Summary of research Published in Fire Technology: (accepted – DOI link will be added when online)
Researchers:
Yudong Liu, James L Urban, Chuanlong Xu, Carlos Fernandez-Pello
In this project we measured the temperature, motion (position & velocity), and size of moving metal sparks and hot particles. The goal is to better understand the danger that such sparks can pose in terms of their ability to start a fire. Here sparks were produced using an abrasive cutting steel cutting rebar. These measurements were done using streak tracing velocimetry, color pyrometry, and image processing.
Temperature History Results (no velocity measurement)
Single spark reacts with air and heats up, bursts and then cools 
Spark bursts into spark fragments which each quickly heat then cool
Temperature & Velocity Results
It can be seen that the sparks start off well concentrated in terms of both temperature and velocity, but as they travel farther they eventual separate into two peaks: one with high temperatures and velocities and another with low temperatures and velocities.