Thermodynamic Evaluation of Gas/Steam Combined Cycle Performance With Active Controlled Film Cooling
DOI:
https://doi.org/10.13052/dgaej2156-3306.2913Keywords:
Active film cooling strategy, gas/steam combined cycle performance, transpiration coolingAbstract
Efficiency of gas turbine cycles can be improved by increasing
the turbine inlet temperature. Advanced gas turbines operate at temperatures far above their material limitations to increase thermal efficiency. So, film cooling technique is mostly used to protect the gas turbine blades from high temperature gases. The film cooling jets penetrate
into the mainstream gas and form a thin film for protecting the blade
surfaces from hot gas. However, due to lift-off effect the attachment of
the coolant jet to the blade wall, downstream, becomes crucial. Plasma
actuator strategy proposed by some of the researchers may be considered to be utilized, to maintain the attachment of jet with the blade-wall
and improve the film cooling effectiveness. In this article the effect of a
proposed active controlled film cooling technique using plasma actuator
strategy on thermodynamic performance of gas/steam combined cycle
has been evaluated and compared with the combined cycle employing
simple film cooling technique as well as with advanced transpiration
cooling technique of gas turbine blades. Reduced coolant requirement
and hence reduced dilution losses with active controlled film cooling as
compared to simple film cooling, results in improved topping as well
as bottoming cycle performance. It is seen that the combined cycle efficiency with active film cooling is comparable to the transpiration cooled
combined cycle efficiency. At a turbine inlet temperature (TIT) of 1900 K,
the combined cycle efficiency with active film cooling strategy is higher
by 0.5% than that with simple film cooling.
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