Simultaneous single-shot laser-based imaging of formaldehyde, OH, and temperature in turbulent flames
In: Proc. Combust. Inst., Jg. 28 (2000) ; Pt. 1, S. 279-286
Zeitschriftenaufsatz / Fach: Maschinenbau
Single-shot formaldehyde (CH2O) laser-induced fluorescence (LIF) imaging measurements in turbulent flames were performed by using XeF excimer laser excitation in the 410 transition of the A1A2-X1A1 electronic system at 353 nm. Background contributions to the CH2O LIF detection were assessed in spectroscopic measurements. Simultaneous two-dimensional mapping of OH LIF, CH2O LIF, and temp. fields was carried out in a std. Bunsen flame. The zones of peak heat release rate localized via the product of OH and CH2O LIF intensities correlated with areas of intermediate temps. In addn., single-shot imaging of the transient formaldehyde distribution was performed in a 150 kW natural gas swirl burner. Formaldehyde distributions in strongly turbulent swirl flames differed significantly from thin layers found in laminar and weak turbulent flames, indicating the presence of low-temp. chem. in preheated gas pockets. The CH2O distribution measured in the swirl flame was compared with averaged fields of temp., OH, and NO concns.