Flange Heat Shield Airflow Ramp for Gas Turbine Thermal Gradient Reduction
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Solution Overview
Problem
The high thermal gradients experienced by the diffuser case in gas turbine engines due to heat transfer from the combustor lead to stress, degradation, and reduced operational life of engine components.
Innovation Solution
A flange heat shield is designed to reduce thermal gradients by creating a gap between its outer surface and the diffuser case, using a nickel alloy material, and featuring an airflow ramp to redirect airflow and notches/mounting tabs for secure attachment, thereby reducing convective heat transfer and thermal stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the combustor is coupled directly to the diffuser case, then heat transfer from the combustor to the diffuser case occurs, but thermal gradients cause stress, deformation, and degradation of the diffuser case
Solution Approach 1:
A flange heat shield is introduced as an intermediary component between the combustor and the diffuser case flange. The heat shield includes an annular body positioned to block direct thermal pathways, with a gap between its outer surface and the diffuser case inner surface to reduce conductive and convective heat transfer, thereby reducing thermal gradients and protecting the diffuser case from thermal degradation
Solution Approach 2:
The heat shield is extracted as a separate, removable component that can be independently installed and maintained. It is not permanently integrated into the diffuser case structure, allowing for easy removal, inspection, and replacement without affecting the main engine case components
2Reliability
If a flange heat shield is installed to reduce thermal gradients, then stress and degradation of the diffuser case are reduced, but the device complexity increases
Solution Approach 1:
The heat shield is divided into modular components including an annular body, multiple mounting tabs spaced circumferentially around the annular body, and notches for engagement with the diffuser case. This segmentation allows for easier manufacturing, quality control, and installation while maintaining effective thermal protection
Solution Approach 2:
The heat shield employs a thin-walled annular body design that provides effective thermal protection without adding significant mass or structural complexity. The thin film approach maintains thermal isolation while being lightweight and easy to install
3Ease of operation
If mounting tabs and notches are added to secure the flange heat shield, then the heat shield attachment is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The mounting tabs include features such as clearance gaps and tolerance zones that accommodate manufacturing variations and assembly misalignments. The notches are designed with generous tolerances to ensure easy engagement, cushioning against the effects of imprecise manufacturing or installation
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 flange heat shield decreases thermal gradients in the diffuser case flange by 20-30%, reducing stress and extending the operational life of engine components by mitigating thermal loads.
Implementation Method 1
an outer surface of the flange heat shield and an inner surface of the engine case define a gap
Implementation Method 2
heat convectively transferred from the combustor to the diffuser case
Implementation Method 3
an airflow ramp located on an inner surface of the engine case forward of the landing
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
A flange heat shield (200; 400; 500) is provided. The flange heat shield (200; 400; 500) may comprise an annular body having a forward end (210) opposite an aft end (220; 420). The forward end (210) of the flange heat shield (200; 400; 500) may comprise a radial snap (214) configured to interface with an inner surface of an engine case. The inner surface of the engine case may comprise an airflow ramp (32) forward of the radial snap (214). The aft end (220; 420) of the flange heat shield (200; 400; 500) may comprise a plurality of notches (422) defining voids on the aft end (420). The aft end (420) of the flange heat shield (400) may also comprise mounting tabs (425) configured to couple the flange heat shield (400) to the engine case.