Why must turbine blades be cooled in many gas-turbine engines?

Turbine blades in gas-turbine engines must be cooled because they operate under extreme conditions that threaten their structural integrity.

Increasing the turbine-inlet temperature is a primary method for improving engine efficiency and power output. However, all materials lose strength at very high temperatures. Because turbine blades rotate at high speeds and are subjected to severe centrifugal stresses, temperatures exceeding 1,100° C necessitate specialized cooling to prevent mechanical failure.12

To manage these high temperatures, engines utilize air drawn directly from the compressor, which is fed through internal passages in the blades. Two common cooling techniques include:2

• Jet impingement: Directing cooling air against the inside of hollow blades.2
• Film cooling: Bleeding air through tiny holes in the blade surface to create a protective cooling blanket.2

By employing these methods, modern aircraft gas turbines are able to operate safely at inlet temperatures exceeding 1,370° C.1