Investigation Into Coupling Techniques for a High Pressure Turbine Blade Tip

In this paper the aero-thermal performance of a high pressure turbine rotor blade is investigated, making use of coupled and uncoupled simulations. The fluid domain is solved via Finite Volume analyses whilst Finite Elements are used in the solid domain. In the CFD model, a temperature distribution is imposed as a boundary condition at the interfaces between the fluid and the solid domain. In the corresponding FE model, a convective zone is applied. The parameters of the convective zone are computed from the CFD analysis. In the uncoupled simulations, the convective zone can make use of a two or three parameters model. In the first case, a linear relation between the heat flux and the wall temperature is assumed, whilst in the second model a parabolic relation is adopted. In the coupled simulation, an iterative process is used where the temperature distribution in the CFD model and the parameters of the convective zone in the FE model are updated at every iteration. The aforementioned three models are applied to a shroudless blade with and without an internal cooling system. When the blade is uncooled, all three methods offer a close prediction of the temperature reached by the component. However, when the blade is internally cooled the convective zone based on two parameters fails to provide a trustworthy prediction. The three-parameter convective zone, on the other hand, shows a closer agreement with the coupled simulation. The couple simulation is then applied to investigate the performance of three different tip configurations, a simple cavity, a novel contoured cavity and a tip with a small winglet. The small winglet shows a significant improvement in aerodynamic performance as well as a reduction in the operative temperature.© 2015 ASME