Non-intrusive measurements and numerical comparison of the axial velocity components in a two-dimensional flow channel for a backward facing step and a rib roughened surface

Axial velocity profiles are presented for the flow over a backward facing step at Reynolds numbers of 29,760 and 51,615. Both the mean velocity and the mean-square fluctuating velocity profiles are compared with those predicted by the k-epsilon model of turbulence. Measurements are also presented for the flow over a rib roughened surface at a mean Reynolds number of 50,150. The experimental geometry investigated is similar to that employed to promote turbulence and thereby improve the overall heat transfer from the fuel element cladding to the gas coolant within the Advanced Gas Cooled Reactor. (author)