Analysis of a Preliminary Design for Multiple Jointed Combined Cycle Engine

This paper is described to give the initial information for representing the analysis of preliminary design of the multiple jointed combined cycle (MJCC) engine which is combined with three different engines, turbine engine, dual mode scramjet (DMSJ) and rocket. In starting a practical design of a combined cycle engine, it is very complex and interactive between sub-engines, so a preliminary design is required and can give the requirement for each sub engine comprising the integrated propulsion such as the program MJCC. Through this paper, how to derive preliminary design and procedure along the pre-defined mission profile are described. Furthermore, the analytical results of the preliminary design are included in this paper. MJCC engine is composed of the representative two combined cycle engines, a combined cycle turbo-ramjet engine, and a combined cycle dual mode scramjet engine with rocket combustor installed in it operating independently and interactively at the different Mach (velocity) range, lower, super and hyper speed. The combined turbo-ramjet engine operates at the range of Mach 0–4 and the rocket combined DMSJ operates Mach 4–8 higher and the MJCC engine also gets thrust only by rocket without incoming air from the intake at the higher Mach 8+ with additional specific oxidizer. For preliminary design and analysis of this engine, first, the mission profile and aerodynamic forces were derived from the result of other research. Next, the required thrusts of sub-engines were obtained with initial stage engine models constructed for this objective considering design and off-design point of each engine. From that, the initial relative size of engine components such as intake, combustor, nozzle is calculated and the effective combination of two engines is suggested considering this relative size. In conclusion, this result certainly can give the guideline for the preliminary design of a combined cycle engine and the initial parameter for the practical design.