| 摘要 |
1,164,847. Gas turbine blades. GENERAL ELECTRIC CO. Aug. 30, 1966, No.38708/66. Heading F1T. A gas turbine blade comprises a thin-walled metal shell 22 of aerofoil cross-section, the outer surface of which defines a flow path for a hot gas stream moving at a high velocity, the gas stream having a boundary layer contiguous with the outer surface in which the gas velocity is substantially reduced, and the interior of the blade defining a plenum chamber. A plurality of discrete, relatively small holes 44 are provided in the shell 22, being closely spaced around the leading edge portion of the aerofoil section and spaced further apart on opposite sides thereof in a chordal direction. The holes 44 are inclined at an angle to the outer surface of the shell 22 and extend in a direction having no component counter to that of the hot gas flow. The plenum chamber is connected to a pressurized source of a gas (e.g. air) coolant, the pressure in the chamber being greater than the maximum hot gas static pressure on the outer surface of the shell 22, coolant gas being discharged through the holes 44 to be entrained in the boundary layer, the holes 44 being disposed relative to one another so that the coolant streams entrained in the boundary layer, cover the entire outer blade surface with coolant gas. The holes 44 are circular in cross-section and preferably taper toward the plenum chamber in order to minimize the velocity of the coolant gas as it approaches the outer blade surface whereby it is entrained to an even greater extent in the hot gas boundary layer. The holes 44 create elliptical openings in the outer blade surface, the layer axes of which are aligned with the stress lines in the blade. The holes 44 are disposed in planes normal to the outer blade surface and to the path of hot gas flow at an angle of 45 degrees or less, preferably between 10 degrees and 30 degrees, to the blade surface. The trailing edge portion of the blade is relatively thick and is heat cooled by inclining the cooling holes 44t in a direction downstream of the gas flow. Cooling holes (not shown) may also extend along the centre of the trailing edge portion. The invention is applicable to both stator and rotor blades of an engine turbine. In the case of a rotor blade, as shown in Fig.4, a platform 42 is integrally formed at the base of the shell 22 and provided with a plurality of discrete, relatively small holes 44p for the passage of coolant gas, and the closed outer end of the shell 22 is provided with a plurality of discrete, relatively small holes 44e so as to be cooled by coolant gas from the plenum chamber defined by the shell interior. In the case of a stator blade (20, Figs. 2, 11, not shown), inclined holes (44l) are provided in the stator blade shroud rings (28, 30) to direct cooling gas on to the exterior of the stator blades.
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