Periodic transition on an axial compressor stator: Incidence and clocking effects: Part II - Transition onset predictions

Transition onset observations from a 1.5-stage axial compressor outlet stat or presented in Part I of this paper are compared with the predictions of c onventional transition correlations applied in a quasi-steady manner The vi scous/inviscid interaction code MISES is used to predict the blade surface pressure distributions and boundary laver development, The temporal variati on in transition onset is then predicted using ensemble-averaged free-strea m turbulence data from the compressor measurements. This simple procedure c aptures most significant features of the complex transition process on the compressor and is clearly superior to fixed transition models based on long -term average free-stream turbulence levels. Parallel computations for both natural and bypass transition modes indicate that the natural transition m ode tends to dominate on the compressor. This is at variance with turbine a irfoil experience, where bypass transition is clearly more important. Compa rison of prediction and experiment highlights the significance of leading e dge potential flow interactions in promoting periodic wake-induced transiti on. Viscous/ inviscid interactions in the neighborhood of transition can al so have an important influence an boundary layer stability and separation p henomena.