Simulation of Primary Film Atomization Due to Kelvin–Helmholtz Instability
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Liquid film atomization under a high-speed air flow (water was considered as the liquid) due to the Kelvin–Helmholtz instability is studied using the volume of fluid (VOF) method. We develop an approach for modeling the primary breakup and use it to investigate the grid convergence, choose the optimal size of the grid cell, and calculate the primary breakup of the film in the channel. The dependences of the mean break-off angle, the velocity modulus, and the Sauter droplet diameter on the longitudinal coordinate of the channel are obtained. The step-by-step averaging over the ensemble of droplets and over time allows us to get smooth coordinate dependences of the characteristics of the ensemble of the droplet. The value of the most useful parameter for engineering applications, the mean Sauter diameter D32 (equal to the ratio of the mean droplet volume to its mean area) is close to that obtained using a semiempirical formula from the literature, based on the experiment where hot wax is atomized by a high-speed airflow. The dependence of the Sauter mean diameter on the thickness of the liquid layer agrees qualitatively with the experimental dependence. The study of the grid’s convergence showed that the number of the smallest droplets increases rapidly with decreasing cell size. Their contribution to the average characteristics of the droplet’s ensemble, however, remains insignificant; nonetheless, their input to the mean characteristics remains insignificant; thus, there is no reason to decrease the grid cell size to account for small droplets.
KeywordsKelvin–Helmholtz instability volume of fluid (VOF) method 2D flow atomization Sauter mean diameter
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- 5.Ménard, T., Tanguy, S., and Berlemont, A., Coupling level set/VOF/ghost fluid methods: validation and application to 3D simulation of the primary break-up of a liquid jet, Int. J. Multiphase Flow, 2007, vol. 33, no. 5, pp. 510–524. https://doi.org/10.1016/j.ijmultiphaseflow.2006.11.001 CrossRefGoogle Scholar
- 6.Berlemont, A., Bouali, Z., Cousin, J., Desjonqueres, P., Doring, M., Menard, T., and Noel, E., Simulation of liquid/gas interface break-up with a coupled Level Set/VOF/Ghost fluid method, in Proceedings of the 7th International Conference on Computational Fluid Dynamics ICCFD7-2105, Big Island, Hawaii, July 9–13, 2012. https://doi.org/www.iccfd.org/iccfd7/assets/pdf/papers/ICCFD7-2105_paper.pdf.Google Scholar
- 9.Ling, Y., Fuster, D., Tryggvason, G., Scardovelli, R., and Zaleski, St., 3D DNS of spray formation in gasassisted atomization, in Proceedings of the 24th International Congress of Theoretical and Applied Mechanics, Montreal, Canada, Aug. 21–26, 2016.Google Scholar
- 10.Chaussonnet, G., Riber, E., Vermorel, O., Cuenot, B., Gepperth, S., and Koch, R., Large Eddy Simulation of a prefilming airblast atomizer, in Proceedings of the 25th European Conference on Liquid Atomization and Spray Systems, Chania, Greece, September 1–4, 2013.Google Scholar
- 16.Raynal, L., Instability on the gas-liquid mixture interface, PhD Thesis, Grenoble: Univ. J. Fourier, 1997.Google Scholar
- 18.Ebner, J., Gerendás, M., Schäfer, O., and Wittig, S., Droplet entrainment from a shear-driven liquid wall film in inclined ducts: experimental study and correlation comparison, in Proceedings of the ASME Turbo Expo 2001, New Orleans, Louisiana, USA, June 4–7, 2001, Paper No. 2001-GT-0115. https://doi.org/10.1115/2001-GT-0115 Google Scholar
- 19.Shalanin, V.A., Eulerian methods for modeling flows with free surface, Molod. Uchen., 2016, no. 2 (106), pp. 258–261.Google Scholar
- 20.Leonov, A.A., Chudanov, V.V., and Aksenova, A.E., Methods of direct numerical simulation in two-phase media, in Trudy IBRAE RAN (Collection of Articles of IBRAE RAS), Bolshov, L.A., Ed., Moscow: Nauka, 2013, no. 14.Google Scholar
- 21.Lyubimov, D.V. and Lyubimova, T.P., About a numerical method for solution of problem with deformable interface, Model. Mekh., 1990, vol. 4, no. 1, pp. 136–140.Google Scholar