Transonic Combustion or TSCi™ is a novel combustion process
based on the patented concept of injection-ignition of fuel. The
process takes advantage of the improved mixing properties of
supercritical fuel to achieve high yet controlled rates of heat
release and high cycle efficiency. However, there is little science
that documents the mixing process, ignition characteristics and
combustion behavior of gasoline-like fuels in supercritical
conditions, let alone the fluid transport properties. Thus,
experimental studies and modeling efforts are necessary to enhance
understanding of this combustion process and for effective
development of this technology.
This paper focuses on the model development and validation
efforts for TSCi™ in an optical pressure chamber. An optically
accessible pressure chamber was used to study the combustion of an
injection-ignited supercritical fuel. Chemistry and Computational
Fluid Dynamics (CFD) models were developed to simulate TSCi™ and
were validated against data from the pressure chamber. This paper
focuses on the validation efforts for supercritical n-heptane
injected at different pressures. The comparison metrics encompassed
fluid jet penetration, ignition delay and lift-off length.
A reduced chemistry model for n-heptane was developed for the
supercritical regime. The reduction process included sensitivity
studies, to match ignition delay timing to results from shock-tube
experiments available in literature. The chemistry model was
implemented in a transient three-dimensional CFD simulation. The
simulation results were then validated against data from the
pressure chamber and the penetration rate, ignition delay and
lift-off-length compared well with the experimental data.