Fuyuto, Takayuki; Kronemayer, Helmut; Lewerich, Burkhard; Brübach, Jan; Fujikawa, Taketoshi; Akihama, Kazuhiro; Dreier, Thomas; Schulz, Christof:

Temperature and species measurement in a quenching boundary layer on a flat-flame burner

In: Experiments in Fluids, Jg. 49 (2010) ; Nr. 4, S. 783 - 795
ISSN: 0723-4864, 1432-1114
Zeitschriftenaufsatz / Fach: Maschinenbau
Abstract A detailed understanding of transport phenomena
and reactions in near-wall boundary layers of combustion
chambers is essential for further reducing pollutant
emissions and improving thermal efficiencies of internal
combustion engines. In a model experiment, the potential of
laser-induced fluorescence (LIF) was investigated for measurements
inside the boundary layer connected to flame-wall
interaction at atmospheric pressure. Temperature and species
distributions were measured in the quenching boundary
layer formed close to a cooled metal surface located parallel
to the flow of a premixed methane/air flat flame. Multi-line
NO-LIF thermometry provided gas-phase temperature distributions.
In addition, flame species OH, CH2O and CO
were monitored by single-photon (OH, CH2O) and twophoton
(CO) excitation LIF, respectively. The temperature
dependence of the OH-LIF signal intensities was corrected
for using the measured gas-phase temperature distributions.
The spatial line-pair resolution of the imaging system was
22 lm determined by imaging microscopic line pairs printed
on a resolution target. The experimental results show the
expected flame quenching behavior in the boundary layer
and they reveal the potential and limitations of the applied
diagnostics techniques. Limitations in spatial resolution are
attributed to refraction of fluorescence radiation propagating
through steep temperature gradients in the boundary layer.
For the present experimental arrangements, the applied
diagnostics techniques are applicable as close to the wall as
200 lm with measurement precision then exceeding the 15–
25% limit for species detection, with estimates of double this
value for the case of H2CO due to the unknown effect of the
Boltzmann fraction corrections not included in the data
evaluation process. Temperature measurements are believed
to be accurate within 50 K in the near-wall zone, which
amounts to roughly 10% at the lower temperatures
encountered in this region of the flames.