Experimental Study On Supression Of Nitrogen Injection To Methane Air Explosion

This thesis to investigate the suppression effect of inert N₂ on gas explosion in medium scale detonation tube.The pressure of detonation tube is tested by new equipment such as pressure and flame test system,transient spectrometer,super-high velocity speckle shadow and so on.The purpose is to acquire flame data,free radical and shock image acquisition.The works are summarizd as follows:（1）To improved pressure and flame data acquisition system,improved vacuum system.Increasing the channel of pressure sensor,designing synchronous control device,using silicon controlled controller to synchronize control of pressure and using Donghua digital data acquisition,the data acquisition can be sustained and the success of data acquisition is increased.（2）These pairs concentration are,M₁（9.5%CH₄--18.5%O₂--72%N₂）,M₂（10.5%CH₄--18.1%O₂--71.4%N₂）,M₃（11.1%CH₄---18.3%O₂---70.6%N₂）.Experiments were carried out to explore effect of N₂ with different equivalent ratios on the overpressure of gas explosion.The effect of N₂ injection on gas deflagration was analyzed by N₂ injection.（3）For different equivalent vivas premixed gases,the free radicals were collected and the free radical strength data were obtained.（4）The laser path and speckle system are debugged,and reliable image of gas burning ripple image is obtained.Some remarks are concluded as follows:（1）The first chapter mainly introduces the research background,domestic and foreign related research status and the main content of the text.（2）In the second chapter,the experimental equipment and test system are introduced,the improved equipment and the updated collection system are described in detail,the experimental steps and the experimental safe operation are summarized.Through many experiments,the pressure flame curve is obtained,the reliability of the experimental equipment is verified,the basic conditions of the experiment are determined,and the characteristics of the first compression wave in the mesoscale detonation tube are explained.The transient spectra were adjusted and the transient spectra of candle self-luminescence were collected.The laser path diagram is modified as well as the imaging effect is improved.Probing into ignition,jet,Donghua data acquisition system,Donghua transient spectrum and hypervelocity schlieren,the time intersynchronous control system is settled.（3）In chapter 3,the influence of the gas explosion process and the explosion suppression were analyzed.The effect of nitrogen injection on gas explosion was compared.The overpressure analysis showed that with the increase of the inert gas N₂ content of the mixed gas,the overpressure of the gas explosion decreased obviously.When the nitrogen gas was not injected,the average value of the gas explosion overpressure was 84 kPa.When there injected the average value of the gas explosion overpressure was 54 kPa,and the amplitude reduction of the explosion was 35.7%.The data of the transient spectrum data showed that the content of OH and CH group decreased with the increase of the N₂ content of the mixed gas.（4）In chapter 4,the conclusion and the problems to be studied are discussed.