The efficiency of a gas turbine engine directly depends on the temperature of the gas flow exiting the combustion chamber and rotating the turbine. The higher its temperature, the greater the work of gas expansion in the turbine and the higher the engine's efficiency, according to the United Engine Corporation (UEC).
Turbine blades must withstand extreme temperatures for extended periods without losing strength or shape — above 2000 Kelvin, which exceeds the melting point of the materials used to manufacture the blades.
Alloying elements are added to the heat-resistant metal alloys from which turbine blades are cast. These include tungsten, cobalt, chromium, molybdenum, rare metals rhenium, ruthenium, and others. The number of such elements can reach 15.
UEC specialists also use thermal barrier and wear-resistant coatings, including ceramic ones, to protect the blades – they reduce heat penetration into the blade body and prevent gas corrosion of materials. However, these methods do not completely protect the blades from overheating, so a convective-film cooling system is used.
The coolant is air drawn from behind the compressor stages and supplied through the cooling system to the turbine flow path. Entering the turbine blades through channels of various cross-sections, the air cools them by convection. Then, through holes of various configurations (perforation, slots), the air is released onto the surface of the blade.
The temperature of this air is lower than the temperature of the gas flow acting on the turbine blades, so the air creates a barrier film on the surface, which protects the blade from the hot gas flow.
Blades are among the most complex parts to design and manufacture in aircraft engines. At UEC enterprises, blades are produced using the most modern technologies. In the next issue, we will talk about one of these technologies — growing single-crystal blades.
Earlier, www1.ru reported that the SJ-100 aircraft flew with the PD-8 engines turned off at a great height: the UAC revealed the meaning of the experiment.
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