| The research of high metal content magnesium based water reaction fuel water ramjet is of great significance.The purpose of this paper is to improve the working performance of the engine,combined with theoretical analysis,experimental research and numerical simulation to study the combustion process of a magnesium-based water ramjet.The analysis has obtained the influence of the working parameters in the combustion chamber on the combustion organization,then optimize the design of the engine working process.First,the thermal calculation of the Mg/AP/HTPB magnesium-based propellant grains is performed to obtain the self-sustaining reaction combustion product composition and proportion,and the applicability of various numerical calculation models to the simulation of the magnesium-based water-reactive metal fuel combustion process is verified.Secondly,a numerical simulation of the combustion process of the magnesium-based propellant engine is carried out.The simulation results are consistent with the literature.It accurately describes the precipitation of magnesium vapor,the progress of the magnesium/water combustion reaction,the evaporation of droplets,and the mixing flow process of gas and water vapor.The distribution of the parameters of the internal flow field was analyzed,and the combustion mechanism of the magnesium-based water ramjet was summarized.Then,the magnesium based water ramjet was optimized.By changing the position of the secondary water inlet,the angle of the primary water inlet,the particle size of the magnesium powder,the size of the droplets,and the water-fuel ratio,the mutual influence and change trend of the parameters of the internal flow field of the engine are analyzed and summarized.The results show that If the distance of the secondary water inlet is too small,the temperature of the combustion zone will drop ahead of time,which will affect the degree of magnesium-water reaction and combustion conditions;if the distance of the secondary water inlet is too large,a large number of water particles will stay in the engine for too short a time and fail to completely evaporate,resulting in the loss of two-phase flow.As the first water inlet angle decreases,the magnesium-water reaction zone moves toward the combustion surface,and the evaporation distance of the water droplets increases,which promotes the combustion efficiency and reaction degree.The evaporation rate of the water droplets also increases.The first water inlet angle between 45 ° and 60 ° should be adopted.With the increase of the secondary water-fuel ratio,the steady pressure of the combustion chamber increases,and the specific impulse and working performance of the engine increase,but there are too many unevaporated water droplets at a certain critical value,and the resulting two-phase flow loss is greater than the working fluid and the thrust specific impulse decreases.There is an optimal water/fuel ration.With the droplet size increases,the amount of heat absorbed by evaporation decreases,and the temperature of the gas phase also rises.When the size of the droplet increases to a certain critical value,the amount of heat absorbed by water droplet evaporation decreases less than the amount of combustion exotherm.The temperature of the zone will drop again and there is a critical atomization particle size.With the particle size of the magnesium powder increases,the magnesium vapor content near the combustion surface decreases,and the magnesium/water gas phase reaction rate decreases.The combustion reaction heat release reduces the droplet evaporation heat absorption,the mixing flow of gas flow and water vapor weakens,and have varying degrees of inhibition on the degree of reaction of the overall combustion process and combustion efficiency.In this paper,the combustion mechanism of water ramjet with high metal content is systematically studied,and the optimization design was carried out by changing the water intake and other ways,which can provide reference for further research on combustion organization. |
PDF Full Text Request