High-repeatability monodisperse droplet generator: project, development and validation

• Grant number: 22/05287-5
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: June 01, 2022
• End date: July 31, 2023
• Field of knowledge: Engineering - Mechanical Engineering - Transport Phenomena
• Principal Investigator: Arthur Vieira da Silva Oliveira
• Grantee: João Marcelo Maris da Silva Filho
• Host Institution: Escola de Engenharia de São Carlos (EESC). Universidade de São Paulo (USP). São Carlos , SP, Brazil
• Associated research grant: 21/01897-0 - Experimental study of droplets impact onto heated walls using combined optical techniques: single droplets, multiple droplets and sprays, AP.JP
• Associated scholarship(s): 22/14365-0 - Characterization of in-house perforated membranes for a droplet train generator, BE.EP.IC

Abstract

Droplet impact research demands a droplet generation system that is capable to provide droplets with a constant volume, i.e. constant diameter. There are several methods to generate droplets; one of the most common is using a syringe pump to supply the desired volume and an impulse system or gravity itself is used to detach the droplets from the needle. The task becomes more challenging for multiple droplet studies, where all the droplets must have the same size and be released at the same time. This undergraduate research project has the objective to develop a droplet generation system for single and multiple droplet studies with good repeatability of droplet diameter and velocity after detachment. The student will need to study the basics of hydrodynamic instabilities and breakup processes and investigate different solutions for droplet detachment in the literature. Initially, the student will test two methods: choosing specific needles to release droplets at a given diameter by gravity and using a mechanical device to hammer the system and detach the droplet. If other solutions are judged appropriate for the project (use of speakers or airflow), those will also be tested. Using Shadowgraph (SDG), the student will perform experiments to evaluate the diameter and velocity of the droplet after release and test systems to generate from one to five droplets. This undergraduate research will provide to the research group with an important component in the new experimental bench to be built at the Mechanical Department of EESC/USP, São Carlos that will be used by two master's students and two direct doctoral students for studies of heat transfer during single and multiple droplet impact onto heated walls.(AU)