Multiline hydroxyl tagging velocimetry measurements in reacting and nonreacting experimental flows

摘要

A compact micro-lens optical system is developed that produces a 7x7 multi-line optical grid for Hydroxyl Tagging Velocimetry (HTV) and generates at least 49 resolvable velocity vectors. Single-photon photodissociation of ground-state H2O by a similar to193-nm ArF excimer laser "writes" a 7x7 beam molecular grid with very long gridlines of superequilibrium OH and H photoproducts in either room air flowfields or in H-2-air flames due to the presence of H2O vapor. The displaced OH tag line positions are revealed through fluorescence by A(2)Sigma(+) (v'=0)<--X(2)Pi(i) (v'=0) OH excitation using a similar to308-nm pulsed frequency-doubled dye laser. Time-of-flight analysis software determines the instantaneous velocity field in either an air nozzle or in a hydrogen/air flame. The OH tag lifetime is measured and compared to theoretical predictions using detailed chemistry. The lifetime of the OH tag is significantly enhanced by the presence of O atoms from 193-nm photodissociation of O-2.