Abstract
Flow and heat transfer in turbomachinery components is a particularly important area where reliable numerical calculation methods are needed. The turbulence and transition phenomena are complex and hence considerable research effort is spent in this area to develop such methods that can be used for design optimisation in practice. Here we report on research carried out with the method of Direct Numerical Simulation (DNS) with the aim of helping to understand the complex phenomena and to provide data for the improvement and testing of engineering transition and turbulence models. Periodic unsteadiness, caused by rotor-stator interaction, and relatively low Reynolds numbers are characteristic for flow in certain turbomachinery components. Both phenomena directly affect blade boundary layer transition, the tendency to separation, heat transfer and flow losses. While industrial CFD procedures are able to accurately predict inviscid flow, the models used for transition and turbulence are still not sufficiently reliable and universal. In turbomachinery cascades, the focus is on flow periodicity caused by oncoming wakes of upstream rotor or stator blade rows which travel through the cascade, generating a very complex flow and transition scenario which are difficult to predict. The authors have investigated this problem by performing a series of Direct Numerical Simulations of transitional flow in turbine-related geometries. This work is briefly summarized here. A more complete summary is given in [1].
