Gas Turbine Composite Airfoil Trailing Edge Bridge
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing composite materials used in gas turbine engine mid-turbine frames face challenges in maintaining a small trailing edge radius for aerodynamic performance, as they tend to bulge open and split due to differential pressure, making it difficult to use a continuous layer of plies at the trailing edge.
Innovation Solution
A composite airfoil design featuring first pressure and suction side layers terminating in ends near the trailing edge, with a bridge wrapped around these ends, and a filler provided between the layers to maintain structural integrity and prevent splitting, constructed from ceramic fibers bonded by a ceramic matrix, such as silicon carbide material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a continuous layer of plies is used at the trailing edge, then manufacturing is simplified, but the trailing edge cannot achieve a small radius for aerodynamic performance
Solution Approach 1:
The airfoil is divided into multiple discrete ply layers that terminate before the trailing edge, allowing the trailing edge to be formed separately with optimized geometry. This segmentation enables both simplified manufacturing of the main airfoil body and precise control of the trailing edge shape for aerodynamic performance.
Solution Approach 2:
A bridge structure is introduced as an intermediary element that connects the terminated ply layers at the trailing edge. This bridge serves as a mediator that joins the segmented plies while maintaining the small trailing edge radius, resolving the conflict between manufacturing simplicity and aerodynamic shape requirements.
2Shape
If the trailing edge is made compact with small radius, then aerodynamic performance is improved, but the structure tends to bulge open and split under differential pressure
Solution Approach 1:
The bridge structure is pre-installed at the trailing edge before the airfoil is subjected to differential pressure during operation. This preliminary placement of the bridge creates a pre-strengthened structure that resists the bulging and splitting forces that will later act on the trailing edge, maintaining both compact shape and structural integrity.
Solution Approach 2:
The airfoil employs composite material construction with multiple ply layers combined with a bridge structure, creating a hybrid composite system. This composite approach allows the trailing edge to achieve both the small radius needed for aerodynamic performance and the enhanced strength required to resist differential pressure forces.
3Shape
If discrete plies are used instead of continuous layer, then small trailing edge radius is achieved, but the trailing edge is prone to splitting under differential pressure
Solution Approach 1:
The discrete ply layers are merged at the trailing edge through the bridge structure, which combines and reinforces the separate plies. This merging action creates a unified, reliable trailing edge structure that maintains the small radius geometry while preventing splitting under differential pressure through the combined strength of the integrated plies and bridge.
Data Source
Figure 1
Figure 2
Figure 3~5
AI summary
An airfoil for a gas turbine engine includes first pressure and suction side layers forming a cavity and terminating in ends near a trailing edge. The first and second suction side layers are constructed from a composite material. A bridge is wrapped about the ends.