The work presented in this paper deals with the synchronous multiwavelength detection of thermal, chemiluminescent and laser-excited 0'0=266nm) emission from spray of a large saturated paraffin (tctradccane) in auto-igniting conditions. Two of these have been selected by varying oxygen molar fraction (0.13 and 0.21) of high pressure (2MPa), high temperature oxidant (900K) stream yielding non-sooting combustion. The main measured spectroscopic feature was an isolated broadband fluorescence signal detected around A.=330nm.This signal is here attributed to aldehyde functionality on the basis of both calibra- tion tests. performed on liquid aldehydes with the same optical set-up, and literature data relative to fluorescence and chemiluminescence measurements in simpler conditions. Furthermore. temporal evolution of this signal. in the conditions reported here. is consistent with two-step ignition kinetics of paraffins to which a large production of aldehydes and ketones is related. Chemiluminescence maximum, due to HCO and C2 radicals, is slightly delayed with respect to the fluorescence maximum and is in synchrony with a minimum of the aldehydic species fluorescence signal. These maxima and minima mark unambiguously the time interval in which combustion evolves in premixed and diffu- sion controlled conditions, when pyrolnic species formation occurs.
Laser excited emission and chemiluminescence from autoigniting spray
de Joannon M;Ragucci R;
2000
Abstract
The work presented in this paper deals with the synchronous multiwavelength detection of thermal, chemiluminescent and laser-excited 0'0=266nm) emission from spray of a large saturated paraffin (tctradccane) in auto-igniting conditions. Two of these have been selected by varying oxygen molar fraction (0.13 and 0.21) of high pressure (2MPa), high temperature oxidant (900K) stream yielding non-sooting combustion. The main measured spectroscopic feature was an isolated broadband fluorescence signal detected around A.=330nm.This signal is here attributed to aldehyde functionality on the basis of both calibra- tion tests. performed on liquid aldehydes with the same optical set-up, and literature data relative to fluorescence and chemiluminescence measurements in simpler conditions. Furthermore. temporal evolution of this signal. in the conditions reported here. is consistent with two-step ignition kinetics of paraffins to which a large production of aldehydes and ketones is related. Chemiluminescence maximum, due to HCO and C2 radicals, is slightly delayed with respect to the fluorescence maximum and is in synchrony with a minimum of the aldehydic species fluorescence signal. These maxima and minima mark unambiguously the time interval in which combustion evolves in premixed and diffu- sion controlled conditions, when pyrolnic species formation occurs.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
