Study On Ignition And Combustion Characteristics Of Magnesium Particles In O₂ Environment

Magnesium is widely used in ramjets of new-generation supersonic missiles due to its low ignition temperature,high combustion calorific value and low oxygen consumption.Because of the extremely complex working environment of ramjets,the oxygen concentration and pressure will change in different working environments.Therefore,it is of great significance to study the ignition-combustion characteristics of magnesium particles under different oxygen concentrations and different pressures to improve the performance of ramjets.In this paper,basis on the summary of metal particles ignition-combustion research at home and abroad,the magnesium particles ignition-combustion experimental research under different oxygen concentrations and different pressures is carried out.An experimental research system was designed and set up,and the magnesium particles ignition-combustion experimental study was carried out with this experimental system.The effects of oxygen concentration and pressure on the ignition temperature,ignition delay,combustion time and maximum combustion temperature of magnesium particles were analyzed.Scanning Electron Microscope(SEM)and Energy Dispersive Spectroscopy(EDS)were used to analyze the macro-microstructure and elemental composition of the magnesium particles combustion production.Based on the microstructure,the effect of combustion environment on the structural strength of combustion production was studied.It was verified that the experimental data in this paper conformed to the droplet combustion model,and the combustion constants of magnesium particles under different working conditions were calculated,which provided support for the establishment of magnesium particles combustion constant database.The experimental research shows:(1)When the oxygen concentration increases,the ignition temperature drops significantly;the ignition delay is almost unchanged;the combustion time increases first and then decreases,and reaches a peak at 40%oxygen concentration;the highest combustion temperature shows an upward trend;the structural strength of combustion production is lower at 40%oxygen concentration.(2)When the environmental pressure increases,the ignition temperature increases;the ignition delay increases;the combustion time decreases;the maximum combustion temperature increases and reaches a peak at 0.15MPa;the structural strength of combustion production is lower at 0.15MPa.(3)When the particle size of magnesium particles is smaller,the test results are in better agreement with the droplet combustion model.