Transitional Flow on Axial Turbomachine Blading

Correlations of data from constant-pressure flows are shown to seriously overestimate the transition length on axial turbomachine blades in regions of positive pressure gradient. The differences largely can be ascribed to the influence of the pressure gradient on the mechanism of laminar-turbu lent transition. A hypothesis of continuous breakdown of laminar instability waves, together with an estimate of the dominant disturbance frequency, is introduced to model the minimum possible length of transitional flow in terms of local boundarylayer parameters. This model should be preferable to a point transition assumption for predicting turbomachine blade flows. In practice, the transition length most probably will lie between the predictions of the minimum length model and those of constant-pres sure flow correlations.