A new method——fixed dynamic method(FDM)

which delt with the issue of designing optimal control law of aeroengine in transient states

was proposed.Firstly

based on a detailed non-linear aerothermodynamic model

it made the errors of nonlinear equations set to zero via extracting all of state variable rates and let the model reach steady-state

which meant the parameters in this state were equal to that in transient state;secondly

according to the given limited conditions respectively

the control laws can be built directly via simple static programming method;finally

merged all of them via Max/Min selection and obtained the optimal control law.The computing results of the improved acceleration control law of some turbofan engine indicate that the FDM is accurate and effective.