| Fire is an extremely destructive and serious threat to people’s lives,health and property safety.In view of the shortcomings of traditional fire extinguishers,this paper uses acoustic waves to extinguish fires,and uses the acoustic fire extinguishing experimental platform built independently to experiment with the waveform,frequency,sound pressure level and arrangement of the device and other parameters,and mainly comes to the following conclusions:(1)Combined with the theory to design the acoustic fire extinguishing device required for the experiment,including power amplifier,loudspeaker and sound cavity.According to the experimental needs,the TDA7498 amplifier circuit with a rated power of 100 W is selected,and the speaker with a rated power of 60 W is selected to meet the amplifier parameters,and two types of sound cavities,cylindrical and tapering,are designed for the subsequent experiments.(2)Using a self-designed acoustic fire extinguishing device,candles were selected as the experimental fuel to conduct comparative experiments on three cases: no acoustic cavity,cylindrical acoustic cavity and tapering acoustic cavity.The effect of the flame affected by sound waves when the device uses different shapes of acoustic cavities is studied through the variation of the flame,and the shape of the acoustic cavity applicable to this device is selected based on the experimental results.The experimental results show that the fire extinguishing effect of the tapering-shaped acoustic cavity is significantly better than others,and the fire extinguishing effect of the device is related to the shape of the acoustic cavity.(3)Using the optimal acoustic cavity asymptotic cavity derived from the previous sequence of experiments,the fire extinguishing times of three waveforms,sine,square and triangle,at different frequencies are investigated separately.Observing the experimental data,it can be seen that the fire extinguishing time of each waveform shows a trend of first decreasing and then increasing,and the shortest time of fire extinguishing occurs at 40 Hz.Non-linear fitting of the experimental data,according to the change in slope of the curve to derive a better fire extinguishing effect of sine waves for 40～80 Hz,square waves for 30～70 Hz,triangle waves for 40～60 Hz,subsequent experiments using only the better fire extinguishing effect of the frequency to study.(4)The range of sound pressure level at the time of the experiment is 90 to 102 d B,the same frequency of sound waves in the sound pressure level is lower when the fire fighting effect is poor,with the increase in sound pressure level,the fire fighting time gradually reduced.The best angle of sine wave is 60°,and it only takes 0.064 s to extinguish the flame at 45 Hz;the best angle of square wave is 60°,and the extinguishing time is the same at 40 Hz and 45 Hz,which is 0.092 s;the best angle of triangle wave is 90°,and it only takes 0.094 s to extinguish the flame at 45 Hz.Under the same conditions,changing the angle of the device has a significant effect on the fire extinguishing time,and the fire extinguishing time is first reduced and then increased after changing the angle.When the sound pressure level is 102 d B,the fire extinguishing effect is improved by 14.7% for sine wave 60° compared to 90°,73.1%for square wave 60° compared to 30°,and 97.5% for triangle wave 90° compared to 30°.The best fire extinguishing parameters of this device were obtained: sine wave,60o,45 Hz,102 d B.The experimental results of the sine wave 60° were fitted nonlinearly to obtain the coupling relationship between fire extinguishing time and sound pressure level and frequency.This paper uses the independent design of acoustic fire extinguishing device to conduct experiments to explore the factors that affect the effectiveness of the device to extinguish the fire,and finally came up with the best fire extinguishing parameters applicable to this device,which provides data support for the subsequent research on acoustic fire extinguishing technology. |
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