НАУЧНИ ТРУДОВЕ НА РУСЕНСКИЯ УНИВЕРСИТЕТ – 2014, том 53, серия 1.2 - 149 - On the influence of the pressure difference on air curtain behavior Emanuil Georgiev, Detelin Markov, Peter Stankov On the influence of the pressure difference on air curtain behavior: The aim of this paper is to present a study on the influence of the pressure differences on a working vertical and horizontal air curtains behavior and sealing efficiency. The study is based on a detailed numerical simulation by means of Computational Fluid Dynamics method - a standard k-ε turbulent model with a pressure based solver at a steady state condition together with a first order upwind discretization scheme were used. Key words: Vertical and horizontal air curtain, CFD, sealing efficiency. INTRODUCTION Air curtains are useful in situations where conventional barriers become unacceptable due to practical, economical or safety reasons. They are used to separate without a physical barrier two adjacent spaces with different indoor environment parameters; an indoor environment from the outdoor environment; warm indoor environment from the cold outdoor environment; cold indoor environment from the hot outdoor environment and to protect the exchange of matter – dust, moisture, pollutants, insects, etc. [1, 2, 3, 4] - Figure 1 [4]. The aim of the study is to evaluate flow pattern and sealing ability of different air curtains under isothermal conditions and various pressure differences between the outdoor environment and the protected space. Figure 1. Schematic representation of an air curtain NUMERICAL DETAILS In order to simulate a working vertical and horizontal air curtains a computational domain was built in Fluent’s preprocessing program Gambit 2.4 – Figure 2. The simulated situation was represented by 3 different volumes - 8x8x8 m for the outdoor environment, a volume of 4x4x4 m representing the protected space. The volumes have been connected through a third domain (a door) with dimensions 2x1x0,32 m (HeightxWidthxLength). On the top of the door a box simulating a conventional vertical air curtain with dimensions 0,25x025x2 m (HeightxWidthxLength) was placed. The suction and discharge nozzles of the vertical air curtain were represented by two rectangulars, with dimensions 0,9x0.05 m (LengthxWidth), placed on the top and respectively on the bottom of the box. The horizontal air curtain was built by a system of nozzles placed on the both sides of the door – four on the right and three on the left side – Figure 3.