It is well known that a higher turbine inlet temperature (TIT) is
desirable to enhance the thermal efficiency of a gas turbine system
although there are difficulties to set the TIT very high. When the
designed TIT exceeds the melting temperature of the turbine
material, to prevent the melting damage it is essential to cool the
system under the melting temperature. The internal cooling flow
of a turbine blade thus plays a key role to enhance the gas turbine
efficiency and durability. Accordingly, elaborate multi-bend
cooling channel systems have been developed to achieve a higher
TIT. The flow inside such a cooling channel becomes complex three
dimensional turbulence as a result of sharp bends of the channel
and high pressure gradients. For designing a cooling channel, it is
hence important to analyse turbulent heat transfer characteristics
inside the channels