Water surface aircraft hydrodynamic modeling method in regular waves
The benchmark database was established through the expansion of limited model test data, which provided support for the hydrodynamic modeling of surface vehicles in waves, solved the problem of large errors in existing hydrodynamic models at high speeds, and realized high-fidelity surface vehicle take-off and landing simulation and control law design.
Patent Information
- Application Number
- CN202411550551.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-01
- Publication Date
- 2025-03-14
AI Technical Summary
The existing hydropower models have large errors at high speeds and cannot meet the requirements of surface aircraft starting/landing simulation, especially in waves, the hydropower modeling of surface aircraft is complex and lacks reliable methods.
The data is expanded using limited model test data and state parameter analysis, and a benchmark database is established to provide hydropower input for the surface take-off simulation process of surface aircraft through interpolation and extrapolation.
It realizes high-fidelity and high-reliability and high-reliability surface aircraft take-off and landing control law design and flight simulation, laying the technical foundation for surface aircraft flight safety situation awareness.
Smart Images
Figure CN119622915A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of high-speed hydrodynamics of surface aircraft, and in particular relates to a hydrodynamic modeling method for a surface aircraft in regular waves. Background Art
[0002] A surface aircraft is a special equipment that integrates high-performance ships and conventional aircraft multidisciplinary high-tech. It has the ability to take off and land on the water surface. Its high-speed hydrodynamic characteristics are key technologies for surface aircraft. In engineering, the analysis of high-speed hydrodynamic characteristics of surface aircraft relies on high-precision model tests and actual machine testing methods, which are costly.
[0003] Simulation of surface aircraft takeoff and landing is another way to analyze its high-speed hydrodynamic characteristics, which depends on the accuracy of the hydrodynamic model. At present, the method of hydrodynamic modeling of surface aircraft is borrowed from the field of ships, especially based on the theory of prismatic planing boats, and empirical theoretical formulas are mostly used. Unlike conventional high-performance ships, surface aircraft have the characteristics of high speed, large attitude changes, and air / hydrodynamic coupling during takeoff and landing. The conventional hydrodynamic model has large errors at high speeds and cannot meet the simulation requirements of surface aircraft takeoff and landing.
[0004] The applicability of surface aircraft in high sea conditions is one of the important factors restricting the further development of its equipment. The technical difficulty is also reflected in the complexity of hydrodynamic modeling of surface aircraft in waves. Surface aircraft have high speed and fast response, and there is a strong nonlinear coupling between them and waves, which makes hydrodynamic modeling more difficult. At present, there is no reliable and effective method for hydrodynamic modeling of surface aircraft in waves. Summary of the invention
[0005] Purpose of the Invention
[0006] In view of the shortcomings of existing conventional hydrodynamic models with large errors at high speeds, the present invention provides a hydrodynamic modeling method for surface aircraft in regular waves. Data expansion is performed based on finite model test data and state parameter analysis, and a benchmark database is established to meet the needs of surface aircraft wave surface takeoff simulation dynamics model, provide reliable model support for high-fidelity and high-reliability surface aircraft takeoff and landing control law design and flight simulation, and lay a technical foundation for subsequent surface aircraft flight safety situation awareness.
[0007] Inventing technical solutions
[0008] A method for modeling hydrodynamics of a surface aircraft in regular waves comprises the following steps:
[0009] (1) Determine the regular wave parameters based on the water surface takeoff scenario of a water surface aircraft;
[0010] (2) Determine the three state parameters that affect the hydrodynamic performance of the aircraft in addition to waves: aircraft speed, height of the center of mass of the aircraft above the water, and pitch angle of the aircraft;
[0011] (3) Based on the water takeoff characteristics of the surface aircraft, the water surface taxiing condition envelope of the aircraft is established with three state parameters as variables, and several conditions inside and outside the envelope are selected;
[0012] (4) Based on several selected working conditions, a fixed-state constraint model test of a surface aircraft in regular waves is carried out to obtain the time-varying curves of the aircraft's drag, lift, and pitching moment in regular waves;
[0013] (5) Based on the frequency of encounter between the aircraft and waves, the stable interval test data is selected, and the time-varying curves of the aircraft's drag, lift, and pitching moment are converted into phase-varying curves as the original data;
[0014] (6) Analyze the original data and aircraft state parameters to determine the regularity between the aircraft speed, center of mass height above water, pitch angle and hydrodynamic data;
[0015] (7) according to the linear law strength between the state parameters and the data, regular data expansion is performed on the pitch angle θ, velocity V, and center of mass height above the water h of the aircraft based on several groups of original test data to obtain a benchmark database containing original data and expanded data;
[0016] (8) Based on the benchmark database, hydrodynamic input is provided for the water surface takeoff simulation process of the surface aircraft through interpolation and extrapolation.
[0017] Preferably, in step (1), three parameters of wavelength λ, wave height A, and period T are used to describe the target waveform of the regular wave.
[0018] Preferably, in step (3), the variation range of the speed V, the center of mass height above the water h, and the pitch angle θ of the aircraft during the water skiing process, as well as the possible variation range of the center of mass height above the water h and the pitch angle θ of the aircraft at different speeds V are estimated to establish the water surface gliding condition envelope of the aircraft.
[0019] Preferably, in step (4), the high-speed trailer in the water pool is connected to the aircraft model through a multi-degree-of-freedom platform. In each working condition, the position where the trailer reaches the target speed and the position of the wave maker are kept fixed, and the wave maker is started when the trailer reaches the target speed position, so as to unify the initial phase of the data under each working condition.
[0020] Preferably, in step (5), data within one cycle after the aircraft and the waves encounter each other for several cycles are selected, and the time data sequence is converted into a phase data sequence as the original data for establishing the hydrodynamic model.
[0021] Preferably, in step (6), the average value of the original phase data is used to analyze the data regularity.
[0022] Preferably, in step (7), the strong linear law state parameter is used as the primary expansion element, and the original data is expanded, and the other two state parameters are expanded in turn, and a benchmark database is obtained based on the finite model test data expansion.
[0023] Preferably, the original data is obtained by a verified numerical simulation method.
[0024] Advantages of the present invention: The present invention expands and establishes a hydrodynamic benchmark database based on finite model test data, provides hydrodynamic input for the wave-based water surface takeoff simulation process of a surface aircraft, and is an implementable solution for hydrodynamic modeling of surface aircraft in waves in engineering applications, which is helpful for subsequent research on surface aircraft control law design, take-off / landing simulation, safety performance evaluation, etc. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Figure 1 It is a flow chart of an embodiment of a method for modeling regular wave hydrodynamics of a water surface vehicle according to the present invention.
[0026] Figure 2 It is a schematic diagram of the connection between the multi-degree-of-freedom platform of the present invention and the aircraft model.
[0027] Figure 3 It is a schematic diagram of aircraft pitch angle state parameter data analysis of the present invention.
[0028] Figure 4 It is a schematic diagram of aircraft speed state parameter data analysis of the present invention.
[0029] Figure 5 It is a schematic diagram of the data analysis of the state parameters of the aircraft center of mass height above water of the present invention.
[0030] Figure 6 The figure is a schematic diagram of the state quantity change of the water surface takeoff simulation aircraft based on the present invention.
[0031] In the figure: 1- multi-degree-of-freedom platform, 2- model. DETAILED DESCRIPTION
[0032] The present invention is achieved through the following technical solutions.
[0033] A method for modeling hydrodynamics of a surface aircraft in regular waves comprises the following steps:
[0034] Step 1: Determine the regular wave parameters
[0035] The target waveform of the regular wave is described using three parameters: wavelength λ, wave height A, and period T.
[0036] Step 2: Determine the aircraft flight status parameters
[0037] The aircraft glides and takes off in regular waves, and only the three-degree-of-freedom motion in the vertical plane is considered. The hydrodynamic force on the aircraft changes with the aircraft speed V, the height of the center of mass above the water h, and the pitch angle θ.
[0038] Step 3: Establish the hydroplaning envelope and select the operating condition
[0039] Based on the characteristics of aircraft water takeoff and engineering experience, the variation range of the aircraft's speed V, center of mass height above the water h, and pitch angle θ during water skiing is estimated, as well as the possible variation range of the aircraft's center of mass height above the water h and pitch angle θ at different speeds V, and the aircraft's water skiing operating envelope is established.
[0040] As shown in Table 1, several operating conditions inside and outside the envelope are selected, including the aircraft speed V, center of mass height above water h, and pitch angle θ parameter conditions (√ is the subsequent model test condition, * is the data expansion condition).
[0041] Step 4: Conduct fixed flight constraint model tests
[0042] like Figure 2 , and conduct regular wave gliding tank tests on aircraft models. The trailer and aircraft model are connected through a multi-degree-of-freedom motion platform. The multi-degree-of-freedom platform is used to adjust the height h of the center of mass of the model from the water and the pitch angle θ under the corresponding working conditions, and the time history curves of the aircraft's drag, lift, and pitch moment in regular waves are measured.
[0043] The position of the wave maker is fixed, and a fixed position of the trailer track is selected. In each set of test conditions, it is preset that the target aircraft speed V is reached when the trailer reaches the above position, and the wave maker is turned on at the same time, so that the initial moment when the aircraft encounters the wave can be used as a unified initial phase.
[0044] Step 5: Phase processing to obtain raw data
[0045] The parameters of the regular wave are fixed, and the encounter frequency υ between the two at different aircraft speeds V is obtained.
[0046] Based on the hydrodynamic data measured by the multi-degree-of-freedom platform, a period of data after the aircraft encounters the regular wave for several (n) periods is selected, and the time data series is converted into a phase data series as the original data for establishing the hydrodynamic model. The conversion relationship between the time data series (t) and the phase data series (φ) is:
[0047]
[0048] Step 6: State parameters and data regularity analysis
[0049] like Figure 3-5 , analyze the regularity of the three state parameters of aircraft speed V, center of mass height above water h, and pitch angle θ and the hydrodynamic phase data.
[0050] There is a strong nonlinear coupling characteristic between the high-speed gliding aircraft and the regular waves. The average value of the original phase data is used to analyze the regularity of the data.
[0051] Step 7: Interpolate and expand according to the regularity of the aircraft state parameters and data
[0052] As shown in Table 1, according to the strength of the linear law between the state parameters and the data, the regular data expansion of the aircraft pitch angle θ, speed V, and center of mass height above the water h was performed based on several groups of original test data to obtain a benchmark database containing original data and extended data.
[0053] Step 8: Linear interpolation to obtain hydrodynamic forces
[0054] When simulating takeoff of an aircraft in regular waves, the hydrodynamic force of the aircraft is predicted by linear interpolation based on the reference database, phase information (φ), and aircraft state parameters (θ, V, h).
[0055] Table 1 Working conditions selection
[0056]
[0057]
[0058] Example
[0059] (1) In order to verify the effectiveness and effect of the method of the present invention, an example is given for illustration. The embodiment comprises the following steps:
[0060] a) As shown in Table 1, establish the operating condition envelope and select 83 groups of test conditions.
[0061] b) If Figure 2 , carry out pool model tests and obtain hydrodynamic data.
[0062] c) If Figure 3 , the test data phase conversion, the regularity analysis of the aircraft state parameters and the hydrodynamic phase data was carried out. The aircraft state parameters θ, V, and h are strongly correlated with the hydrodynamic phase data, among which the linear law between the aircraft pitch angle θ and the hydrodynamic data is the most obvious.
[0063] d) As shown in Table 1, the data of the aircraft pitch angle θ, speed V, and center of mass height above the water h are expanded in turn to obtain a benchmark database containing 83 sets of original test data and 407 sets of expanded data.
[0064] e) Carry out a simulation of a surface aircraft taking off in regular waves.
[0065] (2) Simulation results and analysis:
[0066] like Figure 6 , showing the time history curves of various state parameters during the simulation of the aircraft taxiing takeoff in regular waves ( Figure 6 From top to bottom are aircraft speed V, fuselage angle of attack α, pitch angular velocity q, pitch angle θ, and flight altitude H).
[0067] Depend on Figure 6 It can be seen that the aircraft glides and takes off in regular waves, and the flight speed increases slowly under the action of the control module; the speed is low in the initial stage, and the aircraft has heave and sink motion in the regular waves, resulting in a large change in the fuselage angle of attack under the wind axis system; from the flight altitude H time history curve, it can be seen that the aircraft has an obvious "dolphin jump" phenomenon; in order to enable the aircraft to take off safely, the aircraft, under the action of the control module, realizes the effect of lifting the bow of the aircraft and gradually completes the takeoff from the water, which corresponds to the sudden increase in the pitch angular velocity at a certain moment 4 seconds later and the slow increase in the pitch angle of the aircraft.
[0068] After comparing with previous surface takeoff data, the aircraft posture data displayed by the simulation can reasonably and accurately reflect the entire process of surface aircraft takeoff and flight, and can reasonably perform flight situations such as "dolphin jump" that are difficult to simulate in conventional flight simulations, reflecting the advanced nature and accuracy of the hydrodynamic modeling method.
[0069] The present invention models the hydrodynamics of a surface aircraft in regular waves, and expands the hydrodynamics benchmark database based on finite model test data. While ensuring accuracy and cost, it can reflect the high-speed hydrodynamics of the surface aircraft and the strong nonlinear characteristics of waves. The established hydrodynamic model can be applied to the simulation of takeoff of a surface aircraft in regular waves.
[0070] 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 method for modeling hydrodynamics of a surface aircraft in regular waves, characterized in that: The steps include: (1) Determine the regular wave parameters based on the water surface takeoff scenario of a water surface aircraft; (2) Determine the three state parameters that affect the hydrodynamic performance of the aircraft in addition to waves: aircraft speed, height of the center of mass of the aircraft above the water, and pitch angle of the aircraft; (3) Based on the water takeoff characteristics of the surface aircraft, the water surface taxiing condition envelope of the aircraft is established with three state parameters as variables, and several conditions inside and outside the envelope are selected; (4) Based on several selected working conditions, a fixed-state constraint model test of a surface aircraft in regular waves is carried out to obtain the time-varying curves of the aircraft's drag, lift, and pitching moment in regular waves; (5) Based on the frequency of encounter between the aircraft and waves, the stable interval test data is selected, and the time-varying curves of the aircraft's drag, lift, and pitching moment are converted into phase-varying curves as the original data; (6) Analyze the original data and aircraft state parameters to determine the regularity between the aircraft speed, center of mass height above water, pitch angle and hydrodynamic data; (7) according to the linear law strength between the state parameters and the data, regular data expansion is performed on the pitch angle θ, velocity V, and center of mass height above the water h of the aircraft based on several groups of original test data to obtain a benchmark database containing original data and expanded data; (8) Based on the benchmark database, hydrodynamic input is provided for the water surface takeoff simulation process of the surface aircraft through interpolation and extrapolation.
2. A method for modeling hydrodynamics of a surface aircraft in regular waves as claimed in claim 1, characterized in that: In step (1), three parameters, namely wavelength λ, wave height A and period T, are used to describe the target waveform of the regular wave.
3. The method for modeling hydrodynamics of a surface aircraft in regular waves according to claim 1, characterized in that: In step (3), the variation range of the speed V, the center of mass height above the water h, and the pitch angle θ of the aircraft during the hydroplaning process is estimated, as well as the possible variation range of the center of mass height above the water h and the pitch angle θ of the aircraft at different speeds V, and the water surface hydroplaning condition envelope of the aircraft is established.
4. The method for modeling hydrodynamics of a surface aircraft in regular waves according to claim 1, characterized in that: In step (4), the high-speed trailer in the water pool is connected to the aircraft model through a multi-degree-of-freedom platform. In each working condition, the position where the trailer reaches the target speed and the position of the wave maker are kept fixed. The wave maker is started when the trailer reaches the target speed position, thereby unifying the initial phase of the data under each working condition.
5. The method for modeling hydrodynamics of a surface aircraft in regular waves according to claim 1, characterized in that: In step (5), data within one cycle after the aircraft and the waves have encountered each other for several cycles are selected, and the time data series is converted into a phase data series as the original data for establishing the hydrodynamic model.
6. The method for modeling hydrodynamics of a surface aircraft in regular waves according to claim 1, characterized in that: In step (6), the average value of the original phase data is used to analyze the data regularity.
7. The method for modeling hydrodynamics of a surface aircraft in regular waves according to claim 1, characterized in that: In step (7), the strong linear law state parameter is taken as the primary expansion element, and its original data is expanded. The other two state parameters are expanded in turn, and the benchmark database is obtained based on the finite model test data expansion.
8. The method for modeling hydrodynamics of a surface aircraft in regular waves as claimed in claim 1, characterized in that: The original data are obtained through the verified numerical simulation method.