EXP 1-4 Experimental Set Up
Axisymmetric drop impact dynamics on a wall film of the same liquid
Experimental Setup
Describe briefly the test facility and the measurement procedure
The experimental setup can be divided into three main units including the drop generator, the impact substrate and the observation system.
The drop generator is based on a drop on demand method. A micropump transports the liquid from a tank to the cannula. The drop drips off the cannula tip by gravity as soon as the critical mass is reached. The impact velocity of the drop is varied by altering the height of the cannula tip relative to the liquid film interface. The impact substrate is an aluminium block with a recess of 70 mm diameter and 0.6 mm depth. The recess constrains the liquid so that films with a defined film thickness can be placed. The film thickness is measured by a chromatic line Sensor (Precitec CHRocodile CLS) which allows measuring the film thickness on 192 points aligned on a line of 1 mm length, to assure uniform film thickness. The observation system is described in Section Measurement Quantities and Techniques.
Images are taken with a high-speed CMOS camera (Photron SA-X2), recording the impact at a frame rate of 20000 fps with a magnification of 31 μm/px. A synchronized high-performance LED (Constellation 120E) in combination with a diffuser plate provides a uniform background illumination. When carrying out the experiments, a uniform film of 500 μm thickness is prepared utilizing the film thickness sensor. In the next step, the film thickness sensor is moved and a drop is generated. Shadowgraph images are taken during the drop impact onto the liquid film.
Contributed by: Bastian Stumpf, Milad Bagheri, Ilia V. Roisman, Cameron Tropea, Jeanette Hussong, Martin Wörner, Holger Marschall — Technical University of Darmstadt and Karlsruhe Institute of Technology
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