ABSTRACT
A novel technique has been used for the temporally resolved investigation of the interaction of laser radiation and soot in a flame. Based on established soot vaporisation models we developed a framework to calculate the two-colour four-wave mixing signal obtained in an acetylene/air diffusion flame at atmospheric pressure. The signal comprises a contribution due to soot and, depending on the wavelength of the probe laser, a contribution because of C2, which is generated by vaporising soot. For both parts of the signal we found a good agreement between measured and calculated power dependency. Furthermore, we measured spatial profiles of the signal in a Wolfhard-Parker slot burner. By analysing the different signal contributions we found that depending on the location within the flame there are particles with different C2 yield.
ABSTRACT
Light scattering from laser-induced electrostrictive gratings has been used for simultaneous, instantaneous, nonintrusive, and remote measurements of temperature and velocity in a submerged air jet. We accomplished phase-sensitive detection of scattered light by superimposing two signal beams whose frequencies were Doppler shifted by the movement of the grating. Temperatures in the range 295-600 K and flow velocities in the range 10-100 m/s were measured.