Estimation of liquid volume fraction and droplet number density in automotive paint spray using infrared Thermography- Based visualization technique

A novel infrared thermography-based visualization technique for the measurement of the liquid volume fraction and the droplet number density is presented for two typical automotive paint applicators. The applicators are a high-speed rotary bell atomizer and a high-volume low-pressure air-assisted atomizer. The technique uses an infrared thermography-based measurement in which a uniformly heated blackbody background acts as the emitter or thermal radiation source, and an infrared camera as the receiver. The infrared energy emitted by the radiation source crosses the spray and is captured by the receiver as an attenuation map. The attenuation map is postprocessed using theoretical and empirical equations to extract information from which the liquid volume fraction and the droplet number density are computed, with previously known Sauter mean diameter.