To better meet the demand of refined prediction of the aircraft icing process, the freezing mechanisms and microstructure characteristics in solidification of supercooled water droplets are studied combining the theory of phase-change thermodynamics and kinetics with tests. Based on the Differential Scanning Calorimetry (DSC) test, the effects of cooling rate and nucleation conditions on the solidification characteristics are studied. Icing tunnel tests are carried out at different temperature conditions, and the macroscopic morphology and microstructure characteristics of ice are obtained. The results indicate that icing conditions and cooling rate have great influence on the crystallization behavior of supercooled water. The greater the cooling rate, the greater the crystallization rate. At the same time, the crystallization peak becomes wider, and the initial temperature of crystallization becomes lower, and vice versa. The subcooling and cooling rate have important influence on the macroscopic and microscopic morphology of ice. The greater the subcooling and cooling rate, the more irregular the grains, the larger density and the smaller the grains, and the ice phase looks more opaque. On the contrary, the smaller the subcooling, the lower density and the larger the grains, and the ice phase looks more transparent. Heterogeneous nucleation conditions play an important role in accelerating the crystallization process. The addition of crystal seeds can trigger the crystallization effectively, significantly reducing the supercooling effect. The results lay an important foundation for better understanding the mechanisms of aircraft icing, which has important value for predicting the icing process more accurately.
DU Yanxia
,
XIAO Guangming
,
ZHANG Nan
,
LI Weibin
,
WANG Zixu
,
YI Xian
,
GUI Yewei
. Freezing mechanism and microstructure characteristics in solidification of supercooled water droplets[J]. ACTA AERONAUTICAET ASTRONAUTICA SINICA, 2019
, 40(7)
: 122627
-122627
.
DOI: 10.7527/S1000-6893.2018.22627
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