Turbine Platform Cooling Circuit Segmentation
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Solution Overview
Problem
Turbine blade platforms in gas turbine engines face issues with creep deformation and thermal-mechanical fatigue due to insufficient cooling, leading to potential oxidation from high temperature gradients.
Innovation Solution
A dual cooling circuit system is implemented, where one circuit cools the pressure side and another the suction side of the platform, with optional pedestals to enhance structural integrity, turbulate flow, and increase heat transfer coefficients, providing a film blanket for protection against high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling air is injected through openings in the sealing area, then the blade material is cooled, but the platform walls experience creep deformation due to insufficient cooling
Solution Approach 1:
The cooling system is divided into multiple separate cooling circuits, each serving specific regions of the platform. The first cooling circuit cools the pressure side while the second cooling circuit cools the suction side, allowing targeted cooling of different platform areas to prevent creep deformation while maintaining blade material temperature control
Solution Approach 2:
Different regions of the platform receive customized cooling through dedicated cooling circuits. The pressure side and suction side have separate cooling pathways with potentially different flow rates and temperature characteristics, providing locally optimized cooling quality to address varying thermal loads and prevent localized creep deformation
2Temperature
If cooling air is injected into the hot mainstream flow, then the blade material is cooled, but high temperature gradients in the platform result in thermal-mechanical fatigue
Solution Approach 1:
The platform cooling is segmented into multiple independent circuits that distribute cooling air more evenly across different platform regions. This segmentation prevents localized extreme temperature gradients by providing controlled cooling pathways that reduce thermal stress concentrations
Solution Approach 2:
Cooling air serves as an intermediary substance that is channeled through specific cooling circuits to mediate heat transfer from the platform walls. The controlled introduction of this intermediary through dedicated circuits allows gradual heat removal that reduces temperature gradients and associated thermal-mechanical fatigue
3Temperature
If cooling air is injected into the hot mainstream flow, then the blade material is cooled, but high temperatures cause oxidation of the platforms
Solution Approach 1:
Cooling air acts as a protective intermediary that is introduced through sealing area openings and cooling circuits to form a barrier between the hot oxidizing mainstream flow and the platform surfaces. This intermediary cooling air layer reduces the temperature at the platform-exposed-to-mainstream interface, thereby preventing oxidation while still allowing the blade material to be cooled through the dedicated cooling circuits
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
The dual cooling circuit system allows for higher inlet temperatures while reducing thermal-mechanical fatigue and oxidation risks by improving heat transfer efficiency and structural integrity, thus protecting the platform from creep deformation.
Implementation Method 1
The cooling air flows through each circuit and cools the walls of the platform
Implementation Method 2
The pedestals also turbulate the flow and enhance cooling by increasing the internal heat transfer coefficients
Implementation Method 3
The pedestals also provide conduction paths between the outer and inner wall of the cooling circuit
Implementation Method 4
This film blanket of cooling air further protects the platform walls from the hot gas recovery temperatures
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
An airfoil assembly (20) includes an airfoil (34) extending away from a platform (32). One or more cooling circuits (42, 46) are formed through the platform (32) in order to provide cooling of the platform (32). The cooling circuit (42, 46) may include a downwardly directed inlet (44, 50) receiving cooling air from below the platform (32). The cooling air is then directed in a direction generally parallel to the outer surface of the platform (32) and through exits (38, 54) formed through the outer surface of the platform (32). The cooling circuit (42, 46) may optionally include a plurality of pedestals (56) extending from an outer wall to an inner wall of the cooling circuit to increase the rigidity and the cooling function of the cooling circuit.