The calculation of critical discharge rates with a one-dimensional finite difference model with consideration of discharge geometry

To determine critical discharge rates a one-dimensional finite difference model describing the one- and two-phase flow is used to simulate the fluid flow in the flow path closest to the discharge orifice where local pressure drop is strongest. The critical mass flow rate is limited to sonic flow at the discharge orifice. Thermodynamic nonequilibrium phenomena are taken into account. In the case of a discharge nozzle with a complicated geometry, the calculation of the critical discharge rate depends on how well the streamlines along the nozzle are simulated. A good approximation of the discharge geometry is possible with the 1-D finite difference model. The model was verified by the results of serval experiments. The influence of the discharge geometry has been extensively investigated using the results of the LOBI-nozzle calibration tests