Rotor Blade Tip Rake Angle Reduces Radial Loading
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Gas turbine engine compressor rotor blades experience high radial loading and vibratory stresses due to tip rubs against abradable casings, leading to material fatigue and reduced blade life, especially when the suction side contacts the casing.
Innovation Solution
The rotor blades are designed with a tip portion rake angle that facilitates reduced radial loading during tip rubs by ensuring the concave edge contacts the abradable material instead of the convex edge, thereby minimizing contact and stress induction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the rotor blade is designed with conventional geometry, then the blade structure is simple and easy to manufacture, but the blade experiences high radial loading and vibratory stresses during tip rubs
Solution Approach 1:
The patent applies local quality by modifying only the tip portion geometry while maintaining conventional airfoil shapes and root structures. The rake angle is introduced specifically at the tip to reduce radial loading during tip rubs, rather than redesigning the entire blade. This localized modification reduces complexity compared to a complete blade redesign while achieving the strength improvement.
Solution Approach 2:
The patent changes the geometric parameter of the tip portion by introducing a rake angle that slopes the tip surface. This parameter modification alters the contact mechanics during tip rubs, reducing radial and axial loads. The parameter change is specific to the tip region and maintains compatibility with conventional manufacturing processes.
2Reliability
If the tip portion is modified with a rake angle, then radial loading and blade vibrations are reduced, but manufacturing complexity increases
Solution Approach 1:
The patent segments the blade into distinct regions with different geometric characteristics. The conventional airfoil section is maintained from root to mid-span, while the tip portion features a rake angle modification. This segmentation allows each region to be optimized independently and facilitates conventional manufacturing processes like molding or machining.
Solution Approach 2:
The rake angle is incorporated into the blade design before manufacturing, allowing the modified geometry to be built-in during the fabrication process. This preliminary action ensures the stress-reducing geometry is achieved without requiring post-manufacturing modifications or complex assembly steps.
3Object-affected harmful factors
If the suction side contacts the abradable casing, then tip rubs occur, but high stresses are generated at the root portion
Solution Approach 1:
The patent introduces a new geometric dimension at the tip portion through the rake angle, which slopes the tip surface in a direction that alters the contact mechanics. This dimensional change modifies the contact between the suction side and abradable casing, reducing the transmission of stresses to the root portion while maintaining the necessary aerodynamic profile.
Data Source
AI summary
A method for assembling a rotor assembly and a rotor assembly are provided. The method comprises providing a rotor blade including a first sidewall, a second sidewall, where the first and second sidewalls are connected at a leading edge and a trailing edge and extend in span from a root portion to a tip portion, removing blade material from the tip portion to form a tip portion rake angle that enables the tip portion to extend obliquely between the first and second sidewalls, and coupling the rotor blade to a shaft such that during tip rubs the tip portion rake angle facilitates reducing radial loading induced to the blade during tip rubs.