Turbine Blade Cooling Microcircuit with Internal Flow Features
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Solution Overview
Problem
Existing cooling circuits in turbine engine components are ineffective in maintaining film coverage and prone to cracking due to limitations in heat transfer and exit slot configurations, leading to premature film decay and thermal stress.
Innovation Solution
A cooling microcircuit with internal features such as dog-legged and shaped pedestals, and teardrop-shaped elements that enhance convective efficiency by increasing the heat transfer coefficient and maintaining high cooling fluid velocity, using refractory metal core technology to form exit slots that prevent film blow-out and promote film coverage along the blade surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing cooling circuits are used, then the blade can be cooled, but film coverage is insufficient and cracking occurs prematurely
Solution Approach 1:
The cooling circuit is divided into multiple serpentine passages with internal features (pedestals, dog-legged pedestals, teardrop-shaped elements) segmented along the flow path. This segmentation increases the number of heat transfer zones and extends the cooling fluid's contact time with the blade internal surfaces, preventing premature film decay and extending operational duration
Solution Approach 2:
The cooling circuit design creates dynamic flow conditions through varying passage cross-sections and internal features that accelerate and redirect cooling fluid. This dynamic flow maintains higher cooling effectiveness throughout the blade, extending the duration of protective film coverage
2Reliability
If conventional exit slot configurations are used, then cooling fluid can exit, but film coverage is limited and film blow-out occurs
Solution Approach 1:
Different regions of the cooling circuit have locally optimized features: serpentine passages for extended path length, pedestals for heat transfer enhancement in specific zones, and strategically positioned exit slots. This local optimization ensures stable film formation at critical areas while maximizing overall film coverage area
Solution Approach 2:
The cooling circuit transitions from two-dimensional planar cooling to three-dimensional serpentine pathways with vertical and horizontal components. This dimensional change allows cooling fluid to access and form protective films on multiple surfaces simultaneously, increasing total film coverage area while maintaining stability
3Use of energy by moving object
If cooling fluid velocity is reduced, then pressure drop decreases, but convective efficiency and heat transfer coefficient are reduced
Solution Approach 1:
The serpentine cooling circuit maintains continuous cooling fluid flow throughout the blade with optimized passage geometry. Internal features like pedestals and teardrop elements ensure continuous turbulence and heat transfer enhancement along the entire flow path, maintaining high convective efficiency without excessive pressure drop
Solution Approach 2:
The cooling circuit design changes flow parameters dynamically through varying passage cross-sections and internal features. These parameter changes optimize the balance between velocity (for heat transfer) and pressure drop, achieving high convective efficiency with acceptable energy loss
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 solution achieves high convective efficiency and improved film coverage, reducing cracking and thermal stress on turbine blades by maintaining a protective cooling film and enhancing heat transfer, thereby extending the operational lifespan of turbine engine components.
Implementation Method 1
cooling microcircuit for use in turbine engine components, such as turbine blades, which convectively cools the blade with a high degree of convective efficiency (heat pick-up)
Implementation Method 2
internal features such as a pair of dog-legged pedestals 20 and 22. The pedestals 20 and 22 may be designed and aligned so that in a region 24, the flow of cooling fluid accelerates through the cooling circuit
Data Source
Figure 1~3
Figure 4~5
AI summary
A turbine engine component (12) such as a turbine blade includes an airfoil portion (10) formed by a suction side wall and a pressure side wall, and a cooling microcircuit (14) incorporated in at least one of the suction side wall and the pressure side wall. The cooling microcircuit (14) comprises a channel (11) through which a cooling fluid flows, at least one exit hole (18) for distributing cooling fluid over a surface of the turbine blade, and internal features within the channel (11) for accelerating the flow of cooling fluid prior to the cooling fluid flowing through the at least one exit hole (18).