Towards replacement of turbofan engines afterburners with pulse detonation devices. I

Abstract

The feasibility of placing pulse detonation devices in the rear of a turbofan engine as a new pulse detonation afterburner concept (PDAC) has been assessed in the present study for a given sea level static power condition and an engine size. A turbofan engine with a pulse detonation afterburner was studied and its performance was obtained. The thrust, SFC and specific thrust of a turbofan engine with a conventional afterburner and with the new pulse detonation afterburner concept were calculated and compared. The turbofan engine performance with the new pulse detonation afterburner concept was obtained using multidimensional CFD and cycle analysis as a function of the engine core flow fraction passing through the pulse detonation device. The results showed that the engine performance, in terms of total thrust, SFC and specific thrust, is improved as the engine core flow fraction allowed in the pulse detonation chamber is increased. However, the predicted total thrust, SFC and specific thrust of the turbofan engine with a pulse detonation afterburner fall short than those of a turbofan engine with a conventional deflagration combustion afterburner. The reduction in the turbofan engine performance with a pulse detonation afterburner was attributed to the reduction in initial mixture fuel-air ratio as the core flow products fraction inside the detonation chamber is increased and the neglect of the pulse detonation exhaust stream momentum in the thrust analysis. An analysis, which would address the pulse detonation exhaust stream momentum and the engine nozzle performance, is therefore warranted. 1 Member AIAA Copyright © 2001 by the authors. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission. NOMENCLATURE A = constant cross-sectional area A/B = afterburner Favg = average thrust FPR = fan pressure ratio F = cycle frequency Mmass = mass averaged Mach number OPR = overall pressure ratio P(t) = unsteady pressure at the tube wall Pdrag = pressure acting on left side of thrust wall Pmass = niass averaged initial mixture pressure PPH = Ibm/hr SFC = specific fuel consumption Tcycie = cycle time Tdetonation= detonation time Tfin = filling time = initiation time = mass averaged initial mixture temperature = purging time t = time yi = mixture mass fraction = mixture equivalence ratio