Laser-induced fluorescence for the non-intrusive diagnostics of a fuel droplet burning under microgravity in a drop shaft

摘要

The laser-induced-fluorescence method has been employed for remote, non-intrusive and instantaneous measurements of a fuel droplet burning under microgravity. A fuel droplet was doped with naphthalene and TMPD. The fluorescence emission spectrafrom a droplet subjected to the incident nitrogen laser beam were measured with an image-intensifying optical multichannel analyser. The microgravity was generated in a capsule of a 100 m drop shaft. The results showed that the newly developed diagnosticsystem could be applied successfully for the simultaneous measurements of droplet temperature and diameters of the droplet, flame and soot shell under microgravity. The droplet temperature was determined from the measured ratio of fluorescence emissionintensities at two different wavelengths. The soot shell was located in the vicinity of the droplet surface deep inside the flame during the early stage of the burning and moved away from the droplet with the elapse of time.