Performance analysis of a novel parallel turbine reheat cycle for high speed vehicles

The optimization of the Brayton cycle has gained an increasing worldwide attention due to improve the specific thrust for achieving super cruise. This paper proposes a novel Parallel Turbine Reheat (PTR) cycle, which the second combustor would be placed at bypass of the expansion process, and presents an analytical methodology by which PTR can be simulated at ideal state and actual state. The motivation and the working principle of the PTR cycle are explained in detail. A performance simulation model for the PTR cycle is established with the assumption of equilibrium fuel rich gas as the working fluid in the gas generator. Then parametric cycle studies are performed with the variation of temperature rise ratio of the parallel combustion chamber and bypass ratio at the flight Mach number of 0 and 1.5 respectively. The interrelationships between cycle parameters and their effects on cycle performance are discussed. The results show that the specific thrust will be increased to 20% comparing with the conventional cycle for the reason that makes more fuel energy convert to the propulsion power without increasing the inlet temperature of turbines. The cycle parameters for a practical PTR cycle engine are more applicable for the flight speeds of Mach 1.5. The predicted engine performance shows that the PTR cycle concept exhibits a competitive specific thrust with respect to engine in the state of non-afterburning, and might be a promising propulsion system for super-cruise air-breathing flying vehicles.