Numerical Simulation And Analysis On Exhaust System Of Trijet Combined-Cycle Engine

Trijet combined cycle engine is a new T/RBCC engine designed by The Boeing Company and Aerojet Rocketdyne, which integrates the turbine engine, Ejector Ramjet and Dual Mode Ramjet. This paper presented the overall performance calculation, aerodynamic design and numerical simulation on Trijet combined cycle engine exhaust system; it mainly explored the implementation of continuous thrust operating together by three engines under a wild range of Mach numbers and the flow features of exhaust system under aerodynamic interaction.Firstly, the paper introduced the operating principle of the Trijet engine and analyzed the structure of its exhaust system. On this basis, the overall calculation method of Trijet engine was determined, along with a simplified one-dimensional mathematical model of Ejector Ramjet and a quasi-one-dimensional model of DMRJ scramjet mode. The research on the overall calculation method of Trijet Combined engine was then conducted utilizing the GasTurb software, and the results are compared with result by example in foreign references data.Secondly, the flight envelope of foreign references was reasonably modified and supplied. The research used the inward-turning inlet parameters designed by the Professor Wang Weixing who works in our group for the calculation of input conditions. The engine thrust curves and aerodynamic parameters of the exhaust system were obtained under two ideal state conditions and stationary profile by established Trijet engine overall calculation methods. The speed characteristics were compared and analyzed using two different computational models with flow distributions between the three engines presented.Finally, based on the parameters of the nozzle under fixed surface, the preliminary aerodynamic design of three engine nozzles started. Through using CFD technology, the design scheme was modified and simplified and a more rational aerodynamic solution was achieved. The study of the field of exhaust system was conducted through numerical simulations at design points, five typical off-design points and four-transition modes; the analysis of flow characteristics and mechanism of nozzle flow field was performed as well. The research results have certain reference value to the overall design of the combined cycle engine.