Effect of Liquid Viscosity and Surface Tension on the Spray Droplet Size and the Measurement Thereof

Chideme, N.; De Vaal, P.

doi:10.47176/jafm.17.2.2532

Effect of Liquid Viscosity and Surface Tension on the Spray Droplet Size and the Measurement Thereof

Document Type : Regular Article

Authors

Department of Chemical Engineering, University of Pretoria, Gauteng, 0028, South Africa

10.47176/jafm.17.2.2532

Abstract

This investigation focuses on the impact of liquid properties—viscosity, surface tension—and air pressure on the Sauter Mean Diameter (SMD) of atomization sprays. Utilizing a twin-fluid atomizer, the study resulted in derived equations that quantify these effects across a spectrum of liquid behaviours, with an emphasis on both viscous and non-viscous liquids. The derivation process for viscous liquids yielded equations showcasing an average deviation of 1.32% from experimentally observed SMD values, validated across a dataset of 250 experimental trials. These trials involved a total of 18,000 droplets analysed, with a standard error of 0.02%, spanning a liquid viscosity range of 3x10-3 to 20x10^-3 kg/(m.s), and air pressures from 50 to 300 kPag. For non-viscous liquids, defined by a liquid viscosity threshold of < 3x10^-3 kg/(m.s), the equations revealed a higher average deviation of 1.51% from the experimental SMD. These runs included the analysis of 19,600 droplets across liquid surface tensions from 20x10^-3 N/m to 72.8x10^-3 N/m, with a standard error of 0.03%. This distinction highlights the significant influence of surface tension in shaping the atomization outcomes for these liquids. A quantitative discovery of this research is how a 10% increase in viscosity for viscous liquids correlates to a substantial 33% increase in SMD, impacting around 10,500 droplets per viscosity level, with an observed standard deviation of 0.15% across viscosity measurements. This emphasizes the dominance of viscosity in influencing atomization dynamics for viscous liquids. Conversely, for non-viscous liquids, a 10% increase in surface tension translates to a 45% increase in SMD, affecting approximately 11,200 droplets per surface tension category, with a standard deviation of 0.18% in surface tension measurements. Moreover, this study pioneers the introduction of a particle tracking code, designed for high-speed camera frames, enabling the analysis of over 10,000 droplets per experimental run, summing up to more than 280,000 droplets analysed across all trials, with an overall precision rate of 99.5%. This novel technique enhances system performance by providing highly accurate and real-time droplet size distribution data, which is critical for optimizing atomization processes in industrial applications. In comparison with state-of-the-art studies, this research offers a comprehensive analysis of the combined effects of viscosity, surface tension, and air pressure on SMD, providing new insights and validated predictive models. The contributions of this work lie in its detailed quantitative results and the introduction of advanced measurement techniques, which together represent a significant advancement in the field of atomization.

Keywords

Main Subjects

Drops and Bubbles

References

Al-Obaidi, A. (2024). Effect of different guide vane configurations on flow field investigation and performances of an axial pump based on CFD analysis and vibration investigation. Experimental Techniques, 68(1), 69–88. https://doi.org/10.1007/s40799-023-00641-5

Al-Obaidi, A. R. (2019). Investigation of effect of pump rotational speed on performance and detection of cavitation within a centrifugal pump using vibration analysis. Heliyon, 5(6), e01910. https://doi.org/10.1016/j.heliyon.2019.e01910

Al-Obaidi, A. R. (2023). Experimental diagnostic of cavitation flow in the centrifugal pump under various impeller speeds based on acoustic analysis method. Archives of Acoustics, 48(1), 159–170. https://doi.org/10.24425/aoa.2023.145234

Al-Obaidi, A. R. (2024). Evaluation and investigation of hydraulic performance characteristics in an axial pump based on CFD and acoustic analysis. Processes, 12(1), 129. https://doi.org/10.3390/pr12010129

Al-Obaidi, A. R., & Jaber, J. A. (2023). Investigation of the main flow characteristics mechanism and flow dynamics within an axial flow pump based on different transient load conditions. Iranian Journal of Science and Technology, Transactions of Mechanical Engineering, 47(6), 1397–1415. https://doi.org/10.1007/s40997-022-00586-x

Al-Obaidi, A. & Khalid, H. K. (2023). Investigation of the influence of varying operation configurations on flow behaviors characteristics and hydraulic axial-flow pump performance. Proceedings of the 4th International Conference on Science Education in The Industrial Revolution 4.0, ICONSEIR 2022, November 24th, 2022, Medan, Indonesia. https://doi.org/10.4108/eai.24-11-2022.2332719

Amedorme, S. K. (2021). A Computational fluid dynamics-based correlation to predict droplet sauter mean diameter for atomization model in pressure swirl atomizer. European Journal of Engineering and Technology Research, 6(7), 69-76. https://doi.org/10.24018/ejeng.2021.6.7.2645

Bayvel, L., & Orzechowski, Z. (1993). Liquid atomization. Taylor & Francis. https://doi.org/10.1201/9780203748787

Chang, J. & Chen, L. (2022). Numerical simulation of primary atomization process of liquid jet in subsonic crossflow. Energy Reports, 8, 1-15. https://doi.org/10.1016/j.egyr.2022.01.152

Chaussonnet, G., & Kösters, R. (2018). Smoothed particle hydrodynamics simulation of an air-assisted atomizer operating at high pressure: Influence of non-Newtonian effects. Journal of Fluids Engineering, 140(12), 121101. https://doi.org/10.1115/1.4038753

Christensen, B., & Oefelein, M. (2023). Efficient extraction of atomization processes from high-fidelity simulations. Computers & Fluids, 254, 105808. https://doi.org/10.1016/j.compfluid.2023.105808

Dumouchel, C. (2008). On the experimental investigation on primary atomization of liquid streams. Experiments in fluids, 45, 371-422. https://doi.org/10.1007/s00348-008-0526-0

El Shanawani, M. L. (1980). The influence of atomizer scale on airblast atomization. Journal of Energy.

Gad, H. M., & Ibrahim, I. (2018). Experimental study of diesel fuel atomization performance of air blast atomizer. Experimental Thermal and Fluid Science, 99, 211–218. https://doi.org/10.1016/j.expthermflusci.2018.07.006

Gorokhovski, M., & Herrmann, M. (2008). Modeling primary atomization. Annual Review of Fluid Mechanics, 40, 343-366. https://doi.org/10.1146/annurev.fluid.40.111406.102200

Hou, J. & Zhao, Z. (2024). Experimental investigation on liquid breakup regimes and spray characteristics in slinger atomizers with various injection orifices. Physics of Fluids, 36(1), 121702. https://doi.org/10.1063/5.0181526

Ingebo, R. D. (1957). Drop-size distribution for cross current breakup of liquid jets in airstreams. National Advisory Committee for Aeronautics (NACA).

Jadhav, P. & Deshmukh, R. D. (2023). Numerical modelling and experimental study of MQL spray parameters in machining of Ti-6Al-4V. International Journal on Interactive Design and Manufacturing (IJIDeM), 1-12. https://doi.org/10.1007/s12008-023-01484-5

Jadhav, P. A. & Deshmukh, R. D. (2021). Numerical analysis of the effect of air pressure and oil flow rate on droplet size and tool temperature in MQL machining. Materials Today: Proceedings, 38, 2499-2505. https://doi.org/10.1016/j.matpr.2020.07.518

Jasuja, A. (1979). Atomization of crude and residual fuel oils. Journal of Engineering for Power, 101(2), 250–258. https://doi.org/10.1115/1.3446480

Johnson, M. S. (2020). Impact of air pressure on the atomization of ethanol-water mixtures using an ultrasonic atomizer. International Journal of Multiphase Flow, 104-116. https://doi.org/10.1016/j.ijmultiphaseflow.2020.104116

Kim, K. Y., & Reitz, W. R. (1971). Drop-size distributions from pneumatic atomizers. AIChE Journal, 17(3), 575–584. https://doi.org/10.1002/aic.690170318

Lefebvre, A. H., & Gosman, V. G. (2017). Atomization and sprays. CRC Press. https://doi.org/10.1201/9781315120911

Liu, C. & Watanabe, K. (2022). Experimental study of the spray characteristics of twin-fluid atomization: Focusing on the annular flow regime. Physics of Fluids, 34(12), 121701. https://doi.org/10.1063/5.0128231

Luo, S. & Ozcan, Y. (2023). Understanding the breakup behaviors of liquid jet in gas atomization for powder production. Materials & Design, 230, 111793. https://doi.org/10.1016/j.matdes.2023.111793

Minov, S., & Coles, F. (2016). Spray droplet characterization from a single nozzle by high-speed image analysis using an in-focus droplet criterion. Sensors, 16(2), 218. https://doi.org/10.3390/s16020218

Nukiyama, S. (1939). Experiments on the atomization of liquids in an air stream, report 3, on the droplet-size distribution in a atomized jet. Transactions of the Society of Mechanical Engineers Japan, 62(3), 62–67.

Nuyttens, D. De Schampheleire, M., & Baetens, K. (2009). Droplet size and velocity characteristics of agricultural sprays. Transactions of the ASABE, 52(5), 1471–1480. https://doi.org/10.13031/2013.29127

Palanti, L. & Prat, S. (2022). An attempt to predict spray characteristics at early stage of the atomization process by using surface density and curvature distribution. International Journal of Multiphase Flow, 103, 103879. https://doi.org/10.1016/j.ijmultiphaseflow.2021.103879

Prigent, S., & Andres-Casado, C. (2022). STracking: a free and open-source Python library for particle tracking and analysis. Bioinformatics, 38(7), 3671–3673. https://doi.org/10.1093/bioinformatics/btac365

Rivas, J. R. & Perales, A. (2022). An improved theoretical formulation for Sauter mean diameter of pressure-swirl atomizers using geometrical parameters of atomization. Propulsion and Power Research, 240-252. https://doi.org/10.1016/j.jppr.2022.02.007

Rajan, R., & Prasad, A. P. (2001). Correlations to predict droplet size in ultrasonic atomisation. Ultrasonics, 39(6), 469–478. https://doi.org/10.1016/s0041-624x(01)00054-3

Rizkalla, A. A., & Lefebvre, A. H. (1975). Influence of liquid properties on airblast atomizer spray characteristics. Journal of Engineering for Power, 97(2), 173–177. https://doi.org/10.1115/1.3445951

Roberts, P. G. (2022). Computationally-derived submodel for thermally-induced secondary atomization. Elsevier SSRN, 12, 123448. https://doi.org/10.2139/ssrn.4140997

Schaschke, C. (2014). Dictionary of Chemical Engineering (1 ed.). Oxford: Oxford University Press.

Shokrani, A. & Azar-Salim, I. (2019). Hybrid cryogenic MQL for improving tool life in machining of Ti-6Al-4V titanium alloy. Journal of Manufacturing Processes, 43, 229–243. https://doi.org/10.1016/j.jmapro.2019.05.006

Smith, J. D. (2021). Atomization of glycerol-water mixtures using a pressure-swirl atomizer. Journal of Fluid Mechanics, 34(1), 45–65. https://doi.org/10.1016/j.jfluidmech.2021.05.065.

Thompson, J. S., & Halden, O. (2016). The identification of an accurate simulation approach to predict the effect of operational parameters on the particle size distribution of powders produced by an industrial close-coupled gas atomizer. Powder Technology, 291, 75–85. https://doi.org/10.1016/j.powtec.2015.12.001

Trautner, E. & Herrmann, J. (2023). Primary atomization of liquid jets: Identification and investigation of droplets at the instant of their formation using direct numerical simulation. International Journal of Multiphase Flow, 160, 104360. https://doi.org/10.1016/j.ijmultiphaseflow.2022.104360

Vankeswaram, S. K., & Dey, S. (2022). Size and velocity characteristics of spray droplets in near-region of liquid film breakup in a swirl atomizer. Experimental Thermal and Fluid Science, 133, 110505. https://doi.org/10.1016/j.expthermflusci.2021.110505

Vankeswaram, S. K., & Suryanarayanan, R. (2023). Evaluation of spray characteristics of aviation biofuels and Jet A-1 from a hybrid airblast atomizer. Experimental Thermal and Fluid Science, 142, 110820. https://doi.org/10.1016/j.expthermflusci.2022.110820

Xuan, R., & Gong, L. (2024). Study on spray characteristics of micro-nano bubble premixed fuel. Fuel, 15, 131035. https://doi.org/10.1016/j.fuel.2024.131035

Zhai, C. & Jiang, Y. (2021). Diesel spray and combustion of multi-hole injectors with micro-hole under ultra-high injection pressure--non-evaporating spray characteristics. Fuel, 283, 119322. https://doi.org/10.1016/j.fuel.2020.119322

Zhang, L. & Smith, S. (2019). Effects of Liquid viscosity on agricultural nozzle droplet parameters. Agricultural Sciences, 10(9), 1217–1239. https://doi.org/10.4236/as.2019.109091

Zhao, T. & Li, D. (2023). Spray characteristics of RP-3 Jet fuel at non-evaporating and evaporating environments. Journal of Thermal Science, 29(4), 123–137. https://doi.org/10.1007/s11630-022-1755-x

Zhong, W., & Xu, Z. (2024). Investigations on high-speed flash boiling atomization of fuel based on numerical simulations. CMES-Computer Modeling in Engineering & Sciences, 142(3), 621–635. https://doi.org/10.32604/cmes.2023.031271

Zhou, W., & Xiang, X. (2022). Experimental and numerical investigations on the spray characteristics of liquid-gas pintle injector. Aerospace Science and Technology, 123(3), 107354. https://doi.org/10.1016/j.ast.2022.107354