factors in helicopter tail rotor aeroelastic dynamics analysis are fully considered, high-confidence modeling of the actual physical state of the tail rotor is achieved under the condition that the calculation scale is controllable, and the reliability of tail rotor aeroelastic dynamics modeling and load prediction is improved; the method is particularly suitable for predicting and analyzing the tail rotor load of the single-rotor helicopter with the tail rotor.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of helicopter aeroelastic dynamics, and particularly relates to a bearingless tail rotor aeroelastic dynamics multi-component coupling modeling method. BACKGROUND

[0002] The tail rotor is one of the key components of a helicopter, and reliable tail rotor aeroelastic dynamics modeling is the basis for tail rotor dynamic load analysis and tail boom and tail transmission system dynamics design. The tail rotor is in a complex aerodynamic and structural environment of main rotor interference airflow and tail boom elastic support, and the influence of the rotor interference airflow and the structural coupling with the tail boom need to be considered in the tail rotor aeroelastic dynamics modeling.

[0003] In the current tail rotor dynamics analysis, the influence of the rotor interference airflow is generally considered in the field of aerodynamic load and noise analysis; the blade is taken as a rigid body in the dynamics stability analysis to combine with the beam tail boom model to establish a tail rotor tail boom coupling dynamics model; the aeroelastic coupling effect and the tail rotor tail boom coupling characteristics are not considered in the literature“Dynamic characteristics and dynamic response analysis of heavy helicopter tail rotor”, and various existing analysis models and modeling methods are difficult to be effectively applied to high-confidence tail rotor aeroelastic response analysis. In view of the above problems, the present application provides a bearingless tail rotor aeroelastic dynamics multi-component coupling modeling method, which realizes tail rotor aeroelastic dynamics modeling and analysis in a complex dynamic environment through tail rotor aerodynamic coupling modeling under the action of rotor interference airflow, tail boom / tail rotor structure coupling modeling, and tail rotor structure model coupling considering the tail rotor aerodynamic and tail boom elastic support of the rotor interference. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a bearingless tail rotor aeroelastic dynamics multi-component coupling modeling method in view of the defects in the background art.

[0005] The present application adopts the following technical solutions to solve the above technical problems:

[0006] A bearingless tail rotor aeroelastic dynamics multi-component coupling modeling method, comprising the following steps:

[0007] Step 1), tail rotor aerodynamic modeling under the action of rotor interference airflow is performed;

[0008] Step 1.1), initialize rotor control parameters and rotor wake, solve rotor blade circulation, calculate rotor wake strength and rotor wake spatial distribution based on rotor wake control equation, obtain converged rotor wake vortex and rotor wake spatial distribution through rotor blade circulation and rotor wake iteration solution;

[0009] Step 1.2), calculate rotor load based on rotor control parameters, rotor wake strength and rotor wake spatial distribution, update rotor control input, iterative trim, calculate rotor wake vortex and rotor wake spatial distribution characteristics in trim state , , are rotor wake azimuth angle and rotor wake vortex age angle respectively;

[0010] Step 1.3), establish the aerodynamic model of tail rotor based on Leishman-Beddoes model and free wake model, rotor interference effect is corrected by rotor wake vortex and rotor wake spatial distribution characteristics Induced velocity in tail rotor wake control equation, generate tail rotor wake control equation under the action of rotor interference flow;

[0011] The tail rotor wake control equation is , wherein , are tail rotor wake azimuth angle and tail rotor wake vortex age angle respectively, , is the incoming flow velocity, , , are the induced velocities of the attached vortex, near wake and far wake of the tail rotor at ; , , are the incoming flow velocities of the tail rotor due to the horizontal forward flight and vertical lift of the helicopter, the side slip, is the induced velocity generated by the main rotor interference; , is a rotor vortex segment, is the vector of the rotor vortex segment to the tail rotor wake control point;

[0012] Step 1.4), solve the tail rotor wake ​: The tail rotor control parameters and the tail rotor wake are initialized, the unsteady panel method is used to solve the circulation of the tail rotor blade, the tail rotor wake control equation based on the rotor interference airflow is used to calculate the tail rotor wake intensity and the tail rotor wake spatial distribution, and the converged tail rotor wake vortex and the tail rotor wake spatial distribution are obtained through the iteration of the tail rotor blade circulation and the tail rotor wake.

[0013] Step 1.5), the tail rotor load is calculated based on the tail rotor control parameters, the tail rotor wake intensity and the tail rotor wake spatial distribution, the tail rotor control input is updated, the required tail rotor pull force of the helicopter is realized, and the rotor wake vortex and the tail rotor wake spatial distribution characteristics in the trimming state are calculated . ;

[0014] Step 2), the tail boom / tail rotor structure coupling modeling;

[0015] Step 2.1), the tail rotor blade, the sleeve and the flexible beam structure are modeled by using the 15-node free degree medium deformation beam finite element;

[0016] Step 2.2), the wobble pin of the bearingless tail rotor is connected with the hub and the sleeve through a hinge, the linear motion in the flapping and wobble directions of the blade is constrained, the radial linear motion and three angular motions are released;

[0017] Step 2.3), the tail rotor dynamics equation is established based on the Hamilton action principle as , is the mass matrix of the tail rotor system, is the acceleration of the generalized coordinates of the tail rotor system, is the tail rotor aerodynamic load, is the nonlinear generalized force of kinetic energy, is the nonlinear generalized force of strain energy, is the hub load work coefficient matrix, is the interface load acting on the hub of the tail rotor;

[0018] Step 2.4), the tail boom structure model is established by using the finite element method, the tail rotor tail boom connection degrees of freedom are reserved, and the dynamics equation is , M b , C b , K b are the tail boom structure mass matrix, damping matrix and stiffness matrix respectively, and the degrees of freedom are the interface degrees of freedom of the tail boom connected with the tail rotor, is the dynamic load acting on the tail boom at the interface connected with the tail rotor; , , n is the number of degrees of freedom of the rotor system, then , ;

[0019] Step 2.5), based on the balance condition of the interface force between the tail rotor and the tail boom, i.e. , the calculation is , ; the tail rotor / tail boom coupling model dynamic equation is:

[0020] ;

[0021] Step 3), tail rotor aerodynamic load modeling:

[0022] Based on , , , , , , , , , , , the tail rotor aerodynamic load is calculated by using the blade element theory , the tail rotor aerodynamic load The airfoil normal force coefficient C N , the moment coefficient C M and the chordwise force coefficient C C are calculated by using the Leishman-Beddoes model.

[0023] As a further optimization scheme of the bearingless tail rotor aeroelastic dynamics multi-component coupling modeling method, the 15-node free degree of deformation beam model in step 2.1) includes 3 translational degrees of freedom of the two end nodes, 3 rotational degrees of freedom of the two end nodes, and 2 tensile degrees of freedom and 1 torsional degree of freedom inside the deformation beam.

[0024] As a further optimization scheme of the bearingless tail rotor aeroelastic dynamics multi-component coupling modeling method, the W-L model is used to solve the rotor blade circulation in step 1.1).

[0025] Compared with the prior art, the above technical scheme has the following technical effects:

[0026] The present application realizes tail rotor aeroelastic dynamics modeling and analysis in a complex dynamic environment by tail rotor aerodynamic coupling modeling under the action of rotor interference airflow, tail boom / tail rotor structure coupling modeling, and tail rotor structure model coupling considering the tail rotor aerodynamic and tail boom elastic support of rotor interference. The present application fully considers the coupling factors in helicopter tail rotor aeroelastic dynamics analysis, realizes high-confidence modeling of the actual physical state of the tail rotor under the condition of controllable calculation scale, improves the reliability of tail rotor aeroelastic dynamics modeling and load prediction, and is particularly suitable for tail rotor load prediction and analysis of single-rotor tail rotor helicopters. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 A schematic diagram of a bearingless tail rotor aerodynamic multi-component coupling modeling method of the application;

[0028] Figure 2 A tail rotor wake calculation example under the influence of rotor airflow interference of the application;

[0029] Figure 3 A bearingless tail rotor aerodynamic multi-component coupling modeling method of the application calculates the precision example verification. DETAILED DESCRIPTION

[0030] The technical solutions of the application will be further described in detail below with reference to the accompanying drawings:

[0031] The application can be implemented in many different forms, and should not be considered limited to the embodiments described herein. On the contrary, these embodiments are provided to make the disclosure thorough and complete, and to fully convey the scope of the application to those skilled in the art. In the drawings, components are enlarged for clarity.

[0032] As Figure 1 shown, the application discloses a bearingless tail rotor aerodynamic multi-component coupling modeling method, which fully considers the coupling factors in helicopter tail rotor aerodynamic analysis, improves the reliability of tail rotor aerodynamic modeling and load prediction, and includes the following steps:

[0033] Step 1), tail rotor aerodynamic modeling under the influence of rotor interference airflow;

[0034] Step 1.1), initialize the rotor control parameters and rotor wake, solve the rotor blade circulation using the W-L model, calculate the rotor wake intensity and rotor wake spatial distribution based on the rotor wake control equation, and obtain the converged rotor wake vortex and rotor wake spatial distribution through rotor blade circulation and rotor wake iteration solution;

[0035] Step 1.2), calculate the rotor load based on the rotor control parameters, rotor wake intensity and rotor wake spatial distribution, update the rotor control input, and iteratively trim to calculate the rotor wake vortex and rotor wake spatial distribution characteristics and rotor wake spatial distribution characteristics , , are the rotor wake azimuth angle and rotor wake vortex age angle, respectively;

[0036] Step 1.3), establish an aerodynamic tail rotor aerodynamic model based on the Leishman-Beddoes model and the free wake model, and the rotor interference effect is realized through the rotor wake vortex and rotor wake spatial distribution characteristics Correct the induced velocity in the tail rotor wake control equation to generate the tail rotor wake control equation under the influence of rotor interference airflow.

[0037] The tail rotor wake The governing equation is In the formula, , These are the tail rotor wake azimuth angle and the tail rotor wake vortex leader angle, respectively. , For the incoming flow velocity, , , These are the attached vortex, near wake, and far wake of the tail rotor, respectively. Induction velocity at the location; , , These refer to the incoming flow velocities generated by the tail rotor as the helicopter flies horizontally forward and vertically up and down. The incoming flow generated by sideslip The induced velocity generated by the main rotor interference; , For rotor vortex micro-segment, The vector from the rotor vortex microsegment to the control point of the tail rotor wake;

[0038] Step 1.4) uses a pseudo-implicit prediction-correction algorithm to solve for the tail rotor wake. Initialize the tail rotor control parameters and tail rotor wake. Use the unsteady surface element method to solve the tail rotor blade circulation. Calculate the tail rotor wake intensity and tail rotor wake spatial distribution based on the tail rotor wake control equation under the action of rotor interference airflow. Obtain the converged tail rotor wake vorticity and tail rotor wake spatial distribution by iteratively solving the tail rotor blade circulation and tail rotor wake.

[0039] Step 1.5): Calculate the tail rotor load based on tail rotor control parameters, tail rotor wake intensity, and tail rotor wake spatial distribution; update the tail rotor control input to achieve the required tail rotor thrust for the helicopter; and calculate the rotor wake vorticity under trim conditions. Spatial distribution characteristics of tail rotor wake ,like Figure 2 As shown;

[0040] Step 2), tail boom / tail rotor structure coupling modeling;

[0041] Step 2.1), the tail rotor blades, sleeves, and flexible beam structure are all modeled using finite element method for a 15-node, moderately deformable beam.

[0042] Step 2.2), the oscillation pin of the bearingless tail rotor is connected to the rotor hub and sleeve through a hinge, which constrains the linear motion in the direction of blade flapping and oscillation, and releases the radial linear motion and the three angular motions.

[0043] Step 2.3), the dynamic equation of the tail rotor is established based on Hamilton's principle as , is the mass matrix of the tail rotor system, is the acceleration of the generalized coordinates of the tail rotor system, is the aerodynamic load of the tail rotor, is the nonlinear generalized force of kinetic energy, is the nonlinear generalized force of strain energy, is the hub load work coefficient matrix of the tail rotor, is the interface load acting on the hub of the tail rotor.

[0044] Step 2.4), the tail beam structure model is established using the finite element method, and the tail rotor tail beam connection degrees of freedom are retained, and the dynamic equation is , M b , C b , K b are the mass matrix, damping matrix, and stiffness matrix of the tail beam structure, respectively, and the degrees of freedom are the interface degrees of freedom of the tail beam connected to the tail rotor, is the dynamic load acting on the tail beam at the interface connected to the tail rotor; , , n is the number of degrees of freedom of the rotor system, then , ;

[0045] Step 2.5), based on the force balance condition at the interface of the tail rotor tail beam, i.e. , the following is calculated , ; then the dynamic equation of the tail rotor / tail beam coupling model is:

[0046] ;

[0047] Step 3), tail rotor aerodynamic load modeling:

[0048] Based on , , , , , , , , , , , the blade element theory is used to calculate the tail rotor aerodynamic load , the tail rotor aerodynamic load in the calculation of the airfoil normal force coefficient C N , the moment coefficient C M , and the chordwise force coefficient C CThe Leishman-Beddoes model is used.

[0049] The 15-node free degree of deformation beam model includes 3 translational degrees of freedom of the two end nodes, 3 rotational degrees of freedom of the two end nodes, and 2 tensile degrees of freedom and 1 torsional degree of freedom inside the deformation beam.

[0050] The application fully considers the coupling factors in the helicopter tail rotor aeroelasticity analysis, Figure 3 According to the calculation results of a certain example model, the application realizes tail rotor aeroelasticity modeling and analysis in a complex dynamic environment by tail rotor aeroelastic coupling modeling under the action of a rotor interference airflow, tail beam / tail rotor structure coupling modeling, and tail rotor structure model coupling considering the tail rotor aeroelasticity and the elastic support of the tail beam under the interference of the rotor, and the reliability of tail rotor aeroelasticity modeling and load prediction is higher.

[0051] As can be appreciated by those skilled in the art to which the present technology pertains, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art in the field to which this application belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0052] The above detailed description of the specific embodiments of the present application has further explained the purpose, technical solutions and beneficial effects of the present application, and it should be understood that the above description is only a specific embodiment of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for coupled multi-component aeroelastic dynamics modeling of a bearingless tail rotor, characterized in that, Includes the following steps: Step 1), perform aerodynamic modeling of the tail rotor under the influence of rotor interference airflow; Step 1.1) Initialize the rotor control parameters and rotor wake, solve the rotor blade circulation, calculate the rotor wake intensity and rotor wake spatial distribution based on the rotor wake control equation, and obtain the converged rotor wake vorticity and rotor wake spatial distribution by iteratively solving the rotor blade circulation and rotor wake. Step 1.2): Calculate the rotor load based on rotor control parameters, rotor wake intensity, and rotor wake spatial distribution; update the rotor control input; iteratively trim; and calculate the rotor wake vorticity under trimmed conditions. Spatial distribution characteristics of rotor wake , , These are the rotor wake azimuth angle and the rotor wake vortex angle, respectively. Step 1.3) Establish an aerodynamic model for the tail rotor based on the Leishman-Beddoes model and the free wake model. The rotor interference effect is reflected through the rotor wake vorticity. Spatial distribution characteristics of rotor wake The induced velocity in the tail rotor wake control equation is modified to generate the tail rotor wake control equation under the action of rotor interference airflow. The tail rotor wake The governing equation is In the formula, , These are the tail rotor wake azimuth angle and the tail rotor wake vortex leader angle, respectively. , For the incoming flow velocity, , , These are the attached vortex, near wake, and far wake of the tail rotor, respectively. Induction velocity at the location; , , These refer to the incoming flow velocities generated by the tail rotor as the helicopter flies horizontally forward and vertically up and down. The incoming flow generated by sideslip The induced velocity generated by the main rotor interference; , For rotor vortex micro-segment, The vector from the rotor vortex microsegment to the control point of the tail rotor wake; Step 1.4) uses a pseudo-implicit prediction-correction algorithm to solve for the tail rotor wake. Initialize the tail rotor control parameters and tail rotor wake. Use the unsteady surface element method to solve the tail rotor blade circulation. Calculate the tail rotor wake intensity and tail rotor wake spatial distribution based on the tail rotor wake control equation under the action of rotor interference airflow. Obtain the converged tail rotor wake vorticity and tail rotor wake spatial distribution by iteratively solving the tail rotor blade circulation and tail rotor wake. Step 1.5): Calculate the tail rotor load based on tail rotor control parameters, tail rotor wake intensity, and tail rotor wake spatial distribution; update the tail rotor control input to achieve the tail rotor thrust required by the helicopter; and calculate the rotor wake vorticity under trim conditions. Spatial distribution characteristics of tail rotor wake ; Step 2), tail boom / tail rotor structure coupling modeling; Step 2.1), the tail rotor blades, sleeves, and flexible beam structure are all modeled using finite element method for a 15-node, moderately deformable beam. Step 2.2), the oscillation pin of the bearingless tail rotor is connected to the rotor hub and sleeve through a hinge, which constrains the linear motion in the direction of blade flapping and oscillation, and releases the radial linear motion and the three angular motions. Step 2.3), based on Hamilton's action principle, establish the tail rotor dynamic equation as follows: , Here is the mass matrix of the tail rotor system. The acceleration of the tail rotor system in the generalized coordinate system. For tail rotor aerodynamic load, For nonlinear generalized forces of kinetic energy, For nonlinear generalized forces of strain energy, Work coefficient matrix for hub load, The interfacial load acting on the tail rotor hub; Step 2.4) Establish the tail boom structure model using the finite element method, retaining the tail rotor tail boom connection degree of freedom. The dynamic equation is: M b C b K b These represent the mass matrix, damping matrix, and stiffness matrix of the tail beam structure, and their degrees of freedom. The degree of freedom is the interface on the tail boom that connects to the tail rotor. The dynamic load acting on the tail boom at the interface with the tail rotor; , Let n be the number of degrees of freedom of the rotor system, then , ; Step 2.5), based on the equilibrium condition of the forces at the tail rotor tail boom connection interface, is... Calculated , The dynamic equations for the tail rotor / tail boom coupled model are: ； Step 3), Tail rotor aerodynamic load modeling: based on , , , , , , , , , , The tail rotor aerodynamic load was calculated using blade element theory. Tail rotor aerodynamic load The airfoil normal force coefficient C in the calculation N Torque coefficient C M Chord force coefficient C C The Leishman-Beddoes model was adopted.

2. The bearingless tail rotor aeroelastic dynamics multi-component coupled modeling method according to claim 1, characterized in that, The 15-node moderately deformable beam model in step 2.1) includes 3 translational degrees of freedom at both ends, 3 rotational degrees of freedom at both ends, and 2 tensile degrees of freedom and 1 torsional degree of freedom inside the deformable beam.

3. The bearingless tail rotor aeroelastic dynamics multi-component coupled modeling method according to claim 1, characterized in that, In step 1.1), the WL model is used to solve for the rotor blade circulation.

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