Scaling of two fluid flow heated by fuel rod

General scaling laws for transient two fluid flow heated by a rod are presented. The similarity of these processes can be ensured only by the same volume-time scale with identical model parameters. In the practice the similarity of interfacial friction terms can not be fulfilled, because of volume/diameter/reducing scale. Numerical examples show deviations between the stat variables of the prototype and that of the scaled model, especially in transient mass flow rates. The deviations become significant when the slip of phase velocities exceeds the range of 1.6...1.8 during the transients. The volume- and the time scaling can be carried out, only if the phase velocities are similar/slip equal about 1 at quasi homogeneous flow model/. To maintain the similarity of heat transfer processes of the heated fuel rod can need the scaling of the time