Firstly,a steady state mathematical model was developed for the mixing exhaust afterburner twin spool turbofan engine in full envelope.Secondly,a startup dynamic model was constructed by combining the effects of volume dynamics with the steady model.Then,by extending the volume dynamics theory to idle state,a whole process model was obtained to calculate the startup process,acceleration and deceleration process,turn on/off afterburner process and stop process.Finally,the altitude characteristic was presente...