CN115901163B - Helicopter landing aerodynamic characteristic wind tunnel test method - Google Patents
Helicopter landing aerodynamic characteristic wind tunnel test method Download PDFInfo
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- CN115901163B CN115901163B CN202310221939.XA CN202310221939A CN115901163B CN 115901163 B CN115901163 B CN 115901163B CN 202310221939 A CN202310221939 A CN 202310221939A CN 115901163 B CN115901163 B CN 115901163B
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Abstract
The invention discloses a wind tunnel test method for the pneumatic characteristics of helicopter landing, which adopts a six-degree-of-freedom parallel mechanism to realize the ship attitude simulation, adopts a master-slave mode synchronization method to realize the synchronous acquisition of the helicopter model load and the ship attitude, realizes the combined motion simulation of single degree of freedom or multiple degrees of freedom of the ship through computer control, improves the accuracy of the ship attitude simulation, realizes the synchronous acquisition of the ship attitude and the helicopter load through a master-slave synchronization mode, can acquire abundant data, and has important significance for analyzing and researching the influence relationship between the ship attitude and the helicopter load.
Description
Technical Field
The invention relates to the field of wind tunnel tests, in particular to a wind tunnel test method for the aerodynamic characteristics of a helicopter landing ship.
Background
When a ship sails on the sea, the meteorological conditions are complex, the wind direction is changeable, the vortex of the rotor wing and the ship is mixed with each other along with the flight of the helicopter above the deck, so that a complex coupling flow field is formed, and particularly under high sea conditions, the ship can generate space six-degree-of-freedom motions, and the motions can certainly interfere with the flow field condition in the take-off and landing process of the ship-borne helicopter, so that adverse effects can be brought to the aerodynamic characteristics of the rotor wing and the operation of a driver. The method has important significance for researching the aerodynamic characteristics of ship movement in the process of landing the helicopter under high sea conditions and for safely landing the helicopter. At present, many students in China research the flow field structure of the deck of the ship through CFD numerical simulation means, but less research is disclosed in China on the experiment of the coupling wind tunnel of the ship, and particularly, less experiment research on the aerodynamic characteristics of the helicopter under the coupling of the ship in the dynamic motion situation of the ship body is disclosed in China.
The helicopter landing aerodynamic characteristic experiment method needs to simulate six-degree-of-freedom motion of the ship under high sea conditions, and simultaneously, in order to analyze the correlation between the helicopter landing aerodynamic characteristic and the ship attitude, helicopter load and ship attitude data need to be acquired simultaneously. Therefore, a test method capable of simulating ship movement and data synchronous acquisition is needed, so that the aerodynamic characteristic research in the helicopter landing process is realized, and the influence rule between the helicopter model load and the ship attitude is revealed.
Disclosure of Invention
The invention aims to realize a wind tunnel test method for the aerodynamic characteristics of a helicopter landing, which adopts a six-degree-of-freedom parallel mechanism to realize ship attitude simulation and adopts a master-slave mode synchronization method to realize synchronous acquisition of helicopter model load and ship attitude.
In order to achieve the above object, the present invention provides:
a helicopter landing aerodynamic characteristic wind tunnel test method comprises the following steps:
s1: a six-degree-of-freedom motion mechanism is arranged on the floor of the wind tunnel test section, a ship model is arranged on the upper part of the six-degree-of-freedom motion mechanism, and six-degree-of-freedom motions of heave, sway, pitching, head shaking and rolling of the ship are realized through the six-degree-of-freedom motion mechanism;
s2: the aviation floor parallel to the floor of the wind tunnel test section is provided with a groove, the ship model can pass through the groove,
lifting an aviation floor to the position of a ship model waterline through lifting, wherein the aviation floor is used for simulating the sea surface;
s3: connecting a helicopter model to an aviation floor through a support rod, wherein the helicopter model is connected with the support rod through a six-component balance;
s4: the top of the wind tunnel test section is provided with a ship model attitude acquisition module, and the ship model attitude acquisition module acquires ship model attitude information in real time by adopting an optical track tracking system;
s5: the helicopter load acquisition module acquires the helicopter model load of the analog signal on the six-component balance in real time through the data line;
s6: and synchronously acquiring the attitude information of the optical track tracking system through the control system according to the acquisition feedback of the analog signals.
In the above technical scheme, a gap is reserved between the ship model and the aviation floor in the step S2, and the ship model and the aviation floor are not interfered with each other when the ship model and the aviation floor move mutually.
In the above technical solution, in S6, the specific method for synchronous acquisition includes the following steps:
a1: starting a helicopter load acquisition module to acquire initial readings;
a2: monitoring load and rotating speed in real time by utilizing a helicopter load acquisition module;
a3: controlling the rotating speed of the helicopter model to meet the test requirement, and controlling the total pitch angle of the rotor wing to enable the load to meet the test requirement;
a4: controlling a six-degree-of-freedom motion mechanism to move according to given amplitude and oscillation frequency parameters;
a5: starting a wind tunnel power system, and controlling the wind speed to reach the test required wind speed;
a6: the ship model attitude acquisition module prepares to acquire data and waits for synchronous acquisition signals;
a7: the helicopter load acquisition module starts to acquire data according to the set sampling frequency and sampling points, and simultaneously sends synchronous acquisition signals to the ship model attitude acquisition module;
a8: the ship model attitude acquisition module receives the synchronous acquisition signal and starts to acquire data at the same time;
a9: after the helicopter load acquisition module finishes acquiring according to the set sampling points, sending an acquisition stop signal to the ship model gesture acquisition module, stopping acquisition after the ship model gesture acquisition module receives the acquisition stop signal, and storing data;
a10: changing the amplitude and frequency of the six-degree-of-freedom motion mechanism, and repeating the steps A6-A9 until the test is finished;
a11: and after the test is finished, stopping the six-degree-of-freedom motion mechanism and stopping the wind tunnel power system.
In the above technical solution, in A3, the rotational speed and the total pitch angle of the helicopter model are wirelessly controlled by the remote controller.
In the above-described solution, the six-degree-of-freedom motion includes a single degree of freedom in heave, roll, heave, pitch, yaw, roll, or a motion from a combination of any of several degrees of freedom.
In the technical scheme, the acquisition frequency of the ship model gesture acquisition module is determined according to more than 20 times of the oscillation frequency of the six-degree-of-freedom motion mechanism of the helicopter, the sampling frequency of the helicopter load acquisition module is determined according to 64 times of the ship model gesture acquisition frequency, and the helicopter rotor wing acquires 64 points per rotation.
In the technical scheme, the synchronous acquisition mode adopts a master-slave synchronous mode, the helicopter load acquisition module is the master, and the ship model attitude acquisition module is the slave.
In the above technical solution, the synchronization signal is a TTL level signal output by the data acquisition module, the high level is 5V, and the low level is 0V.
In summary, due to the adoption of the technical scheme, the beneficial effects of the invention are as follows: according to the helicopter landing aerodynamic characteristic wind tunnel test method, the parallel six-degree-of-freedom mechanism is adopted to simulate the motion of the ship on the sea surface, the single-degree-of-freedom or multi-degree-of-freedom combined motion simulation of the ship is realized through computer control, and the accuracy of ship attitude simulation is improved. Through the master-slave synchronous mode, synchronous collection of ship gestures and helicopter loads is realized, rich data can be obtained, and the method has important significance for analyzing and researching influence relations between ship gestures and helicopter loads.
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The invention will now be described by way of example and with reference to the accompanying drawings in which:
FIG. 1 is a schematic layout of a test apparatus;
FIG. 2 is a block diagram of a signal synchronization acquisition process;
FIG. 3 is a timing diagram of signal synchronization acquisition;
fig. 4 is a graph of typical state experiment data.
Detailed Description
All of the features disclosed in this specification, or all of the steps in a method or process disclosed, may be combined in any combination, except for mutually exclusive features and/or steps.
Any feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. That is, each feature is one example only of a generic series of equivalent or similar features, unless expressly stated otherwise.
As shown in fig. 1, the implementation mainly comprises a ship six-degree-of-freedom attitude simulation mechanism, a ship attitude acquisition module and a helicopter load acquisition module, wherein the ship six-degree-of-freedom attitude simulation mechanism is installed on the ground of a wind tunnel test section, an aviation floor is adopted to simulate the sea surface, a through groove is formed in the aviation floor, the through groove is used for lifting the aviation floor to a waterline of the ship model through a ship model in a test, and the sea surface is simulated by the aviation floor. The ship model is arranged on the six-degree-of-freedom gesture simulation mechanism, the six-degree-of-freedom mechanism can realize the combined motion of single degree of freedom or multiple degrees of freedom, and can simulate the ship motion under different sea conditions.
The helicopter model is connected to the aviation floor through the support rod, the helicopter model is connected with the support rod through a six-component balance, when the helicopter model is in a blowing test state, the load of the helicopter model can be obtained through the component balance, the six-component balance converts the load into an analog signal, the analog signal enters the data acquisition module, and the data acquisition module converts the analog signal into a digital signal through A/D conversion and stores the digital signal. In order to meet the test requirements, the ship attitude and the helicopter load must be synchronously acquired, and because the attitude of the ship six-degree-of-freedom motion simulation device is obtained through displacement calculation of six servo driving rods, the attitude data acquired through a six-degree-of-freedom device control system is low in frequency and cannot be synchronously acquired with the helicopter load data. Therefore, the spatial displacement of the ship body mark point is obtained through a plurality of infrared cameras arranged at the top of the wind tunnel, and then the six-degree-of-freedom attitude of the ship is obtained through conversion matrix calculation.
As shown in fig. 2, the steps of synchronous acquisition of ship attitude and helicopter load comprise parameter setting, load monitoring, synchronous signal output and the like. The implementation process is as follows:
firstly, setting sampling frequency and sampling point number of a helicopter load acquisition module according to test requirements, starting to continuously monitor load and rotating speed, and waiting for the stability of the load and the rotating speed of the helicopter; starting a ship attitude simulation mechanism and a wind tunnel, and enabling a ship attitude acquisition module to enter a ready acquisition state after the test state is reached; the helicopter load acquisition module acquires data according to the set sampling frequency and the number of points and outputs TTL level signals through a digital I/O interface; after detecting TTL level signals, the ship attitude acquisition module starts acquisition according to a set sampling frequency; and stopping the collection after the collection is finished, and entering a lower-wheel collection state. Repeating the above process until the test is finished.
In this embodiment, the signal acquisition needs to be strictly performed according to the acquisition time sequence, as shown in fig. 3,
when the pulse rising edge is started to be collected, the ship gesture and the helicopter load start to be collected simultaneously, and the same starting point of the recorded data is ensured. The ship attitude acquisition frequency is determined according to more than 20 times of the ship oscillation frequency so as to ensure enough attitude resolution, the highest ship oscillation frequency in the embodiment is 3Hz, the ship attitude sampling frequency is set to be 60Hz, and the ship attitude acquisition clock has 60 rising edges per second. The helicopter load is a dynamic signal, the load changes periodically every turn of the rotor, and 64 points of each turn are required to be averaged to be one point in order to obtain stable and accurate load. Therefore, the ship attitude acquires data, and the helicopter load needs to acquire 64 points, namely the helicopter load sampling frequency is 64 times of the ship attitude acquisition frequency, and the helicopter load acquisition clock has 60×64=3840 rising edges per second.
In this embodiment, the above experimental method is used to obtain the ship attitude and helicopter lift data in a typical state, and as shown in fig. 4, the incoming flow speed v=20m/s, the ship is vertically and horizontally (combined movement of pitching and rolling) at 3HZ, the pitching amplitude is 2 °, and the helicopter model stress varies with the attitude when the rolling amplitude is 5 °. The distance from the propeller disc to the deck of the helicopter at the hovering position of the helicopter changes periodically when the ship moves, the lift force of the helicopter changes periodically under the same frequency due to the ground effect, and a phase lag exists, so that the aerodynamic law of the helicopter is met.
In the embodiment, the ship gesture movement is controlled by a computer, and different movement states can be realized by changing parameters, so that different test requirements are met, and the test efficiency is improved.
The invention is not limited to the specific embodiments described above. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification, as well as to any novel one, or any novel combination, of the steps of the method or process disclosed.
Claims (7)
1. A helicopter landing aerodynamic characteristic wind tunnel test method is characterized by comprising the following steps:
s1: a six-degree-of-freedom motion mechanism is arranged on the floor of the wind tunnel test section, a ship model is arranged on the upper part of the six-degree-of-freedom motion mechanism, and six-degree-of-freedom motions of heave, sway, pitching, head shaking and rolling of the ship are realized through the six-degree-of-freedom motion mechanism;
s2: the method comprises the steps that a groove is formed in an aviation floor parallel to a floor of a wind tunnel test section, the ship model can penetrate through the groove, the aviation floor is lifted to the waterline position of the ship model through lifting, and the aviation floor is used for simulating sea surfaces;
s3: connecting a helicopter model to an aviation floor through a support rod, wherein the helicopter model is connected with the support rod through a six-component balance;
s4: the top of the wind tunnel test section is provided with a ship model attitude acquisition module, and the ship model attitude acquisition module acquires ship model attitude information in real time by adopting an optical track tracking system;
s5: the helicopter load acquisition module acquires the helicopter model load of the analog signal on the six-component balance in real time through the data line;
s6: and synchronously acquiring the attitude information of the optical track tracking system through the control system according to the acquisition feedback of the analog signals.
2. The helicopter landing aerodynamic feature wind tunnel test method according to claim 1, wherein the method comprises the following steps: and a gap is reserved between the ship model and the aviation floor in the S2, and the ship model and the aviation floor are not interfered with each other when the ship model and the aviation floor move mutually.
3. The helicopter landing aerodynamic feature wind tunnel test method according to claim 1, characterized in that in S6, the specific method of synchronous acquisition comprises the following steps:
a1: starting a helicopter load acquisition module to acquire initial readings;
a2: monitoring load and rotating speed in real time by utilizing a helicopter load acquisition module;
a3: controlling the rotating speed of the helicopter model to meet the test requirement, and controlling the total pitch angle of the rotor wing to enable the load to meet the test requirement;
a4: controlling a six-degree-of-freedom motion mechanism to move according to given amplitude and oscillation frequency parameters;
a5: starting a wind tunnel power system, and controlling the wind speed to reach the test required wind speed;
a6: the ship model attitude acquisition module prepares to acquire data and waits for synchronous acquisition signals;
a7: the helicopter load acquisition module starts to acquire data according to the set sampling frequency and sampling points, and simultaneously sends synchronous acquisition signals to the ship model attitude acquisition module;
a8: the ship model attitude acquisition module receives the synchronous acquisition signal and starts to acquire data at the same time;
a9: after the helicopter load acquisition module finishes acquiring according to the set sampling points, sending an acquisition stop signal to the ship model gesture acquisition module, stopping acquisition after the ship model gesture acquisition module receives the acquisition stop signal, and storing data;
a10: changing the amplitude and frequency of the six-degree-of-freedom motion mechanism, and repeating the steps A6-A9 until the test is finished;
a11: and after the test is finished, stopping the six-degree-of-freedom motion mechanism and stopping the wind tunnel power system.
4. A method of testing the aerodynamic properties of a helicopter landing vessel in accordance with claim 3, wherein in A3 the rotational speed and the total pitch angle of the helicopter model are controlled wirelessly by a remote control.
5. A method of testing the aerodynamic properties of a helicopter landing vessel in accordance with claim 1 or 3, wherein the six degrees of freedom motion comprises a single degree of freedom in heave, roll, heave, pitch, yaw, roll, or a combination of any number of degrees of freedom.
6. The wind tunnel test method for the aerodynamic characteristics of the landing of the helicopter according to claim 3, wherein the acquisition frequency of the ship model attitude acquisition module is determined according to more than 20 times of the oscillation frequency of the six-degree-of-freedom motion mechanism of the helicopter, the sampling frequency of the helicopter load acquisition module is determined according to 64 times of the ship model attitude acquisition frequency, and the helicopter rotor acquires 64 points per revolution.
7. A helicopter landing aerodynamic feature wind tunnel test method according to claim 1 or 3, characterized in that the synchronous acquisition mode adopts a master-slave synchronous mode, the helicopter load acquisition module is the master, and the ship model attitude acquisition module is the slave.
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