PNIPU: Cooling system for gas turbine engine elements

Main Article: Cooling Systems

2024: Modification of the air supply system to optimize cooling efficiency

Perm Polytechnic scientists have optimized the cooling efficiency of the turbine blade by modifying the air supply system. An article with the results of the study was published in the journal Vestnik PNIPU. Aerospace Engineering "No. 75, 2023. This was announced on February 1, 2024 by representatives of the Perm Polytechnic.

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As reported, a gas turbine engine is a thermal machine designed to convert the combustion energy of a fuel into the kinetic energy of a jet jet or into mechanical work on an engine shaft. It consists of a compressor, a combustion chamber, a turbine and auxiliary systems. Gas turbine plants are widely used in power plants as a source of energy.

Rotor blades are an important element of the turbine. They are metal plates with a shank attached to the disk. In order for the blade to operate under a constant flow of hot gas, its continuous cooling is necessary. Otherwise, the mechanical characteristics of the material deteriorate, it quickly fails, becomes not strong enough and reliable for use. In addition, it is important to ensure a guaranteed difference between cooling air and gas, otherwise it is possible that the latter flows into the internal cavities of the rotor blade, which can lead to its destruction.

As of January 2024, different ways of maintaining an acceptable temperature are used, but the creation of modern, more powerful gas turbine engines requires modification of existing turbine element cooling systems. This allows you to cope with increasing loads.

The cooling system is a complex of devices that maintains the required metal temperature of the turbine blades. PNIPU scientists have selected the optimal design of the air supply system, which provides optimal cooling of the rotor blade. To modify the design, the researchers created a design model of a high-pressure turbine. With its help, we studied how changing the geometry of the cooling air supply system will affect its temperature and thermal state of the blade.

Scientists of the Perm Polytechnic University note that the angle of rotation of holes in the deflector, the radius of rounding the edges of these holes, as well as the distance between the holes and the swirl apparatus are of great importance in the design. The deflector is designed for additional protection of the turbine disc against hot gases. Cooled air passes through holes of deflector to rotor blades.

To reduce the temperature of the cooling air, the cooling system uses a "swirler." However, after it, the air flow passes through the holes in the deflector, where hydraulic losses and a decrease in pre-swirling occur. Therefore, it is important to design the holes so that air passes through them continuously. We turned the holes at different angles towards the rotation of the rotor. The results showed that turning the holes in the deflector reduces hydraulic losses of cooling air and increases the flow rate of air into the blade. This allowed to reduce the temperature of the leading edge. explained Sergey Shvalev, PhD student at the Department of Aircraft Engines, PNIPU

Polytechnics noticed that the additional displacement of the deflector holes to the swirl apparatus still optimize the cooling of the rotor blade. And reducing the mixing chamber further reduces the pressure in this cavity, which also reduces air leakage into the axial gap.

The results of the calculations confirmed that the rotation of the holes towards the rotation of the rotor ensures a smooth flow of air through them, increases the pressure at the inlet to the blade, increases the guaranteed difference between the cooling air and the gas flow and reduces the temperature of the blade material. shared Stanislav Sendyurev, Associate Professor, Department of Aircraft Engines, PNIPU

The combined version, proposed by PNIPU scientists, optimizes cooling parameters, reduces the temperature of the leading edge of the turbine blade. Modification of the air supply system makes it possible to effectively cool the rotor blades of a gas turbine plant, while maintaining the strength and durability of their operation. The study will be useful when improving already designed supply systems when the ability to change the design is limited.