Gas Turbine Nozzle Segment with Radially Spaced Cooling Channels
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Solution Overview
Problem
Conventional cooling arrangements in gas turbine engines using ceramic matrix composite materials face challenges with high thermal stress and limited cooling efficiency due to the vertical rib dividing the forward and aft cavities, which increases the risk of airfoil failure when the aft end of the aft cavity is moved closer to the trailing edge.
Innovation Solution
The design incorporates radially spaced internal cooling channels adjacent to the trailing edge of the nozzle airfoil, with horizontally extending ribs that distribute stress and allow the aft ends of the cooling channels to be closer to the trailing edge, enhancing cooling efficiency while reducing the risk of failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a vertical rib is used to divide the forward and aft cavities in conventional CMC nozzle designs, then the cavities can be separately supplied with cooling medium, but the vertical rib creates an area of high thermal stress within the airfoil
Solution Approach 1:
The airfoil is segmented into multiple cooling channels separated by horizontally extending ribs, allowing independent cooling zones without creating high stress concentration points. The segmentation divides the cooling function into multiple radial channels while distributing stress across the rib structures.
Solution Approach 2:
The invention transitions from a vertical rib configuration (chordwise direction) to horizontally extending ribs (radial direction). This dimensional change in rib orientation eliminates the high thermal stress area created by vertical ribs while maintaining effective cooling medium distribution through the airfoil thickness.
2Productivity
If the aft end of the aft cavity is moved closer to the trailing edge to improve cooling efficiency, then cooling performance increases, but the radius at the aft end must be decreased increasing the likelihood of failure due to airfoil ballooning
Solution Approach 1:
The cooling system is segmented into multiple radial cooling channels, each with its own cooling medium supply. This allows the aft ends of the cooling channels to be positioned closer to the trailing edge for improved cooling efficiency while the rib structures provide structural support to prevent airfoil ballooning and failure.
Solution Approach 2:
The cooling channel arrangement transitions from a single large aft cavity with chordwise extension to multiple radially spaced cooling channels. This dimensional reconfiguration allows the cooling channels to extend closer to the trailing edge in the radial direction while maintaining adequate radius and structural integrity through the rib support system.
3Productivity
If horizontally extending ribs are used to define radially spaced internal cooling channels, then cooling efficiency is enhanced by positioning channels closer to the trailing edge, but the device complexity increases
Solution Approach 1:
The horizontally extending ribs serve multiple functions: they define the boundaries of radially spaced cooling channels, provide structural support to prevent airfoil ballooning, and distribute thermal stresses. This multi-functionality reduces the need for additional components, offsetting the increased structural complexity with functional integration.
Solution Approach 2:
The structural support function and cooling channel definition function are merged into the same horizontally extending rib structures. This integration eliminates the need for separate support structures, reducing overall device complexity while achieving enhanced cooling efficiency through proper channel positioning near the trailing edge.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration effectively alleviates local internal stress loads and allows for enhanced cooling performance by positioning the aft ends of the cooling channels closer to the trailing edge, improving the operational efficiency and reliability of the gas turbine engine.
Implementation Method 1
a flow of cooling medium to hot gas path components formed from CMC materials
Implementation Method 2
thermal energy is transferred from the combustion gases to the rotatable turbine components and the stationary turbine components
Data Source
AI summary
A nozzle segment for a gas turbine engine may generally include an airfoil having an exterior surface defining a pressure side and a suction side extending between leading and trailing edges. The airfoil may define an open internal volume within its interior for receiving a cooling medium. The open internal volume may include a primary internal cavity and a plurality of internal cooling channels in flow communication with the primary internal cavity. The primary internal cavity may extend within the interior of the airfoil from a location adjacent to the leading edge to a forward end of each of the internal cooling channels. The internal cooling channels may extend within the interior of the airfoil from the primary internal cavity towards the trailing edge. In addition, the internal cooling channels may be spaced apart radially by a plurality of ribs extending within the interior of the airfoil.