Active control of mixed convection in a rotating periodical two-pass duct by using trailing-wall transpiration

Deals with the flow reversal in a buoyancy-opposed rotating duct that causes heat transfer deterioration. An active technique of trailing-wall transpiration is adopted to check whether if can avoid the flow separation and subsequently improves the heat transfer deterioration Finite-difference method is employed to solve the three-dimensional Navier-Stokes equations and the energy equation. Periodic conditions are used between the entrance and exit of a typical two-pass duct for the closure of the elliptic problem. The predicted results reveal that fluid withdrawal through the trailing wall can avoid the flow separation from the leading wall of the radial-outward duct (ROD) and thus eliminate local hot spots. In addition, the trailing-wall suction not only increases the peripherally averaged heat transfer but also reduces the friction loss in the ROD. In the radial-inward duct (RID) both the peripherally averaged heat transfer and peripherally averaged friction factor are augmented by trailing-wall injection and are degraded by the trailing-wall suction.