The Design Of Shock Tube And Experimental Study On Chemical Mechanism Of Ethylene Combustion

Ethylene is an olefin hydrocarbon fuel of internal combustion engine,gas turbine engines and other propulsion equipment,but also the important small molecule product of the hydrocarbon fuels' thermal cracking process.Under hypersonic condition,the length of stay in the engine combustion chamber and the different reaction paths of ethylene under different temperature and pressure are all concerned.Therefore,it is very important to study the ignition characteristics of ethylene to verify the model of hydrocarbon fuel combustion reaction kinetics.The shock tube can provide the environment of high temperature and high pressure,so it is an effective tool to study the fuel ignition characteristics,and it has the advantages of simple structure and easy to quickly heat,pressurize and accelerate the gas to a high parameter value and so on,so it has been widely used in the experimental study of the combustion of fuel.In this paper,in order to achieve the requirements of the experimental study of shock tube,first of all,the numerical simulation of the flow field in the shock tube is carried out by Fluent numerical simulation,we set up a shock tube experiment platform based on the existing experiments plant design parameters.It is consisted of shock tube,gas distribution system,pressure measurement system and spectroscopic measurement system.Shock tube includes a tube body and the support system;gas distribution includes the high-pressure premixed gas chamber,low-pressure premixed gas chamber,cylinder,vacuum pump group,manometers,vacuum gauges,valves and piping and other components;pressure signal was picked by the pressure electric sensor acquisition,through the charge amplifier,and collected by oscilloscope acquisition;spectroscopic measurement system includes a filters,a monochromator,and a photomultiplier tube.Secondly,after the construction of the shock tube is completed,combined with the theoretical calculation and experiment,the attenuation experiment is carried out to test the shock attenuation rate of the incident shock wave,which analyzes the main influence factors of shock wave attenuation process.The experimental results show that the shock intensity decays with increasing distance,meanwhile,the greater the velocity,the more severe the attenuation;The results also show that the membrane rupture pressure is positively related to the tensile strength of the material,and is positively related to the original thickness of the membrane.Finally,75% and 96% respectively in ethylene dilution,the ethylene,oxygen,argon according to the stoichiometric ratio of 1,the pressure is 1-3tam,Temperatures in the range of 1062-1683 K experimental study,the experiment measured 75% and 96% dilution of ethylene at different temperatures of the ignition delay time to verify the four chemical mechanism model,and it is found that the simulation result of LLNL mechanism has the highest agreement with the experimental data;Then,the oxidation reaction path of ethylene under different temperature and different dilution of argon is analyzed by using Chemkinpro software to simulate LLNL mechanism,which obtains the percentage depletion reaction of C2H4 in 75% dilution is two times in 96% dilution;the six reaction paths of 1100 K into five reaction paths of 1500K;C2H4+H?C2H3+H2,The percentage of C2H4 consumption at 1500 K is about three times the C2H4 consumption percentage at 1100 K.