Systematic measurements of OH chemiluminescence for fuel-lean, high-pressure, premixed, laminar flames

Systematic measurements are reported of OH chemiluminescence from a premixe d laminar flame at pressures and equivalence ratios ranging from 0.5 to 2.5 MPa and 0.66 to 0.86, respectively. The objective was to obtain non-existe nt experimental data and to determine the viability of using OH chemilumine scence as an active-control parameter for high-pressure, premixed flames. T he signal from the first electronically excited state of OH to ground (at 3 05.4 nm) was detected through a band-pass filter with a photo-multiplier tu be. For constant mass flow rate, OH emission decreased significantly with i ncreasing pressure. Emission also monotonically increased with the equivale nce ratio. A linear relationship was observed between increasing mass dow a nd increasing chemiluminescence. These trends support the conclusion that s uitable resolution and dynamic range exist for a high-pressure flame to be adequately controlled to minimize both NOx and CO emissions. Results are pr esented for a simple, active-control system using OH chemiluminescence meas urements to demonstrate flame stabilization for equivalence ratio disturban ces at fixed, elevated pressures. Finally, only qualitative agreement was o bserved between the measurements and numerical predictions of OH chemilumin escence using an adiabatic, freely propagating premixed flame. Although mor e work is required on the chemical-kiinetic mechanism of OH chemiluminescen ce, the modeling effort supports the use of OH chemiluminescence for active -feedback-control applications. O 2000 Elsevier Science Ltd. All rights res erved.