LOCAL HEAT-TRANSFER IN AXIALLY FEEDING RADIAL FLOW BETWEEN PARALLEL DISKS

Experiments and computations were performed to determine the local heat transfer in radial flows between parallel concentric disks. The flow is supplied axially by a feeding orifice placed in one of the disks and becomes radial after being deflected by the frontal disk. The frontal disk is kept isothermal and the other solid surfaces washed by the flow are kept adiabatic. Local heat transfer coefficients were determined using the naphthalene sublimation technique and the analogy between heat and mass transfer. Computations were performed using a finite volume methodology. The local Nusselt number distribution showed a valley at the stagnant region in front of the feeding orifice and a peak at the diffuser entrance where the flow impinges on the frontal disk prior to becoming radial. Depending on the Reynolds number and on the gap between the disks a secondary peak was observed in the diffuser region. The secondary peak is believed to be caused by nonparallelism or unsteadiness of the flow field and was not captured by the numerical model.