This work package accomplishes
aerothermal investigations to study flow and heat transfer for
aerodynamically highly loaded LP and HP turbine blades. The purpose of
the investigations proposed is to improve the physical understanding of
separated flow regions with the goal of optimising cooling
configurations for aerodynamically highly loaded turbine designs.
- Effects of film cooling on suction and pressure side flow
separation under steady and unsteady conditions
- Control of suction and pressure side flow separation by
means of film cooling and streamwise vortices
- Advanced aerothermal modelling of flow separation for low
pressure turbine blades
For high-pressure turbine blades, it is very common for the peak metal
temperature of a blade to be located in the suction surface trailing
edge region. Therefore, the trailing edge is one of the life limiting
areas of the blade. Hence, the motivation for the investigations to be
performed is twofold. The first objective is to investigate how film
cooling can be used effectively in these regions of separated flow,
whereas the second objective is to investigate how film cooling can be
used to re-attach separated flow by re-energising the boundary layer
with the extra kinetic energy from the cooling jets. The turbulent
mixing and 3-D vortices between the film cooling flow and main gas
stream cause aerodynamic losses and affect the boundary layer flow
downstream of the film cooling holes. Therefore, it is important to
consider both the cooling performance and the aerodynamic performance
of the film cooling design in the blade design process.
Furthermore, reducing aerodynamic penalties by improving boundary layer
control will lead to improved SFC of the engine due to a reduction of
the required coolant flow or a higher temperature blade capability
through a more effective use of cooling air. The control of separated
flow will also lead to greater flexibility of blade design, as
aerodynamics, cooling and mechanical design can be optimised to a
greater extent.
For non-film-cooled blades, i.e. LP turbine blades, the investigation
will focus on aerodynamic losses and the development of the blade heat
transfer affected by distinct flow separation zones to enable the
development of physical models for design purposes and a data basis for
CFD validation. |