Numerical and experimental study of airflow patterns and global exchanges through an air curtain subjected to external lateral flow

Abstract

The objective of this study is to experimentally and numerically investigate the aerodynamic behavior and the effectiveness of an air curtain confining cavity and subjected to external lateral stream. Experiments were carried out on a scale down model (1:5) representing a generic configuration of a display case, using LDV and PIV techniques to investigate the air flow characteristics. Two complementary modelling approaches were performed. The first is based on computational fluid dynamics (CFD) which enables to better understand the local air flow characteristics, while the second deals on the global fluxes exchanged between the air curtain, the ambient and the cavity. The good agreement obtained between CFD and experimental results allows to validate the numerical model and also to build the global model. Comparisons of experimental and numerical data obtained with and without external perturbation make it possible to quantify the effect of the perturbation on the air curtain characteristics such as airflow patterns, velocity profiles, maximum velocity decay, half-width jet growth and its stability as well as those related to the global fluxes exchanged between the air curtain and its surroundings. To evaluate the sealing performance of the air curtain with and without external perturbation, dimensionless parameters related to air tightness, thermal entrainment and thermal confinement efficiency were identified and analyzed. It was showed that for higher values of external lateral velocity, the performance of the air curtain was reduced consequently.