Strengthening, expanding and enduring the research collaboration between EESC/USP and LEMTA/UL on droplet impact studies and its applications

• Grant number: 23/14864-9
• Support Opportunities: Regular Research Grants
• Start date: April 01, 2024
• End date: July 31, 2025
• Field of knowledge: Engineering - Mechanical Engineering - Transport Phenomena
• Mobility Program: SPRINT - Projetos de pesquisa - Mobilidade
• Principal Investigator: Arthur Vieira da Silva Oliveira
• Grantee: Arthur Vieira da Silva Oliveira
• Principal researcher abroad: Michel Guy Alain GRADECK
• Institution abroad: Université de Lorraine (UL) , France
• Host Institution: Escola de Engenharia de São Carlos (EESC). Universidade de São Paulo (USP). São Carlos , SP, Brazil
• City of the host institution: São Carlos
• 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 increasing heat dissipation rates in devices require using efficient cooling methods, like microchannels heat sinks and spray cooling systems that are capable of reaching dissipated heat fluxes of several MW/m2. In the case of sprays, to improve this kind of cooling system, it is important to understand in more detail the dynamics and the heat transfer process during the droplet impact on heated surfaces. Studies of droplet impact on heated surfaces are also important to model the dissipated heat in steam-droplet flow, which can occur in evaporators and during a hypothetical loss-of-coolant accident in nuclear reactors. For instance, the droplets impinging on the heated fuel cladding can contribute to heat dissipation by more than 10% if there is a low fraction of droplets and, according to numerical simulations, up to 40% if there is a high fraction of droplets. However, it is necessary to go further: understand how the droplets interact with themselves (multiple-droplet impact) and how they interact with the surface (surface characteristics and texturing). Therefore, two research projects are taking place in Brazil and France at present. In Brazil, a FAPESP Young Investigator project led by Arthur Oliveira, Assistant Professor at EESC/USP, aims to investigate droplet interactions during the impact on heated surfaces. Meanwhile, in France, an ANR project (DROPSURF) led by Guillaume Castanet, Research Director at CNRS and hosted at LEMTA/UL, aims to investigate surface structuring effects on droplet impact. Finally, also at LEMTA, Michel Gradeck, Full Professor at UL, investigates droplets generated in a rewetting front to understand how this surface-liquid interaction during phase change affects droplets' size and velocity by spattering. (AU)