14 documents found, page 1 of 2
Effect of Vapour Bubble Initial Displacement on Droplet Impact onto Liquid Films
Vasconcelos, Daniel; Silva, A. R. R.; Barata, Jorge M MHeat and mass transfer mechanisms regarding droplet impact have been extensively studied for dry surfaces, and in terms of droplet evaporation/combustion during free-fall. On the contrary, the droplet impact phenomena onto heated liquid films is a topic overlooked in the literature and requires further understanding in terms of hydrodynamics and phase change. Therefore, this work focuses on numerically simulati...
The impact of temperature on heated liquid films: Crater and jetting impact dyn...
Vasconcelos, Daniel; Silva, A. R. R.; Barata, Jorge M MThe droplet impact phenomena onto liquid films are a field extensively researched for over a century, which are driven by many practical applications such as heat exchangers, internal combustion engines and spray cooling. Despite the extensive work on wetted surfaces, the influence of temperature on droplet outcome, local evaporation/boiling effects, and liquid film stability has been overlooked in the literatu...
Does liquid film temperature affects single drop impact dynamics?
Mendes, André F. S. F.; Vasconcelos, Daniel; Ribeiro, Daniela; Panão, Miguel; Silva, A. R. R.The effect of liquid film dynamics in the hydrodynamics of an isolated drop impact is a complex phenomenon and not fully understood. Therefore, in this work, an experimental setup built to characterize the impact of an isolated droplet on heated and unheated liquid films consists of a heating element made of an aluminum block with resistances to produce several impact conditions. The parametric studies include ...
Influence of bubble growth and liquid film instabilities on droplet impact phen...
Vasconcelos, Daniel; Silva, A. R. R.; Barata, Jorge M MEvaporation and boiling are processes that occur in many industrial applications involving multiphase flows. For liquid films, however, studies are scarce regarding heat and mass transfer mechanisms and require further research. The main objective of this work is to evaluate bubble formation and detachment, followed by the impact phenomena. Therefore, an experimental setup was built and adapted for this purpose...
Influence of Dimensionless Temperature on Droplet Impact onto Heated Liquid Fil...
Vasconcelos, Daniel; Silva, A. R. R.; Barata, Jorge M MHeat and mass transfer mechanisms related to multiphase flows occur in several applications such as spray cooling, quenching, internal combustion engines and plasma spraying. These mechanisms have become increasingly important due to the need of achieving higher heat rate coefficients associated with phase-change processes, such as evaporation and condensation. Specifically, the phenomenon of droplet impact ont...
Influence of Vapour Bubbles Size and Spacing on Droplet Impact Outcomes under S...
Vasconcelos, Daniel; Silva, A. R. R.; Barata, Jorge M MMultiphase flows are characterised as heterogeneous mixtures of two or more phases, such as gas-liquid or solid-liquid. These are extremely complex due to the underlying dynamics that may occur, which include interfacial phenomena, such as boiling and evaporation, and interactions between phases. Specifically, droplet impact onto heated wetted surfaces has been overlooked in the literature, which involves heat ...
Design and Fabrication of a Low Cost, Push Mode Piezoelectric Stream Droplet Ge...
Cardoso, João; Moura, Cátia Isabel Neves; Ribeiro, Daniela; Vasconcelos, Daniel; Barata, Jorge M M; Silva, AndréThe interest in studying droplet related phenomena has been increasing over the last decades.In the fluid dispensing equipment industry, a major problem is to minimize droplet diameter andto eject droplets in a controlled manner with a low-cost device. Taking all this into account, anew low-cost droplet stream generator was designed and fabricated. The material used to man-ufacture the stream droplet generator ...
Comparison of Commercial and Open-Source CFD Solvers on Surface Tension Dominat...
Vasconcelos, Daniel; Silva, André; Barata, Jorge M MProblems involving multiphase flows require a physical understanding of how the phenomenadevelop and the specific interactions they manifest. For surface tension relevant flows, suchas bubbles and droplets, the importance of modelling and predicting small-scale behaviouris crucial in accurately defining the liquid-gas interface and complex interactions that may takeplace. Axisymmetric numerical simulations of s...
Collision Dynamics of a Single Droplet onto a Heated Dry Surface: Jet Fuel and ...
Pinto, Pedro Miguel Moreira; Vasconcelos, Daniel; Ribeiro, Daniela; Barata, Jorge M M; Silva, AndréUnderstanding the phenomena behind droplet impact is essential to improve the effectivenessin many industrial applications, such as fuel injection in an internal combustion engine andrapid spray cooling of hot surfaces. This study focuses on an experimental investigation ondroplet impact onto a heated wall. The purpose of this work is to analyse the influence of walltemperature on the morphology of a single dro...
A study of droplet deformation: The effect of crossflow velocity on jet fuel an...
Ferrão, Inês; Vasconcelos, Daniel; Ribeiro, Daniela; Silva, A. R. R.; Barata, Jorge M MThe aeronautical sector has been, in the last decade, one of those that most invested in more efficient and ecological solutions in order to reduce significantly greenhouse gas and pollutant emissions. The introduction of biofuels in fuel mixtures for aircraft engines is a promising alternative in this sector. The main objective of this experimental study is understanding the influence of crossflow variation on...