Method and device for determining fire extinguishing agent concentration holding time

Abstract

The invention provides a method and device for determining the concentration maintaining time of a fire extinguishing agent, and belongs to the technical field of hydromechanics, the method comprises the following steps: step 1, calculating a normalized concentration value according to a critical concentration value C < 0% >, the ventilation quantity in unit time and unit area or / and the change multiple of the dose of the fire extinguishing agent in unit time and unit area; 2, calculating the variable quantity delta C% of the concentration; step 3, subtracting delta C% from all concentration values of which the concentrations are not less than the critical concentration value C0% in test data to obtain C3%; and step 4, acquiring the maintaining time T2 when the concentration of the plurality of fire extinguishing agent concentration sampling points is not less than C3%, wherein T2 is the maintaining time of the concentration of the fire extinguishing agent. The error of a theoretical analysis result is reduced to the minimum, and effective data support is provided for the design of a fire extinguishing system.

Description

Technical Field

[0001] The present invention belongs to the technical field of fluid mechanics, and particularly relates to a method and device for determining the maintenance time of a fire extinguishing agent concentration. Background Art

[0002] In order to cooperate with the design work of the helicopter power cabin fire extinguishing system, ground simulation tests are carried out to verify the filling amount of the fire extinguishing agent, the pipeline routing, the arrangement of the injection points, the shape of the nozzle, and the concentration distribution in the cabin after the fire extinguishing agent is ejected. In particular, the pipeline routing, the arrangement of the injection points, and the shape of the nozzle need to be optimized after being verified by ground simulation tests to obtain the optimal fire extinguishing pipeline system and pipeline layout. Usually, in the design stage, a large number of ground simulation tests of the power cabin fire extinguishing system are required, and test data support is provided for various modifications, optimizations, and key technology upgrades of specific helicopters in the future.

[0003] The ground simulation test of the fire extinguishing system is usually completed before the first flight, while the over-temperature of the power cabin usually occurs and can only be detected after the first flight. When the over-temperature phenomenon occurs in the power cabin, the common method is to increase the ventilation volume. The larger the ventilation volume of the power cabin, the more conducive it is to the cooling of the engine surface, but it is not conducive to fire extinguishing. A large ventilation volume is very likely to dilute and disperse the released fire extinguishing agent and cannot reach the required fire extinguishing concentration; on the contrary, a small ventilation volume is conducive to fire extinguishing but not conducive to the heat dissipation of the engine surface. When it is impossible to conduct a fire extinguishing test again after increasing the ventilation volume, it is necessary to re-evaluate the fire extinguishing efficiency of the fire extinguishing system, that is, it is necessary to determine the maintenance time of the fire extinguishing agent concentration. There are two existing ways to determine the maintenance time of the fire extinguishing agent concentration. One is to conduct test verification, and the other is theoretical analysis. The disadvantage of test verification is that the test cycle is long and the cost is high, but the verification is more effective; the disadvantage of theoretical analysis is that the error is relatively large (the actual result is several seconds more), but the cycle is short and the cost is low. Summary of the Invention

[0004] To solve the problems in the prior art that the test verification has a long test cycle and high cost, and the theoretical analysis has a large error, the present invention provides a method for determining the maintenance time of a fire extinguishing agent concentration based on ground simulation test data, which reduces the error of the theoretical analysis result to the minimum, provides effective data support for the design of the fire extinguishing system, and facilitates the designers of the fire extinguishing system to timely understand whether the system performance meets the fire extinguishing requirements during the design (such as the scheme design stage, the detailed design stage, and after the first flight test). The technical solution is as follows:

[0005] In a first aspect, a method for determining the maintenance time of a fire extinguishing agent concentration is provided, and the method includes:

[0006] Step 1: Calculate the normalized concentration value according to the critical concentration value C0%, the change multiple of the ventilation volume per unit time per unit area or / and the fire extinguishing agent dosage per unit time per unit area;

[0007] Step 2, calculate the concentration change ΔC%;

[0008] Step 3: Subtract ΔC% from all concentration values not less than the critical concentration value C0% in the test data to obtain C3%;

[0009] Step 4: Obtain the fire extinguishing agent concentration at multiple sampling points, and maintain the concentration at not less than C3% for a time T2, where T2 is the fire extinguishing agent concentration maintenance time.

[0010] Among them, the critical concentration value C0% is 6%.

[0011] In step 1, when the fire extinguishing agent dosage Q and the space V of the protected area (i.e., the net volume of the power cabin) remain unchanged, the ventilation volume is Q 风1 Become Q 风2 When the ventilation rate per unit area per unit time is changed by β1=Q 风2 / Q 风1 , then the normalized concentration value C2% = 6a / (6a+94aβ1)*100%, a is the coefficient after normalization;

[0012] or,

[0013] When the ventilation volume Q 风 The space V of the protected area (i.e. the net volume of the power compartment) remains unchanged, and the amount of fire extinguishing agent is Q 量1 Become Q 量2 When the fire extinguishing agent dosage per unit area per unit time is changed by multiples of β2 = Q 量2 / Q 量1 , then the normalized concentration value C2% = 6aβ2 / (6aβ2+94a)*100%;

[0014] or,

[0015] When the space V of the protected area (i.e. the net volume of the power cabin) remains unchanged, the amount of fire extinguishing agent is Q 量1 When it becomes Q 量2 , the ventilation volume is determined by Q 风1 Become Q 风2 When the ventilation rate per unit area per unit time is changed by β1=Q 风2 / Q 风1 , the change multiple of the fire extinguishing agent dosage per unit area per unit time β2=Q 量2 / Q 量1 , then the normalized concentration value C2% = 6aβ2 / (6aβ2+94aβ1)*100%.

[0016] In step 2, the concentration change ΔC%=(6-C2)% is calculated.

[0017] Among them, the starting moment of the simultaneous maintenance time T2 is the moment t1 corresponding to the latest intersection point of a fire extinguishing agent concentration curve and C3% in the ascending section of the fire extinguishing agent concentration curve, and the ending moment of the simultaneous maintenance time T2 is the moment t2 corresponding to the earliest intersection point of a fire extinguishing agent concentration curve and C3% in the descending section of the fire extinguishing agent concentration curve.

[0018] Furthermore, after step 4, the method further includes: correcting the simultaneous maintenance time T2 to improve the accuracy of the calculation result:

[0019] When the fire extinguishing agent dosage Q and the space V of the protected area (i.e., the net volume of the power cabin) remain unchanged, and the ventilation volume changes from Q 风1 to Q 风2 [[ID=!0]]at this time, using the change multiple β1 of the ventilation volume per unit time and per unit area = Q 风2 / Q 风1 to calculate the corrected value T2' of the simultaneous maintenance time T2 = T2 - β1 * K1 + K2;

[0020] Or,

[0021] When the ventilation volume Q 风 and the space V of the protected area (i.e., the net volume of the power cabin) remain unchanged, and the fire extinguishing agent dosage changes from Q 量1 to Q 量2 at this time, the change multiple

[0022] β2 of the fire extinguishing agent dosage per unit time and per unit area = Q 量2 / Q 量1 to calculate the corrected value T2' of the simultaneous maintenance time T2 = T2 - K1 + β2 * K2;

[0023] Or,

[0024] When the space V of the protected area (i.e., the net volume of the power cabin) remains unchanged, and the fire extinguishing agent dosage changes from Q 量1 to Q 量2 at this time, and the ventilation volume changes from Q 风1 [[ID=!5]]to Q 风2 at this time, the change multiple of the ventilation volume per unit time and per unit area is β1 = Q 风2 / Q 风1 and the change multiple of the fire extinguishing agent dosage per unit time and per unit area is β2 = Q 量2 / Q 量1 to calculate the corrected value T2' of the simultaneous maintenance time T2 = T2 - β1 * K1 + β 2* K2;

[0025] Among them, the units of T2' and T2 are seconds, K1 is the ventilation volume influence factor, K2 is the fire extinguishing agent dosage influence factor, K1 and K2 are empirical values obtained based on a large amount of test data, the value range of K1 is 0.5 - 1.1, and the value range of K2 is 0 - 0.5.

[0026] In a second aspect, a device for determining the maintenance time of the fire extinguishing agent concentration is provided, including:

[0027] A determination module, configured to:

[0028] Calculate the normalized concentration value according to the change multiple of the ventilation volume per unit time per unit area;

[0029] Calculate the change amount ΔC% of the concentration;

[0030] Subtract ΔC% from all concentration values not less than the critical concentration value C0% in the test data;

[0031] An acquisition module, configured to acquire the simultaneous maintenance time T2 when the concentrations at multiple fire extinguishing agent concentration sampling points are not less than (C0 - ΔC)%, and T2 is the maintenance time of the fire extinguishing agent concentration.

[0032] In a third aspect, a device for determining the maintenance time of the fire extinguishing agent concentration is provided, including a processor and a memory, the processor is configured to execute instructions stored in the memory, and the processor realizes any one of the methods for determining the maintenance time of the fire extinguishing agent concentration in the first aspect by executing the instructions.

[0033] In a fourth aspect, a computer-readable storage medium is provided, in which instructions are stored, and when the instructions run on a processing component of a computer, the processing component is enabled to execute any one of the methods for determining the maintenance time of the fire extinguishing agent concentration in the first aspect.

[0034] In a fifth aspect, a computer program product including instructions is provided, and when the computer program product runs on a computer, the computer is enabled to execute any one of the methods for determining the maintenance time of the fire extinguishing agent concentration in the first aspect.

[0035] The beneficial effects of the present invention are at least as follows:

[0036] The method for determining the maintenance time of the fire extinguishing agent concentration based on ground simulation test data provided by the present invention reduces the error of the theoretical analysis result to the minimum, provides effective data support for the design of the fire extinguishing system, and facilitates the designers of the fire extinguishing system to timely understand whether the system performance meets the fire extinguishing requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a block diagram of the composition of the ground simulation test system for the fire extinguishing system;

[0038] Figure 2 It is a schematic diagram of the fire extinguishing agent concentration curve. Specific embodiments

[0039] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0040] The features and illustrative embodiments of various aspects of the present invention will be described in detail below. In the following detailed description, many specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced without some of these specific details. The following description of the embodiments is only provided to better understand the present invention by showing examples of the present invention. The present invention is in no way limited to any specific arrangements and methods set forth below, but covers any improvements, substitutions and modifications of structures, methods and devices without departing from the spirit of the present invention. Well-known structures and technologies are not shown in the drawings and the following description to avoid unnecessarily obscuring the present invention.

[0041] It should be noted that, without conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other, and the various embodiments may refer to and cite each other.

[0042] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0043] Please refer to Figure 1 , the ground simulation test system for power cabin fire extinguishing consists of the test article 1 (including the fire extinguisher and its pipeline assembly), the companion article 2 (including the engine, engine compartment, exhaust tail nozzle, pipelines, etc.), the flight ventilation volume simulation system 3 (including control valves, fans, pipelines, etc.), and the test system 4 (including the professional fire extinguishing agent concentration measurement system, various sensors, etc.). The test article consists of a fire extinguisher (including fire extinguishing agent), a fire extinguishing pipeline assembly, etc.; the companion article consists of an engine compartment, an engine, an exhaust system, etc.; the test system consists of a dedicated fire extinguishing agent concentration measurement system and various sensors; the flight ventilation volume simulation system consists of a wind volume control valve, an air duct, and a flow sensor.

[0044] During the ground test of the power cabin fire extinguishing system, the ventilation volume in the engine cabin is simulated by the flight ventilation volume simulation system. When the ventilation volume is stabilized at a given value, the electric initiator on the fire extinguisher is detonated. The fire extinguisher sprays the fire extinguishing agent into the power cabin through the fire extinguishing pipeline assembly, and at the same time, the change of the fire extinguishing agent concentration at each measurement point in the power cabin with time is measured by the special fire extinguishing agent concentration measurement system. The simulation of the critical airflow condition during flight is mainly to first obtain the ventilation volume value in the ground simulation test through simulation calculation, and then realize the numerical value of the ventilation volume through the flight ventilation volume simulation system.

[0045] In Embodiment 1, the ventilation volume is changed (increased or decreased) while the fire extinguishing agent dosage remains unchanged. The specific implementation steps of the present invention are as follows:

[0046] S101: It is known that the ventilation volume during the ground simulation test of the power cabin is Q 风1 kg / s, and the test data result is that the concentrations of 12 fire extinguishing agent concentration sampling points are not less than 6% and the maintenance time is T 维 seconds. What is measured in the test is the volume concentration of halon 1301 fire extinguishing agent in the mixed gas (halon 1301 fire extinguishing agent and air) in the power cabin, and the critical concentration value is 6%.

[0047] S102: The volume concentration of the mixed gas

[0048] It can be known from the definition of the volume concentration C of the mixed gas that:

[0049] C = V1 / (V1 + V2) —— (1)

[0050] V1 is the volume of the fire extinguishing agent, and V2 is the volume of air;

[0051] According to the gas equation for normalization, when the volume concentration is 6%, it can be expressed as:

[0052] 6% = 6a / (6a + 94a) * 100%, where a is the coefficient after normalization;

[0053] S103: When the fire extinguishing agent dosage Q and the space V of the protected area (i.e., the net volume of the power cabin) remain unchanged, and the ventilation volume changes from Q 风1 to Q 风2 [[ID=3)5]]the change multiple of the ventilation volume per unit time and per unit area is β1

[0054] (β1 = Q 风2 / Q 风1 ), then referring to S102, the concentration value C2 is:

[0055] C2% = 6a / (6a + 94aβ1) * 100%

[0056] S104: Calculate the change amount ΔC of the concentration;

[0057] ΔC = (6 - C2)%;

[0058] S105: Subtract ΔC from all concentration values not less than 6% in the test data to obtain C3%;

[0059] S106: Determine the simultaneous maintenance time T2 when the concentrations at 12 fire extinguishing agent concentration sampling points are not less than C3%, that is, (6 - ΔC)%;

[0060] The starting moment of the simultaneous maintenance time T2 is the moment t1 corresponding to the latest intersection point of a fire extinguishing agent concentration curve and C3%, and the ending moment of the simultaneous maintenance time T2 is the moment t2 corresponding to the earliest intersection point of a fire extinguishing agent concentration curve and C3%. See Figure 2 .

[0061] S107: Correct T2: T2' = T2 - β1 * K1 + K2 (seconds);

[0062] K1 is the ventilation volume influence factor, K2 is the fire extinguishing agent dosage influence factor. K1 and K2 are empirical values obtained based on a large amount of test data. The range of K1 is 0.5 - 1.1, and the range of K2 is 0 - 0.5.

[0063] Correcting T2 can further improve the accuracy of the calculation result.

[0064] In Example 2, change (increase or decrease) the ventilation volume while keeping the fire extinguishing agent dosage unchanged. The specific implementation steps of the present invention are as follows:

[0065] S101: It is known that the ventilation volume during the power cabin test in the ground simulation test is Q 风1 kg / s, and the test data result is that the simultaneous maintenance time for the concentrations at 12 fire extinguishing agent concentration sampling points not less than 6% is T 维 seconds. What is measured in the test is the volume concentration of halon 1301 fire extinguishing agent in the mixed gas (halon 1301 fire extinguishing agent and air) in the power cabin, and the critical concentration value is 6%.

[0066] S102: Mixed gas volume concentration

[0067] It can be known from the definition of the mixed gas volume concentration C that:

[0068] C = V1 / (V1 + V2) —— (1)

[0069] V1 is the volume of the fire extinguishing agent, and V2 is the volume of air;

[0070] According to the gas equation for normalization, when the volume concentration is 6%, it can be expressed as:

[0071] [[ID=

[0072] S103: When the ventilation volume Q 风 and the space V of the protected area (i.e., the net volume of the power cabin) remain unchanged, and the fire extinguishing agent dosage changes from Q 量1 to Q 量2 , the change multiple of the fire extinguishing agent dosage per unit time and per unit area is β2. Then, referring to S102, the concentration value C2 is:

[0073] C2% = 6aβ2 / (6aβ2 + 94a) * 100%

[0074] S104: Calculate the change in concentration ΔC:

[0075] ΔC = (6 - C2)%;

[0076] S105: Subtract ΔC from all concentration values not less than 6% in the test data to obtain C3%;

[0077] S106: Calculate the simultaneous maintenance time T2 when the concentrations at 12 fire extinguishing agent concentration sampling points are not less than C3%, that is, (6 - ΔC)%;

[0078] The start time of the simultaneous maintenance time T2 is the time t1 corresponding to the latest intersection point of a fire extinguishing agent concentration curve and C3% in the rising section of the fire extinguishing agent concentration curve, and the end time of the simultaneous maintenance time T2 is the time t2 corresponding to the earliest intersection point of a fire extinguishing agent concentration curve and C3% in the falling section of the fire extinguishing agent concentration curve. See Figure 2 .

[0079] S107: Correct T2:

[0080] T2' = T2 - K1 + K2β2 (seconds);

[0081] K1 is the ventilation volume influence factor, K2 is the fire extinguishing agent dosage influence factor. K1 and K2 are empirical values obtained based on a large amount of test data. The range of K1 is 0.5 - 1.1, and the range of K2 is 0 - 0.5.

[0082] In Embodiment 3, while changing (increasing or decreasing) the ventilation volume and the fire extinguishing agent dosage simultaneously, the specific implementation steps of the present invention are as follows:

[0083] S101: It is known that during the ground simulation test, the ventilation volume during the power cabin test is Q 风1 kg / s, and the test data result is that the simultaneous maintenance time of the concentrations at 12 fire extinguishing agent concentration sampling points not less than 6% is T 维 seconds. What is measured in the test is the volume concentration of the halon 1301 fire extinguishing agent in the mixed gas (halon 1301 fire extinguishing agent and air) in the power cabin, and the critical concentration value is 6%.

[0084] S102: Volume Concentration of Mixed Gas

[0085] As can be seen from the definition of the volume concentration C of the mixed gas:

[0086] C = V1 / (V1 + V2) —— (1)

[0087] V1 is the volume of the fire extinguishing agent, and V2 is the volume of air;

[0088] According to the gas equation for normalization, when the volume concentration is 6%, it can be expressed as

[0089] 6% = 6a / (6a + 94a) * 100%, where a is the coefficient after normalization;

[0090] S103: When the space V (i.e., the net volume of the power cabin) of the protected area remains unchanged and the ventilation volume changes from Q 风1 to Q 风2 , the change multiple of the ventilation volume per unit time per unit area is β1 (β1 = Q 风2 / Q 风1 ); when the fire extinguishing agent dosage changes from Q 量1 to Q 量2 , the change multiple β2 of the fire extinguishing agent dosage per unit time per unit area; then referring to S102, the concentration value C2 is:

[0091] C2% = 6aβ2 / (6aβ2 + 94aβ1) * 100%,

[0092] S104: Calculate the change amount ΔC of the concentration:

[0093] ΔC = (6 - C2)%;

[0094] S105: Subtract ΔC from all concentration values not less than 6% in the test data to obtain C3%;

[0095] S106: Obtain the holding time T2 when the concentrations of 12 fire extinguishing agent concentration sampling points are not less than C3% (i.e., (6 - ΔC)%)

[0096] The starting moment of the holding time T2 is the moment t1 corresponding to the latest intersection point of a fire extinguishing agent concentration curve and C3% in the rising section of the fire extinguishing agent concentration curve, and the ending moment of the holding time T2 is the moment t2 corresponding to the earliest intersection point of a fire extinguishing agent concentration curve and C3% in the falling section of the fire extinguishing agent concentration curve. See Figure 2 .

[0097] S107: Correct T2:

[0098] T2' = T2 - K1β1 + K2β2 (seconds);

[0099] K1 is the ventilation volume influence factor, and K2 is the fire extinguishing agent dosage influence factor. K1 and K2 are empirical values obtained based on a large amount of test data. The range of K1 is 0.5 - 1.1, and the range of K2 is 0 - 0.5.

[0100] a) Use the above-mentioned Example 1 to calculate and give an example with the serial number 2 in Table 1:

[0101] β1 = 0.78 / 0.63 = 1.24;

[0102] From the test data, T2 = 2.176 (s) can be obtained;

[0103] After correction, T2’ = 2.176 - 0.88 * 1.24 + 0.42 = 1.5048 (s).

[0104] b) Use the above-mentioned Example 2 to calculate and give an example with the serial number 5 in Table 1:

[0105] β2 = 1.5 / 1.2 = 1.25;

[0106] From the test data, T2 = 2.073 (s) can be obtained;

[0107] After correction, T2’ = 2.073 - 0.95 + 0.11 * 1.25 = 1.2605.

[0108] c) Use the above-mentioned Example 3 to calculate and give an example with the serial number 6 in Table 1:

[0109] β1 = 0.52 / 0.32 = 1.625, β2 = 1.2 / 1.5 = 0.8;

[0110] From the test data, T2 = 1.555 (s) can be obtained;

[0111] After correction, T2’ = 1.555 - 0.53 * 1.625 + 0.21 * 0.8 = 0.7818.

[0112] Table 1 Calculation of the holding time of the present invention

[0113]

[0114] The error in Table 1 is the difference between the measured holding time T 维 and the calculated holding time T2’ of the present invention. It can be seen from Table 1 that:

[0115] 1. The error of the present invention is less than 0.7 s, and the error of the theoretical analysis is greater than 1 s;

[0116] 2. The result calculated by the present invention is smaller than the actual measured value. If the time value calculated by the present invention meets the requirement of the maintenance time, it means that the design of the fire extinguishing system meets the fire extinguishing requirement and no modification is needed. If the time value calculated by the present invention does not meet the requirement of the maintenance time, it is recommended to modify the design of the fire extinguishing system. The result of the theoretical analysis is larger than the actual measured value, and it cannot be determined whether the fire extinguishing system meets the fire extinguishing requirement based on this analysis result. Other factors need to be further considered comprehensively for weighing. It can be seen that the present invention has better effects than the theoretical analysis.

[0117] The embodiment of the present invention further provides a device for determining the maintenance time of the fire extinguishing agent concentration, including:

[0118] A determination module, configured to:

[0119] Calculate the normalized concentration value according to the change multiple of the ventilation volume per unit time and per unit area;

[0120] Calculate the change amount ΔC% of the concentration;

[0121] Subtract ΔC% from all concentration values not less than the critical concentration value C0% in the test data;

[0122] An acquisition module, configured to acquire the simultaneous maintenance time T2 when the concentrations of multiple fire extinguishing agent concentration sampling points are not less than (C0 - ΔC)%, and T2 is the maintenance time of the fire extinguishing agent concentration.

[0123] The specific execution processes of each module can refer to the specific processes of the relevant steps of the above method, and will not be elaborated here.

[0124] The present invention can be applied to the system design of the halon fire extinguishing system or the situation where the ventilation volume increases after the first flight. This method enables engineering and technical personnel to master whether the fire extinguishing system can meet the fire extinguishing requirement. For example, after the ground simulation test of the fire extinguishing system is completed based on a certain ventilation volume and the ventilation volume changes due to other factors, this method can be used to obtain the simultaneous maintenance time when the concentrations of 12 fire extinguishing agent concentration sampling points are not less than 6%. It can be seen that this method has the advantages of improving the system design efficiency, being beneficial to environmental protection (halon fire extinguishing agents seriously damage the ozone layer, and halon fire extinguishing agents with a certain concentration have certain toxicity. The Montreal Protocol stipulates that such items must be stopped from being used), saving the system development cost, etc.

[0125] The above only expresses the implementation manners of the present invention, and the description is relatively specific and detailed, but it cannot be understood as a limitation to the scope of the patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can be made, and these all belong to the protection scope of the present invention. In addition, the parts not elaborated in the present invention are all conventional technologies.

Claims

1. A method for determining the maintenance time of a fire extinguishing agent concentration, characterized in that, The method includes: Step 1: Calculate the normalized concentration value according to the critical concentration value C0%, the change multiple of the ventilation volume per unit time per unit area or / and the extinguishing agent dosage per unit time per unit area; Step 2: Calculate the change amount of concentration ΔC%; Step 3: Subtract ΔC% from all concentration values not less than the critical concentration value C0% in the test data to obtain C3%; Step 4: Obtain the simultaneous maintenance time T2 when the concentrations of multiple extinguishing agent concentration sampling points are not less than C3%, and T2 is the extinguishing agent concentration maintenance time.

2. The method according to claim 1, characterized in that, The critical concentration value C0% is 6%.

3. The method according to claim 2, wherein In Step 1, when the fire extinguishing agent dosage Q and the space V of the protected area remain unchanged, and the ventilation volume changes from Q 风1 to Q 风2 , the change multiple of the ventilation volume per unit time and per unit area is β1 = Q 风2 / Q 风1 , then The normalized concentration value C2% = 6a / (6a + 94aβ1) * 100%, where a is the coefficient after normalization; Or, When the ventilation volume Q 风 and the space V of the protected area remain unchanged, the fire extinguishing agent dosage changes from Q 量1 to Q 量2 . The change multiple of the fire extinguishing agent dosage per unit area per unit time is β2 = Q 量2 / Q 量1 . Then the normalized concentration value C2% = 6aβ2 / (6aβ2 + 94a) * 100%; Or, When the space V of the protected area remains unchanged and the fire extinguishing agent dosage changes from Q 量1 to Q 量2 , and the ventilation rate changes from Q 风1 to Q 风2 , the change multiple of the ventilation rate per unit time and per unit area is β1 = Q 风2 / Q 风1 , and the change multiple of the fire extinguishing agent dosage per unit time and per unit area is β2 = Q 量2 / Q 量1 , then the normalized concentration value C2% = 6aβ2 / (6aβ2 + 94aβ1) * 100%.

4. The method according to claim 3, wherein In Step 2, calculate the change amount of concentration ΔC% = (6 - C2)%.

5. The method according to claim 1, wherein The starting moment of the simultaneous maintenance time T2 is the moment t1 corresponding to the latest intersection point of an extinguishing agent concentration curve and C3% in the rising section of the extinguishing agent concentration curve, and the ending moment of the simultaneous maintenance time T2 is the moment t2 corresponding to the earliest intersection point of an extinguishing agent concentration curve and C3% in the falling section of the extinguishing agent concentration curve.

6. The method according to claim 1, wherein After Step 4, the method further includes: correcting the simultaneous maintenance time T2: When the fire extinguishing agent dosage Q and the space V of the protected area remain unchanged, and the ventilation volume changes from Q 风1 to Q 风2 at this time, using the change multiple β1 of the ventilation volume per unit area per unit time, β1 = Q 风2 / Q 风1 , calculate the corrected value T2' of the simultaneous maintenance time T2 = T2 - β1 * K1 + K2; Or, When the ventilation volume Q 风 and the space V of the protected area remain unchanged, and the fire extinguishing agent dose changes from Q 量1 to Q 量2 , the change multiple of the fire extinguishing agent dose per unit area per unit time is β2 = Q 量2 / Q 量1 . Calculate the corrected value T2’ of the simultaneous maintenance time T2 = T2 - K1 + β2 * K2; Or, When the space V of the protected area remains unchanged and the fire extinguishing agent dosage changes from Q 量1 to Q 量2 , and the ventilation volume changes from Q 风1 to Q 风2 , the change multiple of the ventilation volume per unit time and per unit area is β1 = Q 风2 / Q 风1 , and the change multiple of the fire extinguishing agent dosage per unit time and per unit area is β2 = Q 量2 / Q 量1 , calculate the corrected value T2' of the simultaneous maintenance time T2 = T2 - β1 * K1 + β 2* K2; Wherein, the units of T2' and T2 are seconds, K1 is the ventilation volume influence factor, K2 is the extinguishing agent dosage influence factor, the value range of K1 is 0.5 to 1.1, and the value range of K2 is 0 to 0.

5.

7. An apparatus for determining the maintenance time of a fire extinguishing agent concentration, characterized in that, It includes: A determination module, configured to: Calculate the normalized concentration value according to the change multiple of the ventilation volume per unit time per unit area; Calculate the change amount of concentration ΔC%; Subtract ΔC% from all concentration values not less than the critical concentration value C0% in the test data; An acquisition module, configured to acquire the simultaneous maintenance time T2 when the concentrations of multiple extinguishing agent concentration sampling points are not less than (C0 - ΔC)%, and T2 is the extinguishing agent concentration maintenance time.

8. An apparatus for determining the maintenance time of a fire extinguishing agent concentration, characterized in that, It includes: A processor and a memory, the processor is configured to execute the instructions stored in the memory, and the processor realizes the method for determining the extinguishing agent concentration maintenance time according to any one of claims 1 to 7 by executing the instructions.

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