End-gas auto-ignition leading to knocking combustion is one of the major barriers achieving higher thermal efficiencies in downsized boosted spark-ignition engines. Despite available framework addressing hotspot-induced ignition (detonation peninsula), a quantitative investigation on gasoline surrogates yet be done. In particular, effect negative temperature coefficient (NTC) chemistry distribu...

The ignition delay times of methane/air mixture diluted by N2 and CO2 were experimentally measured in a chemical shock tube. The experiments were performed over the temperature range of 1300-2100 K, pressure range of 0.1-1.0 MPa, equivalence ratio range of 0.5-2.0 and for the dilution coefficients of 0%, 20% and 50%. The results suggest that a linear relationship exists between the reciprocal o...

The periodic flame flashback phenomenon in an ethylene-fueled cavity-based scramjet combustor was numerically investigated by a three-dimensional unsteady Reynolds-averaged Navier–Stokes solver with two-step kinetics. air inflow stagnation temperature is 1225 K, and its Mach number 2.6. Spectral analyses revealed the combustion oscillations flashbacks maintained separated mode establishment/van...

Vitiation air heater (VAH) combustion characteristics for a direct-connect scramjet combustor (DCSC) were experimentally studied. The VAH consists of head, modular chamber, and circular-to-rectangular shape transition (CRST) nozzle. CRST nozzle transforms the circular cross-sectioned rocket-type into rectangular combustor. exit Mach numbers at top, middle, bottom measured using tungsten wedge. ...

Non-equilibrium plasmas may be used to dissociate reactants into radicals. In turn, these radicals react releasing energy and broadening the radical pool and thereby ignite or aid the ignition of a fuel=air mixture. Using methane as an archetypical fuel, this work studies the kinetic pathways that control homogeneous ignition in the presence of radicals, which were previously formed by external...

Skeletal reaction models for n-butane and iso-butane combustion are derived from the detailed gas phase chemistry model of USC Mech II through directed relation graph (DRG) and DRG aided sensitivity analysis (DRGASA) methods. The skeletal models generated from various combustion systems, e.g. auto-ignitions versus premixed flames, n-butane versus i-butane, are compared, and analyzed based on th...

An auto-ignition detonation phenomenon can be initiated by a wedge confined in a channel. A new, self-sustaining, normal detonation wave engine concept is proposed. The detonation processes were numerically modeled with a simplified two-dimensional wedged channel flow that was deemed to emulate a real three-dimensional configuration. The results showed that within certain ranges of incoming flo...

A systematic approach for on-the-fly mechanism reduction is proposed in this paper. The approach consists of element flux analysis and dynamic generation of reduced mechanisms during reactive flow computation. At each time step of the computation, a reduced mechanism is generated based on local conditions and no previous information or analysis is necessary. The approach is demonstrated in a pl...