Heat transfer and flow structure in a detached latticework duct

Highlights: • The clearance is shown to improve the thermal performance of the latticework duct. • Effects of Coriolis force and clearance on heat transfer in a detached latticework are revealed. • Impingement, turn, helical flows and leakage flow are found in the detached latticework duct. -- Abstract: A numerical method was used to study the effect of clearance and rotational number on the thermal performance in a detached latticework duct. The latticework duct, which had four-entry sub-channels, was located in a simplified rectangular channel. The crossing angle for each sub-channel was 45°. The numerical studies were conducted with various clearances (0–0.5) and various rotational numbers (0–0.5). The streamlines, wall shear stress and Nusselt number were analyzed. The results indicated that the detached latticework provided a small mechanical energy loss with considerable heat transfer enhancement. In the traditional latticework duct, the impingement, turn and helical flows dominated the flow structure. The impingement and helical flows brought high Nusselt numbers and high wall shear stress in the latticework duct. In the detached latticework, the leakage flow, which is induced by the clearance, also changed the flow structure and heat transfer significantly. As the clearance was increased, the leakage became strong while the impingement and helical flows became weak. In the rotational condition, the Coriolis force promoted the heat transfer on the suction side but weakened the heat transfer on the pressure side. In addition, the wall shear stress on the suction side and leakage flow were increased under high rotational number.