Damon Honnery

Soot and mixture fraction in turbulent diffusion flames

Abstract Soot volume fraction measurements are made in turbulent ethylene diffusion flames and are compared with predictions. The theoretical model is based on mixture fraction distributions in the flame and measured soot volume fractions are correlated against predicted mixture fraction. The results show that in the lower parts of the flame this formulation is not adequate. However, the maximum soot concentrations further up the flame are less dependent on residence time and a mixture fraction approach may be useful here.

A soot formation rate map for a laminar ethylene diffusion flame

Measured soot volume fraction profiles are combined with the modeled temperatures, velocities, and mixture fractions in an axisymmetric laminar diffusion flame to derive local soot formation rates. The flame is modeled by solving transport equations for momentum, mixture fraction, and enthalpy together with a radiation model. The measured soot concentration profiles are differentiated along the computed particle trajectories. The soot formation rates are correlated with local mixture fraction and temperature. Although the range of mixture fraction-temperature combinations available in this flame is not complete, the map provides quantitative information in the principal soot-producing region.

The visualization of the acoustic feedback loop in impinging underexpanded supersonic jet flows using ultra-high frame rate schlieren

The use of modern ultra-high speed cameras to acquire time-resolved schlieren image sequences of supersonic jet impingement is presented. The use of these cameras, with framerates of up to 1 million frames per second, allows for the first time-resolved visualizations of the impinging jet acoustic feedback loop. The role of upstream travelling acoustic waves in generating perturbations in the jet shear layer at the nozzle exit is also directly observed for the first time. The arrival of the acoustic wave at the nozzle lip generates a sinusoidal variation in density gradient that persists until a distance of

SOOT FORMATION RATES IN DIFFUSION FLAMES : A UNIFYING TREND

\frac{x}{d}=0.3

Two Parametric Models of Soot Growth Rates in Laminar Ethylene Diffusion Flames

. A structure that rapidly evolves into a large-scale vortex ring forms at the trailing edge of this initial instability, first observed at approximately

Effect of nozzle transients and compressibility on the penetration of fuel sprays

\frac{x}{d}=0.25