Planar imaging of hydroxyl in a high-temperature high-pressure combustion facility

Imaging fluorescent combustion species in gas turbine flame tubes - On complexities in real systems

“…Fuel fluorescence is not a factor when imaging far enough downstream of the fuel injector, in the burnt gases region. 13,14 However, the need to understand the physics of the fuel/air mixing and fuel vaporization processes mandates imaging near the fuel injector exit plane. Jet-A, JP-5, and similar aviation fuels typically contain a small percentage of naphthalene and its derivatives.…”

“…However, recent studies have shown that NO LIF and PLIF at high pressure can succeed, through various approaches which include subtracting the O 2 background, doping the flame with NO, selective narrow-band filtering, and judicious laserline selection. [17][18][19][20] Fuel imaging challenges…”

“…It is somewhat more complex than earlier work performed using a single fuel injector because the present focus lies in the primary reaction zone rather than in the burnt gases region. 13,14 The efforts to characterize both the primary zone and the burnt gases zone motivate this report.…”

Excitation/Detection Strategies for OH Planar Laser-Induced Fluorescence Measurements in the Presence of Interfering Fuel Signal and Absorption Effects

“…Regions of high temperature increase thermal NO x formation and may reduce the lifetime of critical engine components (Ref. 2). The ability to track thermal intensity and sites of non-uniform mixing through the presence of OH is useful for testing operating methods, evaluating hardware designs and influencing future modifications to reduce emissions and further enhance combustor performance.…”

“…For example, polycyclic aromatic hydrocarbons (PAHs)-common constituents in aviation fuels that include naphthalene and its derivatives-absorb and emit energy over a broad spectrum often competing with the fluorescent emission bands of the OH molecule (Ref. 2). Spectral interferences may also arise due to elastically scattered light from liquid fuel and, if the flame is luminous, blackbody radiation (Ref.…”