The present paper evaluates two unsteady transition modelling approaches: the prescribed unsteady intermittency method PUIM, developed at Cambridge University and the dynamic unsteady intermittency method developed at Ghent University. The methods are validated against experimental data for the N3-60 steam turbine stator profile for steady and for unsteady inlet flow conditions. The characteristic features of the test case are moderately high Reynolds number and high inlet turbulence intensity, which causes bypass transition. The tested models rely both on the intermittency parameter and are unsteady approaches. In the prescribed method, the time-dependent intermittency distribution is obtained from integral relations. In the dynamic method, the intermittency distribution follows from time-dependent differential equations. For unsteady computations, self-similar wake profiles are prescribed at the inlet of the computational domain. Joint validation of the prescribed and the dynamic unsteady intermittency models against experimental data shows that both methods are able to reproduce the global features of the periodical evolution of the boundary layer under the influence of a periodically impinging wake. The overall quality of the dynamic method is better than that of the prescribed method.

This paper presents the results of tests and validations of the γ-Reθ model proposed by Menter et al. (2006, “A Correlation-Based Transition Model Using Local Variables—Part I: Model Formation,” ASME J. Turbomach., 128, pp. 413–422), which was extended by in-house correlations for onset location and transition length. The tests performed were based on experimental data from the flat plate test cases available at the ERCOFTAC database as well as on experimental data from the turbine blade profile investigated at Czestochowa University of Technology. Further on, the model was applied for unsteady calculations of the blade profile test case, where chosen inlet conditions (turbulent intensity and wake parameters) were applied. For the selected case, numerical results were compared not only with the experimental data but also with the results obtained with other transition models. It was shown that the applied model was able to reproduce some essential flow features related to the bypass and wake-induced transition, and the simulations revealed good agreement with the experimental results in terms of localization and extent of wake-induced transition.

The paper presents an experimental and numerical analysis of the interaction between wakes and boundary layers on aerodynamic blade profiles. The experiment revealed that incoming wakes interact with boundary layers and cause the significant increase of velocity fluctuations in the boundary layer and in consequence shift the transition zone towards the leading edge. The full time evolution of periodic wake induced transition was reproduced from measurements. The numerical simulation of the flow around the blade profile has been performed with the use of the adaptive grid viscous flow unNEWT PUIM solver with a prescribed unsteady intermittency method (PUIM) developed at Cambridge University, UK. The results obtained give evidence that the turbulence transported within the wake is mainly responsible for the transition process. The applied CFD solver was able to reproduce some essential flow features related to the bypass and wake-induced transitions and the simulations reveal good agreement with the experimental results in terms of localisation and extent of wake-induced transition.

The paper presents the results of tests and validations of γ-Reθ model proposed by Menter at al [10], which was extended by in-house correlations on onset location and transition length. The tests performed were based on experimental data on the flat plate Test Cases available at ERCOFTAC Data Base as well as on experimental data of turbine blade profile investigated at Czestochowa University of Technology. Further on, the model was applied for unsteady calculations of the blade profile test case, where chosen inlet conditions (turbulent intensity, wake parameters) were applied. For the selected case numerical results were compared not only with the experimental data, but also with the results obtained with other transition models. It was shown that the applied model was able to reproduce some essential flow features related to the bypass and wake-induced transitions and the simulations reveal good agreement with the experimental results in terms of localisation and extent of wake-induced transition.