Temperature measurement in the trace of water droplet when heating by hot air

In this study, the temperature of a mixture of water vapor and air was measured behind the droplet, which is fixed in a hot air flow. The initial droplet radius varied from 1.3 mm to 1.7 mm. Air flow velocity was 2.5 m/s. The measurements were performed at a distance of 2 mm, 4 mm, and 8 mm from the back droplet surface. The initial air temperature varied in the range of 450-750 K. For the first time, the hypothesis was experimentally proved about significant reduction (from 10 K to 100 K) of gas temperature in the trace of the evaporating water droplet (even when the droplet size is less than 2 mm). The results explained the reasons for considerably different evaporation rates of water droplets during their motion in the form of an aerosol flow in a combustion zone. The study reported the sizes of the temperature trace of droplet, beyond which the temperature of the mixture of water vapor and air differed insignificantly (by less than 10 K) from the temperature of the air stream flowing around the droplet. The results of measuring the temperature of vapor/air mixture in the trace of the evaporating droplet proved the validity of the known models of high-temperature heating and evaporation of water droplets.