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4.7. Infrared imaging: total rebounding of a supercooled drop on a 5 ◦ C
SHS. The diameter of the rebounding drop was measured as 1.3 mm,
and the drop temperature was −3 ◦ C. The heterogeneous nucleation
lasted from the 5.57 ms to the 15.32 ms. The drop in image (u) had
the same temperature as in image (t), indicating negligible influence
of the substrate on the overall heat transfer and phase change within
this short time. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
4.8. A supercooled drop impacted on a SHS at 5 ◦ C. Drop diameter:
1.46 mm, impact velocity: 3.32m/s. The non-spherical drop head
appeared in the first image after impact, i.e. at the 0.05 ms. . . . . . . 110
4.9. Receding of the supercooled drop after impact on a SHS at various
temperatures. The drop diameters were approximately 1.50 mm
and the impact velocities were approximately 3.4m/s. The complete
recordings are listed in Appendix C. . . . . . . . . . . . . . . . . . . . . 112
4.10.A supercooled drop impacted on SHS at −20 ◦ C. Drop diameter:
1.57 mm, impact velocity: 3.41m/s. Nucleation happened during
spreading as shown by the sharp tip at 0.65 ms. Receding was hindered
significantly by the ice structure. . . . . . . . . . . . . . . . . . . 112
4.11.Composition of the mechanical system in the measurement of the
contact temperature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
4.12.Measurement of the contact temperature. T K on substrates at
−10 ◦ C (left) and at −18 ◦ C (right) were measured as −7.5±0.5 ◦ C
and −14.5±0.5 ◦ C respectively, corresponding to the theoretical prediction
of −8 ◦ C and −15 ◦ C. . . . . . . . . . . . . . . . . . . . . . . . . . 117
4.13.The dimensionless minimum receding diameter d ∗ rec−min = d rec−min/d sp−max
on SHSs of different temperatures. The Stefan number is defined as
St = c ice (T m − T B )/L, where T K is contact temperature, T m is the
melting temperature, and L is the latent heat. . . . . . . . . . . . . . . 118
4.14.Rime ice observed in icing wind tunnel tests of Tsao et al. [147]. . . . 119
5.1. The target is mounted on the wheel at the apex of the rotation. The
wheel and the target was encapsulated with 2 mm thick aluminum
plate for the sake of safety. Only one plate is displayed in grey while
the others are made transparent for the purpose of exhibition. The
green parts are extra Polystyrene plates also for the purpose of security.
The pink part at the backside of the motor is the encoder which
provides signals for the motor control. . . . . . . . . . . . . . . . . . . . 126
248 List of Figures