Abstract:
Gaseous and particulate emissions from combustion devices are implicated in many
atmospheric environmental pollution concerns. Lean, premixed, prevaporised combustion is
widely regarded as the most practical technique for reducing these emissions from gas turbine
combustors to levels which will not cause significant environmental impact. This technique has
been proved to be capable of reducing emissions of oxides of nitrogen to ultra low levels.
However, further understanding and development is necessary before LPP combustors can be
reliably fitted in production gas turbines. Particular problems are flashback and autoignition in
the premixer and achieving a stable, lean primary zone. This thesis details a comprehensive
series of measurements made upon a realistic LPP gas turbine combustor. The measurements
elucidate the important, fundamental, physical processes which govern the performance of LPP
combustors whilst providing a challenging and complete data set for CFD model validation.
These measurements include data on the premixer velocity field, the fuel droplet size and
velocities distributions, the fuel concentration in the premixer and primary zone and the
combustion temperature. This has been interpreted to provide useful information such as the
location and rates of fuel-air mixing, the proportion of temporal to spatial fluctuation in fuel
concentration, the premixer swirl number, the flame brush thickness and the effect on mixing
and placement of fuel fraction boiling point. It has been found that for mixing multi-component
fuels in a duct, the rate of mixing and physical placement will depend on the boiling fraction of
the fuel. High boiling point fractions evaporate later, experience longer droplet trajectories and
mix much slower when compared to lower boiling fractions.
