A turbine blade exposed to combustion gas (main-flow gas) during operation of a gas turbine engine is generally cooled by utilizing cooling air (portion of compressed air) extracted from a compressor or a fan of the gas turbine engine. In addition, recently, temperature of combustion gas increases along with increasing of gas turbine engine power, and thereby it is desired to improve cooling of a turbine blade. A Patent Document 1 listed below discloses an art for improving cooling of a turbine blade.
In an inside of the turbine blade disclosed in the Patent Document 1, a cooling channel in which cooling air (portion of compressed air) flows is formed. A bottomed slot extending along a span direction (a height direction of the blade) is formed on a blade surface of the turbine blade. In addition, plural ejection holes for ejecting the cooling air are formed on a bottom of the bottomed slot at intervals along the span direction. Each of the ejection holes communicates with the cooling channel.
During operation of the gas turbine engine, cooling air extracted from a compressor or a fan flows into the cooling channel, so that the turbine blade is cooled from its inside by a convective cooling (an internal cooling). In addition, the cooling air after convectively cooling the turbine blade is ejected from the plural ejection holes to form a cooling film surrounding the blade surface of the turbine blade, so that the turbine blade is cooled by a film cooling (an external cooling).
Here, the cooling air ejected from the ejection holes expands along the span direction in the bottomed slot and stays in the bottomed slot to absorb heat, and then goes out of the bottomed slot to form the cooling film extensively. As a result, cooling of the turbine blade is improved.