DETAILED EXPERIMENTAL AND NUMERICAL HEAT/MASS TRANSFER INVESTIGATIONS IN A ROTATING TWO-PASS COOLANT CHANNEL WITH STAGGERED 45° RIBS

摘要

The investigation described in this paper concentrates on heat/mass transfer measurements and numerical calculations in a rotating coolant channel with square cross section, 180 deg bend and staggered 45 deg rib arrangement. The data shown in this paper were obtained by tests using the naphthalene sublimation technique and calculations with a Reynolds number of 50.000 and Rotation numbers of 0 and 0.1. The influence of ribs and rotation on local heat/mass transfer on all walls and fluid flow is investigated. The results are shown as distributions of local Sherwood number ratios determined experimentally and Nusselt number ratios derived numerically as well as area averaged data. They can be compared by means of the analogy between heat and mass transfer. The experimental results are also compared with results obtained by tests with the smooth non-rotating and rotating model to show the influence of ribs. In order to understand the mass transfer results investigated experimentally and to compare these with numerical results, CFD calculations concerning fluid flow and heat transfer have been carried out with a block structured 3D Navier-Stokes solver. The detailed and the average heat transfer results show a strong enhancement due to the presence of ribs as it was shown by other researchers. In the case of the investigated Rotation number Coriolis forces only have a small influence on heat/mass transfer in the ribbed model. The experimental results show that due to the angled rib arrangement the unribbed side walls show in some cases higher heat transfer levels than the ribbed walls.