ID 227

Global Rainbow Technique: Temperature evolution measurements of super-cold droplets

 

Abstract:

Sprays are worldwide use in many industrials processes such as turbine, spray dryer, combustion chambers, etc,. To master sprays several measurement techniques have been proposed. They are generally based on analysis of light scattered by the droplets. Most of these techniques give access to geometrical parameters of the spray such as density, the size distribution, velocity distribution, size/velocity correlation, etc. However thermo-chemical parameters as the droplets temperature and the droplets composition are also key parameters which must be known to improve efficiency of industrial processes. During the last decades the effort have been made to develop Global Rainbow Technique (GRT) which is able to measure simultaneously size distribution and the refractive index(therefore temperature) with high accuracy. This technique is now easy to use and commercially available. The potential of GRT will be illustrated in ICLASS 2018 conference by the exemplifying case of spray water droplets temperature evolution measurement in a cold wind tunnel. These measurements of super cold droplets temperature are essential to understand icing which can cause the plane to crash. The experiments have been realized in two different scales: • Laboratory scale in a cold cylindrical column with an air temperature down up to -70°C • Industrial scale in a wind tunnel with an air temperature down up to -30°C The robustness, accuracy and validity of the measurements will be discussed.