When water-ramjet engine working, its water-fuel ratio is needed to conform. Taking magnesium-based fuel for example, thermodynamic parameter of different formulation fuel under different water-fuel ratio was calculated with the free energy minimization method. It was found that the effective specific impulse of water-ramjet engine increased first and then decreased with the increasing of water-fuel ratio, so there was the maximum value of it, named optimum specific impulse. The corresponding water-fuel ratio was the best one, and then the performance ability of water-ramjet engine was the maximum one. The temperature of nozzle exit gradually decreased with the increasing of water-fuel ratio. When the temperature was lower than local vaporization temperature, water steam coagulated and it would cause the thrust force to decline. Therefore, when the water-ramjet engine is designed, the value of water-fuel ratio can't exceed the best water-fuel ratio by the premise of guarantee of the temperature of nozzle exit as high as possible.
Experimental Study on the Ignition Process of Single Coal Particles at Microgravity
