Centrifugal effect on the boundary layer on a blade of an axial turbo-machine

Abstract

A study of the effect of centrifugal force acting on the turbulent boundary layer of a blade in a turbo-machine is presented. The study includes experimental work conducted in an apparatus featuring an annular cascade of compressor blades, designed to simulate the flow in a compressor. This is a case of three-dimensional turbulent boundary layer flow end the objects of the study were to find the magnitude of the cross-flow and gain a better understanding of the skewed boundary layers. It is found that the cross-flow which develops in the boundary layer is small with velocities of the order of 1/10 of the through-flow velocities. The study further resulted in the development of a model of skewed, turbulent velocity-profiles, involving two "universal" analytical functions and four parameters. This model has been used with success to describe the measured velocity-profiles. The use of the model and the general result that the cross-flow is small has made it possible to find solutions to the boundary layer integral equations written in a "streamline" coordinate system. Application of the calculation method for the experimental data has been made successfully. A loss parameter is defined and an extension to include the crossflow losses is suggested.