ABSTRACT
The flow fields in nuclear power plants are designed to be as turbulent as possible. However, under certain conditions, it is possible for these flow fields to be both laminar and turbulent in different parts of the plant at the same time. During normal operation, reactor flow fields are designed to be as turbulent as possible because turbulent flows have higher heat transfer coefficients than laminar flows. In turbulent flows, small turbulent eddies appear in the flow field, and the streamlines disappear. These turbulent eddies are superimposed on the overall direction of the flow. However, a laminar flow will have an entirely different radial velocity profile than a turbulent flow, and this is one of the reasons why the wall friction is greater for turbulent flow than it is for laminar flow. Laminar flows have relatively low heat transfer coefficients, and the velocity gradient next to the surface of a fuel rod is normally parabolic.
