Abstract
ABSTRACTThis study investigated the time based spray evolution of chemically modified tapioca starch through three full cone nozzles namely FC-2, FC-3 and FC-3.5. The objective was to study the effect of temperature, viscosity and nozzle orifice diameter on spatio-temporal droplet size-velocity profiles of the sprayed material. Owing to high viscosity, the unheated spraying medium did not exhibit any breakup over time. However, pre-spray heating of the medium at 80°C caused immediate sheet breakup near nozzle exit point at injection pressure of 5 bar. The spray growth from FC-2 was relatively faster than other tested nozzles; the unstable sheet disintegrated into fully developed spray patterns after 250 ms of the injection time. Unlike FC-2, the jet from FC-3 and FC-3.5 exhibited steady breakup at early and late injection stages, however, relatively fast breakup was seen in the middle part of the spray stream. Phase Doppler Anemometry (DualPDA) data showed a linear increase in Sauter Mean Diameter (SMD) with orifice size. At 140 mm downstream, the smallest SMD of 59 µm was obtained with FC-2 nozzle followed by FC-3 (65 µm) and FC-3.5 (83 µm). The overall SMD was decreased by 44.7% with an increase in orifice diameter from 1.19 to 1.59 mm. The droplet velocity in axial direction dropped sharply with time in the range of 100 to 300 ms, thereafter showed negligible decrease over time. Unlike this, the droplet velocity in the radial direction was dropping appreciably even after 300 ms of injection time.
Highlights
The jet flow and atomization of Newtonian and non-Newtonian liquids have been extensively studied during last few decades, it would be extremely difficult to search sufficient literature on the time based flow and spray evolution of native or modified tapioca starch (Suzuki et al, 2005; Jin et al, 2012)
This study investigated the time based spray evolution of chemically modified tapioca starch through three full cone nozzles namely FC-2, FC-3 and FC-3.5
Phase Doppler Anemometry (DualPDA) data showed a linear increase in Sauter Mean Diameter (SMD) with orifice size
Summary
The jet flow and atomization of Newtonian and non-Newtonian liquids have been extensively studied during last few decades, it would be extremely difficult to search sufficient literature on the time based flow and spray evolution of native or modified tapioca starch (Suzuki et al, 2005; Jin et al, 2012). To meet the slow release standards and to qualify as a good coating material, the. The enhanced viscosity can adversely influence the fluid flow and spray coating mechanism, specially, when the sprays are being generated via airless/hydraulic nozzles. When these nozzles are used to spray complex nonNewtonian liquids containing many different chemicals (Mei and Chen, 2008; Naz et al, 2015), the resulting combination of coating medium and spraying system often fails to meet the manufacturer's specifications and the standards set for slow release coated fertilizers. To the author's knowledge, there are no reports on the time function spray
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
