Particle Tracking Velocimetry Applied for Fireworks: A Demonstration of Vector Field Measurement in Hundreds Meter Space

摘要

Particle tracking velocimetry (PTV) is applied for measuring the motions of luminous particles in fireworks. The objective of the study is to clarify the technical problems encountering in large-scale quantitative visualization in natural environment. The major problems are found to be uncontrolled background in nature, low pixel resolution relative to particle size, and large perspective. The ways to deal with these problems in current technological level are discussed. In the application, two cameras are located at 1.3 km from the launching point with 30-degree opening angle to implement 3-D PTV. The transient 3-D velocity distributions of around 200 m-scale diameter fireworks are obtained during the light emission from the explosion till burnout. Moreover, the evolution of the mean particle diameter that decreases continuously with the combustion is estimated with the measured velocity information by the particle's equation of motion.