Eaton Char-Lynn Motor – Aero Motor: How To “Bake” The Test?
This summer, in addition to the traditional “furnace” city, a wide range of hot and humid weather has appeared in various parts of China. Under the ravages of high temperatures, people shouted: heat, heat, heat, just want to “stay with the air conditioner.” However, this heat is not worth mentioning for our aero Motor. To know that the Motor is working, the maximum temperature in the combustion chamber can be as high as 2000 °C. So, how can an aero Motor withstand the “baked” test at such an indescribable high temperature? Air conditioning is definitely not there, but the secret is a few tricks, Eaton Char-lynn Motor
The first trick: cultivation “King Kong is not bad body”
As we all know, aero Motors are heat Motors. The principle is to convert thermal energy into mechanical energy. The higher the temperature that can be withstood, the greater the thrust generated and the higher the performance of the Motor. According to research, for every 100 °C increase in the turbine inlet temperature of a gas turbine Motor, the thrust-to-weight ratio of the Motor can be increased by about 10%.
In the face of rising temperature demands, the cultivation of a pair of “King Kong is not bad” is the root of the Motor. In the past few decades, aviation experts have been working on the development of new high-temperature materials, from wrought alloys to conventional cast alloys, and from directional solidification alloys to single-crystal alloys. The operating temperature of Motor materials has been greatly improved.
Taking turbine blades as an example, in the 1950s, high-temperature alloys replaced high-temperature stainless steels with superior high-temperature performance, which made the turbine blades use a dramatic increase in temperature, reaching 800 °C. In the 1960s, due to the improvement of vacuum smelting level and the development of processing technology, casting superalloys began to become the main material of turbine blades. Then, the directional solidification superalloy improves the strength and plasticity of the alloy by controlling the growth rate of the crystal and optimizing the growth of the grains in the direction of the main bearing force, thereby improving the thermal fatigue properties of the alloy and substantially eliminating the transverse direction perpendicular to the principal stress axis. The grain boundary further reduces defects such as loose casting, alloy segregation and grain boundary carbides, and the use temperature reaches 1000 °C.
In the 1980s, the further development of directional solidification technology for single crystal alloy turbine blades, its temperature resistance, thermal fatigue strength, oxidation resistance and corrosion resistance were significantly improved compared with directional solidified alloys. Many advanced aero Motors use a single Crystal alloys are used as turbine blades. Nowadays, single crystal alloys have been developed to the fifth generation, and the temperature-bearing capacity of the alloys continues to increase.
The second measure: dig a hollow heart and drop “heart fire”
Despite the great achievements in high-temperature materials research, it is still unable to meet the requirements of the aero-Motor performance development for the pre-turbine temperature. In order to resolve this contradiction, the high-temperature components of the Motor began to introduce a cooling system, and the self-cooling was considered from the aspects of design, structure and process. For example, high-pressure turbines, due to high turbine inlet pressure, high-stage pneumatic loads, high centrifugal loads, and high temperatures, usually use a few hundred degrees Celsius of “low” warm air compressed by the compressor into the internal cavity complex cooling structure. Hollow leaves.
In the field of aero Motors, convection cooling, impact cooling, film cooling, and divergence cooling have been developed. Among them, convection cooling is the simplest cooling method, the maximum cooling effect is only about 250 °C; impact cooling, also known as jet cooling, as a branch of convection cooling, the effect is several times higher; film cooling is a kind The cooling method of the small-hole exhaust gas on the surface of the cooled hollow turbine blade is the main method for cooling the high-temperature components of the modern turbine; the divergent cooling is also called the sweat cooling, and the cooling air seeps out from the inner cavity of the blade through the numerous micropores on the wall surface of the blade. Like sweating, it is a new turbo cooling technology. Nowadays, composite cooling, which combines three cooling methods of convection, shock and air film, is widely used in advanced aero Motors.
However, regardless of the cooling method, it improves the turbine blade working environment, and also makes the turbine blade structure and process more complicated. Those maze-like cooling channels are, to a certain extent, the key to reducing the “heart fire”. If the cooling effect of the turbine blades can be increased by 100 ° C, the temperature before the turbine can be increased by 100 ° C, which further improves the performance and driving ratio of the Motor.
The third measure: put on the “fire and fire service”
Faced with the high temperature of thousands of degrees Celsius, the shirtless “King Kong is not bad body” is also delicious. In order to keep the Motor lasting, it is very necessary to have a “fire-fighting suit”. For example, a high temperature protective coating is applied on the surface of the turbine core, guide vanes and working blades at the core of the Motor.
At present, the development of aviation high temperature protective coating has experienced four generations, the first generation of aluminide coating, the second generation of modified aluminide coating, the third generation of MCrAlY coating and the fourth generation of thermal barrier coating. . As a representative of the fourth generation of protective coatings, thermal barrier coatings are one of the best surface protection coatings with the best protection performance and the best application prospects. The thermal barrier coating is a ceramic coating deposited on the surface of a refractory metal or superalloy that acts as a thermal barrier to the substrate and lowers the substrate temperature, allowing the turbine blades to operate at higher temperatures.
The high-performance thermal barrier coating is the “unknown secret” of the Motor of the United States and the United States. With high-performance thermal barrier coatings, the previous life of 200 to 600 hours of Motor, the working life can be extended by 2-3 times, the operating temperature can also be increased by hundreds of degrees Celsius.
In the pursuit of “no higher than only higher” temperature, the aero Motor is definitely a “warrior” facing the high temperature. And this fearless courage comes from all the people who love the aero Motor industry. They use the wisdom and sweat to give the Motor a strong body and reliable protection with life and time.