Browsing by Author "Figueiredo, A. Rui"
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- Empirical correlation to estimate the optimum jet velocity of an air curtainPublication . Goncalves, J. C.; Costa, José; Figueiredo, A. Rui; Lopes, AntónioThis paper presents the results of a parametric study to quantify the influence of some thermal and geometrical parameters (door height) on the performance of an Air Curtain Device (ACD). The experimental facility consists of two similar adjacent rooms connected by a door over which the ACD device was installed. The tracer gas technique was used to calculate the sealing effect achieved with the air curtain at different jet velocities. Using a commercial CFD software, a numerical study was also performed to simulate the heat and mass transfer phenomena, as well as the aerodynamic sealing efficiency. A good agreement was observed between experimental and numerical results, showing that the optimum discharge velocity of the ACD air jet increases almost linearly with the door height, as well as with the temperature difference between both sides of the air curtain. It was possible to establish an empirical correlation that predicts reasonably well the optimum discharge jet velocity of a vertical air curtain device, depending on the temperature difference and the doorway height. An electronic device can be included in the ACD enabling the automatic adjustment of the air curtain jet velocity based this correlation, in order to continuously operate close to maximum sealing efficiency.
- Estudo experimental e numérico do escoamento de um jacto plano originado por um dispositivo de cortina de arPublication . Goncalves, J. C.; Costa, José; Figueiredo, A. Rui; Lopes, AntónioNos domínios comercial ou industrial, são muito utilizadas barreiras aerodinâmicas – designadas por cortinas de ar – para confinar ambientes específicos. Neste trabalho apresenta-se o estudo experimental do jacto originado por um equipamento de cortina de ar. Recorrendo à Mecânica de Fluidos Computacional (CFD, foi também realizado um estudo numérico - 3D. Os resultados obtidos por ambas as vias, experimental e numérica, permitiram a caracterização detalhada do escoamento do jacto, sendo coerentes com o esperado para o problema físico em estudo, e coerentes entre si. Um dos aspectos interessantes observados nos ensaios experimentais, foi que o nível de turbulência inicial do jacto se situou sempre abaixo dos 5%, para as diferentes velocidades impostas ao jacto, o que confirma um bom projecto do bocal de descarga
- Numerical study of the optimal nozzle width and jet orientation in a downward blowing air curtainPublication . C. Goncalves, J.; Costa, José Joaquim Da; Gameiro Lopes, Antonio; Figueiredo, A. RuiThis paper presents a numerical study of the performance of an air curtain device (ACD) installed on top of the access door of a refrigerated room, aiming to quantify the influence of some parameters (nozzle width, initial orientation and discharge velocity of the jet) towards the maximization of the sealing effect. For this purpose, a numerical model was developed to simulate the turbulent non-isothermal 3D airflow generated by the ACD jet, focusing on the period after the door is opened. The situation when the ACD is switched off is taken as the reference for the performance evaluation. The results allow identifying an optimum jet nozzle width corresponding to maximum sealing efficiency and lower jet airflow rate (lower energy consumption in the air curtain operation). For the present conditions (ACD installed outside the refrigerated room), the sealing efficiency is highest with the ACD oriented vertically and is practically unaffected if the jet discharge is directed towards the warmer space. On the contrary, a jet discharged towards the cooler space is very detrimental to the ACD sealing effect