Effects of leading-wall blowing/suction on mixed convective phenomena in aradially rotating multiple-pass duct

A numerical study is performed to examine the transpiration-wall effect on mixed convection in a radially rotating multi-pass square duct connected wi th 180 degrees sharp returns. Uniform injection or suction is applied to th e leading wall of the rotating duct. Finite-difference method is adopted to solve three-dimensional Navier-Stokes equations and the energy equation. P eriodic conditions are used between the entrance and exit of a typical two- pass duct for the closure of the elliptic problem, As predicted, results sh ow that the radial distance from the rotational axis to initiation of flow reversal in the radial-outward duct (ROD) decreases with increasing rotatio nal buoyancy. The appearance of flow reversal is delayed by the leading-wal l blowing but is quickened by the leading-wall suction. The wall-blowing ra te for avoiding the flow reversal in the ROD increases with increasing rota tional buoyancy. Moreover, the axial distribution of peripherally averaged Nusselt number is closely related to the development of cross-flow intensit y. They are increased/decreased with increasing the wall blowing/suction ra re in the ROD but are essentially unaltered in the radial-inward duct (RID) . (C) 1999 Elsevier Science Ltd. All rights reserved.