Flowfield and Performance Analysis of a Three-Dimensional TBCC Exhaust Nozzle

Compared to other engines, turbine-based combined cycle (TBCC) engine is one of the most suitable propulsion systems for hypersonic vehicle. Because of its fine reusability, wide flight envelope, and safety margins, TBCC engine is becoming a more and more important hotspot of research. In this paper, a three-dimensional (3D) over–under TBCC exhaust system is designed, simulated, and the results are discussed, wherein the ramjet flowpath is designed by the quasi-two-dimensional method of characteristics (MOC). A new scheme of rotating around the rear shaft is proposed to regulate the throat area of turbine flowpath. Cold flow experiments are conducted to gain a thorough and fundamental understanding of TBCC exhaust system at on and off-design conditions. To characterize the flow regimes, static pressure taps and schlieren apparatus are employed to obtain the wall pressure distributions and flowfield structures during the experiments. Detailed flow features, as well as the thrust performance, are simulated by the computational fluid dynamics (CFD) method. Both the numerical and experimental results show that the TBCC exhaust nozzle in this study can provide sufficient thrust during the whole flight envelop despite a little deterioration at the beginning of the mode transition. The research provides a new and effective scheme for the exhaust system of TBCC engine.