Open AccessApplication of toluene LIF to transonic nozzle flows to identify zones of incomplete molecular mixing
Author(s) -
Matthias Beuting,
Judith Richter,
Bernhard Weigand,
Thomas Dreier,
Christof Schulz
Publication year - 2018
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.26.010266
Subject(s) - toluene , mixing (physics) , materials science , laser induced fluorescence , quenching (fluorescence) , nozzle , transonic , signal (programming language) , optics , molecular diffusion , molecular physics , analytical chemistry (journal) , fluorescence , chemistry , mechanics , physics , thermodynamics , chromatography , metric (unit) , operations management , organic chemistry , aerodynamics , quantum mechanics , computer science , economics , programming language
Toluene laser-induced fluorescence (LIF) has been applied to image the mixing deficit on the molecular level in the transonic wake of two different blunt-body injectors in a compressible accelerated nozzle flow. A single-color excitation and two-color detection scheme is employed to measure the signal red-shift caused by the quenching effect of molecular oxygen on the fluorescence of toluene, which reduces and red-shifts the LIF signal if both substances interact on a molecular level. To this end, toluene is injected alternatingly with O 2 -contaning and O 2 -free carrier gas into the air main flow. Differences of both signals mark regions where mixing on molecular level is incomplete. A zone of molecular mixing deficit extending several millimeters in stream-wise direction is identified. The effect of local variations in temperature on the sensitivity of this technique is discussed using photo-physical data measured in a stationary low-temperature cell.