Flow destabilization and heat transfer augmentation in an array of grooved passages with developing flow

In the current work, two-dimensional spectral element simulations are used to investigate the heat transfer and fan power performance of the developing regions of finite-length, grooved channel passage arrays, including the accelerating and decelerating flows entering and exiting the arrays. The performance of the grooved channel arrays is compared with that of flat passage arrays with the same average wall center-to-center spacing for Reynolds numbers ranging from 1000 to 3000. The simulations show that unsteadiness develops after a number of groove lengths and results in enhanced heat transfer. The unsteadiness improves the overall heat transfer compared with a flat passage array of equal average channel height by a factor of 1.46 at Re = 1000 and a factor of 2.75 at Re = 3000. The grooves also cause an increase in the required fan power by a factor of 8.56 at Re = 1000 and a factor of 18.10 at Re = 3000. Since past simulations have shown that three-dimensional simulations are necessary to accurately predict heat transfer and fan power performance in transversely grooved passages, the current two-dimensional results will be used as a starting point for a three-dimensional model that will ultimately be used to predict heat transfer and friction factor performance in developing grooved channel flows.