Three-Dimensional Laminar Flow in a Rotating Multiple-Pass Square Channel With Sharp 180-Deg Turns

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Abstract
This paper presents a study of three-dimensional laminar flow in a rotating multiplepass channel connected with 180-deg sharp bends. Fluid-flow fields are calculated for the entire domain via the Navier-Stokes equations through a finite-difference scheme. For closure of this elliptic-type problem, periodical fully developed conditions are employed between the entrance and exit of the two-pass module. Experiments for the stationary two-pass channel are conducted to validate the numerical procedure and data. The emphasis of the present prediction is on the rotating and through-flow rate effects on the fluid-flow and friction characteristics in the straight channel as well as in the turn region. It is found that the rotation-induced Coriolis force significantly raises the wall-friction losses in the straight channel. However, the head loss of the sharp turn is decreased with increasing rotation speed, because the flow discrepancy between the inlet and outlet of the sharp turn is less significant for the higher rotation speed. Moreover, overall pressure-drop penalty across the two-pass channel is found to be enhanced by the rotation speed as well as the duct through-flow rate.