Thermal Mechanical Dimple Array for Combustor Hot Spot Stress Relief
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Solution Overview
Problem
Gas turbine engine combustor panels experience thermal mechanical stresses due to hot spots, leading to cracking and reduced lifespan, and increasing cooling hole density to address this can decrease engine efficiency and deprive other areas of cooling.
Innovation Solution
A thermal mechanical dimple array is strategically placed on combustor wall assemblies to mitigate hot spots by creating indentations that flex away from heat sources, maintaining structural integrity and reducing stress through controlled in-plane stress distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the density of cooling holes is increased near hot spots, then the cooling effect at hot spots is improved, but engine efficiency decreases and cooling to other locations is deprived
Solution Approach 1:
The patent applies local quality by creating dimples with varying depths at different locations on the panel surface. Deeper dimples are positioned at hot spot locations to provide localized stress relief and thermal management, while shallower or no dimples are present in other areas. This non-uniform dimple distribution allows targeted cooling enhancement without requiring increased cooling hole density throughout the entire panel, thereby maintaining engine efficiency while addressing hot spots.
Solution Approach 2:
The patent transitions from a two-dimensional solution (increasing cooling hole density on the panel surface) to a three-dimensional solution by introducing dimples with varying depths into the panel structure. This dimensional change allows the panel to actively manage hot spots through geometric features that modify stress distribution and thermal characteristics without requiring additional cooling holes, thus avoiding the efficiency penalty associated with increased hole density.
2Temperature
If the density of cooling holes is increased near hot spots, then the cooling effect at hot spots is improved, but cooling distribution to other locations is deprived
Solution Approach 1:
The dimple array provides localized stress relief and thermal management at hot spot locations through deeper dimples, while maintaining uniform cooling distribution to other areas. The varying dimple depths create localized modifications to stress and thermal fields without disrupting the overall cooling flow pattern, ensuring that other locations continue to receive adequate cooling while hot spots are specifically addressed.
3Temperature
If cooling holes are added to address hot spots, then hot spot temperatures are reduced, but the panel structure becomes more complex and manufacturing more difficult
Solution Approach 1:
The patent merges the functions of thermal management and stress relief into a single integrated dimple array structure. The dimples serve dual purposes: they modify the thermal field to reduce hot spot temperatures and simultaneously provide stress relief by creating geometric features that redistribute mechanical stresses. This consolidation eliminates the need for separate cooling holes specifically targeted at hot spots, thereby reducing overall panel complexity and simplifying manufacturing while still achieving hot spot mitigation.
4Temperature
If cooling holes are added to address hot spots, then hot spot temperatures are reduced, but manufacturing precision requirements increase
Solution Approach 1:
By merging thermal management and stress relief functions into the dimple array, the patent eliminates the need for precise placement of additional cooling holes at hot spot locations. The dimples can be manufactured using standard forming techniques with less stringent precision requirements compared to drilling and positioning cooling holes. This integration significantly reduces manufacturing precision requirements while still achieving effective hot spot temperature reduction.
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 dimple array effectively reduces thermal mechanical stresses, minimizes cracking, and maintains efficient cooling distribution across the combustor section, enhancing the durability and performance of the gas turbine engine.
Implementation Method 1
A thermal mechanical dimple array is strategically placed on combustor wall assemblies to mitigate hot spots by creating indentations that flex away from heat sources, maintaining structural integrity and reducing stress through controlled in-plane stress distribution
Data Source
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AI summary
A thermal mechanical dimple array for combustor liners of gas turbine engines are located at known hot spots along the liner to reduce stress and minimize cracking. Such arrays have indentations in the liners at the hot spots that act to thermal mechanically flex the liner at the hot spot away from the heat source and distribute stresses such that cracking of the liner is reduced and durability is improved.