Challenges within ventilation systems during accident situations

In order to be able to calculate HEPA filter margins, the mechanical loading at the service location of the filter units must be known. This makes necessary the development of suitable computer codes for modelling fluid dynamic transients. To help estimate the mechanical loading at the service location two fluid dynamic codes were investigated. The first one, called FLOWMASTER, shows good results in calculating steady state conditions, but fails in calculating fluid dynamic transients. The second one, called PROMO, fails in integrating the LAF subroutines like HEPAFIL or HEPAGAS. So the development of the LAF-Code LAFIS was intensified. To reduce the time loss of the numerical calculations for compressible flow-problems, the exact equations of the Δp-V-relation were replaced by an approximation. The exact solution is very close to the approximated solution. The energy equations were formulated, but still not integrated in the LAFIS-Code. Also the preparation of the equations for transient flow problems was finished. (orig.)