Browsing by Issue Date, starting with "2025-04-15"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
- Teoria critica de apoio pedagógico à unidade curricular de Desenho IPublication . Sequeira, João Manuel Barbosa Meneses deO presente manual insere-se no âmbito da unidade curricular de Desenho I, leccionada no 1.º ano do Mestrado Integrado em Arquitectura da Universidade da Beira Interior. Resulta de uma prática pedagógica continuada que, ao longo dos últimos anos, tem procurado articular a formação técnica do desenho com uma reflexão crítica e sensível sobre o papel da representação na génese do projecto arquitectónico. Embora concebido como instrumento de apoio ao ensino, o seu horizonte ultrapassa o contexto estrito da unidade curricular, visando propor um contributo mais amplo para a pedagogia do desenho em arquitectura.
- Droplet Impact onto Heated Wetted Surfaces: A Fundamental StudyPublication . Rodrigues, Daniel de Almeida Vasconcelos ; Silva, André Resende Rodrigues daThe industrialisation and globalisation of the modern world severely increased the demand for energy production, primarily met by a dependence on fossil fuels. The projected exponential growth of the aviation sector will result in an increase in greenhouse gas and pollutant emissions. Due to this, researching sustainable and cleaner alternative fuels is crucial to neutralise the negative effects of conventional fuels. The physical and chemical processes occurring inside a combustion chamber include fluid dynamics, heat and mass transfer, combustion, among others. Specifically, the phenomena regarding the impact of droplets onto solid surfaces and liquid layers are often encountered in internal combustion engines, heat exchangers and spray cooling. Research on these applications focuses on understanding fluid flow and optimising heat and mass transfer mechanisms. Despite this, single droplets impacting onto liquid films are limited to isothermal conditions, as the influence of temperature on liquid films has been overlooked in the literature. Therefore, the primary objective of this work is researching the phenomena of droplet impact onto heated liquid films. An experimental facility was designed and adapted to account for isothermal and non-isothermal conditions. The key aspects of the experimental facility consist of high-speed imaging and heating systems. Prior to the impact phenomena, the liquid film characterisation is required in terms of temperature fields and evaporation rates. Subsequently, various outcomes from droplet impact are evaluated as a function of the liquid film temperature, including central jets, craters, splashing, and bubbling. Qualitative analysis is conducted on outcome development, while quantitative measurements focus on geometric parameters. Theoretical work is performed regarding the propagation of kinematic discontinuities in liquid layers and time scales for crater and central jet evolution, respectively. The experimental data provides a foundation for the implementation and validation of the numerical model. This model solves the incompressible Navier-Stokes equations coupled with the Volume of fluid (VOF) method under a 2D-axisymmetric assumption. The open-source Computational Fluid Dynamics (CFD) software Basilisk is adopted for the numerical simulations. Overall, the liquid film temperature and correspondent thermophysical properties play a major role in the impact dynamics. Higher values of the dimensionless temperature promote and increase the occurrence and number of secondary droplets, respectively. This is associated with lower values of viscosity and surface tension, contributing to higher Reynolds and Weber numbers. For the onset of boiling, the oscillations induced on the liquid film are not sufficient to affect the impact phenomena. The presence of vapour bubbles in the impact region decreases both the crown diameter and height, with its effect being more pronounced for the latter.