Theoretical Analysis of Atomization and Fire Extinguishing Experimental Research on Swirling Water Mist Nozzles with Straight
|School||Southwest Jiaotong University|
|Course||Heating for the gas ventilation and air conditioning engineering|
|Keywords||Swirl nozzle Atomization Structural optimization Numerical Simulation|
Restricted and facing elimination as the halon fire extinguishing agent, water mist fire suppression technology for its environmental pollution, the fire quickly, low water consumption, to demonstrate the broad application prospects the protective objects destructive small, has become fire science frontier research focus. Now use domestic water mist fire extinguishing system, the system pressure is mostly high-pressure areas, due to the complex structure of high-pressure systems, project cost, has a serious impact on the promotion and application of water mist fire suppression technology. Atomizing nozzle is one of the core components of the system in a variety of water mist fire extinguishing system,, nozzle atomization performance will directly affect the designed fire extinguishing system can meet the requirements of different the extinguishing occasions use. Currently, most of the domestic development of high-pressure atomization nozzle structure complex operating parameters are more difficult to control. Therefore, the development of a small size, light weight, simple structure, processing, easy installation, better atomized within the range of medium and low voltage single-phase water mist nozzles, water mist fire suppression technology popularization and application in China significance. Fire science research in the country, there is no the nozzle structures - atomization mechanism - fog field parameters - extinguishing effect as a systems engineering to conduct research, the study by a large number of experiments to obtain first-hand information, and in turn the nozzle structure, fog Mechanism fog field parameters, extinguishing effect relationship between depth discussions, the completion of the research work and major achievements are as follows: one of the topics in the course of the study, the first to design a novel structure, the low pressure spin flow atomizing nozzle, and then using the theoretical studies, numerical simulation, and experimental verification of the method and to optimize its structure parameters. Of the relationship between the parameters of nozzle structure and atomization characteristics corresponding theoretical model by means of FLUENT software the nozzle external flow field numerical simulation to study the nozzle structural parameters of the atomization performance, for the parameter optimization provide a theoretical basis. 2 from the droplet in the air by the force of movement analyzes create droplet motion equations. For typical droplet diameter and different export droplet initial velocity movement of the numerical calculation, draw a basic law of motion of the water mist, determine the terminal velocity and the boundaries of the square of the linear relationship between the diameter of the droplet diameter 80μm. 3. Cold atomization nozzle on the basis of numerical simulation, test and verify the simulation results. The results show that, straight-through design optimized low pressure single fluid swirl atomizing nozzle atomization, firefighting many occasions can completely replace the existing high-pressure atomization nozzle and two-phase flow atomizing nozzle, can be greatly reduced. The water mist system initial investment, but also to make the operation of the system security can be improved. 4 to carry out the simulation study and numerical simulation of water mist in the external airflow disturbance under fire extinguishing effect. Water mist fire extinguishing outside romantic role models, and verified, the results showed that the water mist in the wind speed of no wind and disturbance can fire out, the critical wind speed can not put the fire out. (5) Establish a test platform, to carry out a water mist off the restricted space kerosene pool fire test study, the effects of ventilation, the extinguishing time of the precombustion time and work pressure and other factors, draw burning pool fire confined space flame the core reaction zone, the ventilation control area and the fuel control area. Through trial and qualitative analysis of the water mist oil pool fire extinguished Confined Space dominant mechanism for gas cooling and flame cooling verified through test the indoor fire extinguished analysis model fire extinguished theory, critical water flow calculations underlying assumptions of the model, etc. correctness.