A tip cap for a rotor blade which includes at least one radially extending rib having an abrasive coating thereon for providing a close clearance seal between the rotor blade and the surrounding shroud and also for cleaning the shroud of deposits of material thereon. The tip cap can include a cooling arrangement therein comprising a plurality of cooling passages and a thermal barrier. A method is provided for replacing one tip cap with another and includes the steps of removing a tip cap, machining the end of the rotor blade flat, aligning the replacement tip cap and securing it with the rotor blade.

Tip cap for a rotor blade and method of replacement

A conventional gas turbine blade using a steam cooling system, in which high-pressure steam is supplied to an inner portion of the blade to cool the blade therewith and recover thermal energy, has been proposed but has a problem to be solved concerning its strength. A gas turbine blade capable of solving this problem free from the strength problem and sufficiently resistant to a flow of the high-pressure steam, wherein a cooling medium flow passage extending in the lengthwise direction of the blade is formed in the interior thereof, reinforcing ribs connecting front and rear walls of the blade together and extending in the direction of a flow of the cooling medium being provided in the cooling medium flow passage, whereby the strength of the blade is secured without hampering the flow of the cooling medium.

Gas turbine blade

A turbine blade squealer tip has a cooling passage arrangement which includes a peripheral end wall surrounding a central portion of an end cap of the squealer tip, an outer peripheral groove defined in an outer surface of the peripheral end wall being spaced outwardly from the central portion of the end cap, and a multiplicity of holes extending through the end wall from the outer groove to an internal source of cooling air flow within the turbine blade, bypassing the central portion of the end cap of the squealer tip. The outer groove which receives the flow of cooling air from outlets of the holes tends to trap the air therein so as to form an annular air seal about the outer surface of the squealer tip end wall which impedes leakage of hot gas flow past the squealer tip.

Turbine blade squealer tip peripheral end wall with cooling passage arrangement

A film cooling passage through the external wall of a hollow airfoil for a gas turbine engine has a metering section in series flow relation with a diffusing section leading to the passage outlet at the external surface of the airfoil over which a hot gas flows during operation. The diffusing section is generally rectangular in cross section perpendicular to the axis of the passage. Upstream and downstream longitudinally extending, spaced apart, facing surfaces of the diffusing section are joined together by a pair of spaced apart side walls which face each other and diverge from each other in the longitudinal direction toward the outlet of the passage. These side walls blend, along their length, with the downstream surface as a smooth curve of large radius. The diameter of the corner curvature of the passage is on the same order of magnitude as the distance between the upstream and downstream surfaces of the diffusing section at the location in question. The large corner curvatures, as opposed to filet radii, allow the side walls to diverge from each other at a greater angle without separation of the coolant fluid therefrom, permitting the spreading of smaller amounts of coolant air over a larger area of the airfoil external surface.

Film cooling passages with curved corners

A gas turbine hollow cooled rotor blade in which a plurality of cooling holes (3 and 5) are provided which communicate between a cooling air passage in the blade and the tip squealer portion (1) on the pressure side and between the cooling air passage in the blade and a position in the vicinity of the suction side of a tip cap (4).

Gas turbine rotor blade tip cooling device

An improved tip cap configuration for a turbomachinery blade includes tip cap seats formed integrally with and located on the inner sides of a hollow turbomachinery blade. Tip cap retaining members are also formed integrally with the inner wall of the blade and are spaced a short radial distance from the tip cap seats. The blade is initially provided with a flared open end and the tip caps are positioned on the seats and the flared end is crimped so as to capture the tip cap between the seats and the retaining members. The crimping operation is stopped at a point wherein a smooth outer contour is obtained for the blade in the region of the tip cap. A method of making such a blade is also disclosed.

Turbomachinery blade tip cap configuration

An improved method of making an air-cooled turbine blade includes the steps of casting a root or dovetail portion and an airfoil section which includes a leading edge, a hollow body portion, and a trailing edge having a plurality of coolant holes formed therein to the minimum practical cast opening size. The blade is then positioned in a fixture which provides a sealed, pressurized chamber around the root portion thereof; and the trailing edge of the blade is deformed to decrease the size of the trailing edge holes. The deformation is limited to the wall cross ties between each pair of holes, and the deformation is stopped when a desired trailing edge coolant efflux is achieved. A blade is thus provided which has wall cross ties which are both thinner and wider than achievable with present state-of-the-art investment casting techniques. Apparatus for performing the trailing edge crimping is also disclosed.

William Dean Treece

Papers

Turbomachinery blade tip cap configuration

Air-cooled turbine blade and method of making same

Apparatus for constructing air cooled turbomachinery blading