Steady and Unsteady Transition Modelling in Turbomachinery

In turbomachinery and especially in aircraft engines laminar-to-turbulent transition greatly affects boundary layer development, flow separation, losses, efficiency and heat transfer. So the ability to accurately predict the transition process in a turbomachinery environment is crucial for the design of efficient and reliable machines. But it is extremely difficult to model laminar-to-turbulent transition with a widely applicable predictive scheme. Therefore an increasing number of experimental investigations have been performed in the last years to improve the understanding of the physics of transition and to provide empirical correlations for the use in numerical flow solvers. Recently, transition models based on one-equation transport models have been presented which have some advantages compared to the algebraic models normally used. First computational investigations performed by the aerodynamic group at the institute give very promising results for this kind of models, so that further research on their applicability for unsteady and steady transition processes as well as for the prediction of separated-flow transition seem to be worth while. Achieving progress in this area and expanding the range of validity is the principal aim of the present research proposal. To achieve this goal at first extensive numerical studies will be performed to analyse the strengths and weaknesses of many different approaches. Based on these results the one-equation transition model at the institute will be modified and extended in close co-operation with international research groups and the experimental group at the institute. The final model shall cover steady and unsteady transition processes for attached as well as separated flow for a broad range of applications. It can be easily implemented into existing flow solvers, so that it is intended to be a very valuable tool provided to design engineers for layout of future highly efficient turbomachinery.

In turbomachinery and especially in aircraft engines laminar-to-turbulent transition greatly affects boundary layer development, flow separation, losses, efficiency and heat transfer. So the ability to accurately predict the transition process in a turbomachinery environment is crucial for the design of efficient and reliable machines. But it is extremely difficult to model laminar-to-turbulent transition with a widely applicable predictive scheme. Therefore an increasing number of experimental investigations have been performed in the last years to improve the understanding of the physics of transition and to provide empirical correlations for the use in numerical flow solvers. Recently, transition models based on one-equation transport models have been presented which have some advantages compared to the algebraic models normally used. First computational investigations performed by the aerodynamic group at the institute give very promising results for this kind of models, so that further research on their applicability for unsteady and steady transition processes as well as for the prediction of separated-flow transition seem to be worth while. Achieving progress in this area and expanding the range of validity is the principal aim of the present research proposal. To achieve this goal at first extensive numerical studies will be performed to analyse the strengths and weaknesses of many different approaches. Based on these results the one-equation transition model at the institute will be modified and extended in close co-operation with international research groups and the experimental group at the institute. The final model shall cover steady and unsteady transition processes for attached as well as separated flow for a broad range of applications. It can be easily implemented into existing flow solvers, so that it is intended to be a very valuable tool provided to design engineers for layout of future highly efficient turbomachinery.