Building an experimental database of droplet impact on heated walls using Shadowgraphy and infrared thermography

• Grant number: 23/08266-1
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: September 01, 2023
• End date: August 31, 2024
• 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

Abstract

The use of sprays is already a consensus in various industrial fields. In a combustion engine, for example, it is common to use a fuel injection system through sprays to prevent contact with the chamber walls. Another broad application is based on surface cooling, such as in a fast neutron nuclear reactor. Currently, the development of general models for sprays is limited, especially because this phenomenon is controlled by global average parameters. This difficulty can be overcome through the study and modeling of individual droplets: in addition to the dynamic parameters being similar in both applications, individual droplets, unlike sprays, can be locally controlled. There are many studies in the literature addressing the impact of individual droplets, but most have been limited to simplified measurement and visualization techniques. Therefore, there is a lack of works that combine advanced image analysis and temperature field measurement techniques, enabling a comprehensive phenomenological understanding. Considering the presented context, this Undergraduate Research project proposes the execution of single-droplet impact tests on heated surfaces using simultaneous Shadowgraph and infrared thermography techniques. The objective is to create a robust database by varying several experimental parameters, such as: i) plate thickness; ii) droplet diameter; iii) droplet impact velocity; iv) wall temperature; v) fluid type; and vi) fluid temperature. Finally, an inverse method will be used to estimate the heat flux at the droplet impact point and the energy dissipated during the phenomenon, comparing the experimental results with models available in the literature.