A test platform and test method for compressed air fire extinguishing systems suitable for large-span conditions in ultra-high voltage substations

Abstract

The present invention discloses a compressed air fire extinguishing system test platform suitable for use in large-span UHV substations. The platform relates to the field of fire protection technology and includes a compressed air foam injection system, a foam injection prediction system, and a foam performance testing system. The compressed air foam injection system is used to generate compressed air foam and control experimental operating conditions. The foam injection prediction system includes a video data collection device and a model calibration and prediction device. The video data collection device is used to collect video data of the entire foam injection process of the compressed air foam injection system. The model calibration and prediction device has a built-in data preprocessing program, a model hyperparameter calibration program, and a compressed air foam injection trajectory prediction program. The present invention has the advantage of being able to economically, quickly, and accurately predict the foam injection behavior of a compressed air foam fire extinguishing system suitable for use in large-span UHV substations under different operating conditions.

Description

Technical Field

[0001] The present invention relates to the field of fire protection technology, and in particular to a compressed air fire extinguishing system testing platform and testing method suitable for large-span conditions in ultra-high voltage substations. Background Art

[0002] Due to population growth and accelerated urbanization, complex building structures and a wide variety of combustible materials are increasingly prone to expanding the scale and damage of fires. This is particularly true for buildings like UHV substations, which present significant hazards. While traditional water sprinkler systems can provide cooling, they are ineffective against large-scale, high-energy fires. Conventional firefighting methods face challenges when dealing with large-scale, high-energy combustion.

[0003] Compressed air foam fire extinguishing, as a new fire extinguishing technology, offers certain advantages in suppressing the aforementioned fire situation. Compressed air foam fire extinguishing technology involves mixing compressed air and foaming agent in a specific proportion and applying it to the burning area at high speed, forming a solid, thermally insulating foam layer. This effectively cuts off contact between the fire source and oxygen, extinguishing the flames and preventing the fire from spreading and reigniting. For example, patent publication number CN114100044A discloses a sprinkler device for a compressed air foam fire extinguishing system. However, traditional compressed air foam fire extinguishing technology still has some shortcomings in fire incidents involving long ranges and large spans:

[0004] (1) Limitations of range improvement: Currently, in order to improve the spray range of compressed air foam fire extinguishing systems, most people use manual methods to collect data on the spray trajectory. This is not only time-consuming and labor-intensive, but the errors in the collected experimental data are also large.

[0005] (2) Lack of foam performance: Most compressed air foam fire extinguishing system test platforms only test the macroscopic performance of foam spraying, such as range, coverage and fire extinguishing, but lack attention to the microscopic performance of foam.

[0006] (3) Single driving mode: The traditional compressed air foam fire extinguishing system adopts a single gas driving mode. Since the single gas driving system only uses a single gas source for spraying, its spraying speed and coverage area are limited. Moreover, since only a single gas source is used, the stirring and shearing ability of the foam is relatively weak. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to quickly and accurately predict the foam spraying conditions of a high-range and large-span compressed air foam fire extinguishing system under different working conditions.

[0008] The present invention solves the above technical problems by the following technical means: a compressed air fire extinguishing system test platform suitable for large-span conditions of ultra-high voltage substations, including a compressed air foam injection system, a foam injection situation prediction system and a foam performance testing system;

[0009] The compressed air foam injection system is used to generate compressed air foam and control experimental working conditions;

[0010] The foam injection situation prediction system includes a video data collection device and a model calibration and prediction device. The video data collection device is used to collect video data of the entire foam injection process of the compressed air foam injection system. The model calibration and prediction device has a built-in data preprocessing program, a model hyperparameter calibration program and a compressed air foam injection trajectory prediction program.

[0011] The data preprocessing program is used to process the video data collected by the video data collection device to obtain injection trajectory coordinate data; the model hyperparameter calibration program is used to calibrate the correction coefficient of the compressed air foam injection trajectory model based on the injection trajectory coordinate data obtained by the data preprocessing program; the compressed air foam injection trajectory prediction program is used to use the compressed air foam injection trajectory model based on the determined correction coefficient, input the experimental operating conditions parameters to perform model calculations, and complete the prediction of the injection conditions of the compressed air foam system with a high range and large span.

[0012] The present invention can economically, quickly and accurately predict the foam spraying conditions of a high-range and large-span compressed air foam fire extinguishing system under different working conditions. It is not limited by the experimental scale and can ensure the accuracy and completeness of the experimental data at a relatively mature level.

[0013] As an optimized technical solution, a foam performance testing system is also included, comprising a foam collection tank, a test connector, a foam observation chamber, a microscope, and a data processing device. The foam collection tank is capable of collecting compressed air foam generated by the compressed air foam injection system, and the foam outflow port of the foam collection tank is connected to the foam observation chamber via a pipe. The test connector is provided on the foam collection tank and can be connected to an external pressurizing device, a foam density measuring device, and a foam liquid separation characteristic measuring device, respectively. The microscope is used to observe the compressed air foam in the foam observation chamber, and the microscope is connected to the data processing device. The pressurizing device can provide the required pressure to the inner cavity of the foam collection tank, and the foam density measuring device and the foam liquid separation characteristic measuring device can respectively measure the changes in foam density and foam liquid separation characteristics under different pressures, thereby clarifying the influence of pressure on foam density and foam liquid separation characteristics. The microscope can observe the changes in foam microscopic properties under different pressures in real time, and the data processing device can record and analyze the foam microscopic properties in real time, thereby realizing the measurement and research of foam density, foam liquid separation characteristics, and foam microscopic properties under different pressures, which has practical guiding significance for the transportation of compressed air foam.

[0014] As an optimized technical solution, the foam collection tank includes a tank body, a sealing cover, a foam collection port and a foam outflow port. The sealing cover seals the opening of the tank body, the foam collection port is arranged on the sealing cover, and the foam outflow port is arranged on the tank body; the test joint includes a four-way pipe fitting and a fourth pressure valve. The four-way pipe fitting is arranged on the sealing cover. The four joints of the four-way pipe fitting are respectively connected to the inner cavity of the foam collection tank, the pressurizing device, the foam density measuring device and the foam liquid separation characteristic measuring device, and the fourth pressure valve is provided on the joint connected to the pressurizing device.

[0015] As an optimized technical solution, the tank body is made of transparent material and a scale is provided on the outside of the tank body to facilitate reading the changes in the foam liquid level.

[0016] As an optimized technical solution, the compressed air foam injection system includes a first gas storage device, a first flow control device, a first gas pipeline, a liquid storage device, a gas-liquid pipeline, a second gas storage device, a second flow control device, a second gas pipeline, a gas-liquid premixing chamber, a foam delivery pipeline, a foam mixing cavity and a foam spray pipe; the gas outlet of the first gas storage device is connected to the gas inlet of the liquid storage device through the first gas pipeline, and the foam outlet of the liquid storage device is connected to the gas-liquid inlet of the gas-liquid premixing chamber through the gas-liquid pipeline, and the first flow control device is used to control the gas-liquid flow rate entering the gas-liquid inlet of the gas-liquid premixing chamber; the gas outlet of the second gas storage device is connected to the gas inlet of the gas-liquid premixing chamber through the second gas pipeline, and the second flow control device is used to control the gas flow rate entering the gas inlet of the gas-liquid premixing chamber; the foam outlet of the gas-liquid premixing chamber is connected to the foam inlet of the foam mixing cavity, and the foam outlet of the foam mixing cavity is connected to the foam inlet of the foam spray pipe through the foam delivery pipeline, and the foam spray pipe is provided with a foam nozzle. The dual-air drive mode improves the injection speed and coverage area of ​​the compressed air foam injection system, and has strong stirring and shearing capabilities for the foam. It has the advantages of high performance, light weight, flexibility, environmental friendliness, safety and reliability.

[0017] As an optimized technical solution, the first flow control device includes a first pressure valve and a first flow meter, with the first pressure valve being installed on the first gas pipeline and the first flow meter being installed on the gas-liquid pipeline. The second flow control device includes a second pressure valve and a second flow meter, with the second pressure valve and the second flow meter being installed on the second gas pipeline. The first and second flow meters can monitor the compressed air foam flow in real time.

[0018] As an optimized technical solution, the compressed air foam injection system further includes a third valve and a third pressure valve, and the foam delivery pipeline is provided with a third valve and a third pressure valve.

[0019] As an optimized technical solution, the compressed air foam spraying system also includes a support frame, a knob and an operating chamber. The foam spray pipe is fixedly connected to the interior of the operating chamber through the support frame. The foam spray pipe is installed on the support frame. The threaded knob passes through the side wall of the operating chamber and is threadedly connected to the support frame.

[0020] As an optimized technical solution, the data preprocessing program processes the video data collected by the video data collection device through the Python language. The specific processing flow is to divide the original video data into frames to obtain image data, grayscale and binarize the image data to obtain a jet trajectory contour map, and extract the jet trajectory coordinate data from the jet trajectory contour map and store it.

[0021] A method for testing a compressed air fire extinguishing system suitable for large-span conditions in ultra-high voltage substations employs the high-range, large-span compressed air foam fire extinguishing system test platform. The compressed air foam injection trajectory prediction program derivates a compressed air foam injection trajectory model. First, a force analysis is performed on the foam jet per unit mass as a microelement. The obtained velocities are horizontal and vertical, respectively. Combined with Newton's second law, the following equations are derived:

[0022]

[0023] in, For foam quality, is the foam movement speed, is the characteristic time, is the air resistance, is the force balance correction coefficient equation, is the angle between the foam movement direction and the horizontal ground, is the acceleration due to gravity;

[0024] The highest point of the foam injection trajectory is set as the limit point, and the foam injection trajectory is expressed as two parts: the ascending segment and the descending segment. The correction coefficient equations are constructed for each part, and the differential equation group is established. The differential equation of the ascending segment foam injection trajectory is:

[0025]

[0026] in, is the correction coefficient equation of the force balance in the ascending section, For range, To shoot high, is the length of the foam trajectory, is the correction coefficient for the ascending section;

[0027] Similarly, the differential equation of the foam injection trajectory in the descending section is:

[0028]

[0029] in, is the correction coefficient equation of the force balance in the ascending section, is the correction coefficient for the descending section;

[0030] Air resistance during foam spraying The air resistance equation is:

[0031]

[0032] in, is the air density, is the cross-sectional area of ​​the foam element, is the air resistance coefficient;

[0033] The correction coefficient of the compressed air foam injection trajectory model is substituted into the compressed air foam injection trajectory model to calculate the fit between the model and the experimental data. To iteratively solve;

[0034] The compressed air foam injection trajectory model uses the fourth-order Runge-Kutta method to solve the foam injection trajectory differential equations of the ascending and descending sections, which are expressed as follows:

[0035]

[0036] in, For prediction Shoot high, To find the time step, is the initial position slope, for Calculate the slope at the midpoint, for Calculate the slope at the midpoint, is the slope of the end position;

[0037] Goodness of fit The solution formula is:

[0038]

[0039] in, For experimental data Shoot high, is the average shot height of the experimental data.

[0040] The advantages of the present invention are:

[0041] 1. The present invention can economically, quickly, and accurately predict the foam spraying conditions of a compressed air foam fire extinguishing system suitable for large-span UHV substations under different working conditions. It is not limited by the experimental scale and can ensure the accuracy and completeness of the experimental data at a relatively mature level.

[0042] 2. The foam performance testing system can be used to carry out measurement research on foam density, foam liquid separation characteristics and foam microscopic properties under different pressures, which has practical guiding significance for the transportation of compressed air foam.

[0043] 3. The compressed air foam spraying system adopts a dual-gas drive mode, which improves the spraying speed and coverage area of ​​the compressed air foam spraying system, and has strong stirring and shearing capabilities for the foam. It has the advantages of high performance, light weight, flexibility, environmental friendliness, safety and reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1The diagram is a structural diagram of a compressed air fire extinguishing system test platform suitable for large-span conditions in ultra-high voltage substations according to an embodiment of the present invention.

[0045] Figure 2 It is a structural schematic diagram of a foam collection tank according to an embodiment of the present invention.

[0046] Figure 3 4 is a flow chart of a data preprocessing procedure according to an embodiment of the present invention. DETAILED DESCRIPTION

[0047] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0048] like Figures 1 to 3 As shown, an embodiment of the present invention discloses a compressed air fire extinguishing system test platform suitable for large-span conditions of ultra-high voltage substations, including a compressed air foam injection system, a foam injection situation prediction system and a foam performance testing system.

[0049] The compressed air foam injection system is used to generate compressed air foam and control experimental working conditions such as working flow, foam nozzle elevation angle, foam nozzle nozzle height, and foam nozzle nozzle diameter. The compressed air foam injection system adopts a dual-gas drive mode, including a first gas storage device 1, a first flow control device, a first valve 3, a first gas pipeline 4, a liquid storage device 5, a gas-liquid pipeline 6, a second gas storage device 8, a second flow control device, a second valve 10, a second gas pipeline 11, a gas-liquid pre-mixing chamber 13, a foam mixing cavity 14, a foam delivery pipeline 15, a third valve 16, a third pressure valve 17, a foam spray pipe 18, a support frame 19, a knob 20 and an operating room 21.

[0050] The first flow control device includes a first pressure valve 2 and a first flow meter 7 , and is used to control the gas-liquid flow rate entering the gas-liquid inlet of the gas-liquid premixing chamber 13 .

[0051] The second flow control device includes a second pressure valve 9 and a second flow meter 12 . The second flow control mechanism is used to control the gas flow entering the gas inlet of the gas-liquid premixing chamber 13 .

[0052] The gas outlet of the first gas storage device 1 is connected to the gas inlet of the liquid storage device 5 through the first gas pipeline 4, and the first gas pipeline 4 is provided with a first pressure valve 2 and a first valve 3; the foam outlet of the liquid storage device 5 is connected to the gas-liquid inlet of the gas-liquid pre-mixing chamber 13 through the gas-liquid pipeline 6, and the gas-liquid pipeline 6 is provided with a first flow meter 7; the gas outlet of the second gas storage device 8 is connected to the gas inlet of the gas-liquid pre-mixing chamber 13 through the second gas pipeline 11, and the second gas pipeline 11 is provided with a second pressure valve 9, a second valve 10 and a second flow meter 12; the foam outlet of the gas-liquid pre-mixing chamber 13 is connected to the foam inlet of the foam mixing cavity 14 through a pipeline, and the foam outlet of the foam mixing cavity 14 is connected to the foam outlet of the foam mixing cavity 14 through the foam outlet The foam delivery pipe 15 is connected to the foam inlet of the foam spray pipe 18, and the foam delivery pipe 15 is provided with a third valve 16 and a third pressure valve 17; the foam spray pipe 18 is fixedly connected to the interior of the operating room 21 through a support frame 19, and the foam spray pipe 18 is installed on the support frame 19, and a threaded knob 20 passes through the side wall of the operating room 21 and is threadedly connected to the support frame 19; a foam nozzle is provided on the foam spray pipe 18, and the installation height of the foam spray pipe 18 is adjusted between 0 and 100 cm according to the experimental working conditions, and the elevation angle of the foam nozzle is adjusted between 0 and 90 degrees; the first gas storage device 1 and the second gas storage device 8 both use compressed air cylinders with a pressure reducing valve, each with a capacity of 40 L, and the first gas pipeline 4, the gas-liquid pipeline 6, the second gas pipeline 11 and the foam delivery pipeline 15 are all standard pipelines made of aluminum alloy; this dual-gas drive mode improves the injection speed and coverage area of ​​the compressed air foam injection system, and has strong stirring and shearing capabilities for the foam, and has the advantages of high performance, lightness and flexibility, environmental friendliness, safety and reliability.

[0053] During the experiment, a certain gas-liquid ratio is controlled by the first flow control device and the second flow control device. The gas in the first gas storage device 1 drives the liquid in the liquid storage device 5 to enter the gas-liquid pre-mixing chamber 13, and is pre-mixed with the gas entering the gas-liquid pre-mixing chamber 13 from the second gas storage device 8. The main purpose is to fully refine and foam the foam water solution, and after pre-mixing, it enters the foam mixing cavity 14. The foam mixing cavity 14 is used to hold the generated compressed air foam, and the compressed air foam is sprayed out through the foam nozzle on the foam spray pipe 18.

[0054] The foam injection situation prediction system is used to predict the foam injection situation of the compressed air foam injection system, and includes a video data collection device 22, a data transmission line 23 and a model calibration and prediction device 24; the video data collection device 22 uses a Canon EOS R8 camera to collect video data of the entire foam injection process of the compressed air foam injection system; the video data collection device 22 is fixedly arranged inside the operating room 21, and its position ensures that it can fully cover the entire foam injection process of the foam spray pipe 18; the video data collection device 22 is connected to the model calibration and prediction device 24 through the data transmission line 23, and the model calibration and prediction device 24 has built-in data preprocessing program, model hyperparameter calibration program and compressed air foam injection trajectory prediction program. Based on these three programs, the function of predicting the injection situation of a compressed air foam system with a high range and large span is realized.

[0055] The data preprocessing program is used to process the video data collected by the video data collection device 22 to obtain the injection trajectory coordinate data; Figure 3 The data preprocessing program processes the video data collected by the video data collection device 22 through the Python language. The specific processing flow is to divide the original video data into frames to obtain image data, grayscale and binarize the image data to obtain a jet trajectory contour map, and extract the jet trajectory coordinate data from the jet trajectory contour map and store it in Excel.

[0056] The model hyperparameter calibration program is used to calibrate the correction coefficient of the compressed air foam injection trajectory model based on the injection trajectory coordinate data obtained by the data preprocessing program.

[0057] The compressed air foam injection trajectory prediction program is used to adopt a compressed air foam injection trajectory model based on a determined correction coefficient, input experimental working condition parameters such as working flow, foam nozzle elevation angle, foam nozzle nozzle height, and foam nozzle nozzle diameter to perform model calculations, and complete the prediction of the injection situation of a high-range and large-span compressed air foam system.

[0058] The foam performance testing system is used to test the foam performance of the compressed air foam injection system, such as foam density, liquid separation characteristics and microscopic properties, and includes a foam collecting pipe 25, a foam collecting tank 26, a test joint 27, a foam observation chamber 28, a microscope 29 and a data processing device 30; the foam collecting tank 26 is used to collect the compressed air foam generated by the compressed air foam injection system, the foam collecting port 263 of the foam collecting tank 26 is connected to the foam delivery pipe 15 through the foam collecting pipe 25, and the foam outflow port 264 of the foam collecting tank 26 is connected to the foam observation chamber 28 of a cylindrical transparent material through a pipe; the test joint 27 is set on the foam collecting tank 26 and can be connected to an external pressurizing device, a foam density measuring device and a foam liquid separation characteristic measuring device respectively. a property measuring device; a microscope 29 is used to observe the compressed air foam in the foam observation chamber 28, and the microscope 29 is connected to a data processing device 30; the required pressure can be provided to the inner cavity of the foam collection tank 26 by the pressurizing device, and the changes in foam density and foam liquid separation characteristics under different pressures can be measured respectively by the foam density measuring device and the foam liquid separation characteristic measuring device, so as to clarify the influence of pressure on foam density and foam liquid separation characteristics. The changes in foam microscopic properties under different pressures can be observed in real time by the microscope 29, and the foam microscopic properties can be recorded and analyzed in real time by the data processing device 30, thereby realizing the measurement and research of foam density, foam liquid separation characteristics and foam microscopic properties under different pressures, which has practical guiding significance for the transportation of compressed air foam.

[0059] The foam collection tank 26 includes a tank body 261, a sealing cover 262, a foam collection port 263 and a foam outflow port 264; the sealing cover 262 is sealed at the top opening of the tank body 261, and the tank body 261 and the sealing cover 262 are connected by a flange, and a rubber flange gasket is provided between the tank body 261 and the sealing cover 262; the tank body 261 is made of transparent acrylic material, and a scale is provided on the outside of the tank body 261 to facilitate reading the changes in the foam liquid level; the sealing cover 262 is made of stainless steel; the foam collection port 263 is arranged on the sealing cover 262, and the foam outflow port 264 is arranged at the bottom of the tank body 261.

[0060] The test joint 27 includes a four-way pipe fitting 271 and a fourth pressure valve 272. The four-way pipe fitting 271 is set on the sealing cover 262. The four joints of the four-way pipe fitting 271 are respectively connected to the inner cavity of the foam collection tank 26, the pressurizing device, the foam density measuring device and the foam liquid separation characteristic measuring device. The fourth pressure valve 272 is provided on the joint connected to the pressurizing device.

[0061] The present invention also discloses a method for testing a compressed air fire extinguishing system suitable for use in large-span UHV substations. Using the high-range, large-span compressed air foam fire extinguishing system test platform, the compressed air foam injection trajectory prediction program derivates a compressed air foam injection trajectory model. First, a force analysis is performed on the foam jet per unit mass as a microelement. The resulting horizontal and vertical velocities are then combined with Newton's second law to yield the following equations:

[0062]

[0063] in, is the mass of foam (kg), is the foam movement speed (m / s), is the characteristic time (s), is the air resistance (N), is the force balance correction coefficient equation, is the angle between the foam movement direction and the horizontal ground (°), is the acceleration due to gravity (m 2 / s).

[0064] The highest point of the foam injection trajectory is set as the limit point, and the foam injection trajectory is expressed as two parts: the ascending segment and the descending segment. The correction coefficient equations are constructed for each part, and the differential equation group is established. The differential equation of the ascending segment foam injection trajectory is:

[0065]

[0066] in, is the correction coefficient equation of the force balance in the ascending section, is the range (m), is the shooting height (m), is the length of the foam trajectory (m), is the correction coefficient for the ascending section.

[0067] Similarly, the differential equation of the foam injection trajectory in the descending section is:

[0068]

[0069] in, is the correction coefficient equation of the force balance in the ascending section, is the correction factor for the descending section.

[0070] Air resistance during foam spraying Effect, air resistance The calculation of is related to the solution of the differential equation of the foam injection trajectory. The air resistance equation is:

[0071]

[0072] in, is the air density (kg / m 3 ), is the cross-sectional area of ​​the foam element (m 2 ), is the air resistance coefficient.

[0073] The correction coefficient of the compressed air foam injection trajectory model includes the rising section correction coefficient , Cross-sectional area coefficient of rising section , correction coefficient of descending section and the cross-sectional area coefficient of the descending section The correction coefficient is substituted into the compressed air foam injection trajectory model to calculate the fit between the model and the experimental data. To iteratively solve.

[0074] The compressed air foam injection trajectory model uses the fourth-order Runge-Kutta method to solve the foam injection trajectory differential equations of the ascending and descending sections, which are expressed as follows:

[0075]

[0076] in, For prediction Shooting height (m), To find the time step, is the initial position slope, for Calculate the slope at the midpoint, for Calculate the slope at the midpoint, is the slope at the end position.

[0077] Goodness of fit The solution formula is:

[0078]

[0079] in, For experimental data Shooting height (m), is the average shot height of the experimental data (m).

[0080] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, it should be understood by those skilled in the art that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A compressed air fire extinguishing system test platform suitable for large-span conditions in ultra-high voltage substations, characterized by: Including compressed air foam injection system, foam injection situation prediction system and foam performance testing system; The compressed air foam injection system is used to generate compressed air foam and control experimental working conditions; The foam injection situation prediction system includes a video data collection device and a model calibration and prediction device. The video data collection device is used to collect video data of the entire foam injection process of the compressed air foam injection system. The model calibration and prediction device has a built-in data preprocessing program, a model hyperparameter calibration program and a compressed air foam injection trajectory prediction program. The data preprocessing program is used to process the video data collected by the video data collection device to obtain injection trajectory coordinate data; the model hyperparameter calibration program is used to calibrate the correction coefficient of the compressed air foam injection trajectory model based on the injection trajectory coordinate data obtained by the data preprocessing program; the compressed air foam injection trajectory prediction program is used to use the compressed air foam injection trajectory model based on the determined correction coefficient, input experimental operating condition parameters to perform model calculation, and complete the prediction of the injection situation of the compressed air foam system with a long range and a large span; The compressed air foam spraying system includes a first gas storage device, a first flow control device, a first gas pipeline, a liquid storage device, a gas-liquid pipeline, a second gas storage device, a second flow control device, a second gas pipeline, a gas-liquid premixing chamber, a foam delivery pipeline, a foam mixing cavity and a foam spraying pipe; the gas outlet of the first gas storage device is connected to the gas inlet of the liquid storage device through the first gas pipeline, and the foam outlet of the liquid storage device is connected to the gas-liquid inlet of the gas-liquid premixing chamber through the gas-liquid pipeline, and the first flow control device is used to control the gas-liquid flow rate entering the gas-liquid inlet of the gas-liquid premixing chamber; the gas outlet of the second gas storage device is connected to the gas inlet of the gas-liquid premixing chamber through the second gas pipeline, and the second flow control device is used to control the gas flow rate entering the gas inlet of the gas-liquid premixing chamber; the foam outlet of the gas-liquid premixing chamber is connected to the foam inlet of the foam mixing cavity, and the foam outlet of the foam mixing cavity is connected to the foam inlet of the foam spraying pipe through the foam delivery pipeline, and the foam spraying pipe is provided with a foam nozzle.

2. The compressed air fire extinguishing system test platform suitable for large-span conditions of ultra-high voltage substations according to claim 1 is characterized by: It also includes a foam performance testing system, which includes a foam collection tank, a test connector, a foam observation chamber, a microscope and a data processing device; the foam collection tank is capable of collecting the compressed air foam generated by the compressed air foam injection system, and the foam outflow outlet of the foam collection tank is connected to the foam observation chamber through a pipe; the test connector is arranged on the foam collection tank and can be respectively connected to an external pressurizing device, a foam density measuring device and a foam liquid separation characteristic measuring device; the microscope is used to observe the compressed air foam in the foam observation chamber, and the microscope is connected to the data processing device.

3. The compressed air fire extinguishing system test platform suitable for large-span conditions of UHV substations according to claim 2 is characterized by: The foam collection tank includes a tank body, a sealing cover, a foam collection port and a foam outflow port. The sealing cover seals the opening of the tank body, the foam collection port is arranged on the sealing cover, and the foam outflow port is arranged on the tank body; the test joint includes a four-way pipe fitting and a fourth pressure valve. The four-way pipe fitting is arranged on the sealing cover. The four joints of the four-way pipe fitting are respectively connected to the inner cavity of the foam collection tank, the pressurizing device, the foam density measuring device and the foam liquid separation characteristic measuring device, and the fourth pressure valve is provided on the joint connected to the pressurizing device.

4. The compressed air fire extinguishing system test platform suitable for large-span conditions of UHV substations according to claim 3 is characterized by: The tank body is made of a transparent material, and a scale is provided on the outside of the tank body.

5. The compressed air fire extinguishing system test platform suitable for large-span conditions of UHV substations according to claim 1 is characterized by: The first flow control device includes a first pressure valve and a first flow meter, the first gas pipeline is provided with a first pressure valve, and the gas-liquid pipeline is provided with a first flow meter; the second flow control device includes a second pressure valve and a second flow meter, and the second gas pipeline is provided with a second pressure valve and a second flow meter.

6. The compressed air fire extinguishing system test platform suitable for large-span conditions of UHV substations according to claim 1 is characterized by: The compressed air foam injection system further comprises a third valve and a third pressure valve, and the foam delivery pipeline is provided with the third valve and the third pressure valve.

7. The compressed air fire extinguishing system test platform suitable for large-span conditions of UHV substations according to claim 1 is characterized by: The compressed air foam spraying system also includes a support frame, a knob and an operating chamber. The foam spray pipe is fixedly connected to the inside of the operating chamber through the support frame. The foam spray pipe is installed on the support frame. The threaded knob passes through the side wall of the operating chamber and is threadedly connected to the support frame.

8. The compressed air fire extinguishing system test platform suitable for large-span conditions in ultra-high voltage substations according to claim 1 is characterized by: The data preprocessing program processes the video data collected by the video data collection device through the Python language. The specific processing flow is to divide the original video data into frames to obtain image data, grayscale and binarize the image data to obtain a jet trajectory contour map, and extract the jet trajectory coordinate data from the jet trajectory contour map and store it.

9. A method for testing a compressed air fire extinguishing system suitable for large-span conditions in ultra-high voltage substations, characterized in that: Using the compressed air fire extinguishing system test platform suitable for large-span conditions of ultra-high voltage substations according to any one of claims 1 to 8, the compressed air foam injection trajectory model derivation process of the compressed air foam injection trajectory prediction program first performs a force analysis based on the unit mass of the foam jet as a microelement, and the obtained velocities are horizontal velocity and vertical velocity, respectively. Combined with Newton's second law, the following equation group is obtained: in, For foam quality, is the foam movement speed, is the characteristic time, is the air resistance, is the force balance correction coefficient equation, is the angle between the foam movement direction and the horizontal ground, is the acceleration due to gravity; The highest point of the foam injection trajectory is set as the limit point, and the foam injection trajectory is expressed as two parts: the ascending segment and the descending segment. The correction coefficient equations are constructed for each part, and the differential equation group is established. The differential equation of the ascending segment foam injection trajectory is: in, is the correction coefficient equation of the force balance in the ascending section, For range, To shoot high, is the length of the foam trajectory, is the correction coefficient for the ascending section; Similarly, the differential equation of the foam injection trajectory in the descending section is: in, is the correction coefficient equation of the force balance in the ascending section, is the correction coefficient for the descending section; Air resistance during foam spraying The air resistance equation is: in, is the air density, is the cross-sectional area of ​​the foam element, is the air resistance coefficient; The correction coefficient of the compressed air foam injection trajectory model is substituted into the compressed air foam injection trajectory model to calculate the fit between the model and the experimental data. To iteratively solve; The compressed air foam injection trajectory model uses the fourth-order Runge-Kutta method to solve the foam injection trajectory differential equations of the ascending and descending sections, which are expressed as follows: in, For prediction Shoot high, To find the time step, is the initial position slope, for Calculate the slope at the midpoint, for Calculate the slope at the midpoint, is the slope of the end position; Goodness of fit The solution formula is: in, For experimental data Shoot high, is the average shot height of the experimental data.

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