Numerical study of oblique detonation wave control for fuel blends

Abstract

The current study is motivated to develop control strategies for oblique detonation wave formation on a finite length wedge in a premixed methane-air mixture. The effectiveness of hydrogen blends (0 - 100%) to methaneair premixed mixture (at 300 K) on Chapmann Jouguet (CJ) detonation and oblique detonation wave formation are analyzed for different pressures (20 kPa - 100 kPa) and incoming velocities (2.4 - 3.2 km/s) by using 1-D Zeldovich-von Neumann-Doering (ZND) calculations. It was found that induction length and induction time reduces with higher blends of hydrogen in CJ-ZND analysis as well as oblique detonation wave ZND analysis. Similar effects are observed by adding small amount of reaction promoters (H2O2 or O3) as additives up to 15000 PPM. The two-dimensional numerical simulations for the oblique shock wave (OSW) to oblique detonation wave (ODW) transition for different blends and additions in fuel-air mixtures are performed for wedge at angle θ = 26◦ for incoming flow velocity of 2800 m/s, pressure of 20 kPa and temperature of 300 K. The unsteady reactive Navier-Stokes RANS equations are solved with adaptive grid refinement and robust SAGE chemistry solver on CONVERGE platform using reduced version of GRI mechanism along with ozone sub-chemistry. Two dimensional simulations confirms smooth transition with initiation length 1 cm for stoichiometric hydrogen-air and no ODW formation for methane-air premixed mixtures for 10 cm wedge length. It is also found that 50% hydrogen blending and 10000 PPM of ozone addition to stoichiometric methane-air mixture can establish ODW with initiation lengths of 3.9 cm and 4.0 cm, respectively on a finite length wedge.