Research On Particle Size Distribution Of Combustion Exhaust Gas Of A Rocket Engine

Particles produced during the operation of a solid rocket engine are exposed to the air and form smoke by light scattering or absorption,which is a factor in the characteristic signal of exhaust plume.The characteristic signal leads to the visibility of exhaust plume increasing,which not only disturbs the transmission of missile guidance signal,but also increases the risk of exposing launch platform,has a flushing effect on the launcher,and producing solid particles,which take a certain degree of pollution to the environment.In order to improve the specific impulse of propellants,metal particles are usually added to solid propellants.The metal oxide produced by the combustion of metal particles in propellant is one of the components of engine combustion exhaust particles.In addition,there are products of thermal decomposition by gas erosion from cladding and engine materials.The suppression of engine plume characteristic signal is the development goal of solid rocket engine.This paper will focus on the study of engine combustion exhaust particles in the following aspects.(1)The particles and particle size distribution of solid rocket motor combustion exhaust are studied theoretically,and the numerical simulation of the engine exhaust flow field is carried out based on FLUENT.The error between the numerical simulation results of the wake field without considering the secondary combustion and that without considering the secondary combustion is larger.According to the numerical simulation results,the laser particle sizer is set at a distance of 2.5m from the engine axial direction,and the distance between the transmitting end and the receiving end of the laser particle sizer is 2m.(2)Based on LabVIEW,a test system is designed,which can be used for particle size test,engine performance parameter test and database query,and the engine particle size test experiment is completed with this test system.(3)The particle size and composition of combustion exhaust particles of SRM were analyzed by the collection method.It was concluded that the combustion exhaust particles of SRM were mostly Al2O3 particles and coating particles,and some Pb S particles from ignition powder.For the collected particles with particle size between 0 and 2μm,the distribution trend was consistent,and the repeatability is in a high level for multiple measurements.When the first peak value of small particle size appeared,the particle size was 0.12-0.18μm,and the second peak value appeared at 1.2-3μm.(4)According to the coating layer of different fillers and main materials,the laser particle size analyzer was used to conduct online test of engine combustion exhaust particles,and it was found that when polyurethane was used as the main material and melamine was used as the filler,the particle size of combustion exhaust particles was the smallest,with an average of 397.904μm.