Numerical Analysis of the Effects of Enclosure Geometry and Opening Sizes on the Aerodynamic Performance of Positive-Pressure Ventilators

Authors:
Open Access
Publisher website
Google Scholar
Abstract
The efficiency of positive-pressure ventilation (PPV) in multi-story buildings is determined not only by the technical parameters of the mobile ventilators but also by the geometry of the gas exchange path. This paper presents the results of a computational fluid dynamics (CFD) analysis conducted using the Large Eddy Simulation (LES) approach to evaluate the impact of varying ceiling and outlet window opening areas on tactical ventilation effectiveness. The numerical model was validated against full-scale experimental data, yielding high convergence for the incoming flow parameters—with flow rate and mean pressure deviations of merely 0.4% and 0.6%, respectively—thereby confirming that the Fire Dynamics Simulator (FDS) is a reliable research tool. The simulations evaluated variations in the opening sizes of ceilings (size coefficients: 1.0, 1.25, and 1.5) and windows (size coefficients: 1.0, 1.5, and 2.25). The volumetric flow rate varied widely, ranging from 13,729 m3/h to 19,148 m3/h, while the pressure drop coefficient ranged between 0.09 and 0.55. The findings demonstrate that enlarging the opening cross-sections along the entire gas exchange path reduces local resistance coefficients, consequently enhancing the total flow rate. Conversely, intentional throttling of the outlet opening enables the effective establishment of an overpressure barrier within the ventilated volume. This study confirms that LES modeling facilitates accurate forecasting of flow variables and optimization of tactical rescue operations without requiring costly full-scale field experiments on physical building structures. The data obtained aid incident commanders in selecting optimal opening configurations depending on the operational priority: dynamic smoke clearance or pressure stabilization within the protected volume.
Funding Information
  • AIRSAFE—Smoke Extraction Devices and Systems in Buildings (101/BW/CNBOPPIB/MNiSW/2026)

This publication has 24 references indexed in Scilit: