Thermodynamic calculation and analysis for water ramjet

In order to obtain specific impulse as great as possible, and meanwhile to guarantee appropriate temperature and pressure, a dual water injection system was utilized in water ramjet. Through analysis on working process, corresponding thermodynamic cycle model was established. To investigate the performance of the engine, combining mass conservation equation, chemical equilibrium equation and energy conservation equation, detailed thermodynamic calculation was implemented. An appropriate chamber pressure is given preliminary. The qualitative relationship of performance parameter, such as specific impulse, thrust, exit temperature, etc, versus water-fuel ratio was obtained respectively. Then, the primal water-fuel ratio is determined between 0.5 and 1.9. Guaranteeing the maximum total water-fuel ratio less than 5.1, the specific impulse could achieve optimal value while total water-fuel ratio is equal to 3.5.