Green Ramjets Based on Metal/Water Reaction

Along with much emphasis focusing on the enhancement of operating speed, jet propulsions making full use of atmospheric substances have revealed the profound potential in comparison with turbofans as well as traditional rockets with all propellants brought on board. In this study, inspiration has been drawn from vast available water as one species of reactants not occupying any space against underwater vehicles, a new conceptual ramjet with a multiple water-injection mechanism was to be put forward based on hydro reactive property of several metals. And from a theoretical point, magnesium-based fuel possessing high energy density was chosen as an attractive option for actualizing performance predictions as well as the “green” reaction with water. Note that, water plays a vital role in controlling the combustion process and efficacy exertion for a propulsion system, thus the quantity of injected water should be predicted roundly. Firstly, taking a hydro reactive metal fuel with 60% magnesium by mass as an example, the upper limit of primary water has been estimated approximately as 2.4 owing to ignition condition of magnesium/water reaction. And along with water/fuel ratio, specific impulse reached maximal value of order 5515.90N·s·kg-1 approximately while water/fuel ratio was just 4.6. In addition, higher chamber pressure and higher magnesium mass fraction in hydro reactive metal fuel were both beneficial to ramjet integral performance.