Absolute OH concentration profiles measurements in high pressure counterflow flames by coupling LIF, PLIF, and absorption techniques

Effect of hydrogen addition on NOx formation in high-pressure counter-flow premixed CH4/air flames

“…The experimental facility used in this work, including the high pressure burner and the Laser Induced Fluorescence system, has been detailed previously in [38][39][40], an overview is presented here.…”

Chaotic Diagnostics in a Biodiesel Combustion System Using PLIF and Nonlinear Time Series Analysis▴

“…The appearance of flame image processing technology proposed a significant way for combustion diagnosis. On this basis, the flame detection and diagnosis based on planar laser‐induced fluorescence (PLIF) is widely used to study the evolution of OH radicals, flame characteristics and combustion mechanism during combustion [4–6]. OH radical is an important intermediate product in the combustion process.…”

Kinetic study of the OH + ethylene reaction using frequency‐modulated laser absorption spectroscopy

“…The sensitivity of FM spectroscopy decreases slowly and predictably with increasing temperature and pressure, both due to the changing thermal population of the selected rotational state, and as Doppler broadening and pressure broadening change the absorption line shape and reduce the differential absorption of the radio frequency (RF) sidebands. The calibration of laser‐induced fluorescence (LIF) intensities in environments of changing pressure and composition requires a more complex understanding of fluorescence quenching, energy transfer, and saturation effects, although the absolute sensitivity is generally superior in a fluorescence‐based technique . Compared to scanning a delay time in a laser photolysis, pulsed LIF method, an FM measurement using a continuous laser has the advantage of contributing a real‐time signal to an accumulating average at each shot of the pump laser.…”

“…The calibration of laser-induced fluorescence (LIF) intensities in environments of changing pressure and composition requires a more complex understanding of fluorescence quenching, energy transfer, and saturation effects, although the absolute sensitivity is generally superior in a fluorescence-based technique. 54 Compared to scanning a delay time in a laser photolysis, pulsed LIF method, an FM measurement using a continuous laser has the advantage of contributing a real-time signal to an accumulating average at each shot of the pump laser. The use of the OH vibrational overtone near 1.5 instead of the infrared fundamental near 3 exchanges a lower absorption cross section for a more convenient laser source and a light detector with better sensitivity and enough bandwidth to detect the RF beat signals of FM spectroscopy.…”