Background: In recent years some reactors have experienced significant steam dryer cracking.In some cases

this cracking has necessitated unplanned outages to implement steam dryer repairs and has also resulted in de-rated operation of the affected units.Initial inspection showed it was likely that steam dryer had been damaged by high cycle fatigue due to flow-induced acoustic resonance in the main steam lines.Because of the complexity and acoustic-structure coupling effect

scale model test is adopted to research the mechanism of acoustic fatigue.Purpose: This paper describes the derivations of scaling laws observed to control the system response for phenomena considered to be significant in the real plants.Methods: Basic governing equations of elasticity and acoustics are written in non-dimensional form

non-dimensional groups are defined and derived.Results: Using the reference values in the real plants

the scaling laws and scaling relationships are derived and recognized to enable conversion of model data into real plant predictions.Conclusions: Successful model testing can be achieved if these significant parameters are preserved in the model scale.