Simulations of scalar (OH, CH, and number density) time series and comparisons to experimental data are presented using a laminar flamelet model. Realistic time series for mixture fraction (Z) were constructed by employing measured Z mean and rms values in conjunction with realistic power spectral densities (PSDs), probability density functions (PDFs), and integral time scales. A unique procedure was implemented to permit simultaneous specification of both the PSD and PDF shapes for Z. These Z time series were mapped to other scalar time series by using flamelet state relationships from a strained laminar flame code. The simulated statistics are compared to recent data in hydrogen/methane/nitrogen flames. The predictions of OH and CH time scales directly depend on the time scale for Z; however, they are not identical because of the narrow state relationships for reactive scalars. The model successfully captures complicated features in the radial distribution of OH integral time scales. In a separate inverse calculation, the simulation is used to estimate Z time scales from each of the measured OH, CH, and number density data. In each case the Z time scale is found to be ∼0.75 ms on the jet centerline. In contrast to time scales from non-reacting jet studies, this Z time scale is nearly invariant with axial height and at low axial heights varies only slowly with radial location, implying that convective scaling (jet width/local velocity) may be insufficient for the accurate description of mixing time scales in jets with heat release.
|Number of pages||16|
|Journal||Combustion and Flame|
|State||Published - 2002|
Bibliographical noteFunding Information:
This work has been supported by the Air Force Office of Scientific Research, with Dr. Julian Tishkoff as technical monitor. We would like to thank Rob Barlow (Sandia National Laboratories), Wolfgang Meier (German Aerospace Center), and Christoph Schneider (TU-Darmstadt) for providing their data and for fruitful discussions about this work.
ASJC Scopus subject areas
- Chemistry (all)
- Chemical Engineering (all)
- Fuel Technology
- Energy Engineering and Power Technology
- Physics and Astronomy (all)