Using the advanced staged combustion cycle LOX (liquid oxygen)/kerosene engine as an example

the engine start-up characteristics were investigated. The mathematical model of transient process of the engine was developed based on modular modeling means. The nonlinear hyperbolic partial differential equations governing the unsteady flow of propellant pipelines were solved by the Chebyshev pseudo-spectral method. Furthermore

an extensible simulation library for liquid propellant rocket engines has been elaborated by using the new object-oriented simulation language-Modelica. Simultaneously

by using the simulation library

a staged combustion cycle LOX/kerosene engine model is built on the platform MWorks and forced start-up characteristics of the engine calculated. Results from the numerical simulation agree well with the ground-test data

the relative errors of steady-state are less than 4%

and the dynamic simulation errors are less than 10%

which indicates that the model can accurately predict the transient behavior of the engine. Some rules relating to start-up were simulated. The results demonstrate that solid propellant starter working should be lasted up to the gas generator ignition

and gas generator head should be filled with liquid oxygen when gas generator igniting.