Gas Turbine Airfoil Tip Extension for Leakage Reduction
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Solution Overview
Problem
Axial compressor blades in gas turbine engines face efficiency reduction due to tip leakage and vortex formation, as well as increased stress from fundamental vibratory modes and potential foreign object impacts.
Innovation Solution
The design incorporates a tip extension on the airfoil blades, increasing the tip thickness by at least twice the true thickness, with a side transitional surface extending tangentially from the suction or pressure side surfaces, which helps reduce tip leakage, improves flow efficiency, and enhances durability against foreign objects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the blade tip thickness is increased to reduce tip leakage and improve durability, then the blade becomes more resistant to foreign object damage and leakage losses decrease, but the blade weight increases and the fundamental vibratory modes may shift to higher stress conditions
Solution Approach 1:
The patent applies local quality by adding material only at the blade tip region rather than throughout the entire blade. The tip extension creates a localized thickening that provides enhanced durability and foreign object damage resistance precisely where needed, while maintaining the original thin-blade design and weight characteristics in the rest of the blade structure.
Solution Approach 2:
The patent extends the blade tip in the tangential direction, adding a dimensional element perpendicular to the traditional blade thickness direction. This tip extension creates a three-dimensional structure that projects beyond the original airfoil shape, providing enhanced protection and leakage control without simply increasing the radial thickness of the entire blade.
2Productivity
If the blade tip thickness is increased to reduce tip leakage, then leakage losses decrease and compressor efficiency improves, but the blade complexity increases and manufacturing difficulty rises
Solution Approach 1:
The patent segments the blade structure into distinct regions: the original airfoil portion and the added tip extension portion. This segmentation allows the complex tip extension geometry to be designed and manufactured as a separate feature that can be integrated with the simpler base blade structure, potentially through additive manufacturing or other advanced fabrication techniques.
Solution Approach 2:
The tip extension incorporates curved and tapered geometries with smooth transitions, avoiding sharp angles or abrupt changes. The gradual tapering and curved surfaces facilitate more manageable manufacturing processes compared to complex angular features, while still achieving the desired aerodynamic and structural benefits.
3Stress or pressure
If the tip extension is added to modify fundamental vibratory modes, then stress from resonance is reduced, but the blade manufacturing precision requirements increase
Solution Approach 1:
The patent modifies the blade's vibratory characteristics by changing the mass distribution parameter through the tip extension. By adjusting parameters such as the extension length, thickness, and taper ratio, the fundamental natural frequencies can be shifted away from operating excitation frequencies, reducing resonance stresses without requiring extreme manufacturing precision.
Solution Approach 2:
The tip extension can be manufactured using additive manufacturing or other advanced fabrication methods that allow for complex geometries with controlled material properties. This approach enables precise control over the mass distribution and structural characteristics of the extension, facilitating accurate tuning of vibratory modes while managing manufacturing tolerances.
Data Source
AI summary
An airfoil for a gas turbine engine including a tip extension disposed at the tip of the airfoil body. The tip extension extends from the suction side surface and/or the pressure side surface and defines a tip thickness that is larger than a true thickness of the airfoil body. The true thickness is defined within a plane perpendicular to a root axis and extending transversely to the airfoil chord around a midpoint thereof. The tip extension includes a side transitional surface forming a curve extending tangentially from the side surface and/or the pressure side surface. The tip thickness increases over a radial dimension in the plane that is at least 2 times the true thickness.