Method for evaluating and testing fire extinguishing performance of large fixed-wing unmanned aerial vehicle

Abstract

The invention discloses a large fixed-wing unmanned aerial vehicle fire extinguishing performance evaluation test method, and relates to the field of aviation equipment. The method solves the problem that quantitative evaluation of fire extinguishing agent throwing precision and effective coverage range of a large fixed-wing unmanned aerial vehicle in a complex wind field environment is difficult, scale test parameter design is carried out based on similarity criteria and reference wind tunnel size, and then test model (unmanned aerial vehicle and fire extinguishing agent water tank) and adjustable cabin door structure design are carried out. The unmanned aerial vehicle model is installed on the upper tunnel wall of a wind tunnel through a lifting supporting rod in a back supporting mode, the fire extinguishing agent measuring system is installed on the central axis of a wind tunnel test section and is vertically aligned with a water tank, finally a large fixed-wing unmanned aerial vehicle fire extinguishing performance evaluation wind tunnel test is carried out, the effective range of a fire extinguishing agent is quantitatively treated, and the fire extinguishing performance is evaluated. The test method can effectively research the fire extinguishing performance of the large unmanned aerial vehicle under the influence of the flight speed, the launching angle, the height and the like of the unmanned aerial vehicle.

Description

Technical Field

[0001] The present invention relates to the field of aviation equipment, and in particular to a test method for evaluating the fire extinguishing performance of a large fixed-wing unmanned aerial vehicle (UAV). Background Art

[0002] Drone firefighting has already found some application in firefighting due to its advantages, including high precision delivery, optimized resource utilization, adaptability to complex environments, and intelligent decision-making. However, multi-rotor drones are currently primarily used for urban firefighting. Scenarios such as forest firefighting require drones with larger payloads and longer ranges, creating an urgent need for large fixed-wing drones for forest firefighting. However, when large fixed-wing drones fly at high altitudes and speeds, the trajectory of the extinguishing agent delivery is affected by multiple factors, such as the drone's flight speed, delivery angle, and altitude. Failure to consider these factors in extinguishing agent delivery missions not only fails to improve delivery accuracy and efficiency, and reduce environmental damage, but also easily results in waste of extinguishing agent and fails to achieve effective firefighting results. Therefore, it is crucial to establish a systematic wind tunnel test method for evaluating the firefighting performance of large fixed-wing drones and to study their performance under the influence of multiple factors. Summary of the Invention

[0003] To solve the problem of difficulty in quantitatively evaluating the accuracy and effective coverage of fire extinguishing agent delivery by large fixed-wing UAVs in complex wind environments, the present invention provides a test method for evaluating the fire extinguishing performance of large fixed-wing UAVs, comprising:

[0004] S1: Acquisition of experimental scale parameters: Determine the wingspan of the scaled model based on the wind tunnel width and calculate the scale length; derive the volume of water in the scaled tank, wind speed, and liquid surface tension coefficient based on the similarity criteria of Froude number and Weber number;

[0005] S2: Construction of the scaled drone model: The front and rear bodies are rigidly connected by the main beam to form an aerodynamic shape, and the hatch controller is installed above the hatch to drive the opening and closing of the water tank release port. The scaled drone model is assembled based on the scaled parameters in S1;

[0006] S3: Wind tunnel experimental setup: The scaled-down UAV test model from S2 is fixed to the upper wall of the wind tunnel via adjustable lifting rods as a back support. A measurement system is installed on the central axis of the lower wall of the wind tunnel. The measurement system consists of a rectangular metal plate with a boss, a superabsorbent polymer layer, and an array of equally spaced graduated cylinders.

[0007] A rectangular metal plate with bosses is fixed to the lower tunnel wall. A superabsorbent polymer layer is laid flat on its upper surface and fixed thereto. The area of ​​the superabsorbent polymer material is the same as that of the rectangular metal plate with bosses. An array of M×N graduated cylinders is arranged on the superabsorbent polymer layer, and the array consists of evenly spaced graduated cylinders. The rectangular metal plate with bosses is located on the central axis of the wind tunnel test section, equidistant from the left and right tunnel walls, and close to the incoming flow side. The rectangular metal plate with bosses is vertically aligned with the water tank.

[0008] S4: Testing and Data Processing: After releasing the fire extinguishing agent under stable wind speed, a multi-dimensional performance evaluation of the drone's fire extinguishing accuracy and range is completed by analyzing the liquid volume in the graduated cylinder, calculating the effective fire extinguishing area, and quantifying the evaporation and atomization losses.

[0009] Furthermore, in S1, the wingspan of the scaled model is determined according to the width of the wind tunnel by:

[0010] .7

[0011] implementation, where is the wingspan size of the scaled model, is the wind tunnel width;

[0012] Scale by:

[0013]

[0014] Obtain, among which, is the scale, L s The actual size of the drone;

[0015] The volume of water in the tank after scaling is calculated by:

[0016]

[0017] Obtain, among which, is the volume of water in the scaled-down tank, is the volume of water in the tank;

[0018] The wind speed after scaling is:

[0019]

[0020] Obtain, among which is the scaled wind speed, is the incoming wind speed;

[0021] The surface tension coefficient of the scaled liquid is obtained by:

[0022]

[0023] Obtain, among which, is the surface tension coefficient of the scaled liquid, is the surface tension coefficient of the original liquid.

[0024] Furthermore, in S3, the width x of the rectangular metal plate with the boss is 0.8 times the width of the wind tunnel, and the length is:

[0025]

[0026] Obtain, among which, is the length of the metal plate, H is the maximum height of the water tank in the wind tunnel, g is the acceleration of gravity, and V is the wind speed after maximum scaling.

[0027] Furthermore, in S4, the volume of the liquid in the measuring cylinder is analyzed by determining whether:

[0028]

[0029] Implementation, where is the volume of liquid in the i-th graduated cylinder, is the minimum volume of fire extinguishing agent that must be dropped into the graduated cylinder to achieve effective fire extinguishing. If the above formula is satisfied, it is considered that the amount of water dropped by the drone within the area where the graduated cylinder is located has an effective effect on fire extinguishing.

[0030] Effective fire extinguishing area through:

[0031]

[0032] Obtain, among which, is the effective fire extinguishing area, n is the number of measuring cylinders that meet this condition, is the actual width of the metal plate, is the actual length of the metal plate, is the number of rows in the measuring cup array, The number of rows and columns of the measuring cup array;

[0033] Evaporation and atomization losses through:

[0034]

[0035] Obtain, among which, is the weight of the atomized liquid, is the density of the extinguishing agent, is the total weight of the liquid captured by the graduated cylinder, is the weight of the super absorbent polymer layer after release, is the initial weight of the super absorbent polymer layer;

[0036] The graduated cylinder captures the total weight of the liquid via:

[0037]

[0038] get.

[0039] The beneficial effects of this invention include: through the spatially coordinated design of a scaled model and a measurement system, the fire extinguishing agent release action of a physical drone is accurately replicated in wind tunnel testing, enabling a multi-dimensional performance evaluation of the drone's firefighting accuracy and range. This solution effectively overcomes the distortion in coverage area assessment caused by impact point offset and the atomization missed detection defects caused by the difficulty of separating gas-liquid two-phase flow in traditional methods, significantly improving the reliability and systematic nature of firefighting performance evaluation and providing a high-confidence experimental basis for flight parameter optimization. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 Flow chart of the overall scheme of the method of the present invention;

[0041] Figure 2 Schematic diagram of the wind tunnel test model structure of the method of the present invention;

[0042] Figure 3 Schematic diagram of the measurement system of the method of the present invention;

[0043] In the figure, 1-main beam, 2-door controller, 3-water tank, 4-front body, 5-door, 6-rear body, 7-metal plate with boss, 8-measuring cylinder, 9-high water-absorbent polymer layer. DETAILED DESCRIPTION

[0044] The technical solution of the present invention is further described below with reference to the embodiments, but is not limited thereto. Any modification or equivalent replacement of the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention shall be included in the scope of protection of the present invention. The process equipment or devices not specifically noted in the following examples are all conventional equipment or devices in the art. Unless otherwise specified, the raw materials used in the examples of the present invention can be obtained commercially; unless otherwise specified, the technical means used in the examples of the present invention are all conventional means well known to those skilled in the art.

[0045] Example 1, combined Figure 1 This embodiment describes a test method for evaluating the fire extinguishing performance of a large fixed-wing UAV, including:

[0046] S1: Acquisition of experimental scale parameters: Determine the wingspan of the scaled model based on the wind tunnel width and calculate the scale length; derive the volume of water in the scaled tank, wind speed, and liquid surface tension coefficient based on the similarity criteria of Froude number and Weber number;

[0047] S2: Construction of the scaled drone model: The front and rear bodies are rigidly connected by the main beam to form an aerodynamic shape, and the hatch controller is installed above the hatch to drive the opening and closing of the water tank release port. The scaled drone model is assembled based on the scaled parameters in S1;

[0048] S3: Wind tunnel experimental setup: The scaled-down UAV test model from S2 is fixed to the upper wall of the wind tunnel via adjustable lifting rods as a back support. A measurement system is installed on the central axis of the lower wall of the wind tunnel. The measurement system consists of a rectangular metal plate with a boss, a superabsorbent polymer layer, and an array of equally spaced graduated cylinders.

[0049] A rectangular metal plate with bosses is fixed to the lower tunnel wall. A superabsorbent polymer layer is laid flat on its upper surface and fixed thereto. The area of ​​the superabsorbent polymer material is the same as that of the rectangular metal plate with bosses. An array of M×N graduated cylinders is arranged on the superabsorbent polymer layer, and the array consists of evenly spaced graduated cylinders. The rectangular metal plate with bosses is located on the central axis of the wind tunnel test section, equidistant from the left and right tunnel walls, and close to the incoming flow side. The rectangular metal plate with bosses is vertically aligned with the water tank.

[0050] S4: Testing and Data Processing: After releasing the fire extinguishing agent under stable wind speed, a multi-dimensional performance evaluation of the drone's fire extinguishing accuracy and range is completed by analyzing the liquid volume in the graduated cylinder, calculating the effective fire extinguishing area, and quantifying the evaporation and atomization losses.

[0051] Specifically, this scheme firstly carries out the scaled test parameter design based on the similarity criterion of Froude number Fr and Weber number We, and refers to the wind tunnel size to obtain the size parameters of the UAV, the size parameters of the fire extinguishing agent tank, the wind speed and the surface tension coefficient of the fire extinguishing agent liquid; based on the above size parameters, the test model (UAV and fire extinguishing agent tank) and the adjustable hatch structure are designed; the UAV model is mounted on the upper wall of the wind tunnel in the form of a back support using a retractable support rod. The fire extinguishing agent measurement system is composed of the following components: Figure 3 As shown in the figure, the metal plate is installed on the central axis of the wind tunnel test section and is vertically aligned with the water tank; finally, a wind tunnel test for evaluating the fire extinguishing performance of a large fixed-wing UAV is carried out to quantitatively process the effective range of the fire extinguishing agent and evaluate the fire extinguishing performance.

[0052] Scaled drone models such as Figure 2 As shown, the model includes a metal structure main beam, the front and rear bodies of the drone model, a fire extinguishing water tank, a water tank hatch, and a water tank hatch switch controller. The metal structure main beam provides the overall structural rigidity of the model and realizes the effective connection of various components. The front and rear bodies of the model are made of fiberglass material to ensure the similar aerodynamic shape of the drone model. The water tank is used to store fire extinguishing agent and is fixed to the main beam. The water tank door is controlled by the controller to open and close, realizing the spraying of fire extinguishing agent at a specified time point. The size parameters of the model are selected according to the parameters calculated in step 1.

[0053] Measurement system such as Figure 3As shown in the figure, the physical structure of the measurement system is clearly shown. A metal plate with a boss is fixed to the bottom of the wind tunnel. A highly absorbent layer is laid on the surface and an array of equally spaced measuring cylinders is embedded in it, forming a dual-channel capture device for the distribution of extinguishing agent landing points and atomized residues.

[0054] In S1, the wingspan of the scaled model is determined based on the wind tunnel width by:

[0055] .7

[0056] implementation, where is the wingspan size of the scaled model, is the wind tunnel width;

[0057] Scale by:

[0058]

[0059] Obtain, among which, is the scale, L s The actual size of the drone;

[0060] The volume of water in the tank after scaling is calculated by:

[0061]

[0062] Obtain, among which, is the volume of water in the scaled-down tank, is the volume of water in the tank;

[0063] The wind speed after scaling is:

[0064]

[0065] Obtain, among which is the scaled wind speed, is the incoming wind speed;

[0066] The surface tension coefficient of the scaled liquid is obtained by:

[0067]

[0068] Obtain, among which, is the surface tension coefficient of the scaled liquid, is the surface tension coefficient of the original liquid.

[0069] Specifically, the scaled dimensions of the length and width of the UAV water tank hatch and the scaled dimensions of the water tank height can be obtained based on the scale ruler. Specifically, the scaled dimensions are:

[0070]

[0071]

[0072]

[0073] Obtain, among which, This is the reduced size of the UAV water tank hatch. This is the reduced width size of the UAV water tank hatch. This is the scaled down size of the water tank height. The length of the UAV water tank hatch, The width of the UAV water tank hatch, is the water tank height.

[0074] This step is based on the similarity criterion of Froude number and Weber number. The scaled scale uniformly constrains the flow field gravity effect and liquid surface tension effect to ensure that the scaled model is dynamically similar to the physical process of the real scene.

[0075] In S3, the width x of the rectangular metal plate with the boss is 0.8 times the width of the wind tunnel, and the length is:

[0076]

[0077] Obtain, among which, is the length of the metal plate, H is the maximum height of the water tank in the wind tunnel, g is the acceleration of gravity, and V is the wind speed after maximum scaling.

[0078] In S4, the volume of the liquid in the measuring cylinder is analyzed by determining whether:

[0079]

[0080] Implementation, where is the volume of liquid in the i-th graduated cylinder, is the minimum volume of fire extinguishing agent that must be dropped into the graduated cylinder to achieve effective fire extinguishing. If the above formula is satisfied, it is considered that the amount of water dropped by the drone within the area where the graduated cylinder is located has an effective effect on fire extinguishing.

[0081] Effective fire extinguishing area through:

[0082]

[0083] Obtain, among which, is the effective fire extinguishing area, n is the number of measuring cylinders that meet this condition, is the actual width of the metal plate, is the actual length of the metal plate, is the number of rows in the measuring cup array, The number of rows and columns of the measuring cup array;

[0084] Evaporation and atomization losses through:

[0085]

[0086] Obtain, among which, is the weight of the atomized liquid, is the density of the extinguishing agent, is the total weight of the liquid captured by the graduated cylinder, is the weight of the super absorbent polymer layer after release, is the initial weight of the super absorbent polymer layer;

[0087] The graduated cylinder captures the total weight of the liquid via:

[0088]

[0089] get.

[0090] Specifically, this step determines the effectiveness of spatial coverage by whether the liquid captured by the measuring cylinder reaches the effective fire extinguishing volume threshold, and calculates the actual effective fire extinguishing area by counting the density of the measuring cylinder that meets the conditions. At the same time, the adsorption weight gain of the highly absorbent material and the total recovery volume of the measuring cylinder are combined to complementarily calculate the amount of fire extinguishing agent loss that cannot be recovered due to atomization and dispersion. Finally, the spatial accuracy and material utilization rate of the drone fire extinguishing agent delivery are synchronously quantified to provide data support for optimizing the delivery parameters.

Claims

1. A test method for evaluating the fire extinguishing performance of a large fixed-wing UAV, characterized in that: The method comprises: S1: Acquisition of experimental scale parameters: Determine the wingspan of the scaled model based on the wind tunnel width and calculate the scale length; derive the volume of water in the scaled tank, wind speed, and liquid surface tension coefficient based on the similarity criteria of Froude number and Weber number; S2: Construction of scaled UAV model: rigidly connect the front body (4) and the rear body (6) through the main beam (1) to form an aerodynamic shape, and install the hatch controller (2) above the hatch (5) to drive the release port of the water tank (3) to open and close, and assemble the scaled UAV model in combination with the scaled parameters in S1; S3: Layout of experimental device in wind tunnel: The scaled-down UAV test model in S2 is fixed to the upper wall of the wind tunnel in the form of a back support through an adjustable lifting rod, and a measuring system is installed on the central axis of the lower wall of the wind tunnel; the measuring system includes: a rectangular metal plate with a boss (7), a highly absorbent polymer layer (9), and an array of equally spaced measuring cylinders (8); The rectangular metal plate (7) with the boss is fixedly connected to the lower tunnel wall, and a super absorbent polymer layer (9) is laid flat on the upper surface and fixed. The area of ​​the super absorbent polymer layer (9) is the same as that of the rectangular metal plate (7) with the boss. An array of measuring cylinders (8) is arranged on the super absorbent polymer layer (9). The array includes M×N measuring cylinders (8) arranged in an equidistant arrangement. The rectangular metal plate (7) with the boss is located on the central axis of the wind tunnel test section, equidistant from the left and right tunnel walls, close to the incoming flow side, and the rectangular metal plate (7) with the boss is vertically aligned with the water tank (3). S4: Testing and Data Processing: After releasing the fire extinguishing agent under stable wind speed, a multi-dimensional performance evaluation of the drone's fire extinguishing accuracy and range is completed by analyzing the liquid volume in the graduated cylinder, calculating the effective fire extinguishing area, and quantifying the evaporation and atomization losses.

2. A large fixed-wing UAV fire extinguishing performance evaluation test method according to claim 1, characterized in that: In S1, the wingspan of the scaled model is determined based on the wind tunnel width by: .7 implementation, where is the wingspan size of the scaled model, is the wind tunnel width; Scale by: Obtain, among which, is a scale, Ls is the actual size of the drone; The volume of water in the tank after scaling is calculated by: Obtain, among which, is the volume of water in the scaled-down tank, is the volume of water in the tank; The wind speed after scaling is: Obtain, among which is the scaled wind speed, is the incoming wind speed; The surface tension coefficient of the scaled liquid is obtained by: Obtain, among which, is the surface tension coefficient of the scaled liquid, is the surface tension coefficient of the original liquid.

3. A large fixed-wing UAV fire extinguishing performance evaluation test method according to claim 1, characterized in that: In S3, the width x of the rectangular metal plate with the boss is 0.8 times the width of the wind tunnel, and the length is: Obtain, among which, is the length of the metal plate, H is the maximum height of the water tank in the wind tunnel, g is the acceleration of gravity, and V is the wind speed after maximum scaling.

4. A large fixed-wing UAV fire extinguishing performance evaluation test method according to claim 1, characterized in that: In S4, the volume of the liquid in the measuring cylinder is analyzed by determining whether: Implementation, where is the volume of liquid in the i-th graduated cylinder, is the minimum volume of fire extinguishing agent that must be dropped into the graduated cylinder to achieve effective fire extinguishing. If the above formula is satisfied, it is considered that the amount of water dropped by the drone within the area where the graduated cylinder is located has an effective effect on fire extinguishing. Effective fire extinguishing area through: Obtain, among which, is the effective fire extinguishing area, n is the number of measuring cylinders that meet this condition, is the actual width of the metal plate, is the actual length of the metal plate, is the number of rows in the measuring cup array, The number of rows and columns of the measuring cup array; Evaporation and atomization losses through: Obtain, among which, is the weight of the atomized liquid, is the density of the extinguishing agent, is the total weight of the liquid captured by the graduated cylinder, is the weight of the super absorbent polymer layer after release, is the initial weight of the super absorbent polymer layer; The graduated cylinder captures the total weight of the liquid via: get.

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