Turbine Blade Cooling Circuits with Pin Array Sections
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Solution Overview
Problem
Turbine airfoils in gas turbine engines face high mechanical and thermal stresses due to extreme temperatures and rotational velocities, leading to inefficiencies and reduced part-life, with existing cooling methods like film cooling compromising aero-efficiency and struggling to effectively cool 'dead spots' within the airfoil design.
Innovation Solution
A turbine blade design featuring a hollow airfoil with a leading edge chamber, a trailing edge chamber separated by a partition, and a pin array section with transverse cooling pins that minimize the axial distance between the insert and pin array, enhancing cooling by creating turbulent flow and optimizing the shape for improved heat transfer, thereby reducing the need for film cooling downstream of the throat.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If film cooling is used to cool turbine airfoils, then cooling effectiveness is improved, but aero-efficiency deteriorates
Solution Approach 1:
The invention extracts the cooling function from the external film cooling approach and relocates it to internal cooling circuits within the airfoil structure. Cooling air is circulated through internal passageways and discharged through strategically positioned holes, separating the cooling mechanism from the external airflow path and reducing its negative impact on aero-efficiency.
Solution Approach 2:
The invention introduces internal cooling circuits as an intermediary system between the heat source (hot gas path) and the airfoil structure. The internal circuits act as a mediator that transfers heat away from critical areas through controlled airflow, providing cooling effectiveness while minimizing disruption to the external aerodynamic flow.
2Temperature
If conventional cooling circuits are used, then general cooling is provided, but dead spots remain difficult to cool
Solution Approach 1:
The invention applies local quality by positioning cooling holes and internal circuits at specific locations within the airfoil structure, particularly targeting dead spots and high-heat-flux areas. The cooling system is customized for different regions, with varying hole distributions and circuit configurations optimized for local thermal conditions rather than uniform cooling throughout.
Solution Approach 2:
The invention adds a third dimension to the cooling approach by creating internal three-dimensional cooling circuits within the airfoil structure. Instead of relying solely on two-dimensional surface film cooling, the internal circuits penetrate deep into the airfoil, providing cooling from multiple directions and reaching previously inaccessible dead spots through complex internal passageway geometries.
3Reliability
If internal cooling circuits are extended to reach dead spots, then cooling coverage is improved, but device complexity increases
Solution Approach 1:
The invention segments the cooling system into modular components, including separate leading edge circuits, trailing edge circuits, and intermediate circuits that can be independently designed and optimized. This segmentation allows complex cooling coverage to be achieved through coordinated simple modules rather than a single complex circuit, facilitating manufacturing and maintenance.
Solution Approach 2:
The invention employs nested cooling circuits where internal passageways are contained within the airfoil structure, and cooling holes are positioned within the airfoil wall. The multi-level nested arrangement allows cooling air to travel through internal channels and emerge at strategic locations, achieving comprehensive cooling coverage while maintaining a compact integrated structure.
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 design enhances cooling efficiency, reduces localized hot spots, minimizes the need for film cooling, and increases the aero-efficiency of the turbine engine by effectively cooling previously difficult-to-reach areas, thus extending the part-life and reducing operational stresses on the airfoils.
Implementation Method 1
As the compressed air passes through the airfoil, it convectively cools the airfoil
Implementation Method 2
the supply of compressed air is released through small holes on the surface of the airfoils. Released in this manner, the supply of air forms a thin layer or film of relatively cool air at the surface of the airfoil, which both cools and insulates the part from the higher temperatures that surround it
Data Source
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AI summary
A turbine blade with a generally hollow airfoil (110) having an outer wall (133) that defines a chamber (122) for receiving cooling air, the airfoil (110) comprising a leading edge (112) that resides in an upstream direction, a trailing edge (118) that resides in a downstream direction, a convex suction side (116), a concave pressure side (114), and an insert (128) disposed within the chamber (122) that is configured to initially receive at least a portion of the cooling air entering the chamber (122) and direct the cooling air through a plurality of insert apertures (130) to cool the inner surface of the outer wall (133), the insert (128) further comprising a configuration that generally conforms to the contour of the outer wall (133) of the chamber (122) but in spaced relation thereto, wherein the chamber (122) and insert (128) narrow as they extend toward the trailing edge (118), the insert (128) eventually terminating and the chamber (122) eventually terminating at a pin array section (152), wherein a first distance exists that comprises the generally axial distance between the position of downstream termination point of the insert (128) and the position of an upstream beginning point of the pin array section (152), wherein the pin array section (152), at a downstream end, comprises a plurality of openings that define an inlet to a plurality of trailing edge cooling apertures (144), and wherein the chamber (122), the insert (128), and the pin array section (152) are configured such that the first distance is approximately minimized.