Combustor Heat Shield Variable Cooling Protuberances
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Solution Overview
Problem
Existing heat shields in gas turbine engine combustors face challenges in efficiently managing coolant distribution to effectively cool hot spots while minimizing smoke, unburned hydrocarbon, and CO/NOx emissions.
Innovation Solution
A heat shield design with a back face featuring varying protuberance densities and cooling hole configurations, where higher protuberance density in central regions enhances airflow communication and cooling efficiency, while reduced densities in peripheral regions optimize coolant flow to hot spots, promoting effective heat exchange and reduced pressure drop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If uniform coolant distribution is provided across the heat shield, then cooling coverage is improved, but combustion efficiency deteriorates and emissions increase
Solution Approach 1:
The heat shield back face is divided into multiple regions with different protuberance densities. Central regions have higher protuberance density to enhance cooling where hot spots occur, while peripheral regions have lower density to minimize pressure drop and maintain combustion efficiency. This local differentiation allows targeted cooling without compromising overall combustion performance.
2Temperature
If higher protuberance density is provided throughout the heat shield, then heat exchange efficiency is improved, but pressure drop increases and coolant flow is restricted
Solution Approach 1:
Protuberances are concentrated in central regions where heat transfer is most critical, while peripheral regions have fewer protuberances. This localized approach maximizes heat exchange efficiency in hot spot areas without creating excessive flow resistance across the entire heat shield surface, thereby controlling pressure drop.
Solution Approach 2:
The heat shield back face is segmented into distinct regions (central, inner peripheral, outer peripheral) with different protuberance densities. This segmentation allows each region to be optimized independently - central regions for heat exchange and peripheral regions for flow management - balancing heat transfer efficiency with pressure drop control.
3Temperature
If coolant flow rate is increased to cool hot spots, then cooling effectiveness is improved, but combustion efficiency deteriorates due to reduced air available for combustion
Solution Approach 1:
Cooling air flow is locally enhanced in central regions through higher protuberance density, which directs cooling air precisely where hot spots occur. Peripheral regions maintain lower protuberance density to ensure adequate air supply for combustion, thus achieving effective hot spot cooling without compromising combustion efficiency.
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 by optimizing airflow and heat transfer, reducing emissions and improving combustion efficiency by directing cooling air effectively across the heat shield, thereby managing coolant distribution more efficiently.
Implementation Method 1
The amount of coolant available for cooling the heat shields must be minimized to improve the combustion efficiency and to reduce the smoke, unburned hydrocarbon and CO/NOx emission
Implementation Method 2
the central region being in airflow communication with the outer region and the inner region within the cavity
Data Source
AI summary
A combustor heat shield has a body with heat exchange promoting protuberances extending from a back face thereof. The density of protuberances is less in hot spot regions than in other heat shield regions which require less cooling.