INVESTIGATION ON AN OPTICAL PRESSURE MEASUREMENT USING LASER-INDUCED FLUORESCENCE

Progresses in fluid mechanics are in general linked to the development of appropriate measurement methods to validate the calculation codes. The fine analysis of the flowfields requires the development of non-i ntrusive experimental techniques. The laser-induced fluorescence of a gaseous molecule seeding the gaz flow, can be tied to the flowfieid th ermodynamic parameters such as pressure and temperature. The measureme nt can be performed using two laser excitation techniques: the first o ne is very easy to implement, because only the use of an argon ion las er is required, but signal presents a double dependence on both pressu re and temperature. The second method allows the removal of the temper ature dependence of the fluorescence signal. A narrow band- width sing le line laser is tuned on the center of an iodine absorption line, who se temperature dependence of the Boltz- mann fraction can be neglected . The experimental set-up requires a single line dye laser and a high resolution spectral analysis device. Both methods have been successful ly tested under static conditions, and the experimental results are in good agreement with the theoretical model. Some experimental results of non-intrusive pressure measurements can be expected under flow cond itions in using this technique.