The general objective of this project is to support the development and validation of large eddy simulation (LES) models used to simulate the response of fires to the activation of suppression systems. The focus here is on suppression by gaseous agents. The present experimental configuration is a two-dimensional, plane, buoyancydriven, methane-fueled, turbulent diffusion flame with a controlled...

Direct Numerical Simulations (DNS) have been conducted to study the response of initially laminar spherical premixed methane–air flame kernels to successively higher turbulence intensities at five different equivalence ratios. The numerical experiments include a 16-species/25-step skeletal mechanism for methane oxidation and a multicomponent molecular transport model. Highly turbulent condition...

Two new 14-step and 16-step reduced mechanisms for methane-air combustion were developed with the emphasis on their capabilities to predict NO2 formation. The systematic reduction was carried out by assuming the quasi-steady state for 26~28 species in the starting mechanism with the help of a automatic mechanism reduction code. The two reduced mechanisms reproduce NO2 formation behaviors obtain...

The pulse-burst duration of a compact burst-mode Nd:YAG laser is extended by one order of magnitude compared to previous flashlamp-pumped designs by incorporating a fiber oscillator and diode-pumped solid-state amplifiers. The laser has a linewidth of <2 GHz at 1064.3 nm with 150 mJ per individual pulse at 10 kHz. The performance of the system is evaluated by using the third-harmonic output at ...

Abstract A flamelet-based approach that accounts for turbulence-chemistry interaction has been formulated to simulate NOx formation in turbulent lean premixed combustion. In the simulations, the species NO is transported and solved with the chemical source term being modelled through its formation in flame fronts and its formation rate in post-flame regions. The flame-front NO and post-flame NO...

The speed of propagation of a premixed turbulent flame correlates with the intensity of the turbulence encountered by the flame. One consequence of this property is that premixed flames in both laboratory experiments and practical combustors require some type of stabilization mechanism to prevent blow-off and flashback. The stabilization devices often introduce a level of geometric complexity t...

We report on the development and application of a broadband absorption spectrometer utilizing a pulsed supercontinuum laser light source and dispersion compensating fiber with a single-pass absorption path to obtain absolute methane mole fractions in a laminar nonpremixed CH(4)/air flame supported on a Wolfhard-Parker burner. The basic principle of supercontinuum broadband absorption spectrosco...

The combination of in situ X-ray absorption spectroscopy, X-ray diffraction and on-line catalytic data provided insight into the structure-performance relationship of a flame-made Pd/ZrO(2) catalyst during the total oxidation of methane: upon heating, a sudden reduction accompanied by sintering of the Pd-particles, leads to a significantly lower catalytic activity and a hysteresis during coolin...