aerothermodynamic off-design performance study of a fixed double bypass duct turbofan engine

In this paper, a turbofan engine with double bypass duct (dbp) was studied at design point and off-design conditions. this engine is a separate exhaust, two spool turbofan engine with bleed, turbine cooling, power extraction, and convergent exhaust nozzles. bypass ratio of main and secondary duct is equal one. also, a typical turbofan engine with one bypass duct is considered as the benchmark case (simple engine) and its bypass ratio is 2. simulation results show that dbp engine produces 5.4% thrust more than the simple engine at m=0.8 and altitude of 9296.4 m (design point). dbp engine thrust is more than the simple engine at sl altitude and 9296.4 m at off-design conditions in all flight mach numbers ranging from 0 to 0.8. moreover, the double bypass duct engine sfc is lower than the simple engine at prementioned off-design conditions. thrust per mass flow rate (f/m ̇) was also studied. by increasing f/m ̇, specific fuel consumption is decreased for both engine types. another interesting finding is that at constant f/m ̇, dbp engine sfc is lower than simple engine at all flight altitudes.