This project aims to investigate the mixing of a cold water stream with turbulent hot water jets. This mixing happens in the control-rod guide tubes of several boiling water reactors and appears to trigger low-frequency temperature ﬂuctuations, which could lead to cracks and breaks in the control-rod stems.
High-cycle fatigue caused by temperature fluctuations also occurs in process plants, such as reﬁneries or liqueﬁed natural gas plants.
Overall, our research aims to develop methods for predicting the initiation and growth of fatigue cracks in pipe lines and components where hot and cold water mix, under small- and large-scale yielding.
Thus, inspection intervals and service programs can be established.
Specifically, our large-eddy simulations of turbulent mixing will provide data for a finite element model simulating fatigue crack initiation and growth.
The results will be validated via experiments performed at KTH.