Typical turbomachinery flows are too complex to be
predicted by analytical solutions alone. Therefore numerous
correlations and test data are used in conjunction with numerical
tools in order to design thermally critical components. This
approach can be problematic because these correlations and data
are not fully independent of the boundary conditions applied.
The heat transfer coefficients obtained are not only dependent on
the aerodynamics of the flow but also on the thermal boundary
layer created along the surface. The adiabatic heat transfer
coefficient is the only one which is independent of the thermal
boundary conditions, as long as the energy equation can be considered
linear with respect to the temperature. However, a proper
prediction of the surface temperature cannot be obtained with the
adiabatic heat transfer coefficient alone.
This paper first reviews the concept of adiabatic heat transfer
coefficient and its application to turbomachinery flows. Later,
a concept is introduced to allow interchanging between different
definitions of heat transfer coefficient and boundary conditions,
i.e. constant heat flux or constant wall temperature. Finally, a
typical configuration for measuring the adiabatic heat transfer coefficient
on a turbine blade and the conversion to other definitions
of heat transfer coefficient is presented and evaluated. It is shown
that with the technique presented here even small deficiencies of
some experiments can be compensated for.
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