Nicholas GIBBONS, Lachlan WHYBORN, Vincent WHEATLEY
DOI Number: XXX-YYY-ZZZ
Conference number: HiSST 2024-00159
A pair of high fidelity direct numerical simulations have been developed to study the interaction be-
tween turbulence and chemistry in high-speed combustion. One case considers a time-developing hy-
drogen/air turbulent mixing layer taken from the literature, aiming to verify and demonstrate a newly
improved high-fidelity numerical scheme, and the other will investigate a hydrocarbon, i.e. ethylene,
combustion at effectively the same conditions. The numerical method that has been developed uses a
novel technique for detecting discontinuities to hybridise a low dissipation, central inviscid flux scheme,
with a high-dissipation, shock capturing scheme. The method is successfully verified against the ana-
lytic solution for a steepening nonlinear wave, then applied to the two mixing layer cases. The results
show a number of striking differences between the hydrogen and ethylene cases, including very differ-
ent regimes of premixed vs. nonpremixed combustion and different patterns of heat release over time.
Conditional statistics also show both cases have large variations in temperature that are not correlated
with mixture fraction, an important finding that will need to be addressed in model developments for
highly compressible combustion flows.