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Descrevem-se as metodologias utilizadas num estudo que teve por objectivo a avaliação do efeito de vedação promovido por um aparelho de cortina de ar. Foi utilizada uma instalação experimental à escala real em que, através de um jacto de ar descendente gerado por cima da porta, se procurou manter uma dada diferença de temperatura entre duas salas contíguas. Recorrendo a 16 sondas anemométricas, efectuou-se o mapeamento da temperatura e da velocidade do ar em diversos planos considerados de interesse e, através da aquisição desses dados em contínuo, avaliou-se o desenvolvimento e a estabilidade do jacto durante os primeiros minutos de funcionamento da instalação. Recorreu-se igualmente a uma técnica de medida do tipo “whole-field” em que o campo de temperaturas do ar é medido indirectamente através de um ecrã de baixa massa térmica que serve de alvo a uma câmara termográfica de infra-vermelhos. Ao longo do artigo serão apresentados vários exemplos elucidativos das potencialidades das técnicas descritas anteriormente.

Among the different existing methods to characterise the aerodynamic sealing effect provided by an air curtain device placed over the opening between two contiguous compartments, infrared thermography has revealed to be a very useful tool. Besides allowing the capture, in an expedite way, of instantaneous images of the temperature field in the neighbourhood of the door, the technique hereon described has other advantages, in terms of quick and easy setup, low intrusive character and liability of obtained results. To apply this method, a large sheet of paper was stretched in the direction perpendicular to the opening where the air curtain device has placed to allow the registration of pictures or video sequences with an infrared camera setup in its maximum sensitivity. Good concordance between the thermographs obtained with this technique and the temperature fields measured for the same plane with a rack of 16 low velocity omni-directional thermal anemometer probes allowed its validation. Various elucidative examples of the use of this technique as a complementary tool for analysis and visualization of the complex physical phenomena occurring for the studied flow are presented in this article.

In commercial and industrial activities, there is often a need for reducing or controlling heat and mass transfer between outside environment and indoor compartments with controlled atmosphere, warranting, simultaneously, an easy circulation of people and equipments. In practical terms, the confinement of a given space can be achieved with aerodynamic barriers (air curtains) constituted by one or more air jets. In the present paper, the loss of efficiency of a vertical downward air curtain due to the seesaw permanent movement of a person is analyzed. Results show a systematic loss of the sealing efficiency (10 to 20%) of the air curtain device when the doorway is periodically crossed by a computer controlled manikin “Roberta” relatively to the results obtained without this traversing movement.