Mode transition study of turbine based combined cycle engine concepts

As one of the most challenging technologies for the turbine based combined cycle engine concept with the tandem layout for a hypersonic cruise vehicle, turbofan/ram mode transition study was carried out based on a tested nonlinear combined cycle engine models. Five steps were divided in the transition process to investigate the law on the combined modulation of the five variable geometries and the fuel flow to guarantee stable mode transition. Methods such as adjustment of single geometry, tandem optimization and Latin orthogonal experiment were applied separately or together to accelerate the search for Pareto solutions considering the characteristic difference of the multiple objects optimization problems in the steps. Based on the summarized rules, a new set of transition control law was designed for a new configuration with a more promising set of cycle parameters. The transient simulation shows stable mode transition could also be acquired through proper control of the variables.