Windage loss and heat transfer in high speed, small gap rotating concentric cylinders

Abstract

In engineering, heat transfer in configurations involving two concentric cylinders, where the inner cylinder rotates and the outer cylinder remains at rest, are quite common. Considerable literature has been written on this subject, however a need has been identified which needs to be investigated in more detail. Configurations involving high speed, small gaps and high fluid viscosity, giving rise to very large Taylor numbers, are not well documented and this study investigates this situation. Extensive Computational Fluid Dynamics (CFD) models were produced in order to investigate the heat transfer characteristics. Existing published windage loss data was used in order to validate the CFD models. Correlations found in published literature on heat transfer in concentric cylinders, are only applicable for Taylor numbers much smaller than the Taylor numbers under investigation. However when the Nusselt number is redefined, these existing heat transfer correlations may be extended to much higher Taylor numbers.