Instationary operation of a ventilation system

Ensuring the thermal comfort and improving the ventilation effectiveness are important goals designing ventilation systems. This study describes effects if the ventilation system of a room is run in an instationary operation mode. That means that the inflow velocities are varied in time. The influence of different periodic times of the variation of the inflow velocities is investigated numerically with CFD simulations. The CFD simulation setup is validated by comparing CFD results with experimental data (Aachen Model Room). This comparison shows very similar results for experimental and numerical data. The CFD results show a strong reduction of the occurring time-averaged velocities inside the Aachen Model Room and they show a destruction of large-scale structure like eddies if the ventilation system is run instationary. By varying the periodic time it can be shown that longer periodic times reduce the velocities stronger than shorter periodic times.