The engineering prediction method of ramjet performance was developed

and an integration algorithm oriented model of integrated liquid fuel ramjet was established

which was compatible with group contribution method. The velocity-altitude characteristic

altitude-throttle characteristic

throttle-velocity characteristic and angle of attack characteristic of the specific impulse

thrust coefficient and fuel mass flow rate of the ramjet at angles of attack 0°~6°

altitude 0~18km

Mach number 2.0~3.5 and excess air coefficient 1.0~2.9 were analyzed. Results showed that

the model can predict the performance of ramjet engine without depending on the test data under the condition of integrated algorithm and within the allowable range of group contribution method. The relative error between the calculated results and the technical reference values was less than 14%. Thrust coefficient and specific impulse had basically the same velocity-altitude characteristics and similar altitude-throttle characteristics. The difference between throttle-velocity characteristics of thrust coefficient and specific impulse were obvious under the influence of gas composition.Different from the change of specific impulse and thrust coefficient showing a slowing trend after entering the stratosphere

fuel mass flow rate showed continuity.The higher the velocity

the lower the altitude and the smaller the excess air coefficient was

the higher the fuel mass flow rate was

and vice versa.Taking the angle of attack into account

the larger the angle of attack was

the lower the specific impulse

thrust coefficient and the higher the inlet start Mach number was.The angle of attack-start Mach number curve was approximately linear in a small range

and the non-linearity was intensified when the angle of attack exceeded 5.6°.