Laminar lifted flame velocity measurements for aerosols of metals and mechanical alloys

This research develops and validates a novel experimental methodology for measurements of laminar flame velocities of metal-air aerosols. The experimental technique is based on a recently developed laminar, lifted flame aerosol burner using the electrostatic fluidization to produce a metal aerosol between the electrodes of a plate capacitor. A vertical, decelerated aerosol jet is produced and ignited with the flame position stabilized at the location where the flame propagation velocity becomes equal to the jet velocity with the opposite sign. Therefore, the flame velocity determines the vertical location of the lifted flame. Measurement and data processing methodologies are described. The developed technique was used to compare the flame propagation velocities for pure aluminum and magnesium powders versus flame propagation velocities for a set of aluminum-based metastable solid solutions using Mg, Ti, Zr, Li, MgH₂, or C as solute and prepared using mechanical alloying. It was observed that the flame propagation velocities for all of the tested solid solutions, except the one with carbon, are higher than the flame propagation velocity in the pure aluminum aerosol.