TY - JOUR
TI - Temperature of gases in a trace of water droplets during their motion in a flame
AU - Voitkov Ivan S
AU - Volkov Roman S
AU - Strizhak Pavel A
JN - Thermal Science
PY - 2018
VL - 22
IS - 1
SP - 335
EP - 346
PT - Article
AB - The paper experimentally investigates the integral characteristics of the  processes involved in the reduction of gas temperature by injecting the  aerosol flow of water droplets into a counter flow of combustion products  (period of steady low gas temperature Tg’ compared to the initial Tg, range  of temperature decrease (ΔTg=Tg-Tg’), rate of temperature recovery, the  geometric dimensions of the temperature traces and their lifetime). We use  the following recording devices: fast-response thermocouples (heat inertia  less than 0.1 s), a multichannel recorder, a high-speed video camera (up to  105 frames per second), as well as a cross-correlation hardware and software  package (with optical methods for recording the front and trace of the  aerosol). The temperature trace of an aerosol is defined as the area with the  temperature Tg’ lower than the initial Tg by at least 10 K. We determine how  the following group of factors affects the characteristics of temperature  traces of water droplets: size (0.04-0.4 mm) and concentrations  (3•10-5-11•10-5 m3 of droplet/m3 of gas) of droplets in a pulse, the initial  temperature of water (280-340 K), the duration of a pulse (1-5 s), the  temperature (350-950 K) and velocities (0.5-5 m/s) of combustion products.  The temperature in a trace of water droplets during their motion in a flame  can be reduced due to rapid vaporization or heat exchange between the gases  and water. The conditions are identified, under which the low temperature of  gases in a trace of droplet aerosol can be preserved for a long time (20-30  s). Finally, we forecast the parameters of temperature traces under the  conditions of actual fires with combustion product temperatures over 1000 K.