Rotary kinetic fluid motors or pumps – With passage in blade – vane – shaft or rotary distributor...
Reexamination Certificate
1999-08-02
2001-06-05
Verdier, Christopher (Department: 3745)
Rotary kinetic fluid motors or pumps
With passage in blade, vane, shaft or rotary distributor...
C415S116000, C416S09700R
Reexamination Certificate
active
06241467
ABSTRACT:
DESCRIPTION
1. Technical Field
This invention relates to a stator vane having a cooled interior and more particularly to a stator vane having a coolable platform.
2. Background of the Invention
An axial flow rotary machine, such as a gas turbine engine for an aircraft, has a compression section, a combustion section, and a turbine section. An annular flow path for working medium gases extends axially through the sections of the engine.
The engine adds fuel to the working medium gases and burns the fuel in the combustion section to form hot, pressurized gases. The hot, working medium gases are expanded through the turbine section to extract energy as work from the gases. The energy is transferred to the compression section to raise the pressure of the incoming gases.
The turbine section includes a rotor for receiving this work from the hot working medium gases. The rotor extends axially through the engine. The rotor includes a rotor assembly in the turbine section. The rotor also has a rotor assembly in the compression section. The rotor assemblies have arrays of rotor blades which extend outwardly across the working medium flow path through which the gases are directed. Arrays of rotor blades in the turbine section receive energy from the hot, working medium gases and drive the rotor assembly at high speeds about an axis of rotation. Arrays of rotor blades in the compression section transfer energy to the working medium gases to compress the gases as the airfoils are driven about the axis of rotation by the rotor.
The engine includes a stator disposed about the rotor. The stator has stator assembly having an outer case. The outer case extends circumferentially about the working medium flow path to bound the flow path. The stator assembly has seal elements, such as a circumferentially extending seal member which is disposed radially about the rotor assembly. The seal member is formed of arcuate segments which permit the seal member to change diameter in response to operative conditions of the engine. The seal member is in close proximity to the tips of the rotor blades to form a seal that blocks the leakage of working medium gases from the flowpath.
The stator assembly also has arrays of stator vanes which extend radially inwardly across the working medium flow path. The stator vanes are commonly called vane clusters and have one or more airfoils or stator vanes. The stator vanes are disposed circumferentially about the axis A of the engine and are spaced apart by a small circumferential gap G.
The arrays of stator vanes are disposed upstream of the arrays of rotor blades in both the compression section and turbine section. The stator vanes guide the working medium gases as the gases are flowed along the flow path. Each has an airfoil which is designed to receive, interact with and discharge the working medium gases as the gases are flowed through the engine. The stator vanes have structure, such as an inner platform and an outer platform which bound the flow path for working medium gases.
The airfoils in the turbine section are bathed in hot working medium gases under operative conditions. Certain airfoils in the turbine section, such as stator vanes in the high pressure turbine, are cooled by flowing cooling air through the airfoil to avoid unacceptably high temperatures in the walls of the airfoil. Each stator vane has one or more large openings at its inner end and near its outer end near the outer case for receiving the cooling air.
A feather seal member, commonly called a feather seal, is typically provided in modern engines between each pair of circumferentially spaced stator vanes. The seal member bridges the gap G between the stator vanes to block the leakage of cooling air being supplied to the vane into the working medium flow path by flowing through the gap G. One example, such a coolable array of wall segments is shown in U.S. Pat. No. 4,767,260 issued to Clevenger et al., entitled “Stator Vane Platform Cooling Means”. The feather seal slot typically extends into the vicinity of a rear rail for attaching the stator vane to adjacent structure. In some constructions, a radially extending feather seal is disposed in the rail. In another construction, a pair of feather seals are used to form a cooling air duct to flow cooling air between the feather seals to a downstream location as shown in U.S. Pat. No. 4,688,988 issued to Olsen and entitled “Coolable Stator Assembly for Gas Turbine Engine”. The stator vane typically has many small cooling air holes which extend from the interior of the airfoil to the exterior of the airfoil. The cooling air holes cool the airfoil by convection and discharge cooling air at the gas path surface to provide film cooling to regions of the airfoil such as the leading edge region or the trailing edge region.
The wall segments of the outer air seal and the platforms of the stator vanes are in intimate contact with the hot working medium gases and receive heat from the gases in varying amounts over the surface of the platform. The outer air seal segments and the platforms of the turbine vanes are provided with cooling air from the openings which are in flow communication with internal cooling passages. One example is shown in U.S. Pat. No. 5,413,458 issued to Calderbank entitled “Turbine Vane With A Platform Cavity Having A Double Feed for Cooling Fluid.” In Calderbank, the turbine vane includes a platform cavity having a first inlet located on the pressure side and a second inlet located on the suction side of the stator vane. A cooling passage extends rearwardly from both locations so that flow in the same direction toward the trailing edge of the platform. The flow provides convective cooling and film cooling by discharging cooling fluid through exit conduits such as film cooling holes which extend from the passage to flow surfaces on the platform.
An early example of a cooling scheme for a vane platform is shown in U.S. Pat. No. 3,628,880 issued to Smuland et al., entitled “Vane Assembly and Temperature Control Arrangement.” U.S. Pat. No. 4,017,213 issued to Przirembel entitled “Turbomachinery Vane or Blade with Cooled Platforms” shows arrangements of small cooling conduits for providing a combination of impingement, convection and film cooling to the platform. The selective placing of the conduits includes a conduit which extends through the platform trailing edge for convectively cooling the trailing edge. U.S. Pat. No. 4,946,346 issued to Ito entitled “Gas Turbine Vane” shows a plurality of small conduits which extend through the trailing edge region and film cooling holes used in conjunction with the holes.
Serpentine passages have also been used for cooling outer air seals and for cooling turbine vanes. One example of an outer air seal construction having serpentine passages is shown U.S. Pat. No. 5,538,393 issued Thompson et al. entitled “Turbine Shroud Segment With Serpentine Cooling Channels Having a Bend Passage.” In Thompson, the outer air seal is provided with a plurality of serpentine channels which extend between the sides of the outer air seal segment. A serpentine channel was also used in the U.S. Pat. No. 4,353,679 issued to Hauser, entitled “Fluid-Cooled Element.” In Hauser, the serpentine channel extends rearwardly and from side to side creating a flowpath that moves from the trailing edge forwardly in the platform to discharge film cooling air which then flows rearwardly over the platform.
The above notwithstanding, scientists and engineers working under the direction of Applicants Assignee have sought to develop a relatively simple cooling passage for the trailing edge region of a platform for a stator vane for providing cooling to the platforms of stator vanes.
SUMMARY OF INVENTION
This invention is in part predicated on the recognition that edge regions of the platform for a stator vane near the suction side suffer particularly from heat transfer distress because of end wall effects in the flow in part created by the flow between the arrays of stator vanes. It is also predicated on the recognition that exhausted co
Kane Daniel E.
Merry Brian
Steuber Gary D.
Zelesky Mark F.
Fleisehhauer Gene D.
United Technologies Corporation
Verdier Christopher
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