Reaearch On The Underwater Propulsion System And Combustion Technology Based On Aluminum And Water Combustion

The underwater propulsion system based on aluminum and water combustion has the characteristics of high energy density and long working time,which makes it a hot topic in various countries.The underwater propulsion system structure optimization design is to improve the system energy density and energy utilization efficiency,and the continuous and stable combustion of aluminum and water is the technical bottleneck of the whole system.In this paper,the theoretical calculation method is used to analyze the performance of the underwater dynamic system propulsion system.At the same time,the methods of combining theory,numerical simulation and experiment are used to explore the aluminum particle ignition combustion and the aluminum/water vortex combustor.Finally,the performance of the system and the combustion efficiency of aluminum particles are improved significantly.The performance calculation model of the system was established and the factors of the system performance were analyzed.Through the use of solid heat exchanger and wall surface regenerative cooling heat exchange to obtain high temperature water vapor and high temperature water vapor as fluidized gas,six new underwater power systems were designed.According to the system performance analysis,the newly designed system has its own advantages.The application of high temperature water vapor as a fluidized gas can greatly improve the energy density of the system.And the system with the heat transfer of wall surface regeneration and heat transfer to obtain high-temperature steam has the highest energy density of the system.Under the condition of the thermal equilibrium between the particle and the flow field,a simplified combustion model of aluminum particles is obtained,which can be used for the calculation of the two-phase flow of aluminum and water,and describtion for the particle combustion process completely.The results for this model are verified comparing with the experiment results.Two configurations,circumferential and axial injection of aluminum into the vortex combustor,are designed,and the results show that under certain conditions,aluminum particles can burn efficiently inside the combustor,and the combustion efficiency is more than 95%.In addition,the influence the two kinds of vorte x combustor configurations are analyzed respectively.In the circumferential configuration,within a certain range,adding the concave cavity,reducing the steam inlet velocity and the aluminum particles size are helpful for aluminum particles combustion.The effect of pressure and water-fuel ratio on the combustion of aluminum particles are small.However,when the water-fuel ratio is too large or the pressure is too low,aluminum particles will not be able to maintain combustion in the vortex combustor.In the axial configuration,within a certain range,when the aluminum inlet position is located in the intermediate vortex region or near intermediate vortex region,aluminum particles incident angle is positive,the particle size decreases and the water-fuel ratio increases,the aluminum particles combustion efficiendy is high.Finally,it can be seen that the axial configuration of the vortex combustor is better.The configuration of alumimun and water combustion dual combustor is designed: the pre-combustion chamber is used for the ignition of aluminum particles,and the afterburning chamber is filled with aluminum particles.Numerical simulation results show that this configuration can achieve high efficiency combustion of aluminum and water.As the ratio of high temperature water vapor and aluminum flux decreases,the combustion efficiency decreases gradually.When the ratio is less than a certain value,the aluminum particles will not be able to sustain combustion.The closer the pre-combustion chamber and the first cold water are to each other,the higher the combustion efficiency is.The secondary cold water position has little effect on aluminum particle combustion.In addition,adding cold water at the front end can promote the combustion of aluminum particles,and the combustion efficiency increases with the increase of cold water flow.Besides,excess cold water and too short distance of the entrances between the cold water and aluminum particles will make the aluminum particles fail to maintain combustion.The experimental system of aluminum-steam vortex combustor is designed.The high temperature and high pressure steam is obtained by alcohol and oxygen combustion and then the addition of cold water.The structure of aluminum-steam vortex combustor is designed and the principle test is carried out.The experimental results show that the vortex combustor can realize the combustion of aluminum particles and steam.By increasing the particle collecting section,the problem of nozzle blockage is solved,and the burning efficiency of aluminium particles can be up to 92%.