Aerodynamic Entropy Generation Rate in a Boundary Layer With High Free Stream Turbulence

Abstract

The loss mechanism under consideration in this study is that fraction of turbomachinery blade profile loss 1 due to viscous dissipation and turbulent phenomena in the blade boundary layer. In the consideration of profile loss it is customary to neglect any end wall effects and as such the flow is approximately two-dimensional. Hence loss measurements can be based on cascade tests and boundary layer calculations. It has been proposed in 1 that the concept of entropy generation be used as the key measure of lost performance in turbomachinery, as opposed to the more traditional loss calculation methods based on stagnation pressure and kinetic energy losses. Assessment of loss in terms of the entropy generation rate is not dependant on whether it is examined from the perspective of a stationary or rotating blade row, thereby enabling direct comparison between measurements from cascades and rotating facilities.