Gas Turbine Cooling Hole Diffuser Geometry
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Solution Overview
Problem
Gas turbine engines face challenges in achieving optimal thermal and propulsive efficiencies due to extreme temperatures in the combustor and turbine sections, which require effective cooling methods to extend material capabilities and improve performance.
Innovation Solution
The design incorporates a cooling hole with a diffuser portion that expands from an inlet to an exit area, featuring specific angles and geometries to optimize the area ratio and blowing ratio, enhancing the distribution and effectiveness of cooling air along hot section surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cooling air is tapped from other locations in the engine to cool hot section structures, then cooling effectiveness is improved, but engine overall efficiency deteriorates due to increased cooling air consumption
Solution Approach 1:
The patent changes the geometric parameters of the cooling hole by introducing a diffuser portion with specific area ratios (2.0-10.0) and expansion angles (5-20 degrees). This parameter modification allows the cooling air to expand and reduce momentum, improving film cooling effectiveness while maintaining lower cooling air consumption, thus resolving the contradiction between cooling effectiveness and engine efficiency
Solution Approach 2:
The diffuser portion creates a dynamic expansion of cooling air within the hole structure itself. The gradual expansion geometry transforms the high-momentum cooling air into a lower-momentum flow that adheres better to the surface, dynamically adjusting the flow characteristics to improve cooling performance without requiring additional cooling air
2Speed
If cooling air momentum is high, then cooling air can be delivered effectively through the cooling hole, but the cooling air does not flow effectively along the surfaces due to excessive momentum
Solution Approach 1:
The cooling hole is segmented into distinct functional portions: an inlet portion for receiving cooling air, a diffuser portion for expanding and reducing momentum, and an outlet portion for discharge. This segmentation allows each portion to perform its specific function optimally, transitioning the air from high momentum at inlet to low momentum at outlet for effective surface flow
Solution Approach 2:
The diffuser portion acts as an intermediary element between the inlet and outlet portions. It mediates the momentum transformation by providing a gradual expansion geometry that reduces cooling air momentum from its initial high value to a lower value suitable for surface flow, preventing both excessive momentum penetration and insufficient cooling
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 cooling efficiency by reducing the momentum of cooling air, allowing it to flow more effectively along surfaces, thereby enhancing the thermal and propulsive performance of the engine while minimizing the use of cooling air.
Implementation Method 1
a diffuser portion in communication with the inlet portion. The diffuser portion defines an exit area through a second surface
Implementation Method 2
The diffuser portion defines an exit area through a second surface. An area ratio of the exit area to the inlet area is between 2.5 and 8
Data Source
Figure 1~2
Figure 3~5
Figure 6A~8B
AI summary
A component (62) of a gas turbine engine includes a cooling hole (68) extending from a first side (72) to a second side (70) that includes an inlet portion (74) disposed about an axis (76) that defines an inlet area (80) through a first surface. The cooling hole (68) further includes a diffuser portion (86) in communication with the inlet portion (74). The diffuser portion (86) defines an exit area (88) and an area ratio of the exit area (88) to the inlet area (80) is provided that provides improved cooling efficiencies.