Film Cooling In Turbines

by Song Xue on May 24, 2018 4:43:24 PM

Turbine inlet temperature is one of the most critical parameters in the Brayton cycle of gas turbine engines. One way to increase the cycle efficiency is to increase the turbine inlet temperature, as illustrated in Figure 1. Here, a typical Brayton cycle T-S diagram chart visualizes the impact of higher turbine inlet temperatures on higher efficiency. Indeed, the area between the solid curves through points 0-3-4-8 represents the useful power generated by the turbine. The cycle efficiency can be calculated by dividing this area by the total area below curve 3-4, being the heat input. The dash lines convey the cycle with increased turbine inlet temperature, and the new cycle efficiency is the area in 0-3’-4’-8 curves divided by the area below curve 3’-4’. It is easy to see how a higher turbine inlet temperature increases cycle efficiency. Because of pursuing higher efficiency in modern gas turbine engine design, turbine inlet temperature has been pushed to a level that most material cannot withstand without effective cooling. Figure 2 shows the increasing trend of turbine inlet temperature since the 1940’s. Since the 1970’s, the turbine inlet temperature has been above material capability through the introduction of turbine cooling techniques.

Designing Gas Turbines - It Really Requires Rocket Science

by Barbara Shea on Feb 16, 2017 3:31:58 PM

Engineers who design aircraft engines face a conundrum. Gas turbines in aircraft engines have to operate at very high temperatures for thermal efficiency and power output. These high temperatures put thermal stresses on the turbine blade materials. This requires that the blades be cooled. The most common way of doing this is using cooled air extracted from the engine’s compressor. Sadly, this air extraction decreases the thermal efficiency of the engine.

Benefits of the Cooled Turbine Airfoil Agile Design System

by Concepts NREC on Sep 1, 2016 1:30:00 PM

Achieving optimum performance and efficiency in a gas turbine engine requires pushing operating temperatures as high as possible. In fact, many gas turbine engines in service today operate at hot-gas temperatures which are much greater than the incipient melting point of typical turbine airfoil base alloys. Successful operation in this extreme gas temperature environment requires turbine airfoils be designed using special high-temperature alloys, metallic and ceramic coatings, and complex cooling configurations.

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