Experimental Study on Ignition Process of a Magnesium-Based Water Ramjet Engine

The concept of the water ramjet engine is an underwater propulsion system that simply uses hydroreactive fuel combusting with seawater to generate thrust. Because of the absence of the oxidant onboard, a water ramjet possesses a great potential to improve specific impulse. A vitiated heater is commonly used to simulate stagnation temperatures and pressures of the incoming air in real flight conditions, whereas for the underwater application of ramjet engines, owing to the incompressibility of water flow, only mass flow rates and elevated pressures need to be duplicated at the water inlets. Therefore, the design considerations were simplified for the testing system of water ramjet engines. The selection of magnesium in the propellants was based on a higher ignition performance of it than that of aluminum and boron, which makes the direct employment of water into the engine possible.