Impact of rib shape on heat transfer using LES

Abstract

Numerical studies of the flow field and heat transfer in a fully developed ribbed channel have been performed using Large Eddy Simulation (LES). Validation of the LES against measurements shows encouraging agreement. An immersed boundary method (IBM) has been implemented and validated for use with LES to solve the challenge of varying complex rigid geometries. Ten different rib shapes are investigated aiming to improve heat transfer performance, i.e., square, perforated, triangular with increasing height in the flow direction, triangular with decreasing height in the flow direction, pentagonal with increasing height in the flow direction, pentagonal with decreasing height in the flow direction, house-shaped, groove-shaped, semicircular and arc. The triangular rib with increasing height in the flow direction, with the largest recirculation bubble, was found to provide the best heat transfer performance (accounting for pressure loss), giving up to 7% greater heat transfer than the basic square profile. Ribs with larger recirculating zones tend to provide better heat transfer performance. Rounded-corners with the shortest recirculation zones deteriorated heat transfer performance. Adding round edges to the triangular_up ribs to fit manufacturing conditions, led to heat transfer performance reduction of 12–16%.