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Experimental Analysis of Post-Impact Drop Spread Behavior and Prediction of Maximum Spread Factor

Raghuram, Avinash

Abstract Details

2013, MS, University of Cincinnati, Engineering and Applied Science: Mechanical Engineering.
ABSTRACT An experimental study of normal impact of pure liquid droplets on a dry horizontal substrate and their spread-recoil behavior is presented in this thesis. Measurement of the drop spread diameter and liquid film height variaitons during the post-impact spreading process were carried out using a high speed camera (2000 fps) and image processing. To understand the influence of drop size/weight on the spread process, experiments were conducted for a range of drop sizes (0.8lc < D < 2lc) for water, ethylene glycol and propylene glycol for low to moderate Weber numbers (We < 160). A hydrophilic substrate (glass) as well a hydrophobic substrate (PFTE) were employed as the test surfaces. Eight test liquids encompassing a wide range of physical properties are utilized to understand the effect of liquid property on the maximum spread factors. To understand the effect of surface tension, maximum spread factors for liquids with similar viscosity but varying surface tensions are compared. Similarly, the effect of viscosity on maximum spread factors is also presented. For the range of impact velocities, liquid properties and nature of the substrates studied, the influence of drop size on the temporal variations are found to be similar. For the same Weber number, the larger drop size results in higher spread factors and maximum spread values, while no marked variations are observed in terms of the flattening factor. A scaling factor based as a function of the Bond number is shown to capture the effect of dop size on the maximum spread factor. Furthermore, it is observed that the maximum spread factors for all liquids exhibit a power law behavior of the form, ßmax = c1 * We p for We > 10, with each liquid possessing a different slope, p, and c1 value based on its properties. The slope values are found to be a linear function of the adhesive force between the liquid and the hydrophilic surface, while the sessile drop spread and the c1 values are found to be a linear function Bo' 0.5 /Oh' 0.12, which is obtained as a result of force balance on a sessile drop. For We < 10, the maximum spread curves are asymptotically matched with sessile drop spread. A correlation for the prediction of maximum spread factor is developed which is capable of predicting the maximum spread on any hydrophilic surface (contact angle less than 90º) for a wide range of liquid properties. The predictions using the correlation agree well (±10%) with the experimental data available in literature.
Raj Manglik, Ph.D. (Committee Chair)
Milind Jog, Ph.D. (Committee Member)
Seetha Ramaiah Mannava, Ph.D. (Committee Member)
117 p.

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Citations

  • Raghuram, A. (2013). Experimental Analysis of Post-Impact Drop Spread Behavior and Prediction of Maximum Spread Factor [Master's thesis, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1377868179

    APA Style (7th edition)

  • Raghuram, Avinash. Experimental Analysis of Post-Impact Drop Spread Behavior and Prediction of Maximum Spread Factor. 2013. University of Cincinnati, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1377868179.

    MLA Style (8th edition)

  • Raghuram, Avinash. "Experimental Analysis of Post-Impact Drop Spread Behavior and Prediction of Maximum Spread Factor." Master's thesis, University of Cincinnati, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1377868179

    Chicago Manual of Style (17th edition)