Amphibious aircraft single-engine failure joint simulation method

Abstract

The invention discloses a single-engine failure joint simulation method for an amphibious aircraft, which comprises the following steps of: firstly, establishing an aerodynamic force and control surface control model and a hydrodynamic model, solving six-degree-of-freedom motion of a flow field and the aircraft by the hydrodynamic model to obtain an aircraft state, and outputting and transmitting aircraft state data to the aerodynamic force and control surface control model; the aerodynamic force and the control surface angle in the control surface control model are controlled based on the PID theory, aerodynamic force data are obtained and loaded on the hydrodynamic model in an external force mode, and simulation of the single-shot failure interruption takeoff process is completed through real-time two-way coupling. According to the method, the influence of aerodynamic force and hydrodynamic force on the amphibious aircraft is separated, the aerodynamic force and the hydrodynamic force are calculated separately, and a simulation model can be simplified.

Description

Technical Field

[0001] The invention belongs to the technical field of amphibious aircraft joint simulation, and in particular relates to a single-engine failure joint simulation method for amphibious aircraft. Background Art

[0002] The OEI power state is for the engine shutdown phenomenon of twin-engine or multi-engine aircraft due to common reasons such as poor fuel supply or air intake, mechanical failure, ice accumulation in the cloud, and improper use of the anti-icing system. After an amphibious aircraft fails on the water surface, it is affected by both aerodynamics and hydrodynamics. At the same time, the pilot will also control the rudder, aileron, throttle, etc. to control the aircraft attitude. The actual single-engine failure test flight is very dangerous.

[0003] CN114860388 B introduces a joint simulation method based on the conversion of FMU models into Modelica models, which converts FMU models into Modelica models and conducts joint simulation with Modelica language models in the Modelica compilation environment. CN114818362 B introduces a multi-FMU model joint simulation propulsion method and system, but it is only a method optimization, which improves the simulation accuracy and simulation efficiency, can effectively handle the simulation of pathological systems, and does not specify the simulation object and problems. CN118238997 A introduces a single-engine failure test flight method for intelligent aircraft, which is only a single-engine failure test flight method based on an intelligent flight system and has nothing to do with joint simulation. Summary of the invention

[0004] Purpose of the Invention

[0005] In view of the problem of single engine failure of amphibious aircraft, the present invention provides a single engine failure joint simulation method for amphibious aircraft.

[0006] Inventing technical solutions

[0007] A single-engine failure joint simulation method for amphibious aircraft is disclosed. The method first establishes an aerodynamic force and rudder control model and a hydrodynamic force model. The hydrodynamic force model obtains the aircraft state by solving the flow field and the six-degree-of-freedom motion of the aircraft, and transmits the aircraft state data output to the aerodynamic force and rudder control model. The rudder angle in the aerodynamic force and rudder control model is controlled based on PID theory to obtain aerodynamic force data and load it on the hydrodynamic force model in the form of external force. The simulation of the single-engine failure interrupted takeoff process is completed through real-time two-way coupling.

[0008] Preferably, the simulation objects of the hydrodynamic simulation model include the hull of an amphibious aircraft and the geometric shapes of pontoons.

[0009] Preferably, the hydrodynamic model is solved by a two-phase flow solver in combination with the overlay grid technique and the DFBI rigid body six-degree-of-freedom motion.

[0010] Preferably, in the process of solving the hydrodynamic model, the fluid control equations are solved based on the finite volume method, and the SSTk-ω turbulence model is used to simulate the turbulence problem. The DFBI model is used to integrate and calculate the surface forces and moments of the amphibious aircraft, and then the six-degree-of-freedom motion of the aircraft is solved based on the six-degree-of-freedom motion equation.

[0011] Preferably, in the aerodynamic and rudder control model: a propeller thrust curve is obtained based on the aircraft throttle, speed, propeller performance data, parking thrust attenuation data, and throttle reduction thrust attenuation data; the aircraft body aerodynamic force and torque are obtained based on the aircraft angle of attack, sideslip angle, thrust coefficient, and speed; based on the aircraft pitch angle, roll angle, and yaw angle, PID control is used to control the aircraft rudder, and the aerodynamic force and torque increment after the rudder changes are obtained.

[0012] Preferably, the method of using PID control to realize the control of the aircraft control surface by the pneumatic and control surface control model is as follows: according to the posture of the aircraft in the current state, the elevator, aileron and rudder are controlled in real time based on the PID control theory, and after the corresponding rudder angle is obtained, the aerodynamic increment of the control surface is obtained by using the corresponding wind tunnel test database and loaded onto the aircraft, thereby realizing the control of the control surface.

[0013] Preferably, the hydrodynamic model is solved using STAR-CCM+ commercial software.

[0014] Preferably, the method comprises the following steps:

[0015] The first step is to import the hull and pontoon model (the geometric model of the hydrodynamic model calculation includes the hull and pontoon model) into the STAR-CCM+ commercial software, establish the calculation domain, divide the calculation domain grid, select the solution model, and give the calculation domain boundary conditions;

[0016] Step 2: Set up the DFBI rigid body motion model;

[0017] Step 3: Establish an aerodynamic force and control surface model to obtain the propeller thrust curve, the aerodynamic force and torque of the aircraft body; according to the expected aircraft attitude, use the PID controller to control the aircraft elevator, aileron, and rudder, and after obtaining the corresponding rudder angle, use the wind tunnel test database of the elevator, aileron, and rudder to obtain the corresponding aerodynamic force and torque increment, and then add the body aerodynamic force and propeller thrust to output;

[0018] Step 4: Couple the hydrodynamic model with the aerodynamic and rudder control model in the STAR-CCM+ commercial software. Then input the aircraft aerodynamic force and torque calculated by the aerodynamic and rudder control model and load them into the external force part of the DFBI six-degree-of-freedom model. This completes the numerical simulation of single-engine failure of amphibious aircraft based on the joint simulation of FMU and CFD.

[0019] Preferably, the contents set in the second step include the aircraft mass, center of mass, moment of inertia, degrees of freedom to be solved, external forces and external moments.

[0020] Preferably, in the third step, the signals input to the aerodynamic force and control surface model include the aircraft speed, angle of attack, pitch angle, yaw angle, tension coefficient, and initial angle of the control surface; the signals output by the aerodynamic force and control surface control model include the total aerodynamic force and torque of the aircraft and the angles of the elevator, aileron, and rudder.

[0021] The advantages of the present invention are as follows: the method separates the influence of aerodynamic force and hydrodynamic force on amphibious aircraft, calculates aerodynamic force and hydrodynamic force separately, simplifies the simulation model, reduces the number of overall grids, avoids the influence of splashing on the virtual disk of the engine, significantly reduces the amount of calculation, shortens the calculation time, and realizes the control of the aircraft elevator, aileron, and rudder control surfaces based on PID, can quickly and batch obtain single-engine failure conditions under different working conditions, and provide a reference for flight test work. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of CFD and FMU joint simulation data exchange.

[0023] Figure 2 It is a schematic diagram of the aerodynamic and rudder surface control model.

[0024] Figure 3 It is a CFD hydrodynamic simulation model.

[0025] Figure 4 It is a comparison of the pitch angle curves of simulation and actual test flight.

[0026] Figure 5 It is a comparison of the elevator curves of simulation and actual test flight.

[0027] Figure 6 It is a comparison of the yaw angle curves of simulation and actual test flight.

[0028] Figure 7 It is a comparison of the rudder curves between simulation and actual test flight.

[0029] Figure 8 It is a comparison of the speed curves of simulation and actual test flight. DETAILED DESCRIPTION

[0030] The present invention is achieved through the following technical solutions.

[0031] A single-engine failure joint simulation method for an amphibious aircraft includes an aerodynamic force and rudder control model (FMU implementation) and a hydrodynamic force model (CFD implementation). The rudder angle in the aerodynamic force and rudder control model (FMU implementation) is controlled based on PID theory, and the aerodynamic force data is loaded on the hydrodynamic model in the form of external force. The simulation of the single-engine failure interrupted takeoff process is completed through real-time two-way coupling.

[0032] like Figure 1 As shown, the real-time data exchange (based on FMU) between the aerodynamic force and rudder control model and the hydrodynamic model (CFD) is carried out. The aerodynamic force and rudder control model obtains the aircraft aerodynamic force and aerodynamic moment based on the aircraft state, and loads them to the CFD hydrodynamic simulation model in the form of external force.

[0033] like Figure 2 As shown, the aerodynamic and control surface control model obtains the propeller thrust curve based on the aircraft throttle, speed, propeller performance data, parking thrust attenuation data, and throttle-reduction thrust attenuation data; obtains the aircraft body aerodynamic force / torque based on the aircraft angle of attack, sideslip angle, thrust coefficient, and speed; and uses PID control to control the aircraft control surfaces based on the aircraft pitch angle, roll angle, and yaw angle, and obtains the aerodynamic force / torque increment after the control surfaces change.

[0034] It is also necessary to consider the aerodynamic increment after the pilot manipulates the control surfaces, which mainly includes the rudder (controls the aircraft's heading), ailerons (controls the aircraft's roll), and elevators (controls the aircraft's pitch attitude angle). The aerodynamic increment of the control surface is mainly related to the angle at which the pilot manipulates the control surface. The pilot will adjust the corresponding control surface according to the aircraft's heading, roll angle, and pitch attitude angle, so this part of the force is unknown in advance. This part of the aerodynamic modeling is based on FMU construction, and PID control theory is used to simulate the pilot's manipulation. It is mainly based on the attitude of the aircraft in the current state, and the control surfaces (elevators, ailerons, and rudders) are controlled in real time based on PID control theory. After obtaining the corresponding rudder angle, the corresponding wind tunnel test database is used to obtain the aerodynamic increment of the control surface and load it onto the aircraft to achieve control of the control surface.

[0035] like Figure 3As shown, the hydrodynamic model is built using STAR-CCM+ commercial software. The simulation objects include the amphibious aircraft hull and the geometric shape of the pontoon. The hydrodynamic model is solved using the traditional two-phase flow solver, combined with the overlapping grid technology and the DFBI rigid body six-degree-of-freedom motion. The CFD commercial software solves the fluid control equation, namely the NS equation, based on the finite volume method, and uses the SST k–ω turbulence model to simulate turbulence problems. The DFBI model is used to integrate and calculate the surface forces and moments of the amphibious aircraft, and then solves the six-degree-of-freedom motion of the aircraft based on the six-degree-of-freedom motion equation, including aircraft displacement, velocity, acceleration, etc. The NS equation is as follows:

[0036]

[0037] CFD simulation software only solves the hydrodynamic effects of the aircraft, and also needs to consider propeller thrust, aerodynamic force, and the increment of aerodynamic force after the pilot manipulates the control surfaces. Among them, propeller thrust and aerodynamic force can be directly obtained based on wind tunnel test data. This part of the force can be obtained by interpolation based on the aircraft state, and then loaded onto the aircraft in the form of external force. It should be noted that the propeller thrust is a decay process after the critical engine fails and the pilot closes the throttle, and the propeller thrust decay curve needs to be obtained based on test flights or experiments. This part of the content can be completed in the FMU model.

[0038] The file format of the FMI standard is called "Functional Simulation Unit" (FMU), and there are two different protocols or forms: model exchange (import and export) and collaborative simulation (master-slave). The main difference between the two protocols is that in model exchange, the FMU uses the solver of the import tool for simulation, while in collaborative simulation, the FMU uses its own solver for simulation. This patent is mainly based on the collaborative simulation method. According to the aircraft yaw angle, pitch angle and roll angle solved by the imported STAR-CCM+ commercial software, a PID controller is written to obtain the aircraft rudder, elevator and aileron angles, and then the aerodynamic force increment of the control surface is obtained according to the rudder, elevator and aileron wind tunnel test database, and then it is output to the STAR-CCM+ commercial software, loaded to the aircraft in the form of external force, and then the aircraft motion is solved.

[0039] The process of establishing the numerical model of single-engine failure of amphibious aircraft mainly includes: the first step is to import the hull and pontoon model into the STAR-CCM+ commercial software, establish the calculation domain, divide the calculation domain grid, select the solution model, including turbulence model, multiphase flow model, unsteady model, and give the boundary conditions of the calculation domain; the second step is to set the DFBI rigid body motion model, mainly setting the aircraft mass, center of mass, moment of inertia, degree of freedom for solution, and external force / external torque, aerodynamic force and rudder aerodynamic force / torque need to be provided by the FMU model; the third step is to establish the FMU model, and the input signals include aircraft speed, angle of attack, pitch angle, yaw angle, pull coefficient, initial angle of rudder, etc. The propeller thrust can be obtained based on the aircraft speed, throttle angle and the attenuation curve after propeller failure; the aerodynamic force / torque of the aircraft body is obtained based on the aircraft attitude using the airframe wind tunnel test database; according to the expected aircraft attitude, the aircraft elevator, aileron and elevator rudder angle are controlled using a PID controller, where the rudder angle control speed and the maximum rudder angle need to be limited according to the actual state. After obtaining the corresponding rudder angle, the elevator, aileron and rudder wind tunnel test database is used to obtain the corresponding aerodynamic force / torque increment, which is then output after adding the airframe aerodynamic force and propeller thrust. The FMU output signal mainly includes the total aerodynamic force / torque of the aircraft and the angles of the elevator, flap and aileron. Step 4: Couple the CFD simulation model with the FMU model, select the FMU joint simulation model in the STAR-CCM+ commercial software, monitor the aircraft speed, attitude, displacement, etc. in the STAR-CCM+ commercial software, and correspond them to the FMU input signal one by one to ensure that the STAR-CCM+ commercial software monitoring data can be normally output to the FMU model, and then input the aircraft aerodynamic force / torque calculated by the FMU model and load it into the external force part of the DFMI six-degree-of-freedom model. Then, the numerical simulation of single-engine failure of amphibious aircraft based on the joint simulation of FMU and CFD can be completed.

[0040] The single-engine failure joint simulation should be divided into three stages. The aerodynamic model should be able to transmit data according to the parameters required for each stage. In the first stage, the aircraft is in the uniform taxiing stage. At this time, the aircraft attitude is stable and only the pitch and heave degrees of freedom of the aircraft need to be considered. In the second stage, the throttle of a single engine of the aircraft is reduced to release all degrees of freedom of the aircraft. In the third stage, the throttle of the remaining engines is reduced 1.5s after the critical engine fails. The control surfaces are involved in the control of the entire process.

[0041] During the simulation process, the CFD hydrodynamic simulation model obtains the aircraft status (including angle of attack, sideslip angle, yaw angle, pitch angle, speed, etc.) by solving the flow field and the aircraft's six-degree-of-freedom motion, and transmits these data outputs to the aerodynamic and rudder control model to obtain the aircraft's elevator rudder angle, aileron angle, and azimuth angle, and further obtains the aircraft's aerodynamic force / torque, which is input into the CFD hydrodynamic simulation model and loaded into the aircraft's aerodynamic center in the form of external force. The two are coupled and exchange data to complete the numerical simulation of an amphibious aircraft's interrupted takeoff after a single engine fails on the water surface. Figures 4 to 8 A comparison between simulation and actual test flight data is given, illustrating the reliability of this patented method.

[0042] The protection scope of the present invention is not limited to the above-mentioned embodiments. Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the scope of the present invention. If these changes and modifications fall within the scope of the claims of the present invention and their equivalents, the present invention is intended to include these changes and modifications.

Claims

1. A joint simulation method for single engine failure of an amphibious aircraft, characterized in that: The method first establishes an aerodynamic and rudder control model and a hydrodynamic model. The hydrodynamic model obtains the aircraft state by solving the flow field and the six-degree-of-freedom motion of the aircraft, and transmits the aircraft state data output to the aerodynamic and rudder control model. The rudder angle in the aerodynamic and rudder control model is controlled based on PID theory to obtain aerodynamic data and load it on the hydrodynamic model in the form of external force. The simulation of the single-engine failure interrupted takeoff process is completed through real-time two-way coupling.

2. The single engine failure joint simulation method for an amphibious aircraft according to claim 1, characterized in that: The simulation objects of the hydrodynamic simulation model include the amphibious aircraft hull and the geometric shape of the pontoon.

3. The single engine failure joint simulation method for an amphibious aircraft according to claim 1, characterized in that: The hydrodynamic model is solved by using a two-phase flow solver combined with overlapping grid technology and DFBI rigid body six-degree-of-freedom motion.

4. The single engine failure joint simulation method for an amphibious aircraft as claimed in claim 3, characterized in that: In the process of solving the hydrodynamic model, the fluid control equations are solved based on the finite volume method, and the SST k-ω turbulence model is used to simulate the turbulence problem. The DFBI model is used to integrate and calculate the surface forces and moments of amphibious aircraft, and then the six-degree-of-freedom motion of the aircraft is solved based on the six-degree-of-freedom motion equation.

5. The single engine failure joint simulation method for an amphibious aircraft according to claim 1, characterized in that: In the aerodynamic and control surface model: the propeller force curve is obtained based on the aircraft throttle, speed, propeller performance data, parking force attenuation data, and throttle reduction force attenuation data; The aerodynamic force and moment of the aircraft body are obtained based on the aircraft's angle of attack, sideslip angle, pull coefficient, and speed. Based on the aircraft's pitch angle, roll angle, and yaw angle, PID control is used to control the aircraft's control surfaces, and the aerodynamic force and moment increments after the control surfaces change are obtained.

6. The single engine failure joint simulation method for an amphibious aircraft as claimed in claim 5, characterized in that: The method of using PID control to control the aircraft's control surfaces in the aerodynamic and control surface control model is as follows: according to the aircraft's current posture, the elevator, aileron, and rudder are controlled in real time based on PID control theory. After obtaining the corresponding rudder angle, the corresponding wind tunnel test database is used to obtain the aerodynamic increment of the control surface and load it onto the aircraft to achieve control of the control surface.

7. The single engine failure joint simulation method for an amphibious aircraft as claimed in claim 6, characterized in that: The hydrodynamic model was solved using STAR-CCM+ commercial software.

8. The single engine failure joint simulation method for an amphibious aircraft as claimed in claim 7, characterized in that: The method comprises the following steps: The first step is to import the hull and pontoon models into the STAR-CCM+ commercial software, establish the computational domain, divide the computational domain mesh, select the solution model, and set the computational domain boundary conditions; Step 2: Set up the DFBI rigid body motion model; Step 3: Establish an aerodynamic force and control surface model to obtain the propeller thrust curve, the aerodynamic force and torque of the aircraft body; according to the expected aircraft attitude, use the PID controller to control the aircraft elevator, aileron, and rudder, and after obtaining the corresponding rudder angle, use the wind tunnel test database of the elevator, aileron, and rudder to obtain the corresponding aerodynamic force and torque increment, and then add the body aerodynamic force and propeller thrust to output; Step 4: Couple the hydrodynamic model with the aerodynamic and rudder control model in the STAR-CCM+ commercial software. Then input the aircraft aerodynamic force and torque calculated by the aerodynamic and rudder control model and load them into the external force part of the DFBI six-degree-of-freedom model. This completes the numerical simulation of single-engine failure of amphibious aircraft based on the joint simulation of FMU and CFD.

9. The single engine failure joint simulation method for an amphibious aircraft as claimed in claim 8, characterized in that: The settings in the second step include the aircraft mass, center of mass, moment of inertia, degrees of freedom to be solved, external forces and external moments.

10. The single engine failure joint simulation method for an amphibious aircraft according to claim 8, characterized in that: In the third step, the input signals of the aerodynamic force and control surface model include aircraft speed, angle of attack, pitch angle, yaw angle, tension coefficient, and initial angle of the control surface. The output signals of the aerodynamic force and control surface control model include the total aerodynamic force and torque of the aircraft and the angles of the elevator, aileron, and rudder.

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