Abstract: The combined turbo piston engine is comprised of a diesel and a gas turbine, of which the three operating modes (single diesel mode, single gas turbine mode and the combined diesel and gas turbine mode) can be chosen according to the power need of the vehicle. The engine is assumed to have the advantages of diesel and gas turbine to acquire high thermal efficiency and high power density at the same time. The configuration of the combined engine is presented. The theoretical cyclic thermal efficiency and specific work of the engine under the three modes are studied. The formula of thermal efficiency and work weight ratio are deduced. According to the set parameters of the cycle, the thermal efficiency and work weight ratio of the three modes are calculated. A diesel engine and a gas turbine with similar rated power are chosen to make up the combined turbo piston engine. A simulation model of the combined engine is built in GT-Power, and the performances of the engine under the rated condition are calculated. The results show that the combined turbo piston engine can acquire high thermal efficiency and high power density.

Key words: ordnance science and technology, combined turbo piston engine, Diesel-Brayton cycle, theoretical cycle analysis