Eventos Anais de eventos
CREEM2025
CREEM 2025 - XXXI Congresso Nacional de Estudantes de Engenharia Mecânica Congresso Nacional de Estudantes de Engenharia Mecânica
Detecção da coalescência de gotas por fluorescência induzida por laser
Submission Author:
Gabriel De Souza , SP , Brazil
Co-Authors:
Gabriel De Souza, Arthur Vieira da Silva Oliveira
Presenter: Gabriel De Souza
doi://10.26678/ABCM.CREEM2025.CRE2025-0117
Abstract
Droplet impact on surfaces occurs in several industrial applications, such as cooling of heated metals, agricultural spraying, and material deposition in additive manufacturing. Although many studies focus on single droplet impacts, real-world situations involve interactions between multiple droplets. When a droplet already adhered to the substrate is struck by another, the coalescence between them can substantially modify the spray behavior. Understanding these processes is essential to model impact phenomena accurately. In this work, we explore the coalescence resulting from droplet impact using laser-induced fluorescence. One of the droplets was labeled with the fluorescent dye sulforhodamine B (10−6 mol/L), while the other was undyed. The interactions were captured by a high-speed camera (5,000 fps, 15.22 µm/pixel). A high energy, high-frequency pulsed laser was used for fluorescent excitation, and background illumination was used to improve visualization. Even for different impact velocities and distances between droplet centers, we observed the formation of a fluorescent neck that marked the beginning of coalescence, followed by mixing of the fluids. We present the details of this result of detecting the beginning of coalescence and discuss the difficulties of quantifying mixing (in volumetric fraction) due to optical effects.
Keywords
LIF, Sprays, Mecânica dos fluidos
