Methods and techniques used in increasing gas temperature in front of the gas turbine engine turbine

Abstract

The paper presents methods and techniques used in increasing gas temperature in front of the turbine blades of the gas turbine engine making it possible in the aggregate to reach the gas temperature of 2300 K. Gas turbine blades made on the basis of the best nickel alloys could operate for a long time without cooling at the temperature of not more than 1300 K. Convective-film cooling today appears to be the most effective method of air cooling the blades, due to which (in combination with the heat-shielding coatings) gas temperature of 2000 K is reached in the fifth-generation gas turbine engines. Significant increase in the efficiency of the turbine blades internal cooling (convective, convective-film, porous) is obtained with using the external cooling, i.e. decreasing the cooling air temperature by the cooling resource of the external environment: atmospheric air (secondary air), water and fuel. External cooling when using the convective-film cooling makes it possible to increase gas temperature in front of the turbine blades by 0.6 ... 1.5 K for each degree in the cooling air temperature decrease. A circulating heat exchanger is proposed, which lowers the cooling air temperature almost to the ambient temperature making it possible in combination with the known methods and techniques for increasing the gas temperature (heat-resistant materials, heat-shielding coatings, convective-film cooling) to increase gas temperature in front of the turbine blades by 300...400 K and bring it up to at least 2300 K. This would allow today to start creating stoichiometric and hyperforced gas turbine engines and to increase the bypass turbojet engines efficiency up to 45%. Air-liquid cooling is a variation of the turbine blades external cooling. The possibility (technical solutions were patented) of introducing the air-liquid cooling in gas turbine engines at the high flight speeds, including the turbojet engines, was studied.