Indirect measurement method of inner wall temperature of scramjet with a state observer

A state observer-based method is developed for the indirect online measurement of the inner wall temperature using the out surface temperature and pressure of a scramjet combustor. A mathematical model is established to describe the heat transfer from gas to combustor wall and inside combustor wall as well. A proportional integral observer is developed using the mathematical model for establishing the relationship between the observed inner wall temperature and the experimentally measurable parameters, including the out surface temperature and pressure. Numerical simulations and ground experiments are carried out with a direct-connect hydrocarbon fueled scramjet combustor to prove the validity of the proportional integral observer. Test results indicate the proportional integral observer method could be used to measure the inner wall temperature of the scramjet combustor.