| A simple, new model is developed to predict the transition in attached and separated shear layers in turbomachinery. The model controls the onset of transition through the production of turbulence kinetic energy and is based on the value of the vorticity Reynolds number, a concept introduced by Van Driest and Blumer (1963). The model has been calibrated for use with the Menter (1994) SST turbulence model. No additional transport equations are solved. The new transition model has been validated against a large number of challenging experimental cases, including the ERCOFTAC T3 series (Savill, 1993a,b) of test cases and a low-pressure turbine blade operating at very low Reynolds numbers under steady conditions and subjected to periodically impinging wakes. For the attached shear layers, the predictions were as good as or better than those obtained with well-established empirical correlations. Surprisingly, the model gave good results even for cases where the transition occurred in the free shear layer of a separation bubble or was caused by a periodically impinging wake. |
