General Electric Company

Kenneth A Darrow

James T Dakin

John W Daly

Paul Harriman Kydd

Daniel P Smith

Myron C Muth

Gasper Pagnotta

Robert K Alff

Methods are disclosed for more practical construction of liquid-cooled buckets able to efficiently transport heat energy from the inside of the airfoil skin surface in contact with hot gas to the outer surface of preformed tubes recessed into the bucket core, through which tubes liquid coolant is passed during operation. The bucket is made of a series of preformed solid components, which are assembled, consolidated and then converted into a unified structure. In each arrangement illustrated one of the preformed solid components is a flat bimetallic sheet comprising an erosion, corrosion resistant layer and a layer of high thermal conductivity, these layers being joined by an optimized metallurgical bond.

Method of manufacture of cooled turbine or compressor buckets

Individual coolant passages in the airfoil portion of a liquid-cooled turbine bucket are each provided with a plurality of inwardly protruding circumferentially-extending crimps or rings located at spaced intervals along each passage, each crimp, protrusion or ring extending along the inner periphery in a plane generally perpendicular to the wall of the coolant passage at that location. The main flow of liquid coolant moving in each such individual passage during turbine operation under the combined influence of centrifugal and Coriolis forces is broken up and dispersed over an enlarged area of the interior of the coolant passage upon encountering the protrusions.

Liquid-cooled turbine bucket with enhanced heat transfer performance

Individual coolant passages in the airfoil portion of a liquid-cooled turbine bucket are provided with means whereby the main flow of liquid coolant moving in each such individual passage during turbine operation under the influence of centrifugal force is split into a pair of flows with each sub-flow moving along a generally helical path. Also, the splitting means is provided with means to interrupt each sub-flow so as to enlarge significantly the internal wall area of such coolant passage with which the liquid coolant makes contact. In the embodiment described the splitting means is a twisted tape member bonded along its edges within a tubular coolant passage and the interrupting means are a series of inwardly-directed slots in the edges of the tape.

Liquid-cooled, turbine bucket with enhanced heat transfer performance

A flexible, low porosity airfoil skin is described which includes multilayer flexible, annealed metallic mesh members consisting of two or three such members selected from the class consisting of nickel, Monel alloy, and stainless steel, the members having a mesh size from 60 to 100, the members interlocked mechanically, and the skin having a thickness reduction in the range from 2.5 to 3.0. Such a flexible, low porosity airfoil skin is useful as a covering structure and is particularly useful as a skin or as a substrate for a cooled non-linear airfoil-shaped body, such as a turbine or compressor blade.

Flexible, low porosity airfoil skin

Individual coolant passages in the airfoil portion of a liquid-cooled turbine bucket are each provided with a plurality of spanning elements spaced along, affixed in and extending across each passage whereby the main flow of liquid coolant moving in each such individual passage during turbine operation under the influence of centrifugal force is broken up. Each spanning element has one end thereof approximately centered in the region of the passage at that station therealong, which will be the most rearwardly disposed during rotation of the bucket in operation. In the embodiment described the spanning elements are cylindrical pins of circular cross-section disposed generally parallel to each other.

A method of forming an airfoil-shaped body is described which includes providing a core with cooling channels recessed into the surface thereof, affixing a calendered multilayer flexible mesh screen substrate to the surface of the core, applying braze alloy and brazing the assembly thereby filling completely the mesh screen pores and bonding further the mesh member substrate to the core, and applying an erosion-corrosion resistant layer over the brazed mesh member substrate completing the airfoil-shaped body.

Method of manufacture of cooled airfoil-shaped bucket

Airfoil-shaped bucket cores having grooves recessed into the surfaces thereof must be covered with an outer layer to provide the requisite aerodynamic and wearing surface and to define the cooling passages. In order to apply this outer layer by flame spraying (or comparable method of particle deposition), the core surface is first covered with a substrate layer. This substrate layer is provided with means by which later-applied surface coating material will be anchored in place. Thereafter, the outer material is applied (as by flame spraying, for example) and the surface thereof is ground and polished to dimension as may be needed.

Before skins are brazed on airfoil cores having cooling channels recessed into the surfaces thereof, the surfaces of the cooling channel walls are covered with a layer of oxide material. The oxide formation selected is one that is not reducible in dry hydrogen. Thereafter, when the normally employed hydrogen or vacuum brazing operation is conducted to apply the airfoil skin, the oxide-covered sides of the cooling channels will not be wet by the molten braze alloy. Plugging of the covered cooling channels during manufacture is thereby greatly reduced.

Unitary turbine bucket construction equipped for liquid cooling thereof independently of other rotor-mounted liquid distribution or metering means is disclosed. The unitary construction comprises an airfoil-shaped core portion (with skin); a platform portion (with skin); a shank portion and a root portion; a plurality of first coolant passages beneath the skin on the pressure and suction faces of the core portion; a plurality of second coolant passages disposed beneath the skin in the platform portion and interconnected with the first coolant passages on a one-to-one basis as sets of coolant passages; a plurality of arcuate gutters integral with the bucket construction located radially inward of the core portion at the leading and trailing edges of the bucket, and holes extending through the gutters in the generally radial direction with each of said holes being in flow communication with a separate one of the sets of coolant passages.

Liquid-cooled turbine bucket with integral distribution and metering

Stirrer construction adapted for both vertical and rotational movements is described for use in a fixed bed coal gasifier. Rabble arms projecting from a depending shaft are arranged as an upper and a lower set. The rabble arms in the lower set each present shear edges at and adjacent the tips thereof in order to be lowered into the ash zone, when desired, to break away the hard sintered masses that tend to develop along the wall there. Also, the lower set of rabble arms is designed for use in the combustion ('hot') zone to break up or loosen clinker formation with minimum damage to the ceramic liner in this portion of the gasifier. The rabble arms in the upper set are longer than the rabble arms in the lower set and extend closer to the wall of the gasifier being used both in order to center the stirrer shaft and to stir the upper regions of the coal bed.

Growing community of inventors

Sprakers, NY, United States of America

Kenneth A Darrow