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Turbine blades

Turbine blades

  •  After the combustion chamber has introduced the heat energy into the mass airflow and delivered it evenly to the turbine inlet nozzles, the nozzles must prepare the mass airflow to drive the turbine rotor. The stationary vanes of the turbine.
  • the turbine blades. Since the disk is bolted or welded to the shaft, the blades can transmit to the rotor shaft the energy they extract from the exhaust gases.
  • The disk rim is exposed to the hot gases passing through the blades and absorbs considerable heat from these gases. In addition, the rim also absorbs heat from the turbine blades by conduction.
  • Hence, disk rim temperatures are normally
  • high and well above the temperatures of the more remote inner portion of the disk.
  •  As a result of these temperature gradients, thermal stresses are added to the rotational stresses. There are various methods to relieve, at least partially, the aforementioned stresses. One such method is to bleed cooling
  • air back onto the face of the disk.
  • Another method of relieving the thermal stresses of the disk is incidental to blade installation. A series of grooves or notches, conforming to the blade root design, are broached in the rim of the disk. These grooves allow attachment of the turbine blades to the disk; at the same time, space is provided by the notches for thermal expansion of the disk.
  • Sufficient clearance exists between the blade root and the notch to permit movement of the turbine blade when the disk is cold. During engine operation, expansion of the disk decreases the clearance. This causes the blade root to fit tightly in the disk rim.

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