Gas Turbine Blade Trailing Edge Cooling via Segmented Pin Field
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Solution Overview
Problem
Existing gas turbine blade cooling systems face challenges in optimizing heat transfer and reducing temperature variations at the trailing edge, particularly under high-temperature and pressure conditions, with existing designs being complex and inflexible in addressing cooling requirements across different regions.
Innovation Solution
A cooled blade design featuring a radially extending aerofoil with a lip overhang, multi-pass serpentine flow channels, a staggered pin field with increasing pin dimensions, turbulators for enhanced turbulence, and a pressure side bleed, optimized to minimize aerodynamic losses and improve heat transfer, with specific geometric ratios and arrangements to meet local flow and manufacturing criteria.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a multi-pass serpentine cooling system with flow bends is used, then the cooling coverage is improved, but the aerodynamic losses and flow disturbances increase
Solution Approach 1:
The cooling system is divided into multiple separate cooling passages instead of a single serpentine path. Each passage has its own straight inlet and outlet sections, segmenting the flow path to eliminate flow bends and reduce aerodynamic losses while maintaining cooling coverage through multiple parallel passages.
Solution Approach 2:
Different regions of the trailing edge are cooled by dedicated cooling passages optimized for their specific thermal requirements. The pin field configuration varies locally to address hot spots, with pins strategically positioned to provide enhanced cooling where needed without affecting other regions.
2Productivity
If the trailing edge is kept thin for efficiency, then the aerodynamic performance is improved, but the cooling requirements become more critical and difficult to meet
Solution Approach 1:
The trailing edge cooling is achieved through multiple discrete cooling passages rather than a single thick cooling structure. This segmentation allows the trailing edge to remain thin for aerodynamic efficiency while distributing cooling functions across multiple passages that collectively manage the thermal load.
Solution Approach 2:
The pin dimensions are optimized with specific diameter and height ratios (h/d = 0.5 to 2.0) to maximize cooling effectiveness in the thin trailing edge region. The pin field configuration parameters are adjusted to provide sufficient cooling capacity without increasing trailing edge thickness.
3Temperature
If uniform cooling is applied across the trailing edge, then temperature distribution is improved, but the complexity of the cooling system increases
Solution Approach 1:
The cooling system uses multiple parallel passages with simple, identical geometries rather than a complex single serpentine path. This segmentation achieves uniform cooling distribution through symmetry and repetition, simplifying manufacturing while maintaining temperature uniformity across the trailing edge.
Solution Approach 2:
All cooling passages are designed with identical geometry and spacing, creating a homogeneous cooling structure that naturally distributes cooling uniformly across the trailing edge. The pin field uses consistent pin dimensions and spacing to maintain uniform cooling without requiring complex variable geometry.
4Productivity
If cooling air requirements are reduced for efficiency, then the overall system efficiency is improved, but the cooling capability at critical regions becomes insufficient
Solution Approach 1:
Multiple parallel cooling passages distribute the limited cooling air more effectively across the trailing edge surface area. Each passage contributes to the overall cooling, providing adequate local heat transfer with reduced total cooling air requirements compared to a single high-flow serpentine passage.
Solution Approach 2:
The pin dimensions and spacing are optimized to enhance heat transfer coefficients with lower flow rates. The specific pin geometry parameters (diameter, height, spacing ratios) are tuned to maximize cooling effectiveness per unit of cooling air consumed.
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 design achieves optimized local heat transfer, reduced temperature variations, and improved cooling efficiency while maintaining mechanical integrity, effectively addressing the cooling challenges at the trailing edge of gas turbine blades.
Implementation Method 1
a plurality of radial internal flow channels connected via flow bends to form a multi-pass serpentine for a cooling flow... a trailing edge ejection region for cooling the trailing edge
Implementation Method 2
the cooling flow from the trailing edge passage to the pressure side bleed is mainly determined by a staggered field of pins... to increase the flow turbulence and to improve the heat transfer
Implementation Method 3
a pressure side bleed... running essentially parallel to the trailing edge and being connected over its entire length with a pressure side bleed
Data Source
AI summary
The invention relates to a cooled blade (10) for a gas turbine, comprising a radially extending aerofoil (11) with a leading edge (15), a trailing edge (16), a suction side (17) and a pressure side (18), whereby a lip overhang is provided on the suction side of the trailing edge (16), further comprising a plurality of radial internal flow channels (19, 19a,b) connected via flow bends to form a multi-pass serpentine for a coolant flow, whereby a trailing edge ejection region (21) is provided for cooling said trailing edge (16), said trailing edge ejection region (21) comprising a trailing edge passage of said multi-pass serpentine running essentially parallel to said trailing edge (15) and being connected over its entire length with a pressure side bleed (28).An optimized cooling is achieved by mainly determining the cooling flow from the trailing edge passage (19b) to the pressure side bleed (28) by means of a staggered field of pins, which is provided between said pressure side bleed (28) and said trailing edge passage (19b), with the lateral dimension of said pins increasing in coolant flow direction.