Turbine blades, discs and casings

1. Turbine blade
The turbine blade belongs to the hot end part of the aeroengine, which needs to work under the environment of high temperature and high pressure. It is the blade with the highest manufacturing difficulty in the turbofan engine. The high-temperature and high-pressure gas expands and works in the turbine, driving the turbine to rotate at high speed to drive the compressor. The air flow enters the tail nozzle through the turbine outlet, the pressure decreases, the speed increases, and finally discharges the engine to generate power.
The structure and material of turbine blades are constantly upgraded. In the mid-20th century, the second-generation engine was mainly used. The typical model was Spey mk202, which mainly used solid turbine blades. After that, more advanced hollow turbine blades were gradually used. The fifth generation engine F135 has adopted double-layer wall ultra cold / cast cold turbine blades.
Turbine blades are generally made of high-temperature alloy or titanium aluminum alloy, which are processed by precision casting to form blade blanks with small margin and high quality. With the improvement of engine performance, high pressure turbine blades have gradually developed into directional crystallization and single crystal material blades.
Directional crystallization is a casting process in which the molten alloy crystallizes and solidifies in the opposite direction of heat flow in the investment casting shell. The turbine blade formed by this process has high thermal fatigue and thermal shock resistance.
2. Disc parts
It mainly includes turbine disk, compressor disk and integral blade disk. Blisk structure is a new type of disc integrated structure developed on the basis of conventional disc separation structure. It has the advantages of weight reduction, grade reduction, efficiency increase and reliability improvement. The materials are generally titanium alloy and superalloy.
Turbine disk and compressor disk are rotor components of aeroengine. Turbine disk is used to install and fix turbine blades to transmit power on aeroengine. It bears complex loads under high temperature, high pressure and high speed working environment.
3. Gearbox
The main load-bearing components of aeroengine are the key components of the engine to bear load and contain. They are typical thin-walled structural parts.
Its main function is to protect the core engine of the engine and provide support for external engine components such as fuel pump, lubricating oil pump, generator, gearbox and pipelines; The inner side is mainly equipped with stator and combustion chamber, which together with the rotor assembly form an air circulation channel.
According to the function, the casing can be divided into fan casing, outer casing, intermediate casing, compressor casing, combustion chamber casing, etc. Most of the casing materials are titanium alloy and superalloy. In the processing process, we need to focus on controlling the high-precision geometric tolerance and thin-wall processing deformation.

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