面向高马赫数固体超燃的液氨冷却特性

In this work, liquid ammonia is used as a new nitrogen-based coolant. Considering the real operating temperature and pressure of the scramjet engine, a three-dimensional numerical model is established to analyze the flow and heat transfer characteristics of liquid ammonia. The thermal properties were calculated by PR equation and Chung method. The phase change of ammonia was calculated by Lee evaporation model. Pyrolysis of ammonia is also considered. The flow heat transfer characteristics of liquid ammonia under different temperatures and pressures were studied considering the process of phase change and pyrolysis. The cooling feature of ammonia was compared with traditional hydrocarbon fuel. The heat sink of liquid ammonia and hydrocarbon fuel was compared and analyzed under the same condition. The results show that the heat transfer capacity of liquid ammonia increases with the increase of pressure. When pressure increase from 3 MPa to 17 MPa, heat transfer coefficient increases by 8.02%. Under same mass flow rate, heat transfer coefficient of ammonia is higher and the wall temperature decreases by 36.3% in non-pyrolysis zone and 9.1% in pyrolysis zone.