Combustor Dome Heat Shield Cooling via Impingement Holes
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Solution Overview
Problem
Existing heat shields in gas turbine engine combustors face challenges in efficiently cooling the dome panel while minimizing coolant usage to reduce smoke, unburned hydrocarbon, and CO/NOx emissions.
Innovation Solution
A combustor and dome heat shield assembly featuring heat shield sectors with protuberances and impingement cooling holes aligned with reduced-height pin fins, which enhance heat exchange and airflow to optimize cooling without increasing pressure drop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If more coolant is used to cool the heat shields, then the cooling effectiveness is improved, but the combustion efficiency deteriorates and emissions increase
Solution Approach 1:
The patent applies local quality by creating different cooling zones on the heat shield back face. Impingement holes are strategically positioned to direct coolant jets at specific high-heat areas, while protuberances of varying heights create localized turbulence in regions where heat flux is highest. This targeted approach concentrates cooling where needed most, achieving effective heat shield cooling with reduced overall coolant flow, thereby preserving combustion efficiency.
Solution Approach 2:
The patent employs dynamics by using protuberances that create dynamic turbulence and flow separation. The varying heights of protuberances cause the coolant flow to detach and reattach, creating turbulent mixing that enhances heat transfer coefficients. This dynamic flow pattern allows for more effective cooling with less coolant compared to steady, laminar flow configurations.
2Temperature
If coolant flow is increased to improve heat exchange, then cooling performance is improved, but pressure drop increases
Solution Approach 1:
The patent applies preliminary action by positioning impingement holes to direct coolant jets onto the heat shield back face before the hot gases can cause excessive heating. The protuberances are pre-configured to create turbulence and extend the coolant-gas interaction path length. This preliminary cooling action reduces the temperature gradient and heat transfer requirements, allowing effective cooling at lower pressure drops.
Solution Approach 2:
The patent uses another dimension by adding the third dimension of protuberance height to the otherwise two-dimensional heat shield back face. This vertical dimension creates flow path lengthening and multi-level turbulence zones, enhancing heat transfer surface area and cooling effectiveness without requiring increased coolant flow rate, thus avoiding excessive pressure drop.
3Temperature
If protuberances are added to the heat shield back face to enhance cooling, then heat transfer efficiency is improved, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the heat shield back face into multiple zones with different protuberance heights and configurations. Each zone is tailored to address specific thermal loading patterns. This segmented approach allows for optimized heat transfer in each region while maintaining a modular structure that can be manufactured using standard techniques, balancing complexity with performance.
Solution Approach 2:
The patent employs parameter changes by varying the height, diameter, and spacing of protuberances across different regions of the heat shield back face. These parameter variations are optimized to match local heat flux distributions. By changing geometric parameters rather than fundamental structure, the patent achieves enhanced heat transfer while maintaining manufacturability and reasonable structural complexity.
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 configuration improves heat transfer efficiency, reduces emissions, and minimizes coolant usage while maintaining combustion efficiency by directing cooling air effectively across the heat shield surface.
Implementation Method 1
a plurality of impingement cooling holes defined through the dome, the impingement cooling holes substantially aligned with the second plurality of protuberances
Implementation Method 2
the back face having a heat exchange promoting protuberance pattern thereon
Data Source
AI summary
Impingement hole patterns are provided in a combustor dome panel to provide efficient cooling of a combustor dome heat shield. The impingement holes are substantially aligned or located above partial height protuberances provided on the back face of the heat shield.