CN109703770B - Shipboard aircraft landing assisting method based on wind-finding laser radar and CFD database - Google Patents
Shipboard aircraft landing assisting method based on wind-finding laser radar and CFD database Download PDFInfo
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Abstract
The invention discloses a shipboard aircraft landing assisting method and a shipboard aircraft landing assisting system based on a wind-measuring laser radar and a CFD database. According to the method, the CFD model of the target ship is corrected based on the wind-measuring laser radar, when the CFD database is established, only the wind speed information of the area near the lower slide line of the carrier-based aircraft is reserved, the optimal data table of the CFD database is matched according to the radial speed measured by the wind-measuring laser radar in real time, and then the wind speed information of the landing area of the carrier-based aircraft is obtained, so that the landing of the carrier-based aircraft is assisted. The method overcomes the defects that the conventional CFD calculation is slow and cannot give a result in real time and the wind lidar can only measure the radial speed, has the excellent characteristics of high prediction precision, good stability, low prediction time complexity, high spatial resolution and the like, can be applied to a carrier landing decision and control system of a carrier-based aircraft, and improves the accuracy and the safety of carrier landing.
Description
Technical Field
The invention relates to the fields of Computational Fluid Dynamics (CFD), pneumatic databases and wind lidar, in particular to a ship-borne aircraft landing assisting method and a system for estimating the speed of a down-sliding line of a ship-borne aircraft by combining actual measurement data of the wind lidar and the CFD databases.
Background
Some large-scale surface ships can be used for taking off and landing of carrier-based aircraft, the carrier-based aircraft is used as the main attack force of the ship, the key technology is how to ensure safe landing in a very severe environment, if the problem of safe and accurate landing cannot be solved, the ship loses due fighting force, wherein the interference of ship wake flow is one of the main factors influencing the successful landing of the carrier-based aircraft, the horizontal interference influences the airspeed and pitching motion of the aircraft, the vertical disturbance influences the flight height, and the lateral disturbance easily causes the aircraft to roll, so that the key problem of the landing of the carrier-based aircraft is that each speed component of the wake flow is obtained.
At present, the research aiming at the wake flow of a large naval vessel mainly depends on three modes of wind tunnel test, numerical simulation and direct measurement of a real vessel.
The inventor of the invention finds out through research that: the wind tunnel test can save a large amount of cost, can control changeable test environment, is an important means for researching the flow field distribution around the ship, but the size effect of the scaling model and the wall surface of the wind tunnel influence the test result. And the details of the local flow field cannot be captured, so the difference between the wind tunnel test result and the real ship flow field exists. The traditional real-vessel measurement method, such as a hot wire probe, has the disadvantages of high cost, poor safety and very limited measurement range of the anemometer. The Doppler wind measurement laser radar is known as the most effective method for atmospheric wind field remote sensing, has the advantages of high space-time resolution, low altitude, no blind area, high measurement precision, good electromagnetic compatibility, continuous observation in day and night and capability of realizing full coverage from the ground to the height of 110km, but aiming at the special problems of carrier-based aircraft landing, the distance resolution of the conventional wind measurement laser radar is still not high enough, only can measure the radial speed in real time, cannot directly obtain the sub-speeds in three directions and cannot be directly applied to a carrier-based aircraft control system. The Computational Fluid Dynamics (CFD) obtains the discrete distribution of a flow field of fluid flow on a continuous area by solving a differential equation for controlling the fluid flow, thereby approximately simulating the fluid flow condition, and has the advantages of low cost, complete information, high distance resolution and capability of simulating various states in the actual process. Therefore, in order to successfully land the carrier-based aircraft on the ship, an auxiliary system capable of accurately acquiring the wind speed information of the downhill line in real time is urgently needed.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention aims to provide a ship-borne aircraft landing assisting system based on a wind-measuring laser radar and a CFD (computational fluid dynamics) database, which can output the horizontal speed, the lateral speed and the vertical speed on a down slide line of a ship-borne aircraft in real time by combining the CFD database according to the radial speed measured by the wind-measuring laser radar, provide speed information for a ship-borne aircraft control system in time, provide reference for a pilot and a signal officer by predicting a flight track, and assist the ship-borne aircraft to land safely and accurately.
The invention is realized by the following steps:
a shipboard aircraft landing assisting method based on a wind-finding laser radar and a CFD database comprises the following steps:
establishing a Computational Fluid Dynamics (CFD) model of the target vessel according to the geometric parameters of the target vessel;
correcting the CFD model according to wind speed data measured by a wind lidar; the wind measuring laser radar is arranged on a target naval vessel;
selecting preset parameters to discretize the boundary conditions of the modified CFD model, and establishing a CFD database for the carrier-based aircraft to land on a target ship;
acquiring the radial speed of the shipboard aircraft in the direction of a downslide line measured by a wind measurement laser radar in real time;
matching the radial speed with a data table in an established CFD database to obtain a matched optimal data table; the optimal data table comprises a plurality of sub-speeds; the component speeds comprise a horizontal speed, a lateral speed and a vertical speed;
converting the plurality of partial speeds into geodetic speeds under a geodetic reference system according to the ship speed output by a built-in GPS module of the wind lidar;
and feeding back the ground component speed to a flight control system of the carrier-based aircraft.
Further, the modifying the CFD model according to the wind speed data measured by the wind lidar includes:
and comparing and verifying the radial wind speed measured by the wind lidar with the CFD model calculation result, adjusting the calculation domain, the grid quality, the boundary condition and the turbulence model in the CFD model according to the comparison and verification result, and obtaining the modified CFD model.
Further, the selecting the predetermined parameter interval to discretize the boundary condition of the modified CFD model includes:
selecting the size and the direction of deck wind to discretize the boundary condition of the CFD model after correction; the deck wind is the speed of the incoming flow in front relative to the target ship, and the calculation cost is reduced. Deck wind has the greatest influence on flow field spatial distribution; the front is the direction of the target vessel.
Further, when the CFD database is established, the air speed information of the downslide line in the target area near the downslide line of the carrier-based aircraft is output in batch and stored according to the standard format, and the storage space is reduced.
The downslide wind speed information comprises 11 variables which are sequentially an elevation angle, a yaw angle, a deck wind size, a deck wind direction, a radial speed size, a horizontal component speed, a lateral component speed, a vertical component speed, a horizontal coordinate, a lateral coordinate and a vertical coordinate.
Further, the matching the radial velocity with a data table in an established CFD database includes:
and indexing a data table corresponding to the elevation angle and the pitch angle in a CFD (computational fluid dynamics) database according to the elevation angle and the yaw angle of the wind lidar, and matching the radial speed with the indexed data table.
Further, before converting the plurality of partial speeds into the geodetic speed in the geodetic reference system according to the ship speed output by the built-in GPS module of the wind lidar, the method further includes: optimizing a plurality of sub-speeds in an optimal data table according to a preset optimization model based on the radial speed measured by the wind lidar in real time;
the optimization model is as follows:
x0＝[ui,vi,wi]；
ub＝[ui+ub,vi+vb,wi+wb]；
lb＝[ui-ub,vi-vb,wi-wb]；
wherein, f (x) is an optimization objective function, f (x) is the sum of the radial velocity measurement value of each measuring point and the absolute value of the radial velocity residual error of the optimal data table, and minf (x) is the minimum value of f (x); vi eFor measuring the radial velocity of the wind lidar in real time,
is the elevation angle, theta is the yaw angle, uiAs horizontal velocity, v, of the measuring pointiAs the lateral velocity of the measuring point, wiFor vertical velocity of the measured point, ub is the upper boundary of the optimization variable, lb is the lower boundary of the optimization variable, ubIs a preset maximum variation amount v of horizontal velocitybAt a predetermined maximum variation of lateral velocity, wbIs the preset maximum variation amount of the vertical speed.
Correspondingly, a ship-based aircraft helps system of falling based on anemometry laser radar and CFD database includes:
the CFD model establishing module is used for establishing a computational fluid dynamics CFD model of the target vessel according to the geometric parameters of the target vessel;
the CFD model correction module is used for correcting the CFD model according to wind speed data measured by the wind lidar; the wind measuring laser radar is arranged on a target naval vessel;
the CFD database establishing module is used for selecting preset parameters to discretize the boundary conditions of the corrected CFD model and establishing a CFD database aiming at the situation that the carrier-based aircraft lands on a target ship;
the radial speed acquisition module is used for acquiring the radial speed of the shipboard aircraft in the direction of the downhill sliding line measured by the wind measurement laser radar in real time;
the optimal data table acquisition module is used for matching the radial speed with a data table in an established CFD database to acquire a matched optimal data table; the optimal data table comprises a plurality of sub-speeds; the component speeds comprise a horizontal speed, a lateral speed and a vertical speed;
and the geodetic speed acquisition module is used for converting the plurality of geodetic speeds into the geodetic speed under the geodetic reference system according to the ship speed output by the built-in GPS module of the wind lidar.
And the landing assisting module is used for feeding the geodetic velocity back to a flight control system of the carrier-based aircraft.
Further, the method also comprises the following steps:
the optimization module is used for optimizing a plurality of sub-speeds in the optimal data table according to a preset optimization model based on the radial speed measured by the wind lidar in real time;
the optimization model is as follows:
x0＝[ui,vi,wi]；
ub＝[ui+ub,vi+vb,wi+wb]；
lb＝[ui-ub,vi-vb,wi-wb]；
wherein f (x) is an optimization objective function, f (x) is the sum of the radial velocity measurement value of each measuring point and the absolute value of the radial velocity residual error of the optimal data table, and Vi eFor measuring the radial velocity of the wind lidar in real time,
is the elevation angle, theta is the yaw angle, uiAs horizontal velocity, v, of the measuring pointiAs the lateral velocity of the measuring point, wiFor vertical velocity of the measured point, ub is the upper boundary of the optimization variable, lb is the lower boundary of the optimization variable, ubIs a preset maximum variation amount v of horizontal velocitybAt a predetermined maximum variation of lateral velocity, wbIs the preset maximum variation amount of the vertical speed.
The shipboard aircraft landing assisting method and system based on the wind measurement laser radar and the CFD database overcome the defects that the CFD calculation is slow, the result cannot be given in real time, and the wind measurement laser radar can only measure the radial speed, have the excellent characteristics of high prediction precision, good stability, low prediction time complexity, high spatial resolution and the like, can be applied to a shipboard aircraft landing decision and control system, and assist and improve the accuracy and safety of shipboard landing.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on the drawings without creative efforts.
Fig. 1 is a flowchart of a shipboard aircraft landing assisting method based on a wind lidar and a CFD database according to an embodiment of the present invention;
fig. 2 is a flowchart of a shipboard aircraft landing assisting system based on a wind lidar and a CFD database according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a method for establishing CFD wind speed data and a data structure according to an embodiment of the present invention;
fig. 4 is a schematic diagram of a system operating principle according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention are clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention.
Example (b):
fig. 1 is a flowchart of a shipboard aircraft landing assisting method based on a wind lidar and a CFD database according to an embodiment of the present invention; as shown in fig. 1, a ship-based aircraft landing assisting method based on a wind lidar and a CFD database is characterized in that: the method comprises the following steps:
and step S1, establishing a Computational Fluid Dynamics (CFD) model of the target vessel according to the geometric parameters of the target vessel.
Wherein the target vessel is used for taking off and landing of the carrier-based aircraft.
Step S1 specifically includes: and acquiring the geometric parameters of the target vessel, acquiring a mesh file of the target vessel by adopting professional mesh division software according to the geometric parameters, and initially establishing a Computational Fluid Dynamics (CFD) model of the target vessel.
CFD is a short term for Computational Fluid Dynamics (Computational Fluid Dynamics), an emerging cross discipline in which Fluid Dynamics and computer disciplines are fused with each other, and it starts from a calculation method and obtains an approximate solution of a Fluid control equation by using the rapid calculation capability of a computer.
And establishing a CFD model of the target naval vessel by selecting a reasonable grid quality model, a reasonable boundary condition type setting model, a computation domain model and a turbulence model.
Step S2, correcting the CFD model according to wind speed data measured by the wind lidar; the wind measuring laser radar is arranged on a target naval vessel.
Wind lidar, also known as doppler wind lidar, is known as the most effective method for remote sensing of atmospheric wind fields. The wind measuring laser radar emits laser pulses (ultraviolet to infrared) to the atmosphere to interact with the atmosphere, the optical telescope collects backward scattering signals of atmospheric aerosol particles and atmospheric molecules and then inputs the signals into the optical receiver, and the wind speed is inverted by analyzing the radial Doppler frequency shift of emitted laser. The device has the advantages of high space-time resolution, low altitude, no blind area, high measurement precision, good electromagnetic compatibility, continuous observation in day and night and capability of realizing full coverage from the ground to the height of 110 km.
The scanning mode of the wind lidar comprises the following steps: PPI: constant zenith angle mode (azimuth change); RHI: constant azimuth mode (elevation change); DBS: a vertical profile; LOS: the fixed position is continuously observed.
In one embodiment of the invention, the wind lidar may scan in PPI, i.e. constant zenith angle mode, to obtain radial wind speed information in the measurement direction.
Specifically, the step S2 of correcting the CFD model according to the wind speed data measured by the wind lidar includes:
and comparing and verifying the radial wind speed measured by the wind lidar with the CFD model calculation result, wherein the radial wind speed data measured by the wind lidar comprises the radial wind speed and the corresponding measurement angle and position information. And adjusting a computational domain, grid quality, boundary conditions and a turbulence model in the CFD model according to the comparison and verification result to obtain the modified CFD model. The corrected CFD model and the radial wind speed measured by the wind lidar have better consistency.
The CFD model which is initially established is corrected and verified by using real ship measurement data of the wind measuring laser radar, and the rationality and accuracy of the corrected CFD model can be guaranteed.
And step S3, selecting preset parameters to discretize the boundary conditions of the corrected CFD model, and establishing a CFD database for the carrier-based aircraft to land on the target vessel.
In one embodiment, the CFD model in step S2 is used to calculate a target vessel wake field under all possible inflow conditions through discrete boundary conditions, extract coordinates and wind speed information of an area near a ship-based aircraft glideslope in each working condition, and construct a small wind speed database according to a standard data format.
In one embodiment, the selecting the predetermined parameter interval to discretize the boundary condition of the modified CFD model in step S3 includes:
selecting the size and the direction of deck wind with the largest influence on flow field space distribution to discretize the boundary condition of the modified CFD model; the deck wind is the speed of the incoming current in front relative to the target vessel.
When the CFD database is established and boundary condition dispersion is carried out, the size and the direction of deck wind (wind speed relative to a target vessel reference system) which has the largest influence on flow field space distribution are selected for dispersion, so that the calculation working condition can be greatly reduced, and the calculation cost is saved. And secondly, only the wind speed information of the area near the carrier-based aircraft is reserved, the data size of a single working condition is only about 10kB, and the total size of the CFD database is hundreds of megameters, so that the storage cost and the index time are greatly reduced.
When the CFD database is established, outputting the air speed information of the downslide line in a target area near the downslide line of the carrier-based aircraft in batches, and storing the information according to a standard format; the lower slide line is a landing track of the carrier-based aircraft landing to the target vessel.
The downslide wind speed information comprises 11 variables which are sequentially an elevation angle, a yaw angle, a deck wind size, a deck wind direction, a radial speed size, a horizontal component speed, a lateral component speed, a vertical component speed, a horizontal coordinate, a lateral coordinate and a vertical coordinate.
After the CFD database is corrected, speed reference information can be provided for the carrier-based aircraft to land according to the radial speed measured by the laser radar in real time and the corrected CFD database; specifically, the method comprises steps S4-S7.
And S4, acquiring the radial speed of the shipboard aircraft in the direction of the slide line in real time by the wind-measuring laser radar.
The wind measurement laser radar realizes pitching motion and yawing motion through two servo motors, can output a pitch angle and a yawing angle of a scanning line in real time, and is internally provided with a GPS (global positioning system) module for recording and outputting real-time ship speed; the ship speed is the movement speed of the target ship.
The wind measurement laser radar is arranged on a self-stabilizing platform of a Fresnel lens optical landing assistant system on a target ship port, so that not only can the light beam of the laser radar be prevented from being influenced by the left and right swinging of a ship body, but also the laser scanning line can be ensured to be closest to the down slide line of a ship-borne aircraft.
The measuring direction of the wind lidar comprises the direction of a slide line of the carrier-based aircraft, namely the landing direction of the carrier-based aircraft.
Step S5, matching the radial velocity with a data table in an established CFD database to obtain a matched optimal data table; the optimal data table comprises a plurality of sub-speeds; the component velocities include a horizontal velocity, a lateral velocity, and a vertical velocity.
In one embodiment, the step S5, the matching the radial velocity with the data table in the established CFD database includes:
and indexing a data table corresponding to the elevation angle and the pitch angle in a CFD (computational fluid dynamics) database according to the elevation angle and the yaw angle of the wind lidar, and matching the radial speed with the indexed data table.
Preferably, the wind lidar in step S4 is aligned to the ship-based aircraft equal-angle downhill line to perform radial velocity scanning, a data table closest to the actually measured data is matched in the micro database as an optimal data table according to the pitch angle, the yaw angle and the real-time measured radial velocity output by the servo system of the wind lidar, and the corresponding optimal horizontal velocity, lateral velocity and vertical velocity are extracted.
And step S6, converting the plurality of partial speeds into geodetic speeds under a geodetic reference system according to the ship speed output by the built-in GPS module of the wind lidar.
In a preferred embodiment, the method further comprises step S7 of feeding back the ground partial velocity to a flight control system of the carrier-based aircraft.
In a preferred embodiment, before the step S6 converts the plurality of partial velocities into the geodetic velocities in the geodetic reference system according to the ship speed output by the built-in GPS module of the wind lidar, the method further includes:
s8, optimizing a plurality of sub-speeds in the optimal data table according to a preset optimization model based on the radial speed measured by the wind lidar in real time;
the optimization model is as follows:
x0＝[ui,vi,wi]；
ub＝[ui+ub,vi+vb,wi+wb]；
lb＝[ui-ub,vi-vb,wi-wb]；
wherein f (x) is an optimization objective function, f (x) is the sum of the radial velocity measurement value of each measuring point and the absolute value of the radial velocity residual error of the optimal data table, and Vi eFor measuring the radial velocity of the wind lidar in real time,
is the elevation angle, theta is the yaw angle, uiAs horizontal velocity, v, of the measuring pointiAs the lateral velocity of the measuring point, wiFor vertical velocity of the measured point, ub is the upper boundary of the optimization variable, lb is the lower boundary of the optimization variable, ubIs a preset maximum variation amount v of horizontal velocitybAt a predetermined maximum variation of lateral velocity, wbIs the preset maximum variation amount of the vertical speed.
Based on the optimal component velocity in the optimal data table matched in the step S5 and the radial velocity measured by the radar in real time, the component velocity is further corrected by adopting an optimization algorithm, and the wind speed at the position on the lower slide line except the radar measuring point is obtained by interpolation of the measuring point optimization result.
Based on the corrected downslide wind speed information in the step S6 and the ship speed information provided by the GPS, the downslide wind speed under the geodetic reference system is obtained and fed back to the carrier-based control system, so that the carrier-based aircraft is helped to correct the flight state in time, and the influence of wake flow is inhibited.
In one embodiment, the method further comprises: and inputting the geodetic speeds in the three directions into a ship-borne aircraft dynamics equation, further predicting the flight track of the ship-borne aircraft, and displaying the flight track on a user interface in real time to provide reference for decisions of pilots and signal officers.
As shown in fig. 2, correspondingly, the present invention further provides a ship-based aircraft landing assisting system based on a wind lidar and a CFD database, including:
the CFD model establishing module is used for establishing a computational fluid dynamics CFD model of the target vessel according to the geometric parameters of the target vessel;
the CFD model correction module is used for correcting the CFD model according to wind speed data measured by the wind lidar; the wind measuring laser radar is arranged on a target naval vessel;
the CFD database establishing module is used for selecting preset parameters to discretize the boundary conditions of the corrected CFD model and establishing a CFD database aiming at the situation that the carrier-based aircraft lands on a target ship;
the radial speed acquisition module is used for acquiring the radial speed of the shipboard aircraft in the direction of the downhill sliding line measured by the wind measurement laser radar in real time;
the optimal data table acquisition module is used for matching the radial speed with a data table in an established CFD database to acquire a matched optimal data table; the optimal data table comprises a plurality of sub-speeds; the component speeds comprise a horizontal speed, a lateral speed and a vertical speed;
the geodetic velocity acquisition module is used for converting the plurality of geodetic velocities into geodetic velocities under a geodetic reference system according to the ship velocity output by the built-in GPS module of the wind lidar;
and the landing assisting module is used for feeding the geodetic velocity back to a flight control system of the carrier-based aircraft.
In one embodiment, the system further comprises:
the optimization module is used for optimizing a plurality of sub-speeds in the optimal data table according to a preset optimization model based on the radial speed measured by the wind lidar in real time;
the optimization model is as follows:
x0＝[ui,vi,wi]；
ub＝[ui+ub,vi+vb,wi+wb]；
lb＝[ui-ub,vi-vb,wi-wb]；
wherein f (x) is an optimization objective function, f (x) is the sum of the radial velocity measurement value of each measuring point and the absolute value of the radial velocity residual error of the optimal data table, and Vi eFor measuring the radial velocity of the wind lidar in real time,
is the elevation angle, theta is the yaw angle, uiAs horizontal velocity, v, of the measuring pointiAs the lateral velocity of the measuring point, wiFor vertical velocity of the measured point, ub is the upper boundary of the optimization variable, lb is the lower boundary of the optimization variable, ubIs a preset maximum variation amount v of horizontal velocitybAt a predetermined maximum variation of lateral velocity, wbIs the preset maximum variation amount of the vertical speed.
The method of the present invention is described in detail below with a specific application scenario.
And establishing a geometric model according to the appearance structure of the target vessel, and keeping the main body structure of the target vessel to ignore local micro structures with small influence on a flow field in the geometric modeling process in order to reduce the number of grids and the calculation complexity. The simulation of the target ship wake field belongs to the simulation of an external flow field, the outer boundary of a calculation region should be theoretically at infinity at the periphery of a target ship, but in actual calculation, a limited calculation domain can be adopted to replace an infinite calculation domain, and when the calculation domain is much larger than a model, for example, the volume of the calculation domain is 500-1000 times of that of the target ship, the calculation amount can be reduced while the calculation accuracy is ensured.
The whole calculation domain is processed in a mixed grid mode combining unstructured grids and structured grids, the warship body geometric structure of a target ship is complex, tetrahedral unstructured grids are adopted around the warship body geometric structure to achieve a good effect, the warship body surface grids are encrypted to accurately capture surface flow field information, hexahedral structured grids are adopted on the peripheries of the rest of warships, fine grids are adopted in a concerned ship carrier down-slide line area, coarse grids are adopted on the rest of warship carrier down-slide line area to control the grids to be in the order of tens of millions, when the boundary condition is set, an inlet is a Velocity-inlet, an outlet and an upper boundary are set as a Pressure-outlet, the ship surface and a sea level are set as Wall surfaces (Wall), the left and right boundaries of the calculation area are set as a Velocity inlet and a Pressure outlet according to the wind direction, namely, the windward side is a Velocity inlet, and the leeward side is set as a Pressure outlet. The ship wake field belongs to high-Reynolds-number turbulence, a standard k-epsilon model is selected for steady-state calculation in a turbulence model during numerical solution, a SIMPLE algorithm is adopted for a pressure-speed coupling term in a momentum equation, a second-order windward format is adopted for the momentum equation and the turbulence viscosity, and a second-order space discrete format is adopted for the pressure equation.
When the forward inflow condition is fixed, the spatial distribution of the steady-state flow field at the tail of the target ship is unique theoretically, and the CFD model is adopted to carry out steady-state numerical simulation on the wake flow field, so that the flow field distribution under the inflow condition can be obtained.
Before a CFD database is established, firstly, model correction and verification are carried out by using real ship test data of a wind lidar, the specific operation is that the radial speed of a plane corresponding to radar PPI scanning (fixed elevation angle) in a CFD simulation result is extracted and compared with test data, and the CFD model is repeatedly corrected by improving the calculation domain, the grid quality and the boundary condition until the CFD simulation result is better in integral coincidence with the test result, wherein the radial speed expression of the CFD simulation is as follows:
q is the position coordinate of the laser radar under the target vessel coordinate system, H is the position of a radar measuring point under the target vessel coordinate system, and V is the resultant speed of the measuring point under the target vessel coordinate system.
The method for establishing CFD wind speed data and the data structure of the invention are shown in FIG. 3, and the discretization of the incoming flow conditions is firstly carried out. Parameters such as the speed, the direction, the temperature, the viscosity and the pressure of the front incoming flow and the running speed of a target ship influence the distribution of the wake flow of the ship, wherein the influence of the size, the direction and the speed of the front incoming flow on the spatial distribution of the wake flow field is the largest. Two parameters of deck wind (speed of front incoming flow relative to a target ship) and wind direction are selected to disperse the boundary condition of the speed entrance, and the tail flow speed under the geodetic reference system can be corrected through the ship speed output by the GPS, so that the complexity of the speed entrance is greatly reduced, and the storage space and the calculation cost are also saved.
In order to cover all possible inflow conditions in the running process of a target vessel, the size and the direction of deck wind can be divided into a plurality of discrete working conditions according to preset interval intervals and precision.
And when the CFD calculation result is processed, the angle of the carrier-based aircraft downslide line is firstly obtained, and only the wind speed information of the target area near the carrier-based aircraft downslide line is output in batch. In order to cover all possible downslide line areas, the target area may be divided into multiple parts at equal intervals, and multiple sets of downslide lines are generated.
Each of the downslide wind speed information includes 11 variables, which are an elevation angle, a swing angle, a deck wind size, a deck wind direction, a radial speed size, a horizontal component speed, a lateral component speed, a vertical component speed, a horizontal coordinate, a lateral coordinate and a vertical coordinate in sequence. According to the computing power of the current High Performance Computing (HPC) server, the computation of all working conditions can be completed within one week, and the CFD database construction can be completed by storing all the downwash wind speed information according to the standard format shown in FIG. 3.
The working principle schematic diagram of the landing assistant system of the shipboard aircraft is shown in fig. 4, and the specific working process is as follows:
the Doppler wind measurement laser radar realizes pitching and yawing motions through 2 servo motors, the built-in GPS module is used for recording and outputting the motion condition of a target ship, the precision of the servo motors is controlled within 1', and the laser radar is installed on a self-stabilizing platform of a Fresnel lens optical landing aid system on the port of the target ship on the premise of not influencing the work of the Fresnel lens optical landing aid system, so that the laser radar beam is not influenced by the left and right swinging of a ship body, and the laser scanning line is closest to a down slide line of the ship. When the laser radar works, the elevation angle and the yaw angle of the radar scanning head are controlled through the servo control system to be aligned with the carrier aircraft downslide line. And after the laser signal is processed by a radar signal system, the measured radial speed and position information are output.
In order to improve the database indexing efficiency, when actual measurement data are matched with database data, a data table of corresponding elevation angles and pitch angles in a database is indexed according to the elevation angles and the yaw angles output by a laser radar servo control system, so that the data matching range is greatly reduced.
When the data are matched, recording the radial velocity, the component velocity and the coordinate of the current data table by using a data table D, and simultaneously calculating and recording the sum delta of the residual absolute values of the actually measured data of the wind-measuring laser radar and the radial velocity in the current data table, wherein the data table corresponding to the minimum delta is an optimal data table, namely:
wherein Vi eRadar as the ith stationMeasurement data, ViThe data of the ith measuring point is database data, and n is the total number of the measuring points. And then, starting to match the next data table, transmitting the information of the current data table to the data table D when the delta is smaller than the currently recorded delta, otherwise, directly matching the next data table, and repeating the steps until all the data tables are matched, wherein the wind speed of the data table D is closest to the actual downhill line wind speed.
In order to further improve the approximation degree of the minute speed and the real wind field, an optimization algorithm is called to correct the minute speed, wherein an optimization objective function f (x) is the sum of the measured value of the radial speed of each measuring point and the absolute value of the residual error of the radial speed of the data table D, and an optimization variable is the minute speed of each point. The optimization model used is as follows:
x0＝[ui,vi,wi]；
ub＝[ui+ub,vi+vb,wi+wb]；
lb＝[ui-ub,vi-vb,wi-wb]；
wherein u isi、viAnd wiHorizontal speed, lateral speed and vertical speed of a measuring point, ub and lb are upper and lower boundaries of an optimized variable, ui、viAnd wiThe recommended values of the maximum variation of the component velocity are 3m/s, 1m/s and 1 m/s. The optimization model is a multivariable linear optimization problem, a simplex method is preferably selected, and an optimal solution can be rapidly obtained. Further, the speed of the target vessel in the coordinate system is corrected by using the ship speed information output by the laser radar GPS, so that the horizontal speed (U), the lateral speed (V) and the vertical speed (W) in the geodetic coordinate system are obtained. The component speeds in the three directions have two functions, one is to feed the component speed information back to the carrier-based aircraft flight control system to help the carrier-based aircraft flight control system to make corresponding control response so as to inhibit the influence of wake flow. Another effect is to divide the velocityAnd substituting the information into a ship-borne aircraft kinetic equation, predicting the flight track of the ship-borne aircraft, and displaying the flight track on a user interface in real time to provide reference for the decision of a signal officer and a pilot.
The method overcomes the defects that the CFD calculation is slow and cannot give a result in real time and the wind lidar can only measure the radial speed, has the excellent characteristics of high prediction precision, good stability, low prediction time complexity, high spatial resolution and the like, can be applied to a carrier landing decision and control system of the carrier-based aircraft, and assists and improves the accuracy and the safety of the carrier-based landing.
Compared with the prior art, the invention has the following gain effects:
(1) according to the real ship measurement data of the laser radar, the CFD of the target ship is repeatedly corrected and verified, and an accurate and reasonable CFD model can be obtained.
(2) When the CFD database is established and boundary condition dispersion is carried out, the size and the direction of deck wind (relative to the ground wind speed of a target vessel reference system) which has the largest influence on flow field space distribution are selected for dispersion, so that the calculation working condition is greatly reduced, and the calculation cost is saved. And secondly, only the wind speed information of the area near the carrier-based aircraft is reserved, the data size of a single working condition is only 10kB, the total size of the CFD database is hundreds of megameters, and the storage cost and the index time are greatly reduced.
(3) The wind measurement laser radar is arranged on a self-stabilizing platform of a Fresnel lens optical landing assistant system on a port of a target ship, so that not only can the light beam of the laser radar be prevented from being influenced by the left and right swinging of a ship body, but also the laser scanning line can be ensured to be closest to a slip line of a carrier-based aircraft.
(4) When the actual measurement data of the wind lidar is matched with the CFD database, the data area corresponding to the elevation angle and the pitch angle in the CFD database is firstly indexed according to the elevation angle and the yaw angle output by the wind lidar servo control, the data matching range is narrowed, and the retrieval efficiency is improved.
(5) Based on the matched optimal sub-speed and the radar real-time measured radial speed, an optimization algorithm is adopted to further correct the sub-speed, and the accuracy of the sub-speed is further improved.
(6) The partial velocity is converted into the partial velocity of a geodetic reference system by using the GPS, and the method can be applied to an attitude system of a flight control system and can also be applied to flight trajectory prediction.
It should be noted that other non-described parts of the present invention are well known to those skilled in the art, and those skilled in the art can find relevant documents according to the names or functions of the present invention, and thus are not further described.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (7)
1. A ship-borne aircraft landing assisting method based on a wind-measuring laser radar and a CFD database is characterized by comprising the following steps: the method comprises the following steps:
establishing a Computational Fluid Dynamics (CFD) model of the target vessel according to the geometric parameters of the target vessel;
correcting the CFD model according to wind speed data measured by a wind lidar; the wind measuring laser radar is arranged on a target naval vessel;
selecting preset parameters to discretize the boundary conditions of the modified CFD model, and establishing a CFD database for the carrier-based aircraft to land on a target ship;
acquiring the radial speed of the shipboard aircraft in the direction of a downslide line measured by a wind measurement laser radar in real time;
matching the radial speed with a data table in an established CFD database to obtain a matched optimal data table; the optimal data table comprises a plurality of sub-speeds; the component speeds comprise a horizontal speed, a lateral speed and a vertical speed;
optimizing a plurality of sub-speeds in an optimal data table according to a preset optimization model based on the radial speed measured by the wind lidar in real time; the optimization model is as follows:
x0＝[ui,vi,wi]；
ub＝[ui+ub,vi+vb,wi+wb]；
lb＝[ui-ub,vi-vb,wi-wb]；
wherein f (x) is an optimization objective function, Vi eFor measuring the radial velocity of the wind lidar in real time,
is the elevation angle, theta is the yaw angle, uiAs horizontal velocity, v, of the measuring pointiAs the lateral velocity of the measuring point, wiFor vertical velocity of the measured point, ub is the upper boundary of the optimization variable, lb is the lower boundary of the optimization variable, ubIs a preset maximum variation amount v of horizontal velocitybAt a predetermined maximum variation of lateral velocity, wbThe maximum variation amount of the preset vertical speed;
converting the plurality of partial velocities into geodetic velocities in a geodetic reference system;
and feeding back the ground component speed to a flight control system of the carrier-based aircraft.
2. The method of claim 1, wherein the modifying the CFD model according to anemometry lidar measured wind speed data comprises:
and comparing and verifying the radial wind speed measured by the wind lidar with the CFD model calculation result, adjusting the calculation domain, the grid quality, the boundary condition and the turbulence model in the CFD model according to the comparison and verification result, and obtaining the modified CFD model.
3. The method of claim 2, wherein when the CFD database is established, the down-line wind speed information in the target area near the carrier aircraft down-line is output in batch and stored according to a standard format;
the downslide wind speed information comprises 11 variables which are sequentially an elevation angle, a yaw angle, a deck wind size, a deck wind direction, a radial speed size, a horizontal component speed, a lateral component speed, a vertical component speed, a horizontal coordinate, a lateral coordinate and a vertical coordinate.
4. The method according to claim 1 or 2, wherein the selecting the predetermined parameter interval discretizes the boundary condition of the modified CFD model, and comprises:
selecting the size and the direction of deck wind to discretize the boundary condition of the CFD model after correction; the deck wind is the speed of the incoming current in front relative to the target vessel.
5. The method of claim 4, wherein when the CFD database is established, the down-line wind speed information in the target area near the carrier aircraft down-line is output in batch and stored according to a standard format;
the downslide wind speed information comprises 11 variables which are sequentially an elevation angle, a yaw angle, a deck wind size, a deck wind direction, a radial speed size, a horizontal component speed, a lateral component speed, a vertical component speed, a horizontal coordinate, a lateral coordinate and a vertical coordinate.
6. The method of claim 1, wherein matching the radial velocity to a table in an established CFD database comprises:
and indexing a data table corresponding to the elevation angle and the pitch angle in a CFD (computational fluid dynamics) database according to the elevation angle and the yaw angle of the wind lidar, and matching the radial speed with the indexed data table.
7. The utility model provides a ship-borne aircraft helps system of falling based on anemometry laser radar and CFD database which characterized in that: the method comprises the following steps:
the CFD model establishing module is used for establishing a computational fluid dynamics CFD model of the target vessel according to the geometric parameters of the target vessel;
the CFD model correction module is used for correcting the CFD model according to wind speed data measured by the wind lidar; the wind measuring laser radar is arranged on a target naval vessel;
the CFD database establishing module is used for selecting preset parameters to discretize the boundary conditions of the corrected CFD model and establishing a CFD database aiming at the situation that the carrier-based aircraft lands on a target ship;
the radial speed acquisition module is used for acquiring the radial speed of the shipboard aircraft in the direction of the downhill sliding line measured by the wind measurement laser radar in real time;
the optimal data table acquisition module is used for matching the radial speed with a data table in an established CFD database to acquire a matched optimal data table; the optimal data table comprises a plurality of sub-speeds; the component speeds comprise a horizontal speed, a lateral speed and a vertical speed;
the optimization module is used for optimizing a plurality of sub-speeds in the optimal data table according to a preset optimization model based on the radial speed measured by the wind lidar in real time; the optimization model is as follows:
x0＝[ui,vi,wi]；
ub＝[ui+ub,vi+vb,wi+wb]；
lb＝[ui-ub,vi-vb,wi-wb]；
wherein f (x) is an optimization objective function, f (x) is the sum of the radial velocity measurement value of each measuring point and the absolute value of the radial velocity residual error of the optimal data table, and Vi eFor measuring the radial velocity of the wind lidar in real time,
is the elevation angle, theta is the yaw angle, uiAs horizontal velocity, v, of the measuring pointiAs the lateral velocity of the measuring point, wiFor vertical velocity of the measured point, ub is the upper boundary of the optimization variable, lb is the lower boundary of the optimization variable, ubIs a preset maximum variation amount v of horizontal velocitybAt a predetermined maximum variation of lateral velocity, wbThe maximum variation amount of the preset vertical speed;
the earth part velocity obtaining module is used for converting the plurality of part velocities into earth part velocities under an earth reference system;
and the landing assisting module is used for feeding the geodetic velocity back to a flight control system of the carrier-based aircraft.
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