Jet flow anti-push self-stabilizing spray gun device for high-altitude fire extinguishing unmanned aerial vehicle

Abstract

The application provides a jet flow counter-thrust self-stabilizing spray gun device for high-altitude fire extinguishing unmanned aerial vehicles, and relates to the technical field of fire-fighting unmanned aerial vehicles.The device comprises a main spray pipe with an elevation angle θ and a counter-force spray pipe with a direction opposite to that of the main spray pipe.By limiting the elevation angle θ of the main spray pipe to be between 11° and 60°, the diameter of the counter-force spray pipe is smaller than that of the main spray pipe, the diameter ratio is greater than 5 / 4, and the outlet surface pressure of the counter-force spray pipe is higher than that of the main spray pipe, the horizontal component of the back force of the main spray pipe is balanced by the counter-thrust of the jet flow of the counter-force spray pipe, so that the attitude disturbance of the unmanned aerial vehicle during jet flow fire extinguishing is effectively inhibited, and the pitch attitude deviation is always controlled within a safe range (for example, less than 12°). The application solves the instability problem of the existing fire extinguishing unmanned aerial vehicle caused by the jet flow back force, ensures the flight safety, reduces the flow loss through parameter optimization, and improves the fire extinguishing operation efficiency and the overall system energy efficiency.

Description

Technical Field

[0001] This invention relates to the field of firefighting drone technology, and in particular to a jet reverse thrust self-stabilizing spray gun device for high-altitude firefighting drones. Background Technology

[0002] With rapid urbanization and a surge in the number of high-rise buildings, high-rise fire fighting has become a major challenge. Traditional firefighting methods face bottlenecks such as height limitations and slow response times. Existing firefighting drones, when spraying extinguishing agents, are prone to aircraft instability, loss of control, or even crashes due to the recoil generated by the nozzle; while setting the nozzle to a large pitch angle to reduce the horizontal force obstructs the field of view of onboard detection equipment (such as cameras). Although foreign countries have technologies for designing reaction-force nozzles, these suffer from problems such as excessively large pipe diameter increasing weight and drag, excessive energy consumption or flow loss leading to low firefighting efficiency, and overly complex and heavy vector thrust systems. Therefore, there is an urgent need for a drone spray gun device that can effectively balance spray recoil, ensure flight stability, and not significantly sacrifice firefighting efficiency. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention proposes a fire extinguishing spray gun structure that can improve the stability of drones.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: a jet thrust self-stabilizing spray gun device for high-altitude firefighting drones, characterized in that: it includes a water inlet pipe, a main nozzle connected to the water inlet pipe, and a reaction force nozzle connected in parallel to a branch of the water inlet pipe; the axis of the main nozzle forms an acute angle θ with the plane of the drone fuselage (i.e., the horizontal plane); the reaction force nozzle is oriented in the opposite direction to the spray direction of the main nozzle; the outlet inner diameter d2 of the reaction force nozzle is smaller than the outlet inner diameter d1 of the main nozzle, and d1 / d2 ≥ 5 / 4; the outlet gauge pressure p2 of the reaction force nozzle before spraying is greater than the outlet gauge pressure p1 of the main nozzle before spraying; by coordinating the design of the main nozzle elevation angle θ, the pipe diameter ratio of the main nozzle and the reaction force nozzle, and the outlet gauge pressure of the two nozzles, the reverse thrust generated by the reaction force nozzle and the component of the recoil force of the main nozzle on the fuselage plane are dynamically balanced.

[0005] Preferably, the elevation angle θ of the main nozzle ranges from 11° to 60°.

[0006] Preferably, a first booster pump for increasing the injection pressure and flow rate of the main nozzle is installed on the main inlet pipe.

[0007] Preferably, a second booster pump for increasing the gauge pressure before the reaction force nozzle is installed on the branch before the reaction force nozzle is injected. The second booster pump is a low-flow high-pressure pump.

[0008] The principle is as follows: the main nozzle sprays fire-extinguishing water (such as water) upwards, generating a recoil force FA1, the horizontal component of which is FA1·cosθ. By setting a reaction force nozzle with a smaller diameter but higher gauge pressure in the opposite direction to the main nozzle, a small stream of high-speed water is sprayed to generate a reverse thrust FA2. Through parameter design, FA2 is balanced with FA1·cosθ, thereby counteracting the horizontal interference force brought by the main jet, and keeping the UAV's attitude (especially the pitch angle) within a safe flight range (e.g., less than 12°).

[0009] In other words, when a drone carries a spray gun for firefighting, the recoil of the water spray will significantly challenge the limits of the drone's self-stabilization system. Most of this recoil is reflected in the horizontal direction, while the external force reflected in the longitudinal direction can be overcome by the drone's takeoff weight and longitudinal stability capability. As we all know, the takeoff weight of drones is relatively large, while the lateral stability limit is very limited. Therefore, this solution is to design the nozzle so that when the drone sprays water for firefighting, some of the water flow is sprayed back at the reaction force nozzle, forming a reaction force that offsets or weakens the reverse force of the main water spray. Attached Figure Description

[0010] Figure 1 The diagram shows a simplified connection of the inlet pipe, main nozzle, and reaction force nozzle, illustrating the included angle θ. Detailed Implementation

[0011] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.

[0012] High-altitude firefighting drones utilize multi-rotor drone platforms, but drones have limited flight stability. Therefore, it's crucial to minimize the interference caused by the recoil of the fire extinguishing material sprayed from the spray gun. This paper designs a spray gun consisting of a main nozzle and a reaction nozzle to achieve overall recoil-free or low-recoil spraying for the drone system. Among the spray gun components, the nozzle diameter, gauge pressure, flow rate, and main nozzle elevation angle determine the spray gun's performance and are key aspects of its design. Therefore, parameter analysis and performance analysis are conducted to ensure the spray gun meets design requirements, particularly the selection of the main nozzle-to-reaction nozzle diameter ratio and gauge pressure.

[0013] When the ratio of the main nozzle to the reaction nozzle diameter and the gauge pressure are not properly selected: Inaccurate control: If the reaction nozzle is too small relative to the main nozzle, the control force it generates may be too weak to quickly and accurately adjust the drone's attitude.

[0014] Thrust loss: If the reaction force nozzle is too large, it will divert too much of the main flow, weakening the main fire extinguishing force and reducing fire extinguishing efficiency.

[0015] The main nozzle is designed with an elevation angle between 11 and 60 degrees.

[0016] Based on experimental data and published invention patents (patent number CN114180067A, 2021), when there is no reaction force nozzle, from the perspective of acceptable flight conditions for the UAV, the angle θ between the nozzle and the UAV plane is preferably in the range of 12.24◦ ≤ θ ≤ 84.2◦. For ease of calculation, rounding is preferred to 12◦ ≤ θ ≤ 85◦.

[0017] Experiments have shown that the safe pitch angle range (relative to the aircraft itself) is less than 12°. When the main nozzle pitch angle is between 11° and 60°, adjusting the pipe diameter ratio and gauge pressure allows the recoil force generated by the jet to achieve a dynamic balance with the reaction force of the nozzle, keeping the UAV's attitude deviation within 12°. If the pitch angle is less than 11°, the main nozzle sprays almost horizontally, significantly increasing the horizontal component of the recoil force, which can easily cause the UAV to deviate from the safe attitude range (exceeding 12°), leading to flight instability. If the pitch angle is greater than 60°, the vertical component of the jet is too high, resulting in excessive lift burden on the UAV, causing problems such as aircraft swaying, control failure, and the UAV's inability to observe the fire scene.

[0018] Experiments have shown that when the main nozzle elevation angle is limited to 11°-60°, the deviation of the UAV from its initial attitude during spraying operations is always less than 12°, which fully meets the safety requirements of the aircraft and enables it to stably perform firefighting tasks.

[0019] A booster pump is installed at the water inlet pipe to increase the gauge pressure before the main nozzle sprays, thereby increasing the spray distance and flow rate and enhancing the fire extinguishing effect.

[0020] A small-flow, high-pressure booster pump is installed before the reaction force nozzle to increase the gauge pressure before injection, thereby reducing the nozzle diameter and flow rate and minimizing overall flow loss. Figure 1 As shown.

[0021] The effects of pipe diameter ratio, gauge pressure, jet velocity, and reaction force on water consumption in a dual-nozzle structure were systematically studied using orthogonal experimental design. The results show that the diameter of the reaction force nozzle should be smaller than that of the main nozzle, but the gauge pressure before jetting should also be increased accordingly. When the pipe diameter ratio of the main nozzle to the reaction force nozzle, d1 / d2, is ≥5 / 4, adjusting the gauge pressure p2 before jetting the reaction force nozzle can achieve a dynamic balance between water consumption and system stability.

[0022] Test data shows that the diameter of the reaction nozzle must always be smaller than that of the main nozzle, and the two nozzle diameters are linked and adapted to each other. When the main nozzle diameter decreases from 0.025m to 0.019m, the corresponding reaction nozzle diameter is adjusted from "maximum not exceeding 0.019m" to "maximum not exceeding 0.016m". If the reaction nozzle diameter is not smaller than that of the main nozzle, it will directly lead to an imbalance in the jetting power and a significant increase in water consumption.

[0023] The linkage effect of gauge pressure: The smaller the diameter of the reaction force nozzle, the higher the gauge pressure required before injection. For example, when the diameter of the reaction force nozzle is 0.025m, the gauge pressure needs to be increased from the conventional 0.7MPa to 1.5-3MPa; while when the diameter of the main nozzle is 0.05m and the diameter of the reaction force nozzle is 0.04m (diameter ratio 5:4), a gauge pressure of 0.6MPa can maintain stable injection, without the problem of a sudden increase in flow rate due to excessively high gauge pressure or weak injection due to excessively low gauge pressure.

[0024] Multi-parameter synergistic effect: The jet velocity, reaction force, water consumption, and system stability are directly related. For example, when the main nozzle is 0.05m and the reaction force nozzle is 0.04m, the jet velocity is 34.641m / s, the reaction force is 1508N, the main nozzle elevation angle is 39.8254°, the cosα value is 0.768, and the jet flow rate is within a reasonable range.

[0025] Nozzle flow rate and outlet gauge pressure analysis Derivation of premises and symbols To simplify calculations and eliminate interference from secondary factors, the following assumptions are set: (1) The water flow is an incompressible fluid (water has very low compressibility, which can be ignored in engineering scenarios); (2) The water flow velocity is uniform at the nozzle outlet, with no radial diffusion (only axial momentum is considered); (3) Energy loss, gravity, and air resistance of the water flow within the nozzle are ignored (focusing on the core relationship between pressure and momentum); (4) The change in water flow velocity from the nozzle inlet to the outlet is driven only by the outlet gauge pressure (the inlet velocity is much smaller than the outlet velocity, which can be approximated as 0). The compliance and its significance are shown in Table 1.

[0026]

[0027] Step-by-step derivation process of general reverse thrust Taking the nozzle inlet (section 1, the connection between the nozzle and the hose) and outlet (section 2, the terminal section where the water flows out of the nozzle) as the research sections, Bernoulli's equation is applied:

[0028] After simplification, the relationship between the outlet flow rate and the outlet gauge pressure is obtained:

[0029] The simplified condition is: the nozzle inlet and outlet heights are approximately the same (z1 ≈ z2), and the gravitational potential energy terms cancel each other out; The inlet water flow comes from the fire hose, and the flow velocity v1 is much smaller than the outlet flow velocity v2 (v1 ≈ 0); The gauge pressure at section 2 is approximately equal to atmospheric pressure p2 ≈ p0, while the inlet gauge pressure p1 is ultimately converted into outlet kinetic energy, therefore p1 ≈ p − p0 (engineering approximation).

[0030] Substituting mass flow rate and velocity, derive the relationship between recoil force and velocity, gauge pressure, and flow rate. According to the momentum theorem The relationship between recoil force and nozzle outlet velocity can be obtained from the mass flow rate of the water flow (3):

[0031] Substituting into equation (2), we can obtain equation (4) relating recoil force and outlet gauge pressure:

[0032] According to the definition of flow rate q = Av, the relationship between recoil force and flow rate q and gauge pressure p can be obtained (5):

[0033] Force balance relationship between the main nozzle and the reaction nozzle 4.0.1 Force Balance Analysis Considering the pitch angle of the main nozzle relative to the fuselage, the horizontal component of the main nozzle's thrust reverse force should be balanced with the thrust reverse force of the reaction nozzle (6):

[0034] Using equation (5), the flow-pressure relationship between the main nozzle and the reaction nozzle can be obtained as (7):

[0035] Alternatively, we can obtain the formula for calculating the flow rate of the reaction nozzle (8) and the formula for calculating the elevation angle of the main nozzle (9):

[0036] Using formula (4) and Formulas (10) and (11) can be obtained to determine the pipe diameter and pressure relationship between the main nozzle and the reaction nozzle:

[0037] Alternatively, we can obtain the formula for calculating the diameter of the reaction nozzle (12), the formula for calculating the elevation angle of the main nozzle (13), and the formula for calculating the gauge pressure before the reaction nozzle sprays water (14):

[0038] Using formulas (12)-(14), we can select the appropriate main nozzle elevation angle and the reaction force nozzle pre-spray surface. Pressure. For example, if the inner diameter of the main nozzle is determined to be d1 = 25mm and the gauge pressure is p1 = 1Mpa, then by using formula (2) and the flow rate definition q = Av, it can be calculated that the initial velocity of the water flow from the main nozzle is maintained at v1 = 44.7m / s and the fire extinguishing water flow rate of the main nozzle is maintained at q1 = 21.94l / s. According to different pipe diameters and gauge pressures, the pitch angle can be calculated as shown in Table 2:

[0039] Similarly, after selecting and determining the main nozzle inner diameter d1 = 25mm, gauge pressure p1 = 1Mpa, and pitch angle θ, the gauge pressure p2 before water spraying from the reaction force nozzle can be calculated using formula (14) according to different pipe diameter ratios d1 / d2. Tables 3, 4, and 5 show the required gauge pressure p2 of the reaction force nozzle for different pipe diameter ratios when θ = 10◦, θ = 20◦, and θ = 30◦, respectively.

[0040]

[0041]

[0042] Analysis of calculation results When the diameter of the reaction nozzle remains constant and the gauge pressure of the reaction nozzle changes, the flow loss increases with the increase of the gauge pressure p2 of the reaction nozzle, and the elevation angle of the main nozzle decreases with the increase of p2.

[0043] When the main nozzle diameter is the same, the smaller the reaction force nozzle diameter, the smaller the flow loss, but the reaction force nozzle gauge pressure p2 needs to be increased.

[0044] In other words, when the main nozzle diameter is fixed, the smaller the reaction force pipe diameter d2 and gauge pressure p2, the larger the main nozzle elevation angle and the less flow loss. When both the main nozzle diameter and elevation angle are fixed, to reduce flow loss, a smaller reaction force pipe diameter d2 and corresponding reaction force water flow gauge pressure p2 should be selected.

[0045] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. A jet thrust reverse self-stabilizing spray gun device for high-altitude firefighting drones, characterized in that, The system includes an inlet pipe, a main nozzle connected to the inlet pipe, and a reaction force nozzle connected in parallel to a branch of the inlet pipe. The axis of the main nozzle forms an elevation angle θ with the plane of the UAV fuselage. The spray direction of the reaction force nozzle is opposite to that of the main nozzle. The outlet inner diameter d2 of the reaction force nozzle is smaller than the outlet inner diameter d1 of the main nozzle, and d1 / d2 ≥ 5 / 4. The outlet gauge pressure p2 of the reaction force nozzle before spraying is greater than the outlet gauge pressure p1 of the main nozzle before spraying. By configuring the elevation angle θ, the outlet inner diameters d1 and d2, and the outlet gauge pressures p1 and p2, the reverse thrust generated by the reaction force nozzle is balanced with the recoil force generated by the main nozzle on the fuselage plane.

2. The jet thrust reverse self-stabilizing spray gun device for high-altitude firefighting drones according to claim 1, characterized in that, The elevation angle θ ranges from 11° to 60°.

3. The jet thrust reverse self-stabilizing spray gun device for high-altitude firefighting drones according to claim 1, characterized in that, On the main inlet pipe, before the water is diverted to the reaction force nozzle, there is a first booster pump for increasing the pressure of the water flowing to the main nozzle.

4. The jet thrust reverse self-stabilizing spray gun device for high-altitude firefighting drones according to claim 1, characterized in that, A second booster pump is provided on the branch leading to the reaction force nozzle to increase the gauge pressure p2 at the outlet before the reaction force nozzle is injected.

5. A jet thrust reverse self-stabilizing spray gun device for a high-altitude firefighting drone according to claim 4, characterized in that, The second booster pump is a low-flow, high-pressure pump.

6. A jet thrust reverse self-stabilizing spray gun device for a high-altitude firefighting drone according to any one of claims 1 to 5, characterized in that, The reaction force nozzle is a single nozzle.

7. A jet thrust reverse self-stabilizing spray gun device for high-altitude firefighting drones according to any one of claims 1 to 5, characterized in that... The reaction force nozzle consists of multiple nozzles evenly distributed circumferentially.

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