Theoretical And Experimental Research On Magnesium-based Fuel Water Ramjet

Water ramjet as a new concept propulsion system takes high-energy metal fuel and uses water as oxidizer. For merits of high specific impulse, simple structure and good safety, it is the best propulsion system for the future subaqueous weapon of high speed and long voyage. In this dissertation, focusing on the magnesium-based fuel water ramjet, the operation process and the performance of the engine are investigated systematically using the method of theory analysis, numerical simulation and experiment. The stable operation of the engine is achieved, and the performance is improved remarkably. The results can provide theoretical basis for the design of water ramjet.Based on the analysis of the operation process of water ramjet, the model of thermal cycling is established. The influences of metal fuel composition, work parameters and condensation phase product on the theoretical performance are researched by thermal calculation. The ability of performance adjustment of the choked and unchoked water ramjet is analyzed, and the unchoked water ramjet is studied in detail.The 1-D, two phases, multi species and reacting flow model of magnesium-based fuel water ramjet is established, and the chemical dynamics model of magnesium-water is derivated. The flow field of the engine is calculated based on the 1-D simulation model. Through comparing the calculation results with the experiment results, the validity of program is validated and the model is modified. The characteristic of the flow field is analyzed when the engine operates stably after once and twice water injection. The program can provide research means for obtaining performance parameter quickly at the design stage.The 3-D numerical simulation of magnesium-based water ramjet is developed based on the 3-D, multi-phase turbulent simulation model. The process of combustion and flow after once and twice water injection in the engine is analyzed. The model is validated by the experiment results, and it is the theoretical basis for investigating the influences of structure and work parameters on the performance of water ramjet. The variety law of the performance and the distribution of the flow field for the water ramjet are obtained through 3-D numerical simulation under different work parameters such as water injection mass, velocity, position, number of the orifice, the diameter of the atomization droplet and the structure of the water ramjet. The results can provide theoretical basis for designing the engine reasonably and improving the performance.The engine and the system for water ramjet experiment are designed, and the method of the operation parameter design and experiment data handling are also presented. The once combustion performance of magnesium-based fuel is surveyed through the experiment. After realizing the stable work of the experiment engine, the influence that four structures of the engine, once water/fuel ratio, and the burn rate of the fuel make on operation process and the combustion efficiency of the engine are researched. The experiment of twice water injection is developed, and as a result the performance of the experiment water ramjet is improved remarkably. The experiment results can provide important technical support for manufacturing and applying the water ramjet.The conclusions achieved in the dissertation will surely promote the application of the magnesium-based water ramjet. Therefore the research will be of great theoretical value as well as engineering practice meaning for the propulsion of the future high speed subaqueous weapon research.