What are the working environment and service conditions of turbine blades of aircraft engines?

The working environment and service conditions of aero-engine turbine blades are very bad. The following are specific functions:

1. The working temperature is high and unevenly distributed. With the development of turbine engine, its thrust-to-weight ratio is getting larger and larger, which leads to that the turbine inlet temperature needs to increase by about100 C for every increase of thrust-to-weight ratio of aero-engine. In order to continuously improve the thrust-to-weight ratio of the engine, the temperature at the turbine inlet is also increasing. At present, the turbine inlet temperature of the fourth generation military engine has reached 1850-2000 K, and the temperature distribution in different parts of the blade is extremely uneven.

2. The working stress is complex and large. The rotating speed of turbine rotor blades is usually around 12000 rpm. In the case of high-speed rotation, turbine blades will produce great centrifugal force due to their own mass. During the service period of the blade, the centrifugal tensile stress that the blade may bear is about 140 MPa, while the average centrifugal tensile stress of the blade root reaches 280~560 MPa. At the same time, the stress distribution of blades in service is uneven.

3. The working environment is very corrosive. The working environment includes high temperature, high humidity, corrosive atmosphere, cold and hot cycle, etc. This will have an impact on the material and performance of turbine blades. For example, in high temperature and corrosive atmosphere, the surface of turbine blades may be oxidized and corroded.

4. Work under high pressure and alternating pressure. When the turbine blade rotates at high speed, it will be subjected to periodically changing centrifugal stress and aerodynamic force, which may lead to fatigue cracks and fractures of the blade.

Therefore, turbine blades must have the characteristics of high temperature resistance, high strength, corrosion resistance and fatigue resistance to ensure the safety and reliability of the engine. At the same time, the design and manufacture of blades need to fully consider their working environment and use conditions to ensure that they can meet the requirements.