Airfoil Baffle Seal Insert for Blocking Parasitic Cooling Flow
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Solution Overview
Problem
In gas turbine engines, the gap between the baffle insert and the internal rib of the airfoil allows air to flow along a less preferred path, reducing the effectiveness of convective cooling on the hot surfaces of the airfoil.
Innovation Solution
A seal element, such as a rope seal or wire seal, is arranged within the gap between the aft portion of the baffle insert and the internal rib, allowing it to move and engage sealingly under pressure differentials, thereby blocking airflow along the less preferred path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the gap between the baffle insert and internal rib is reduced by welding the baffle as far aft as possible, then airflow along the second flow path is reduced, but the reliability of maintaining the gap is compromised due to thermal expansion and material changes during operation
Solution Approach 1:
The seal element is designed to be movable within the gap between the baffle insert and internal rib, allowing it to dynamically adjust its position in response to pressure differentials and thermal expansion. This dynamic capability enables the seal to maintain effective sealing under varying operating conditions, resolving the contradiction between reducing parasitic airflow and maintaining reliability through thermal expansion accommodation.
Solution Approach 2:
The seal element utilizes the existing pressure differential across the baffle as a self-actuating mechanism to push itself into the sealing position. This self-service approach eliminates the need for additional actuation systems or complex mechanical constraints, allowing the seal to automatically adapt to operational changes while maintaining reliable sealing against parasitic airflow losses.
2Productivity
If a seal element is introduced to block the gap between the baffle insert and internal rib, then airflow along the preferred convective cooling path is ensured, but the device complexity increases
Solution Approach 1:
The seal element is designed as a simple, replaceable component that can be easily installed and replaced if needed. This approach uses a relatively simple sealing element rather than a complex mechanical system, accepting that the seal may wear or fail over time but simplifying the overall device complexity and maintenance requirements.
Solution Approach 2:
The seal element utilizes a flexible, compliant material that can deform and adapt to the gap geometry between the baffle insert and internal rib. This flexible sealing approach achieves effective sealing without requiring complex mechanical structures, thereby maintaining cooling effectiveness while minimizing device 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
The seal element ensures that the cooling air flows along the preferred path, enhancing convective cooling on the hot surfaces of the airfoil and reducing parasitic leaks.
Implementation Method 1
A seal element is arranged in a gap between an aft portion of the baffle insert and the internal rib. The seal element is free floating such that a pressure differential across the seal element causes the seal element to sealingly engage between the aft portion of the baffle insert and the internal rib
Implementation Method 2
The seal element is configured to form a fluid seal between the aft portion of the baffle insert and the internal rib
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
Airfoils (400) for gas turbine engines are described. The airfoils (400) include an airfoil body (402) having a pressure and a suction side wall (406, 404) and an internal rib (414) and defining a cavity (410) between, at least, the pressure side wall, the suction side wall, and the internal rib. A baffle insert (416) is arranged within the cavity (410) and includes a sealing portion arranged adjacent to the internal rib (414) of the airfoil body (402) with a gap (428) therebetween. A seal element (426) is arranged within the cavity and located in the gap (428). The seal element (426) is free to move relative to each of the baffle insert (416) and the airfoil body (402) within the gap (428). When a pressure differential exists across the seal element (426), the seal element will sealingly engage between the sealing portion of the baffle insert (416) and the internal rib (414) of the airfoil body (402) to block a flow through the gap (428).