Dynamic modeling method for multi-propeller tilt-rotor aircraft

Abstract

The invention belongs to the field of dynamics of high-speed rotor aircrafts, and particularly relates to a dynamics modeling method for a multi-propeller tilt rotor aircraft. The method comprises the following steps: establishing a non-rotating blade model as a wing model, discretizing by using a finite element method, assigning any unit number and unit node division, and setting as a rigid body or an elastic body as required; establishing a rigid hub thrust rotor model; establishing a rigid propeller hub lift rotor model; connecting structural dynamics interfaces of'rotor body rigid body 'assemblies of the rigid propeller hub thrust rotor model and the rigid propeller hub lift rotor model with structural dynamics interfaces created on the non-rotating blades to obtain a rotor-wing coupling structure model; and on the rotor wing-wing coupling structure model, establishing a rotor wing-wing coupling aerodynamic force model considering the aerodynamic interference of the rotor wing slip flow on the wing.

Description

Technical Field

[0001] This application belongs to the field of dynamics of high-speed rotorcraft, and particularly relates to a dynamic modeling method for a multi-rotor tilt-rotor aircraft. Background Art

[0002] For a multi-rotor tilt-rotor configuration aircraft, the existing dynamic calculation method is to separately establish the isolated rotor models and wing models of each rotor, and calculate them separately. Then, the calculated loads are added to the wing as external loads for analysis to obtain the deformation and motion of the wing under load. Then, the results are, in turn, passed to the isolated rotor model as boundary conditions for another calculation of the isolated rotor. This process is repeated iteratively many times until the calculation results converge. Using this method for dynamic simulation of a multi-rotor tilt-rotor configuration aircraft, the calculation process is very cumbersome, and the iterative process requires a large amount of computing resources. At the same time, since the coupling between the wing and the rotor is not completed, this method is not accurate enough in simulating the rotor-wing aeroelastic coupling phenomenon. Summary of the Invention

[0003] Object of the Invention: To provide a dynamic simulation model for a multi-rotor tilt-rotor configuration aircraft, which can be used to perform dynamic simulation calculations on multiple rotors and wings simultaneously, and can accurately simulate the structural coupling and aerodynamic interference between the rotor and the wing.

[0004] Technical Solution:

[0005] The present invention provides a dynamic modeling method for a multi-rotor tilt-rotor aircraft, including:

[0006] Establish a non-rotating blade model as the wing model, discretize it using the finite element method, specify any number of elements and element node divisions, and set it as a rigid body or an elastic body as needed;

[0007] Establish a rigid hub thrust rotor model. The rigid hub thrust rotor model consists of 4 blades, does not include an automatic pitch control device, and the thrust rotor is suspended at the wing tip;

[0008] Establish a rigid hub lift rotor model. The rigid hub lift rotor model consists of 4 blades, does not include an automatic pitch control device, and the lift rotor can be suspended at any spanwise position of the wing. Multiple sets of lift rotors can be suspended at different spanwise positions;

[0009] Connect the structural dynamics interfaces of the "rotor-airframe rigid body" components of the rigid hub thrust rotor model and the rigid hub lift rotor model to the structural dynamics interfaces created on the non-rotating blades to obtain a rotor-wing coupled structure model;

[0010] On the rotor-wing coupled structure model, establish a rotor-wing coupled aerodynamic force model considering the aerodynamic interference of the rotor slipstream on the wing.

[0011] Furthermore, the rotor-wing coupled aerodynamic model supports free customization of airfoils, and different airfoils are adopted for the blades and the wing at different spanwise positions.

[0012] Furthermore, a non-rotating blade model is established as the wing model, including:

[0013] Establish a wing model in the helicopter aerodynamic performance calculation software:

[0014] First, establish a set of rotors, set the rotor speed, the number of rotor blades, the forward tilt angle of the rotor shaft, set the spanwise position of the concentrated mass distribution points of the blades to the positions where the thrust rotors and lift rotors on the aircraft are connected to the wing, and finally set the number of elements, node distribution, and airfoil distribution according to the requirements of simulation accuracy.

[0015] Furthermore, a rigid hub thrust rotor model is established, including:

[0016] Establish a thrust rotor model in the helicopter aerodynamic performance calculation software: First, establish a set of rotors, set the rotor speed, the number of rotor blades, the blade section parameters, the spanwise distribution of airfoils, the spanwise position of the pitch hinge, and the pitch hinge stiffness parameters according to the actual situation of the simulation object, and then set the forward tilt angle of the rotor shaft to -90 degrees.

[0017] Furthermore, a rigid hub lift rotor model is established, including:

[0018] Establish a lift rotor model in the helicopter aerodynamic performance calculation software: First, establish multiple sets of rotors equal to the number of lift rotors of the simulation object, set the speed, the number of rotor blades, the blade section parameters, the spanwise distribution of airfoils, the spanwise position of the pitch hinge, and the pitch hinge stiffness parameters of each set of rotors according to the actual situation of the simulation object, and then set the forward tilt angle of each rotor shaft to -90 degrees.

[0019] Furthermore, connect the structural dynamics interfaces of the "rotor-airframe rigid body" components of the rigid hub thrust rotor model and the rigid hub lift rotor model to the structural dynamics interfaces created on the non-rotating blades to obtain a rotor-wing coupled structural model, including:

[0020] Use the CAMRAD CORE command to establish a structural connection between the lift rotor and the wing: Add 1 geometric feature point to the element where the wing is connected to the lift rotor, number it as the 5th geometric feature point, edit the coordinates of the 5th feature point in the element system to the coordinates of the actual position of the point where the wing is connected to the lift rotor in the element system; Add a structural dynamics interface to the element where the wing is connected to the lift rotor, number it as the 4th structural dynamics interface, and edit the base point of the 4th structural dynamics interface to the 5th geometric feature point; Change the input end of the structural dynamics interface component between the lift rotor and the airframe to the 4th structural dynamics interface established above;

[0021] Use the CAMRAD CORE command to establish a structural connection between the thrust rotor and the wing; change the feature coordinate system direction of the second geometric feature point of the last element of the wing to (-90, -90, 0), and then change the input end of the structural dynamics interface component between the thrust rotor and the fuselage to the second structural dynamics interface of the last element of the wing.

[0022] Furthermore, on the rotor-wing coupled structure model, establish a rotor-wing coupled aerodynamic force model considering the aerodynamic interference of the rotor slipstream on the wing, including:

[0023] Run the helicopter aerodynamic performance calculation software for the first dynamic simulation to obtain the thrust coefficients and induced velocities of the lift rotor and the thrust rotor. Calculate the aerodynamic interference coefficients of the lift rotor and the thrust rotor based on the obtained thrust coefficients and induced velocities. The calculation formula is:

[0024] where V i is the calculated aerodynamic interference coefficient; e is the natural logarithm constant, V is the forward flight speed of the aircraft, V1 is the induced velocity of the lift rotor and the thrust rotor obtained from the first dynamic simulation, C T is the thrust coefficient of the lift rotor and the thrust rotor obtained from the first dynamic simulation, and h is the distance from the rotation center of the lift rotor and the thrust rotor to the quarter chord line of the wing;

[0025] Assign the aerodynamic interference coefficients obtained from the first calculation to the lift rotor and the thrust rotor in the helicopter aerodynamic performance calculation software;

[0026] Run the helicopter aerodynamic performance calculation software for the second calculation to obtain the final dynamic simulation results.

[0027] Beneficial effects:

[0028] This invention can solve the problem of dynamic simulation calculation of the multi-rotor tilt configuration rotorcraft. Using the model described in the present invention, the iterative process can be eliminated to simulate the aeroelastic coupling dynamic phenomenon of the multi-rotor tilt configuration rotorcraft with high accuracy. Moreover, the number of rotors, the rotor aerodynamic structure parameters, and the wing aerodynamic structure parameters can all be arbitrarily given, which can meet the simulation calculation requirements in the design work of the multi-rotor tilt configuration rotorcraft. Description of the Drawings

[0029] Figure 1 Schematic diagram of the multi-rotor tilt wing for the implementation case.

[0030] Figure 2 Modeling command diagram of the lift rotor in the implementation case.

[0031] Figure 3 Command diagram for wing modeling in the implementation case

[0032] Figure 4 CORE command diagram for creating the wing-rotor structural dynamics interface in the implementation case

[0033] Figure 5 Calculation result diagram for the implementation case Detailed implementation manners

[0034] To make the objectives, technical solutions and advantages of the implementation of this application clearer, the technical solutions in the implementation manners of this application will be described in more detail below with reference to the accompanying drawings in the implementation manners of this application. In the drawings, the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions from beginning to end. The described implementation manners are some but not all of the implementation manners of this application. The implementation manners described below with reference to the drawings are exemplary and are intended to explain this application and should not be construed as a limitation of this application. All other implementation manners obtained by those of ordinary skill in the art based on the implementation manners in this application without making creative efforts fall within the scope of protection of this application. The implementation manners of this application will be described in detail below with reference to the drawings.

[0035] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "axial direction", "vertical", "upper", "lower", "upper end", "bottom end", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the protection scope of the present invention.

[0036] The present invention provides a multi-rotor tilting configuration rotorcraft dynamics simulation model, as Figure 1 shown, the model includes:

[0037] 1) A wing model, which is discretized using the finite element method, can specify any number of elements and element node divisions, and can be set as a rigid body or an elastic body as needed;

[0038] 2) A rigid hub thrust rotor model, which consists of 4 blades, does not include a swashplate, and the thrust rotor is suspended at the wing tip;

[0039] 3) A rigid hub lift rotor model, which consists of 4 blades, does not include a swashplate, the lift rotor can be suspended at any spanwise position of the wing, and multiple sets of lift rotors can be suspended at different spanwise positions;

[0040] 4) Rotor-wing coupled aerodynamic force model, which supports free customization of airfoils. The blades and wings can adopt different airfoils at different spanwise positions, and the aerodynamic interference of the rotor slipstream on the wing can be taken into account.

[0041] Key points of the present invention:

[0042] 1) Establish a non-rotating blade model in the helicopter aerodynamic performance calculation software, discretize it into an optional number of finite elements according to the model accuracy requirements, and determine the airfoil distribution along the span.

[0043] Specifically, establish a wing model in the helicopter aerodynamic performance calculation software. The specific method is to first establish a set of rotors, set the rotor speed to 0, set the number of rotor blades to 1, set the forward tilt angle of the rotor shaft to 0 degrees, set the spanwise position of the concentrated mass distribution point of the blade to the position where the thrust rotor and lift rotor on the aircraft are connected to the wing, and finally set the number of elements, node distribution, and airfoil distribution according to the simulation accuracy requirements. Its code is as Figure 3 shown.

[0044] 2) Establish a thrust rotor model in the helicopter aerodynamic performance calculation software, and determine its blade section parameters, airfoil spanwise distribution, spanwise position of the pitch hinge, and pitch hinge stiffness parameters.

[0045] Specifically, establish a thrust rotor model in the helicopter aerodynamic performance calculation software. The specific method is to first establish a set of rotors, set the rotor speed, number of rotor blades, blade section parameters, airfoil spanwise distribution, spanwise position of the pitch hinge, and pitch hinge stiffness parameters according to the actual situation of the simulation object, and then set the forward tilt angle of the rotor shaft to -90 degrees; its code is as Figure 2 shown.

[0046] 3) Establish a lift rotor model in the helicopter aerodynamic performance calculation software, establish multiple rotor models according to the actual number of rotors, and respectively determine their blade section parameters, airfoil spanwise distribution, spanwise position of the pitch hinge, and pitch hinge stiffness parameters.

[0047] Specifically, establish a lift rotor model in the helicopter aerodynamic performance calculation software. The specific method is to first establish multiple sets of rotors equal to the number of lift rotors of the simulation object, set the speed, number of rotor blades, blade section parameters, airfoil spanwise distribution, spanwise position of the pitch hinge, and pitch hinge stiffness parameters of each set of rotors according to the actual situation of the simulation object, and then set the forward tilt angle of each rotor shaft to -90 degrees;

[0048] 4) Use the core command to create a structural dynamics interface on the non-rotating blade. The interface is located at the point where the lift rotor connects to the wing. Connect the structural dynamics interface of the "rotor body rigid body" component in the lift rotor model to the structural dynamics interface created on the non-rotating blade. Connect the structural dynamics interface of the "rotor body rigid body" component in the thrust rotor model to the structural dynamics interface on the end of the non-rotating blade.

[0049] Specifically, use the CAMRAD CORE command to establish a structural connection between the lift rotor and the wing. Add a geometric feature point to the unit connecting the wing and lift rotor, number it as geometric feature point 5, and edit the coordinates of feature point 5 in the unit system to the coordinates of the actual position of the point connecting the wing and lift rotor in the unit system; add a structural dynamics interface to the unit connecting the wing and lift rotor, number it as structural dynamics interface 4, and edit the base point of structural dynamics interface 4 to geometric feature point 5; change the input end of the structural dynamics interface component between the lift rotor and the fuselage to the structural dynamics interface 4 established above;

[0050] Use the CAMRAD CORE command to establish a structural connection between the thrust rotor and the wing. Change the feature coordinate system orientation of feature point 2 of the last element of the wing to (-90, -90, 0). Then, change the input of the Structural Dynamics Interface component between the thrust rotor and the fuselage to the Structural Dynamics Interface 2 of the last element of the wing.

[0051] 5) Run the helicopter aerodynamic performance calculation software to perform the initial dynamic simulation to obtain the drag coefficient and induced velocity of the lift rotor and thrust rotor. The aerodynamic interference coefficient of the lift rotor and thrust rotor is calculated based on the obtained drag coefficient and induced velocity. The calculation formula is: Where V i is the calculated aerodynamic interference coefficient; e is the natural logarithmic constant, V is the forward flight speed of the aircraft, V1 is the induced speed of the lift rotor and thrust rotor obtained from the initial dynamics simulation, C T is the drag coefficient of the lift rotor and thrust rotor obtained from the initial dynamics simulation, h is the distance between the rotation center of the lift rotor and thrust rotor and the quarter chord line of the wing;

[0052] 6) Assign the aerodynamic interference coefficient obtained from the initial calculation to the lift rotor and thrust rotor in the helicopter aerodynamic performance calculation software;

[0053] 7) Run the helicopter aerodynamic performance calculation software for secondary calculation to obtain the final dynamic simulation results.

[0054] Example 1

[0055] This embodiment provides a solution for performing dynamic simulation on a multi-rotor tilting configuration rotorcraft using a dynamic simulation model of the multi-rotor tilting configuration rotorcraft, to solve the problem of the lack of a simulation model for the multi-rotor tilting configuration rotorcraft. The specific steps are as follows:

[0056] Step 1: Observe and analyze the multi-rotor tilting configuration rotorcraft to be calculated, and clarify that the model includes 2 pairs of lift rotors, which are respectively suspended at 0.8 m and 2.4 m from the wing root, and 1 pair of thrust rotors, which are suspended at the wing tip;

[0057] Step 2: Observe and measure the lift rotors, and clarify that the lift rotors are composed of 4 blades, the radius of the blade disc is 0.7 m, a pitch hinge is provided at 0.035 m from the blade root for each blade, clarify the distribution of the blade section parameters along the span, and clarify the distribution of the airfoil parameters along the span;

[0058] Step 3: Observe and measure the thrust rotors, and clarify that the lift rotors are composed of 4 blades, the radius of the blade disc is 0.7 m, a pitch hinge is provided at 0.035 from the blade root for each blade, clarify the distribution of the blade section parameters along the span, and clarify the distribution of the airfoil parameters along the span;

[0059] Step 4: Establish the overall aircraft topology structure in the helicopter aerodynamic performance calculation software, set the total number of rotors to 4, Rotor 1 is a non-rotating rotor, Rotors 2 and 3 are lift rotors, and Rotor 4 is a thrust rotor, and set the coordinates of the hub center of each rotor in the fuselage system according to the surveying and mapping data of the object to be simulated;

[0060] Step 5: Set the detailed parameters of Rotor 1. According to the surveying and mapping data of the wing of the object to be simulated, set the radius of the non-rotating rotor, the distribution of the linear density along the span, the distribution of the flapping stiffness along the span, the distribution of the lead-lag stiffness along the span, the distribution of the torsional stiffness along the span, and the distribution of the airfoil along the span in the helicopter aerodynamic performance calculation software;

[0061] Step 6: Set the detailed parameters of Rotors 2, 3, and 4. According to the surveying and mapping data of the lift rotors and thrust rotors of the object to be simulated, set the spanwise position of the pitch hinge, the number of blades, the distribution of the blade linear density along the span, the distribution of the flapping stiffness along the span, the distribution of the lead-lag stiffness along the vibration mode, the distribution of the torsional stiffness along the span, and the distribution of the airfoil along the span in the helicopter aerodynamic performance calculation software;

[0062] Step 7: Use the CAMRAD CORE command to connect the structural dynamics interface on the "fuselage-rotor assembly" of Rotor 2 with the structural dynamics interface at the coordinate (0.8, 0, 0) on the non-rotating Rotor 1;

[0063] Step 8: Use the CAMRAD CORE command to connect the structural dynamics interface on the "fuselage rotor assembly" of rotor 3 to the structural dynamics interface at the coordinates (2.4, 0, 0) on the non-rotating rotor 1;

[0064] Step 9: Use the CAMRAD CORE command to connect the structural dynamics interface on the "fuselage rotor assembly" of rotor 4 to the structural dynamics interface at the coordinates (4, 0, 0) on the non-rotating rotor 1;

[0065] Step 10: Set the calculation requirement environment in the helicopter aerodynamic performance calculation software, including wind speed, air pressure, and temperature;

[0066] Step 11: Run the CAMRAD calculation module to perform the dynamic calculation of the multi-rotor tilting configuration rotorcraft. After waiting for the calculation to end, view the output file to obtain the dynamic calculation results of the multi-rotor tilting configuration rotorcraft as Figure 5 shown.

[0067] In summary, the present invention proposes a dynamic simulation model for a multi-rotor tilting configuration rotorcraft. The present invention uses CAMRAD to establish a wing simulation model and a rotor simulation model, and uses the CORE command ( Figure 4 ) to add a structural dynamics interface between the wing and the rotor, so that the aeroelastic coupling effect between the rotor and the wing can be accurately simulated in one calculation, achieving the purpose of performing dynamic simulation calculations on the multi-rotor tilting rotorcraft.

[0068] After considering the specification and practicing the disclosure herein, those skilled in the art will readily conceive of other embodiments of the present disclosure. This application is intended to cover any variations, uses, or adaptations of the present disclosure that follow the general principles of the present disclosure and include known common knowledge or conventional technical means in the technical field not disclosed in the present disclosure. The specification and embodiments are only regarded as exemplary, and the true scope and spirit of the present disclosure are pointed out by the following claims.

[0069] It should be understood that the present disclosure is not limited to the exact structures described above and shown in the drawings, and various modifications and changes can be made without departing from its scope. The scope of the present disclosure is only limited by the appended claims.

Claims

1. A dynamic modeling method for a multi-rotor tilt-rotor aircraft, characterized in that Including: Establish a non-rotating blade model as the wing model, discretize it using the finite element method, specify any number of elements and element node divisions, and set it as a rigid body or elastic body as needed; Establish a rigid hub thrust rotor model. The rigid hub thrust rotor model consists of 4 blades, without a swashplate, and the thrust rotor is suspended at the end of the wing; Establish a rigid hub lift rotor model. The rigid hub lift rotor model consists of 4 blades, without a swashplate, and the lift rotor can be suspended at any spanwise position of the wing, and multiple sets of lift rotors can be suspended at different spanwise positions; Connect the structural dynamics interfaces of the "rotor-airframe rigid body" components of the rigid hub thrust rotor model and the rigid hub lift rotor model to the structural dynamics interfaces created on the non-rotating blade to obtain a rotor-wing coupled structure model; On the rotor-wing coupled structure model, establish a rotor-wing coupled aerodynamic force model considering the aerodynamic interference of the rotor slipstream on the wing.

2. The method according to claim 1, wherein The rotor-wing coupled aerodynamic force model supports free customization of airfoils, and different airfoils are used for the blades and the wing at different spanwise positions.

3. The method according to claim 1, characterized in that, Establish a non-rotating blade model as the wing model, including: Establish a wing model in the helicopter aerodynamic performance calculation software: First, establish a set of rotors, set the rotor speed, the number of rotor blades, the forward tilt angle of the rotor shaft, set the spanwise position of the concentrated mass distribution point of the blade to the position where the thrust rotor and the lift rotor of the aircraft are connected to the wing, and finally set the number of elements, node distribution, and airfoil distribution according to the needs of the simulation accuracy.

4. The method according to claim 1, characterized in that, Establish a rigid hub thrust rotor model, including: Establish a thrust rotor model in the helicopter aerodynamic performance calculation software: First, establish a set of rotors, set the rotor speed, the number of rotor blades, the blade section parameters, the spanwise distribution of the airfoil, the spanwise position of the pitch hinge, and the pitch hinge stiffness parameters according to the actual situation of the simulation object, and then set the forward tilt angle of the rotor shaft to -90 degrees.

5. The method according to claim 1, wherein Establish a rigid hub lift rotor model, including: Establish a lift rotor model in the helicopter aerodynamic performance calculation software: First, establish multiple sets of rotors equal to the number of lift rotors of the simulation object, set the speed, the number of rotor blades, the blade section parameters, the spanwise distribution of the airfoil, the spanwise position of the pitch hinge, and the pitch hinge stiffness parameters of each set of rotors according to the actual situation of the simulation object, and then set the forward tilt angle of each rotor shaft to -90 degrees.

6. The method according to claim 1, wherein Connect the structural dynamics interfaces of the "rotor-airframe rigid body" components of the rigid hub thrust rotor model and the rigid hub lift rotor model to the structural dynamics interfaces created on the non-rotating blade to obtain a rotor-wing coupled structure model, including: Use CAMRAD CORE commands to establish a structural connection between the lift rotor and the wing: Add 1 geometric feature point to the element where the wing is connected to the lift rotor, number it as the 5th geometric feature point, and edit the coordinates of the 5th feature point in the element system to be the coordinates of the actual position of the point where the wing is connected to the lift rotor in the element system; Add a structural dynamics interface to the element where the wing is connected to the lift rotor, number it as the 4th structural dynamics interface, and edit the base point of the 4th structural dynamics interface to be the 5th geometric feature point; Change the input end of the structural dynamics interface component between the lift rotor and the fuselage to the 4th structural dynamics interface established above. Use CAMRAD CORE commands to establish a structural connection between the thrust rotor and the wing; Change the direction of the feature coordinate system of the 2nd geometric feature point of the last element of the wing to (-90, -90, 0), and then change the input end of the structural dynamics interface component between the thrust rotor and the fuselage to the 2nd structural dynamics interface of the last element of the wing.

7. The method according to claim 1, wherein On the rotor-wing coupled structure model, establish a rotor-wing coupled aerodynamic force model considering the aerodynamic interference of the rotor slipstream on the wing, including: Run the helicopter aerodynamic performance calculation software to perform the initial dynamic simulation, obtain the lift coefficients and induced velocities of the lift rotor and the thrust rotor, and calculate the aerodynamic interference coefficients of the lift rotor and the thrust rotor based on the obtained lift coefficients and induced velocities. The calculation formula is: Where V i is the calculated aerodynamic interference coefficient; e is the natural logarithm constant, V is the forward flight speed of the aircraft, V1 is the induced velocity of the lift rotor and the thrust rotor obtained from the initial dynamic simulation, C T is the pull coefficient of the lift rotor and the thrust rotor obtained from the initial dynamic simulation, and h is the distance between the rotation center of the lift rotor and the thrust rotor and the quarter chord line of the wing; Assign the aerodynamic interference coefficients obtained from the initial calculation to the lift rotor and the thrust rotor in the helicopter aerodynamic performance calculation software. Run the helicopter aerodynamic performance calculation software to perform the secondary calculation to obtain the final dynamic simulation results.

8. 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 described in any one of claims 1-7.

Images