Research On Detonation Performance Based On Powder-assisted Explosion Scheme

In recent years,pulse detonation technology has been widely used in industrial production.Because of the strong shock,fast chemical reaction and very stable propagation process of detonation wave.It can be used in pulse engine,nano material preparation,explosion spraying and boiler descaling.The main operation methods of obtaining detonation wave are direct initiation and indirect initiation.Direct initiation requires a huge amount of ignition energy which needs thousands to millions of joules.Such a large ignition energy is impractical for multiple pulse detonation test.It is necessary to find a suitable method to effectively initiate.In addition,metal dust explosion accidents in factories and dust chain explosion accidents in university laboratories often occur.Dust explosion has always been an important factor endangering the safety of production.Study on the explosion characteristics of dust and the detonation effect of mixture of combustible gas and dust.It is very important for the utilization of explosion energy and accident prevention.This paper focuses on the study of the initiation effect of gaseous detonation dust and the experimental measurement of gas-solid two-phase mixed explosion.This paper mainly discusses the following aspects:(1)This paper expounds the combustion mechanism of combustible dust explosion and the limitation of gas phase initiation.Besides,it includes the combustion and explosion characteristics of two-phase mixture in explosion.Analyzes and introduces the C-J detonation theory.Summarizes the common detonation initiation modes and characteristics.(2)A complete set of powder assisted explosion experiment system is set up.A 17 L experiment main device which can be used for gas phase / gas-powder two-phase combustion explosion is designed.The improvement design of powder spraying system and the test of powder spraying effect.In addition,the parameters and working principle of each experiment equipment are introduced in detail.(3)Simulating the process of acetylene gas explosion in different equivalence ratio under premixed condition with FLUENT software.It Compares with the experimental parameters.The error of comprehensive experimental factors is about 14.1%,which is in good agreement with each other.In addition,the time of premixing was measured.When the time of premixing reaches 40 minutes,it can be considered as complete premixing.The results show that the explosion pressure of the non premixed acetylene gas increases firstly.Then it stays at the same level with the increase of the concentration.In addition,the maximum pressure rise rate increases first and then decreases in numerical value.The explosion pressure of acetylene is almost unaffected and the maximum pressure rise rate decreases under the initial pressures of 25kpa,50k Pa and 75kpa Trend.(4)The principle of gas-solid two-phase explosion is analyzed and introduced.The comparison experiment of two kinds of powder spraying methods is carried out when premixed / non premixed.The results show that the change of powder spraying mode has little effect on the parameter explosion.Under the mode of non premixed,the effect of different initial pressure dust is mainly reflected in the middle area of the container when the top injected.The effect is mainly reflected in the middle and bottom area when the bottom injected.Besides,The effects of different particle size of carbon powder and dust concentration on the detonation performance were studied.Under certain conditions,nano carbon powder has a good detonation aid performance.When the dust concentration is 60 mg/L and90 mg/L,the acetylene gas with volume fraction of 8.00 vol.% and 12.00 vol.% can achieve detonation state.With the increase of dust concentration and combustible gas concentration,the detonation characteristics will be improved.