Water body model design method of fire extinguishing airplane

Abstract

The invention belongs to the technical field of water throwing simulation design of fire extinguishing aircrafts, and discloses a water body model design method of a fire extinguishing aircraft, which comprises the following steps of: analyzing a picture when the aircraft throws water, and drawing a quadratic curve on a plane by imitating the shape of a water body so as to simulate the shape of the water body; and then the expansion thickness of watering is determined by using a circular automatic turbulent flow jet principle, and the two-dimensional curve is stretched into a three-dimensional model. And then smooth transition treatment is carried out to ensure that the airflow is not obviously separated. After the three-dimensional model is established, CFD simulation software is imported for grid division, and a simulation model is established; the designed three-dimensional model is used for entity processing and can be used for simulating a water body in a wind tunnel test. The technical problem that a water body model in CFD simulation and a wind tunnel test is difficult to simulate is solved, the method has the advantages of being low in cost and short in processing period in the wind tunnel test, and the scheme evaluation efficiency in the initial stage of fire extinguishing aircraft design is greatly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of water-dropping simulation design of fire-fighting aircraft, and in particular relates to a design method for simulating a water body by using a rigid model. Background Art

[0002] When a large firefighting aircraft is flying while dropping water, the release of a large amount of water in a short period of time will not only cause problems with the dynamic response of the carrier aircraft, but the sudden appearance of a large amount of water under the fuselage will block the flow of airflow, and the airflow will separate behind the water mass, causing a large area of ​​negative pressure area to appear on the rear part of the fuselage. The suction force on the rear fuselage and the lower surface of the horizontal tail will increase, causing the aircraft to rise sharply in a short period of time, affecting the safe flight of the aircraft.

[0003] In order to ensure flight safety, it is necessary to use wind tunnel tests and CFD simulation methods to study the changes in the aerodynamic characteristics of the aircraft during the water-dropping process of the fire extinguisher. CFD simulation of the water-dropping process requires the use of a multiphase flow model, but the multiphase flow grid requires high accuracy, has great convergence difficulties, and has a long calculation cycle, which places high demands on computing resources. Wind tunnel tests require the redesign and processing of the water-dropping model, the addition of a door motion mechanism and a water storage tank, which is costly. Therefore, it is difficult to meet the requirements for scheme evaluation in the early stages of fire-fighting aircraft design. Summary of the invention

[0004] The purpose of the present invention is to provide a design method for simulating water bodies with a rigid model, so as to solve the problem that water body models are difficult to simulate in CFD simulation and wind tunnel tests.

[0005] The technical solution of the present invention is achieved in this way:

[0006] A method for designing a water body model of a fire-fighting aircraft comprises the following steps:

[0007] Analyze photos of airplanes dropping water, and draw a quadratic curve on a plane to simulate the shape of the water.

[0008] Then the circular automatic turbulent jet principle is used to determine the extended thickness of the sprinkler, and the two-dimensional curve is stretched into a three-dimensional model;

[0009] Then perform a smooth transition to ensure that the airflow does not separate significantly;

[0010] After the three-dimensional model is established, it is imported into the CFD simulation software for meshing and establishing a simulation model;

[0011] The designed three-dimensional model can be used for solid processing and can be used for wind tunnel testing to simulate water bodies.

[0012] As a further solution of the present invention: the quadratic curve shape characteristics of the water body shape mainly depend on the amount of water thrown and the form of the cabin door, ensuring that the straight line dimension at the top of the curve is consistent with the throwing direction of the aircraft cabin door, and the shape of the curve is determined by a water throwing test.

[0013] As a further solution of the present invention: the three-dimensional model design of the water body shape is performed by stretching the quadratic curve along the span direction, and the stretching boundary is determined by the diffusion angle.

[0014] As a further solution of the present invention: the diffusion angle is determined according to the circular automatic turbulent jet principle, and its value is 14.04°.

[0015] As a further solution of the present invention: a smooth transition treatment is performed on the interface between the surfaces to ensure that the airflow does not have obvious separation.

[0016] As a further solution of the present invention: the water body model entity is processed as follows: after the digital model is established, it can be processed into a hollow model according to the digital model, and materials with lower density such as wood are used for processing as much as possible, and the model is connected to the wind tunnel wall with tension wires to fix it in the corresponding position.

[0017] An electronic device, characterized in that it comprises: a processor and a memory storing a computer program, and when the processor runs the computer program, the steps of the water body model design method are implemented.

[0018] A computer storage medium, characterized in that a computer program is stored therein, and when the computer program is executed by a processor, the steps of the water body model design method are implemented.

[0019] The beneficial effects of this application are:

[0020] 1. The rigid model of this application does not require high mesh accuracy in CFD simulation, is easy to simulate, and has fast convergence, short calculation cycle, and design advantages.

[0021] 2. The present application has low cost and short processing cycle in wind tunnel testing, which greatly improves the efficiency of scheme evaluation in the early stage of fire-fighting aircraft design.

[0022] The present application is further described in detail below in conjunction with the accompanying drawings of the embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a schematic diagram of a quadratic curve of a water body shape in the present invention;

[0024] Figure 2 It is a front schematic diagram of the water body model designed by the present invention;

[0025] Figure 3It is a side schematic diagram of the water body model designed by the present invention;

[0026] Figure 4 This is a photo of the water body model of the present invention being fixed in the wind tunnel after being processed. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical scheme and advantages of the implementation of the present invention clearer, the technical scheme in the embodiment of the present invention will be described in more detail in conjunction with the drawings in the embodiment of the present invention. In the drawings, the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The described embodiments are part of the embodiments of the present invention, not all of the embodiments. The embodiments described below with reference to the drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limitations on the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Figure 1 to Figure 4 Embodiments of the present invention are described in detail.

[0028] In a first aspect, the present invention provides a method for designing a water model of a fire-fighting aircraft, which comprises the following steps:

[0029] Analyze photos of airplanes dropping water, and draw a quadratic curve on a plane to simulate the shape of the water.

[0030] Then the circular automatic turbulent jet principle is used to determine the extended thickness of the sprinkler, and the two-dimensional curve is stretched into a three-dimensional model;

[0031] Then perform a smooth transition to ensure that the airflow does not separate significantly;

[0032] After the three-dimensional model is established, it is imported into the CFD simulation software for meshing and establishing a simulation model;

[0033] The designed three-dimensional model can be used for solid processing and can be used for wind tunnel testing to simulate water bodies.

[0034] The specific implementation steps are as follows:

[0035] A design method for simulating water bodies with a rigid model. Compared with the multiple flow modes and processing water injection models of CFD simulation, it can mainly achieve rapid simulation of water bodies while ensuring the reliability of simulation data.

[0036] The quadratic curve of the water body shape is shown in Figure 1 The shape shown, its shape characteristics mainly depend on the amount of water thrown and the form of the cabin door, to ensure that the straight line dimension at the top of the curve is consistent with the throwing direction of the aircraft cabin door. The shape of the curve is determined by a water throwing test.

[0037] The three-dimensional design of the water body shape refers to Figure 2 and Figure 3 As shown in the figure, the quadratic curve in the text is stretched along the span direction, and the diffusion angle is used to determine its stretching boundary. The diffusion angle is determined according to the principle of circular automatic turbulent jet, and its value is 14.04°. Then, a smooth transition is performed on the interface between the surfaces to ensure that the airflow does not have obvious separation. According to the simulation results, after adding the water body model, the pitch moment coefficient of the aircraft changes by 0.146, and the elevator needs to be deflected down by 4.42° to balance the aircraft, which is basically consistent with the test flight results.

[0038] The fixed reference of the water model in the wind tunnel is as follows: Figure 4 As shown in the figure, after the digital model is established, it can be processed into a hollow model according to the digital model, and wood and other materials with low density can be used for processing as much as possible, and the model can be connected to the wall of the wind tunnel with tension wires to fix it in the corresponding position. This ensures that after the water body model is positioned, while ensuring the water body influence, the model can be reliably connected and the bracket interference is small.

[0039] The design method of simulating water bodies with a rigid model proposed in the present invention realizes the design of a simulated water body model through the process, and compares the simulation data with the test flight data to ensure the rationality of the model design. Then, the model is processed according to the digital model, and the relative position of the water body and the aircraft is determined, and the water body model is fixed in the wind tunnel using a tension line, while ensuring that the connection is reliable and the bracket interference is small, thereby improving the work efficiency of the scheme evaluation in the early stage of the fire-fighting aircraft design.

[0040] In a second aspect, the present invention provides an electronic device, comprising: a processor and a memory storing a computer program; in practical applications, the number of processors may be one or more; the number of memories may be one or more. When the processor runs the computer program, the water body model design method applied to the electronic device is implemented.

[0041] The memory may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memories. The non-volatile memory may be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), a magnetic random access memory (FRAM), a flash memory, a magnetic surface memory, an optical disk, or a compact disc read-only memory (CD-ROM); the magnetic surface memory may be a disk memory or a tape memory. The volatile memory may be a random access memory (RAM), which is used as an external cache. By way of example and not limitation, many forms of RAM are available, such as static random access memory (SRAM), synchronous static random access memory (SSRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDRSDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous link dynamic random access memory (SLDRAM, SyncLink Dynamic Random Access Memory), and direct RAM bus random access memory (DRRAM, Direct Rambus Random Access Memory).

[0042] The memory of the present invention is used to store various types of data to support the operation of the electronic device. Examples of these data include: any computer program used to operate on the electronic device, such as an operating system and an application; contact data; phone book data; messages; pictures; videos, etc. Among them, the operating system includes various system programs, such as a framework layer, a core library layer, a driver layer, etc., which are used to implement various basic services and process hardware-based tasks. The application program may include various applications, such as a media player (Media Player), a browser (Browser), etc., which are used to implement various application services. Here, the program that implements the method of the embodiment of the present invention may be included in the application program.

[0043] In a third aspect, the present invention further provides a computer storage medium, wherein a computer program is stored in the computer storage medium, and the computer storage medium may be a ferromagnetic random access memory (FRAM), a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), a flash memory, a magnetic surface memory, an optical disk, or a compact disc read-only memory (CD-ROM), etc.; or it may be various devices including one or any combination of the above memories, such as a mobile phone, a computer, a tablet device, a personal digital assistant, etc. When the computer program stored in the computer storage medium is executed by a processor, the water body model design method applied to the above electronic device is implemented.

[0044] So far, the purpose of the present invention has been achieved.

[0045] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for designing a water model of a fire-fighting aircraft, characterized in that: The following steps are involved: Analyze photos of airplanes dropping water, and draw a quadratic curve on a plane to simulate the shape of the water. Then the circular automatic turbulent jet principle is used to determine the extended thickness of the sprinkler, and the two-dimensional curve is stretched into a three-dimensional model; Then perform a smooth transition to ensure that the airflow does not separate significantly; After the three-dimensional model is established, it is imported into the CFD simulation software for meshing and establishing a simulation model; The designed three-dimensional model can be used for solid processing and can be used for wind tunnel testing to simulate water bodies.

2. The water model design method for a fire-fighting aircraft according to claim 1, characterized in that: The quadratic curve shape characteristics of the water body shape mainly depend on the amount of water thrown in and the form of the cabin door, ensuring that the straight line size at the top of the curve is consistent with the direction of the aircraft cabin door. The shape of the curve is determined by a water throwing test.

3. The water model design method for a fire-fighting aircraft according to claim 2, characterized in that: The three-dimensional model design of the water body shape is performed by stretching the quadratic curve along the span direction, and the stretching boundary is determined by the diffusion angle.

4. The water model design method for a fire-fighting aircraft according to claim 3 is characterized in that: The diffusion angle is determined according to the circular automatic turbulent jet principle, and its value is 14.04°.

5. The water model design method for a fire-fighting aircraft according to claim 4, characterized in that: The interfaces between surfaces are smoothly transitioned to ensure that there is no obvious separation of airflow.

6. The water model design method for a fire-fighting aircraft according to claim 5, characterized in that: The water body model entity is processed as follows: after the digital model is established, it can be processed into a hollow model according to the digital model, and materials with lower density such as wood are used as much as possible for processing, and the model is connected to the wind tunnel wall with tension wires to fix it in the corresponding position.

7. An electronic device, characterized in that: include: A processor and a memory storing a computer program, wherein when the processor runs the computer program, the steps of the water body model design method according to any one of claims 1 to 6 are implemented.

8. A computer storage medium, characterized in that A computer program is stored, and when the computer program is executed by a processor, the steps of the water body model design method according to any one of claims 1 to 6 are implemented.

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