Freezing of droplets colliding with a cold surface
- Univ. of Toronto, Ontario (Canada). Dept. of Mechanical Engineering
Impact of droplets of paraffin wax (melting point 70 C) on a polished aluminum surface was studied experimentally. Droplet impact was photographed, and the spread diameter and liquid-solid contact angle measured from photographs. Impact velocity was varied from 0.8 m/s to 2.6 m/s and surface temperature from 23 C to 73 C. For low impact velocities (< 2 m/s) splat edges solidified before droplet spread was complete, restricting movement of liquid. Photographs showed liquid recoiling in the droplet center during impact on a cold surface (23 C); the recoil reduced as the surface temperature approached the melting point of the droplet. When the impact velocity was increased, surface temperature had less effect on droplet spread, and recoil was not observed. A one-dimensional model of droplet solidification was used to derive a dimensionless parameter s*, which was a measure of the thickness of the solid layer formed at the cold surface. Solidification did not affect droplet spreading for s* < 8 {times} 10{sup {minus}3}. A simple energy conservation model was used to predict the maximum extent of liquid droplet spread when solidification was negligible. Predictions from the model were found to agree well with experimental measurements.This is applicable for spray forming of metals.
- OSTI ID:
- 462605
- Report Number(s):
- CONF-950828-; ISBN 0-7918-1705-9; TRN: IM9719%%75
- Resource Relation:
- Conference: 1995 National heat transfer conference, Portland, OR (United States), 5-9 Aug 1995; Other Information: PBD: 1995; Related Information: Is Part Of 1995 national heat transfer conference: Proceedings. Volume 4: Transport phenomena in manufacturing and materials processing; Transport phenomena in materials joining processes; Transport phenomena in net shape manufacturing; HTD-Volume 306; Mahajan, R.L. [ed.] [Univ. of Colorado, Boulder, CO (United States)]; PB: 261 p.
- Country of Publication:
- United States
- Language:
- English
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