Nonintrusive Droplet Characterization System

A novel nonintrusive laser probe for measurement of the structure of velocity flow fields for ground testing of aircraft turbine engines will be developed. A narrowband ArF excimer laser will be used to photo-dissociate O2. The O (1D) photoproducts rapidly react with ambient O2 to form O3, and thus "write" a line of tagged O3 molecules. After a fixed time delay, a novel approach to O atom detection will be employed to "read" the displaced ozone line. A second laser sheet (XeCl-pumped double-dye laser) will measure the progress of the tagged O3 by photodissociating ozone, and monitoring the O atom photoproduct by two-photon planar laser induced fluoresence (PLIF). The spatial displacement of the tagged line will be used to measure the velocity in time-of-flight fashion. The proposed innovation is the development of an entirely new photofragment flow tagging technique suitable for low temperature, subsonnic, unseeded flows, and application to inlet flows of aircraft turbine engines. The use of an intensified CCD camera will ensure that large areas of the flow will be imaged.