Helicopter flight safety boundary identification method, device, equipment, medium and product

Abstract

The invention discloses a helicopter flight safety boundary identification method, device and equipment, a medium and a product, and relates to the field of helicopters.The method comprises the steps that terrain information, wind environment information, helicopter design parameters and a motion state are obtained; according to the terrain information and the wind environment information, wind speed distribution characteristics in a complex environment are determined through CFD simulation; constructing a helicopter flight mechanical model according to the helicopter design parameters and the motion state; coupling the helicopter flight mechanical model with the wind speed distribution characteristics to obtain a helicopter flight dynamic model; determining a threat area according to the wind speed distribution characteristics and the helicopter flight dynamics model; the threat area comprises a wind speed threat area, a manipulation threat area, a posture threat area, a power threat area and a vortex ring threat area; and combining the threat areas to determine the flight safety boundary. According to the application, the expandability and environmental adaptability of helicopter flight safety boundary identification are improved.

Description

Technical Field

[0001] The present application relates to the field of helicopters, and in particular, to a method, device, equipment, medium and product for identifying the flight safety boundary of a helicopter. Background Art

[0002] Helicopters have unique capabilities of vertical takeoff and landing, hovering in the air, and flying at very low altitudes, playing an irreplaceable role in military and civilian fields. However, when flying in complex environments, according to different terrain characteristics, there may be complex environmental flow fields. For example, urban building clusters often cause turbulent environments such as downdraft and street acceleration, mountains will have roller-shaped airflows and large mountain backflows, and there are complex ship island shedding vortices around ships. When a helicopter is performing a mission, the unstable airflow in the environment directly acts on the helicopter blades, generating unsteady pulsating loads, seriously affecting the flight performance and handling characteristics of the helicopter, and increasing the flight risk. Therefore, carrying out research on the flight safety boundary of helicopters in various environments can predict and avoid the flight danger areas caused by complex environmental wind fields in advance, improve the survival ability of helicopters, and guide the design of flight strategies. Summary of the Invention

[0003] The purpose of the present application is to provide a method, device, equipment, medium and product for identifying the flight safety boundary of a helicopter, which can improve the scalability and environmental adaptability of helicopter flight safety boundary identification.

[0004] To achieve the above purpose, the present application provides the following solutions:

[0005] In a first aspect, the present application provides a method for identifying the flight safety boundary of a helicopter, including:

[0006] Obtaining terrain information, wind environment information, helicopter design parameters and motion states;

[0007] Using CFD simulation to determine the wind speed distribution characteristics in a complex environment according to the terrain information and the wind environment information;

[0008] Constructing a helicopter flight mechanics model according to the helicopter design parameters and the motion states;

[0009] Coupling the helicopter flight mechanics model with the wind speed distribution characteristics to obtain a helicopter flight dynamics model;

[0010] Determining a threat area according to the wind speed distribution characteristics and the helicopter flight dynamics model; the threat area includes a wind speed threat area, a handling threat area, an attitude threat area, a power threat area and a vortex ring threat area;

[0011] Merging the threat areas to determine the flight safety boundary.

[0012] Optionally, the wind speed distribution characteristics in a complex environment are determined by using CFD simulation based on the terrain information and the wind environment information, specifically including:

[0013] Extract terrain features according to the terrain information;

[0014] Determine the average wind speed at different heights according to the wind environment information;

[0015] Set the initial parameters of the flow field, and perform CFD simulation on the flow field according to the terrain features and the average wind speed at different heights to obtain the wind speed distribution characteristics in a complex environment.

[0016] Optionally, a helicopter flight mechanics model is constructed according to the helicopter design parameters and the motion state, specifically including:

[0017] Interpolate and solve the mechanical information of each component at the aerodynamic center according to the helicopter design parameters and the motion state; the mechanical information includes three-direction forces and moments;

[0018] Perform coordinate transformation according to the mechanical information of each component at the aerodynamic center to obtain the mechanical information at the center of gravity of the whole aircraft;

[0019] Construct a helicopter flight mechanics model according to the mechanical information at the center of gravity of the whole aircraft based on the six-degree-of-freedom rigid body motion equation.

[0020] Optionally, a threat area is determined according to the wind speed distribution characteristics and the helicopter flight mechanics model, specifically including:

[0021] Determine the wind speed threat area according to the environmental velocity field and the turbulent kinetic energy distribution of the distribution characteristics;

[0022] Determine the spatial operation characteristic cloud map based on the joystick magnitude according to the helicopter flight mechanics model;

[0023] Determine the operation threat area according to the spatial operation characteristic cloud map and the joystick margin threshold;

[0024] Determine the spatial attitude characteristic cloud map based on the helicopter attitude angle value according to the helicopter flight mechanics model;

[0025] Determine the attitude threat area according to the spatial attitude characteristic cloud map and the attitude angle threshold;

[0026] Determine the spatial power characteristic cloud map based on the required power of the helicopter according to the helicopter flight mechanics model;

[0027] Determine the power threat area according to the spatial power characteristic cloud map and the power threshold;

[0028] Determine the vortex ring limit criterion based on the environmental wind speed, rotor induced velocity, and tail rotor induced velocity according to the helicopter dynamics model;

[0029] Determine the vortex ring threat area according to the vortex ring limit criterion.

[0030] Optionally, the joystick margin threshold is that the joystick margin of each channel is greater than 10%.

[0031] Optionally, the power threshold is that the helicopter engine margin is greater than 10%.

[0032] In a second aspect, the present application provides a helicopter flight safety boundary identification device, including:

[0033] An acquisition module for acquiring terrain information, wind environment information, helicopter design parameters, and motion states;

[0034] A distribution feature determination module for determining the wind speed distribution feature in a complex environment by using CFD simulation according to the terrain information and the wind environment information;

[0035] A construction module for constructing a helicopter flight mechanics model according to the helicopter design parameters and the motion states;

[0036] A coupling module for coupling the helicopter flight mechanics model with the wind speed distribution feature to obtain a helicopter flight dynamics model;

[0037] A threat area determination module for determining a threat area according to the wind speed distribution feature and the helicopter flight dynamics model; the threat area includes a wind speed threat area, a control threat area, an attitude threat area, a power threat area, and a vortex ring threat area;

[0038] A flight safety boundary determination module for merging the threat area to determine the flight safety boundary.

[0039] In a third aspect, the present application provides a computer device, including: a memory, a processor, and a computer program stored on the memory and executable on the processor, where the processor executes the computer program to implement the helicopter flight safety boundary identification method described in any one of the above.

[0040] In a fourth aspect, the present application provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, it implements the helicopter flight safety boundary identification method described in any one of the above.

[0041] In a fifth aspect, the present application provides a computer program product, including a computer program, and when the computer program is executed by a processor, it implements the helicopter flight safety boundary identification method described in any one of the above.

[0042] According to the specific embodiments provided in the present application, the present application has the following technical effects:

[0043] The present application provides a helicopter flight safety boundary recognition method, device, equipment, medium and product. By determining the wind speed distribution characteristics in complex environments based on terrain environment and wind environment information, and coupling the wind speed distribution characteristics with the helicopter flight mechanics model, taking into account the characteristics of the environmental wind field, a helicopter flight safety analysis method based on environment-helicopter coupling is formed, improving the environmental adaptability. And a threat area is constructed based on the limitations of wind speed, maneuvering, attitude, power and vortex ring factors, thereby further improving the scalability and environmental adaptability. Brief Description of the Drawings

[0044] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0045] Figure 1 It is an application environment diagram of a helicopter flight safety boundary recognition method in an embodiment of the present application;

[0046] Figure 2 It is a flowchart of a helicopter flight safety boundary recognition method provided in an embodiment of the present application;

[0047] Figure 3 It is a schematic diagram of the process of a helicopter flight safety boundary recognition method provided in an embodiment of the present application;

[0048] Figure 4 It is a CFD solution flowchart of a helicopter flight safety boundary recognition method provided in an embodiment of the present application;

[0049] Figure 5 It is a structural diagram of the flight dynamics model provided in an embodiment of the present application;

[0050] Figure 6 It is a simulated environmental wind speed characteristic diagram provided in an embodiment of the present application;

[0051] Figure 7 It is a schematic diagram of discrete analysis points in the spatial domain around a mountain provided in an embodiment of the present application;

[0052] Figure 8 It is a schematic diagram of discrete analysis points in the spatial domain around a building provided in an embodiment of the present application;

[0053] Figure 9The spatial operation feature cloud map provided by an embodiment of the present application;

[0054] Figure 10 The spatial attitude feature cloud map provided by an embodiment of the present application;

[0055] Figure 11 The spatial power feature cloud map provided by an embodiment of the present application;

[0056] Figure 12 The schematic diagram of the vortex ring threat area under the balanced state of the helicopter provided by an embodiment of the present application;

[0057] Figure 13 The structural schematic diagram of a computer device provided by an embodiment of the present application. Detailed implementation manners

[0058] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0059] To make the above objects, features, and advantages of the present application more obvious and understandable, the present application will be further described in detail below in conjunction with the accompanying drawings and specific implementation manners.

[0060] So far, there is no general analysis method for the research on the flight safety boundary of helicopters in complex environments. When conducting safety analysis under large-scale flow field interference, the traditional approach is to analyze the balance characteristics of helicopters at key points on the flight takeoff and landing routes, and use the wind speed and wind direction limits at the takeoff and landing points as the safety boundaries. However, in the real environment, there are diverse flight tasks, making it difficult to form a unified description of the flight route. Moreover, single-point research cannot effectively evaluate potential systematic risks, and only obtaining environmental wind limits cannot compensate for specific threats. Therefore, this application provides a method for identifying the flight safety boundary of helicopters based on the coupling of aerodynamics and flight mechanics, which is used to identify the dynamic safety boundary when helicopters fly in complex environments (such as mountains, cities, ships, etc.). This method conducts terrain modeling on the complex environment and performs accurate wind field numerical simulations, then discretizes the environmental space domain and selects analysis points in the key areas of the wind field, deeply calculates the full-aircraft balance characteristics of the helicopter at the analysis points, and finally compares with the helicopter's control, attitude, power, and vortex ring limits to obtain the dynamic safety boundary of the helicopter flying in the complex environment; it involves the fields of flight dynamics and computational fluid dynamics of rotorcraft. Based on the helicopter control specifications, a comprehensive analysis of the environmental wind field, control travel, fuselage attitude, power consumption, and vortex ring limits is carried out to formulate environmental threat criteria, and considering the restrictions of environmental obstacles on the pilot's vision and control space, a dynamic flight safety boundary of the helicopter in the environmental space is formed, providing a guide for the safe flight of helicopters.

[0061] The method for identifying the flight safety boundary of a helicopter provided by the embodiments of this application can be applied, for example, Figure 1In the application environment shown. Among them, the terminal 102 communicates with the server 104 through the network. The data storage system can store the data that the server 104 needs to process. The data storage system can be set separately, integrated on the server 104, placed on the cloud or other servers. The terminal 102 can send the terrain information, wind environment information, helicopter design parameters and motion state to be processed to the server 104. After receiving the terrain information, wind environment information, helicopter design parameters and motion state to be processed, for the terrain information, wind environment information, helicopter design parameters and motion state to be processed, the server 104 uses CFD simulation to determine the wind speed distribution characteristics in the complex environment according to the terrain information and the wind environment information; constructs a helicopter flight mechanics model according to the helicopter design parameters and the motion state; couples the helicopter flight mechanics model with the wind speed distribution characteristics to obtain a helicopter flight dynamics model; determines a threat area according to the wind speed distribution characteristics and the helicopter flight dynamics model; the threat area includes a wind speed threat area, a maneuver threat area, an attitude threat area, a power threat area and a vortex ring threat area; merges the threat areas to determine a flight safety boundary. The server 104 can feedback the obtained flight safety boundary to the terminal 102. In addition, in some embodiments, the helicopter flight safety boundary recognition method can also be implemented by the server 104 or the terminal 102 alone. For example, the terminal 102 can directly perform flight safety boundary recognition for the terrain information, wind environment information, helicopter design parameters and motion state, or the server 104 can obtain the terrain information, wind environment information, helicopter design parameters and motion state from the data storage system and perform flight safety boundary recognition for the terrain information, wind environment information, helicopter design parameters and motion state.

[0062] Among them, the terminal 102 can be, but is not limited to, various desktop computers, laptop computers, smartphones, tablets, Internet of Things devices and portable wearable devices. The Internet of Things devices can be smart speakers, smart TVs, smart air conditioners, smart in-vehicle devices, etc. The portable wearable devices can be smart watches, smart bracelets, head-mounted devices, etc. The server 104 can be implemented by an independent server or a server cluster composed of multiple servers, and can also be a cloud server.

[0063] In an exemplary embodiment, as Figure 2 shown, a method for recognizing a helicopter flight safety boundary is provided. This method is executed by a computer device, and specifically can be executed alone by a computer device such as a terminal or a server, or jointly executed by a terminal and a server. In the embodiments of the present application, taking this method applied to Figure 1 the server 104 in

[0064] Step 201: Obtain terrain information, wind environment information, helicopter design parameters, and motion state.

[0065] Step 202: Use CFD simulation to determine the wind speed distribution characteristics in complex environments based on the terrain information and the wind environment information.

[0066] Step 203: Construct a helicopter flight mechanics model based on the helicopter design parameters and the motion state.

[0067] Step 204: Couple the helicopter flight mechanics model with the wind speed distribution characteristics to obtain a helicopter flight dynamics model.

[0068] Step 205: Determine the threat areas based on the wind speed distribution characteristics and the helicopter flight dynamics model; the threat areas include a wind speed threat area, a control threat area, an attitude threat area, a power threat area, and a vortex ring threat area.

[0069] Step 206: Combine the threat areas to determine the flight safety boundary.

[0070] Implementing the above steps 201 to 206 can improve the scalability and environmental adaptability of helicopter flight safety boundary recognition.

[0071] In an exemplary embodiment, step 202 specifically includes:

[0072] Extract terrain features based on the terrain information. Determine the average wind speed at different heights according to the wind environment information. Set the initial parameters of the flow field, and perform CFD simulation on the flow field based on the terrain features and the average wind speed at different heights to obtain the wind speed distribution characteristics in complex environments.

[0073] In practical applications, environmental modeling and wind field simulation need to be carried out first. By establishing a typical terrain and average wind model and using CFD simulation to obtain the wind speed distribution characteristics in complex environments, the wind speeds at different positions are subsequently superimposed on the flight dynamics model to affect the overall aircraft balance characteristics on the one hand, and are used for dividing the environmental wind speed threat areas on the other hand. The specific steps are as follows:

[0074] The first step is to establish a typical terrain / environmental obstacle model. To establish a typical terrain / environmental obstacle model, first extract the typical terrain features in the environment, only focus on the terrain undulation for natural environment modeling, only consider the overall building shape for urban area modeling, etc. After establishing the simplified terrain geometry, draw the unstructured grid required for CFD analysis.

[0075] Step 2: Establish a wind environment model. The wind environment only considers the average wind characteristics. The average wind profile is described according to the exponential law, and the profile wind speed is used as the wind speed at the corresponding height as the far-field inflow velocity to form the CFD inlet boundary condition. For the exponential wind profile, the expression for the variation of the average wind speed along the height is as follows:

[0076]

[0077] In the formula, \(z_0\) and are the standard reference height and the average wind speed at the standard reference height respectively. According to the national standard wind force level division, the height of 10 m is used as the average wind reference height; \(z\) and are the average wind speeds at any height and any height respectively; \(\alpha\) is the ground roughness index.

[0078] Step 3: Read the configuration file. Set the parameters required for CFD calculation in the configuration file. The configuration file is organized in JSON format, which describes each grid block and its file name, including the initial parameters of the flow field (determine the inflow velocity using the above average wind profile), the solution control parameters (the spatial / temporal discretization format and turbulence model set for each block of grids, the unsteady time step, the maximum number of calculation iterations, etc.), and the post-processing and output settings. Among them, the control parameters, post-processing, and output settings are all set in advance.

[0079] Step 4: Solve the flow field. Set the computational domain as a cuboid, set the impenetrable surfaces such as the environmental terrain / obstacle surfaces as walls, and the other penetrable boundaries (allowing the fluid to flow in and out freely without obstruction) as free flow conditions. The velocity input uses the average wind synthesized in Step 2. Conduct CFD simulation. When the calculation converges, the wind speed distribution characteristics such as the velocity, pressure, density, and turbulent kinetic energy in the flow field as shown in Figure 6 can be obtained. Figure 6 In (a), it is the cross-wind velocity distribution around the mountain body. Figure 6 In (b), it is the vertical wind velocity distribution around the mountain body.

[0080] As shown in Figure 4 , the established CFD solution program flow: 1) Read the configuration, which describes the initial parameters of the flow field and the solution control parameters; 2) Read the grid file, and discretize the terrain geometric model into an unstructured grid form available for CFD; 3) Initialize the flow field, use the exponential average wind profile to directly assign values to the global flow field to reduce the subsequent calculation convergence time; 4) Solve the flow field, select the spatial / temporal discretization format and turbulence model according to the solution configuration of the corresponding grid block, and perform iterative calculations. 5) Output and post-process, output the wind speed and turbulent kinetic energy at the grid points in the computational domain for subsequent analysis.

[0081] In an exemplary embodiment, step 203 specifically includes:

[0082] Interpolate and solve for the mechanical information of each component at the aerodynamic center according to the helicopter design parameters and the motion state; the mechanical information includes three-directional forces and moments.

[0083] Perform coordinate transformation based on the mechanical information of each component at the aerodynamic center to obtain the mechanical information at the center of gravity of the whole aircraft.

[0084] Construct a helicopter flight mechanics model based on the mechanical information at the center of gravity of the whole aircraft according to the six-degree-of-freedom rigid-body motion equations.

[0085] In practical applications, after completing the CFD simulation, flight dynamics modeling is carried out to analyze the balance characteristics of the helicopter during flight in complex environments. First, the coordinate transformation relationship between components needs to be established. Then, an aerodynamic force model is established for each component, and an environmental wind speed coupling interface is reserved in the combined velocity solving module of each component, so that the influence of environmental wind speed can be introduced during calculation. The differences in the aerodynamic forces and moments of components in different environmental winds will ultimately affect the balance characteristics of the whole aircraft. Steps 203 and 204 specifically include the following steps:

[0086] First step, establish the coordinate transformation relationship. An inertial coordinate system is established with the ground plane as the reference and fixed on the ground. The body coordinate system is obtained based on the attitude angles, and the wind axis system is determined according to the angle of attack and sideslip angle of the body. Since the motion state of a single blade needs to be considered in the rotor calculation, the hub coordinate system is obtained based on the longitudinal and lateral installation angles of the hub. On this basis, the azimuth angle is introduced to establish the rotor rotation coordinate system, and finally the blade coordinate system is obtained based on the blade flapping motion state. If the tail rotor axis is not perpendicular to the longitudinal plane of the body, the transformation relationship between the tail rotor coordinate system and the body coordinate system also needs to be established through the tail rotor tilt angle. Form the above transformation relationships into matrices, and the conversion of the three-directional forces and moments of each component between any coordinate systems can be achieved by multiplying vectors with matrices.

[0087] Second step, establish the component aerodynamic force model. According to the helicopter design parameters (dimensions, mass, shape) and the motion state (speed, angular velocity, acceleration, angular acceleration), considering the mutual interference between components, combined with the lift and drag coefficients of each component in the wind tunnel test, interpolate and solve for the forces and moments of each component at its aerodynamic center, and integrate the three-directional forces and moments of all components to the center of gravity of the whole aircraft through the coordinate transformation in the first step. Finally, a helicopter flight mechanics model is formed according to the six-degree-of-freedom rigid-body motion equations.

[0088] The dynamic equations for the movement of the helicopter's center of gravity and its rotation around the center of gravity are:

[0089]

[0090] Among them, u, v, and w are the velocity components along the horizontal axis of the aircraft, the velocity components along the longitudinal axis of the aircraft, and the velocity components along the vertical axis of the aircraft respectively; are the velocity derivatives along the horizontal, longitudinal and vertical axes of the aircraft; p, q, r are the angular velocities along the horizontal, longitudinal and vertical axes of the aircraft; is the angular velocity derivative along the horizontal, longitudinal and vertical axes of the aircraft; m is the mass; F X 、F Y 、F Z is the force along the horizontal, longitudinal and vertical axes of the aircraft; L, M, N are the moments around the horizontal, longitudinal and vertical axes of the aircraft, I and ω * denote the cross product matrix of the inertia matrix and the angular velocity, respectively, and

[0091]

[0092] Among them, I XX is the inertia moment of the body about the X axis, I XZ is the product of the inertia of the body about the X-axis and the Z-axis, I YY is the inertia moment of the body about the Y axis, I ZZ is the inertia moment of the body about the Z axis, I ** All of them are design parameters.

[0093] The helicopter flight dynamics model can be obtained by combining the blade flapping motion equation with the helicopter rigid body dynamics equation. Its simplified form is:

[0094]

[0095] Where, t is time; U is the control quantity, including the total pitch, lateral and longitudinal cyclic pitch change, and tail rotor total pitch; X is the state quantity, including speed, angular velocity, and attitude angle; W wind is the ambient wind speed, is the state derivative.

[0096] The third step is wind field data processing and data coupling. Since the CFD calculation results are stored on unstructured grid points, the calculation results are interpolated and stored in a structured manner, and the wind field file containing the scattered point position coordinates and three-way wind speed information is provided to the flight dynamics model. In the flight dynamics model, the wind speed at the aerodynamic center of the component is obtained by position interpolation, and the ambient wind speed is decomposed according to the lateral, longitudinal, and vertical directions of the aircraft. The coupling of the ambient wind field and the bare machine model is achieved by numerically superimposing the wind speed at the aerodynamic center of the component and the motion speed. At this point, a flight dynamics model has been established, which can solve the downwash speed, control amount, attitude, and power of the helicopter in a balanced state under a complex wind field.

[0097] like Figure 5The structure of the flight dynamics model shown in the figure is as follows: according to the helicopter design parameters, such as the position of the center of mass and the geometric dimensions of the components, the aerodynamic models of the rotor, tail rotor, fuselage, and tail surface are established respectively. When modeling the rotor, the blades are divided into several micro-segments, the first-order flapping of the blades is retained, and the rotor downwash speed is calculated through dynamic inflow; the external wind field speed and the interference speed between components are superimposed on the micro-segment center and the aerodynamic center of other components through position interpolation; finally, the blade flapping motion equation and the helicopter six-degree-of-freedom rigid body dynamics equation are combined to obtain the bare-metal model of helicopter flight dynamics. Through this model, the downwash speed of the rotor and tail rotor, helicopter control, attitude, power consumption, etc. in the equilibrium state can be calculated. Figure 7 and Figure 8 They are discrete analysis points in the mountainous area and the surrounding environment of the building set according to the environmental characteristics. The analysis points should be located in the key influence areas of the windward side and the leeward return flow. The flight dynamics model can be further used to calculate the equilibrium characteristics at the grid points in the figure.

[0098] In an exemplary embodiment, step 205 specifically includes:

[0099] The wind speed threat area is determined according to the environmental velocity field and turbulent kinetic energy distribution of the distribution characteristics.

[0100] A spatial operation characteristic cloud diagram is determined based on the joystick magnitude according to the helicopter flight dynamics model.

[0101] The manipulation threat area is determined according to the spatial manipulation characteristic cloud map and the joystick margin threshold.

[0102] A spatial attitude characteristic cloud map is determined based on the helicopter attitude angle value according to the helicopter flight dynamics model.

[0103] The posture threat area is determined according to the spatial posture feature cloud map and the posture angle threshold.

[0104] A spatial power characteristic cloud diagram is determined based on the helicopter's required power according to the helicopter flight dynamics model.

[0105] A power threat area is determined according to the spatial power characteristic cloud map and the power threshold.

[0106] The vortex ring limitation criterion is determined according to the helicopter dynamics model based on the ambient wind speed, the rotor induced speed and the tail rotor induced speed.

[0107] The vortex ring threat area is determined according to the vortex ring limitation criterion.

[0108] In practical applications, the joystick margin threshold is that the joystick margin of each channel is greater than 10%. The power threshold is that the helicopter engine margin is greater than 10%.

[0109] Specifically, the environmental wind speed threat area is divided according to the wind field speed and turbulent kinetic energy characteristics, and the control, attitude, power, and vortex ring threat areas are divided according to the analysis results of the overall aircraft balance characteristics. The above five threat areas are combined, and their envelope is used as the flight safety boundary, which specifically includes the following steps:

[0110] The first step is to divide the wind speed threat area. First, analyze the environmental velocity field and turbulent kinetic energy distribution obtained in the fourth step of the wind field simulation. The specific limit is that the standard deviation of the environmental vertical velocity does not exceed 1.75 m / s, and the turbulent kinetic energy is not greater than 4.59 m 2 / s 2 , and the over-limit area is divided into the wind speed threat area that threatens the safety of the helicopter in the environment. Select the key influence areas in the environment according to the wind speed characteristics, and comprehensively consider the obstacles and the size of the helicopter, and set discrete analysis points in the key influence areas.

[0111] The second step is to divide the control threat area. As Figure 9 shown, where Figure 9 (a) in it is the spatial control characteristic cloud diagram of the collective pitch lever movement, Figure 9 (b) in it is the spatial control characteristic cloud diagram of the longitudinal lever movement. Using the flight dynamics model, place the center of mass of the helicopter at the analysis point, consider the influence of the environmental wind (open the wind speed interpolation interface), and carry out the overall aircraft balance characteristic analysis. Display the control lever movement values of each discrete point on a single diagram in different colors to form a spatial control characteristic cloud diagram. The remaining amount of the control lever in each channel being greater than 10% is safe, that is, the collective pitch advance amount limit is 10% < δ col <90%, the foot pedal control amount limit is 10% < δ ped <90%, the lateral control lever amount limit is 10% < δ lat <90%, the longitudinal control lever amount limit is 10% < δ lon <90%, and the area beyond the limit is the control threat area.

[0112] The third step is to divide the attitude threat area. As Figure 10 shown, where Figure 10 (a) in it is the spatial attitude characteristic cloud diagram of the roll angle, where Figure 10Figure (b) is the spatial attitude characteristic cloud map of pitch and roll angles. Using the flight dynamics model, the helicopter's center of mass is placed at the analysis point, considering the influence of environmental wind (opening the wind speed interpolation interface), and the full aircraft balance characteristics are analyzed. The helicopter attitude angle values at each discrete point are displayed in different colors to form the spatial attitude characteristic cloud map. Classified by helicopter model and environmental obstacle degree, the safety range of attitude angles for small helicopters and in a narrow environmental space is smaller, and conversely, the limit can be appropriately relaxed. For example, for the UH-60A helicopter in a mountainous environment, the attitude limits are roll angle -8° < Φ < 8°, pitch angle -4° < Θ < 7°; while in an urban environment, the limits for the same model helicopter can be adjusted to roll angle -6° < Φ < 6°, pitch angle -4° < Θ < 6°, and the over-limit area is the attitude threat area.

[0113] Step 4, divide the power threat area. If Figure 11 as shown, where Figure 11 Figure (a) is the required power characteristic cloud map of the helicopter in the wind field around the building, Figure 11 Figure (b) is the required power characteristic cloud map in a mountainous environment. Using the flight dynamics model, the balance characteristics analysis can also obtain the power consumed by the main rotor and tail rotor when the helicopter maintains a balanced state. The sum of the two is the required power of the helicopter at the spatial analysis point. The helicopter required power values at each discrete point are displayed in different colors to form the spatial power characteristic cloud map. Combining the helicopter engine model and power, it is required to reserve 10% of the engine margin for safety. For example, the UH-60A helicopter is equipped with two General Electric T700-GE-700 turboshaft engines, with a single-engine power of 1165 kW. When the required power exceeds 2097 kW, it enters the power threat area; while the Z-11 helicopter is equipped with a WZ-8D type turboshaft engine with a limit of 440 kW. When the required power exceeds 396 kW, it enters the power threat area.

[0114] Step 5, divide the vortex ring threat area. Using the flight dynamics model, the balance characteristics analysis can obtain the induced velocities of the main rotor and tail rotor when the helicopter is in a balanced state. Combining the Peters vortex ring criterion and the Gao-Xin vortex ring criterion, a vortex ring limit criterion is formed based on the environmental wind speed and the induced velocities of the main rotor and tail rotor. Peters in the United States proposed based on the dynamic inflow theory and momentum theory: when the projection of the free stream velocity vector on the wake velocity vector is negative, the main rotor enters the vortex ring state, that is, the analytical expression of the vortex ring boundary is:

[0115]

[0116] where, v0 is the equivalent induced velocity of the main rotor at the blade disk; V x is 's horizontal component (positive for forward flight); Vy is the vertical component (positive for upward). According to the Peters boundary, the horizontal velocity component V x is greater than 0.62v h (v h is the induced velocity of the rotating component), the helicopter will not enter the vortex ring state.

[0117] The Gao-Xin criterion indicates that when the projection of the free-stream velocity vector in the opposite direction of the rotor wake velocity vector exceeds a certain critical value, the rotor enters the vortex ring state, and this critical value is exactly equal to the critical velocity V y when entering the vortex ring state during vertical descent. Through experiments, the critical velocity V y when entering the vortex ring state during vertical descent is equal to 0.28v h (v h is the induced velocity of the rotating component). Thus, we have:

[0118]

[0119] Since the helicopter and the obstacle remain relatively stationary during the spatial domain analysis, the body motion velocity is converted into the environmental wind speed criterion. Also, because the helicopter has multiple rotating components, in this application, for the rotor: the environmental horizontal wind speed greater than 0.62v h is the safe zone, and the environmental vertical wind speed greater than 0.28v h is the vortex ring threat zone; for the tail rotor: the environmental horizontal wind speed greater than 0.62v h is the safe zone, and the environmental lateral wind speed greater than 0.28v h is the vortex ring threat zone, and the intermediate velocity range is the transition zone.

[0120] Such as Figure 12 is a schematic diagram of the vortex ring boundary of the helicopter in the near-building area under the balanced state divided by the environmental velocity. Among them, Figure 12 in (a) is a schematic diagram of the rotor vortex ring restriction area under the building wind field, Figure 12 in (b) is a schematic diagram of the tail rotor vortex ring restriction area under the building wind field. The horizontal velocity in the white area is relatively large, and there is no vortex ring danger. Entering the blue area indicates that the environmental horizontal wind speed is less than 0.62v h while the orange area indicates that the environmental vertical velocity is greater than 0.28v h , and the overlapping area of the two is the vortex ring threat zone.

[0121] Step 6: Form the dynamic flight safety boundary in the spatial domain. In the previous steps 1 to 5, the wind speed, control, attitude, power, and vortex ring threat areas are obtained respectively. The five threat areas are merged into the comprehensive environmental threat area, and the envelope line of the threat area is the flight safety boundary in this complex environment. When parameters such as the environmental wind speed, wind direction, and altitude change, the range of the threat area changes. After analyzing according to the same steps, the dynamic flight safety boundary that changes with the environmental wind conditions can be obtained.

[0122] This application aims at the safety requirements of helicopters flying in complex environments, breaks through the key technologies of multi-disciplinary coupled modeling and flight safety design for helicopter flight, and establishes a technology for identifying the dynamic behavior safety boundary of helicopters in the spatial domain based on the coupling of "environment-helicopter". According to the flight mission requirements of helicopters in complex environments, CFD and flight mechanics methods are applied to the research of helicopter flight simulation and flight safety boundary design. Based on the unsteady RANS equation, a numerical simulation method for environmental wind fields is established, and a helicopter flight mechanics model coupled with the characteristics of environmental wind fields is established. Analyses of helicopter control, attitude, power consumption, and vortex ring threats are carried out at discrete points in the spatial domain. Further combined with the environmental wind speed criterion, the dynamic flight safety boundary of the helicopter is comprehensively formed.

[0123] As Figure 3 shown, the technical solution is as follows:

[0124] Step 1: Model the terrain and wind field environment. First, establish typical simplified terrains of various complex terrains, such as isolated hills in mountainous environments and isolated buildings in cities. Model the terrain environment and describe the wind field model through the mean wind profile, respectively providing the geometric and inflow velocity conditions required for CFD calculations.

[0125] Step 2: Simulate the wind field and process the data. Input the geometry and inflow velocity obtained in the first step into the CFD calculation program, use the mean wind profile formed according to the environmental characteristics as the far-field boundary, carry out CFD numerical simulation calculations, obtain the flow field velocity and turbulent kinetic energy distributions. On the one hand, it can be used for dividing the wind speed danger area. On the other hand, by inputting the flow field velocity into the flight mechanics model, the coupling of the environment and the helicopter is realized, and the interference of the environment on the helicopter is introduced.

[0126] Step 3: Model the flight mechanics and interpolate the wind field. Establish a flight mechanics model based on the physical model, and the full-aircraft balance characteristics can be calculated at a predetermined speed. According to the configuration parameters of the helicopter, establish the aerodynamic models of each component, and form a flight mechanics analysis model based on the six-degree-of-freedom rigid body motion equation. Interpolate and superimpose the three-dimensional velocity of the flow field obtained by CFD at the aerodynamic centers of each component of the helicopter to realize the coupling of the CFD and flight mechanics models.

[0127] Step 4: Discretization of the environmental space domain and analysis of flight threats. Discretize the key areas near environmental obstacles to form analysis points, such as mountaintops, windward slopes, and leeward sides in mountainous environments, rooftops, building sides, building windward sides, and leeward sides near buildings. Conduct an analysis of the overall aircraft balance characteristics at the analysis points, and divide the control, attitude, power, and vortex ring threat areas according to the helicopter model limitations. Combine the wind field data obtained in Step 2, and divide the wind speed threat area according to the conditions of the vertical velocity mean square deviation and the turbulent kinetic energy limit value.

[0128] Step 5: Identification of the flight safety boundary. Merge the five types of threat areas obtained in Step 4. The area outside all threat areas is the safe flight area, and the envelope of the threat areas forms the flight safety boundary in space. The safety boundary changes with the environmental wind speed and the helicopter flight state, so it is called the dynamic flight safety boundary.

[0129] Through the above steps, a method for analyzing the helicopter flight safety boundary in the space domain applicable to various complex environments is proposed for the first time. Aiming at the helicopter safety flight requirements in complex environments, terrain environment and wind environment modeling and analysis are carried out according to the characteristics of the environmental wind field. By establishing a helicopter flight dynamics model, the helicopter balance characteristics analysis can be realized, and a helicopter flight safety analysis technology based on the coupling of "environment - helicopter" is formed. Facing problems such as control failure and attitude overrun caused by the turbulent wind field in complex environments, a safe flight boundary considering factors such as control, attitude, power, and vortex ring is constructed, and the analysis method has good scalability and environmental adaptability.

[0130] Based on the same inventive concept, the embodiment of the present application also provides a helicopter flight safety boundary identification device for implementing the helicopter flight safety boundary identification method involved above. The solution provided by this device to solve the problem is similar to the solution recorded in the above method. Therefore, the specific limitations in one or more embodiments of the helicopter flight safety boundary identification device provided below can refer to the limitations on the helicopter flight safety boundary identification method in the above text, and will not be elaborated here.

[0131] In an exemplary embodiment, a helicopter flight safety boundary identification device is provided, including:

[0132] An acquisition module, configured to acquire terrain information, wind environment information, helicopter design parameters, and motion states;

[0133] A distribution characteristic determination module, configured to determine the wind speed distribution characteristics in a complex environment by using CFD simulation according to the terrain information and the wind environment information;

[0134] A construction module, configured to construct a helicopter flight mechanics model according to the helicopter design parameters and the motion states;

[0135] A coupling module, configured to couple the helicopter flight mechanics model with the wind speed distribution characteristics to obtain a helicopter flight dynamics model;

[0136] A threat area determination module, configured to determine a threat area according to the wind speed distribution characteristics and the helicopter flight dynamics model; the threat area includes a wind speed threat area, a maneuver threat area, an attitude threat area, a power threat area, and a vortex ring threat area;

[0137] A flight safety boundary determination module, configured to merge the threat areas to determine a flight safety boundary.

[0138] In an exemplary embodiment, a computer device is provided. The computer device may be a server or a terminal, and its internal structure diagram may be as shown in Figure 13 The figure. The computer device includes a processor, a memory, an input / output interface (Input / Output, abbreviated as I / O), and a communication interface. Among them, the processor, the memory, and the input / output interface are connected through a system bus, and the communication interface is connected to the system bus through the input / output interface. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program, and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the computer device is used to store flight safety boundary data. The input / output interface of the computer device is used to exchange information between the processor and external devices. The communication interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, it implements a method for identifying the flight safety boundary of a helicopter.

[0139] Those skilled in the art can understand that Figure 13 The structure shown in is only a block diagram of some structures related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine some components, or have different component arrangements. In an exemplary embodiment, a computer device is provided, including a memory and a processor. A computer program is stored in the memory, and when the processor executes the computer program, the above method embodiments are implemented.

[0140] In an exemplary embodiment, a computer-readable storage medium is provided, storing a computer program, and when the computer program is executed by a processor, the above method embodiments are implemented.

[0141] In an exemplary embodiment, a computer program product is provided, including a computer program which, when executed by a processor, implements the above method embodiments.

[0142] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data for analysis, stored data, displayed data, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use, and processing of relevant data need to comply with relevant regulations.

[0143] Those of ordinary skill in the art can understand that all or part of the processes of implementing the above method embodiments can be completed by instructing relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the above method embodiments. Among them, any reference to a memory, database, or other medium used in the embodiments provided in this application can include at least one of non-volatile and volatile memories. Non-volatile memories can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetoresistive random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memories can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM), etc.

[0144] The databases involved in the embodiments provided in this application can include at least one of relational databases and non-relational databases. Non-relational databases can include distributed databases based on blockchain, etc., without limitation. The processors involved in the embodiments provided in this application can be general-purpose processors, central processors, graphics processors, digital signal processors, programmable logic devices, data processing logics based on quantum computing, etc., without limitation.

[0145] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0146] Specific examples are used in this article to elaborate on the principles and implementation manners of the present application. The description of the above embodiments is only used to help understand the method and its core idea of the present application; at the same time, for those of ordinary skill in the art, according to the idea of the present application, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation to the present application.

Claims

1. A method for identifying the flight safety boundary of a helicopter, characterized in that, The helicopter flight safety boundary recognition method includes: Obtaining terrain information, wind environment information, helicopter design parameters, and motion state; Determining the wind speed distribution characteristics in a complex environment by using CFD simulation based on the terrain information and the wind environment information; Constructing a helicopter flight mechanics model according to the helicopter design parameters and the motion state; Coupling the helicopter flight mechanics model with the wind speed distribution characteristics to obtain a helicopter flight dynamics model; Determining a threat area according to the wind speed distribution characteristics and the helicopter flight dynamics model; the threat area includes a wind speed threat area, a control threat area, an attitude threat area, a power threat area, and a vortex ring threat area; Merging the threat areas to determine the flight safety boundary.

2. The helicopter flight safety boundary recognition method according to claim 1, characterized in that, Determining the wind speed distribution characteristics in a complex environment by using CFD simulation based on the terrain information and the wind environment information, specifically including: Extracting terrain features according to the terrain information; Determining the average wind speed at different heights according to the wind environment information; Setting the initial parameters of the flow field, and performing CFD simulation on the flow field according to the terrain features and the average wind speed at different heights to obtain the wind speed distribution characteristics in a complex environment.

3. The helicopter flight safety boundary recognition method according to claim 1, wherein Constructing a helicopter flight mechanics model according to the helicopter design parameters and the motion state, specifically including: Performing interpolation to solve the mechanical information of each component at the aerodynamic center according to the helicopter design parameters and the motion state; the mechanical information includes three-directional forces and moments; Performing coordinate transformation according to the mechanical information of each component at the aerodynamic center to obtain the mechanical information at the center of gravity of the whole aircraft; Constructing a helicopter flight mechanics model according to the mechanical information at the center of gravity of the whole aircraft based on the six-degree-of-freedom rigid body motion equation.

4. The helicopter flight safety boundary recognition method according to claim 1, wherein Determining the threat area according to the wind speed distribution characteristics and the helicopter flight dynamics model, specifically including: Determining the wind speed threat area according to the environmental velocity field and the turbulent kinetic energy distribution of the distribution characteristics; Determining a spatial operation characteristic cloud map based on the control stick value according to the helicopter flight dynamics model; Determining the control threat area according to the spatial operation characteristic cloud map and the control stick margin threshold; Determining a spatial attitude characteristic cloud map based on the helicopter attitude angle value according to the helicopter flight dynamics model; Determining the attitude threat area according to the spatial attitude characteristic cloud map and the attitude angle threshold; Determining a spatial power characteristic cloud map based on the required power of the helicopter according to the helicopter flight dynamics model; Determining the power threat area according to the spatial power characteristic cloud map and the power threshold; Determining a vortex ring limit criterion based on the environmental wind speed, rotor induced velocity, and tail rotor induced velocity according to the helicopter dynamics model; Determining the vortex ring threat area according to the vortex ring limit criterion.

5. The helicopter flight safety boundary recognition method according to claim 4, characterized in that, The control stick margin threshold is that the margin of each channel control stick is greater than 10%; 6. The helicopter flight safety boundary recognition method according to claim 4, characterized in that, The power threshold is that the margin of the helicopter engine is greater than 10%; 7. A helicopter flight safety boundary recognition device, characterized in that The helicopter flight safety boundary recognition device includes: An acquisition module, configured to acquire terrain information, wind environment information, helicopter design parameters, and motion state; A distribution characteristic determination module, configured to determine the wind speed distribution characteristics in a complex environment by using CFD simulation based on the terrain information and the wind environment information; A construction module, configured to construct a helicopter flight mechanics model according to the helicopter design parameters and the motion state; A coupling module, configured to couple the helicopter flight mechanics model with the wind speed distribution characteristics to obtain a helicopter flight dynamics model; A threat area determination module, configured to determine a threat area according to the wind speed distribution characteristics and the helicopter flight dynamics model; the threat area includes a wind speed threat area, a maneuver threat area, an attitude threat area, a power threat area, and a vortex ring threat area; A flight safety boundary determination module, configured to merge the threat areas to determine a flight safety boundary.

8. A computer device, comprising: A memory, a processor, and a computer program stored on the memory and executable on the processor, wherein the processor executes the computer program to implement the helicopter flight safety boundary recognition method according to any one of claims 1-6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the helicopter flight safety boundary recognition method according to any one of claims 1-6.

10. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by the processor, it implements the helicopter flight safety boundary recognition method according to any one of claims 1-6.

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