Study On Characteristics Of Self-rotating Spray With Pre-mixed Compressed Air And Water For Extinguishing Fires

After halon fire extinguishing agent was banned,water mist fire extinguishing technology began to be applied in engineering.At present,more water mist fire extinguishing technologies are used,such as high-pressure water mist,two phase flow water mist and water mist with additives.This paper analyzes and summarizes existing water mist fire extinguishing methods,and designs a premixed compressed air and water mist extinguisher.The experimental platform was built to study the atomization and extinguishing characteristics of the premixed self-rotating spray.The numerical simulation was used to verify spray atomization performance and fire extinguishing effectiveness.The atomization and fire suppression mechanism of premixed self-rotating mist is also summarized.In the atomization performance experiment,the atomization performance of different mixers,different nozzles and different rod angles were tested by particle size analyzer,include droplet size,effective range,effective radius of spray and uniformity of fog field.The optimum structure parameters of spray system and the ratio of water flow and gas flow rate were determined.The influence of water flow rate and gas flow rate on atomization performance was analyzed,and the best spray parameters were determined.Compared with the high pressure water spray,the spray performance is better than that of high pressure water spray.In the numerical simulation,a three-dimensional cone nozzle model was firstly established by using computational fluid dynamics software FLUENT19.0.Comparison of atomization effects of two spray methods,results show that the pre-mixed compressed air and water spray is superior to high-pressure water spray in particle size and velocity distribution,and is consistent with the spray performance test.Secondly,a fire extinguishing model is built by FDS.According to the FLUENT results,the atomization parameters of the two spray modes are set up to observe the extinguishing effect.The results show that the pre-mixed compressed air and water spray is faster than the high-pressure water mist.Finally,the flame is extinguished at different distances by spray.The simulation results show that spray can effectively extinguish fire in the range of 2.5m.When placed 2.2m,the greater the radial distance,the worse the fire extinguishing effect.In the standard confined space,a self-rotating spray with pre-mixed compressed air and water extinguishing gasoline flame experiment was conducted.When the nozzle aperture is 3mm,the best extinguishing effect is.When the water flow increases,the fire extinguishing time first decreases and then increases.When the water flow is 9L/min,the fire extinguishing time is the shortest.Compared with the same water flow of high pressure water spray,the pre-mixed compressed air and water spray extinguished the flame rapidly and the scope of fire extinguishing was larger.The results are in agreement with the numerical study,which verifies the effectiveness of self-rotating mist with pre-mixed compressed air and water fire extinguishing.Through the above research,results show that self-rotating spray with pre-mixed compressed air and water It has high fire extinguishing efficiency.The device has simple structure and low cost,and is suitable for practical engineering application in fire-fighting.