Gas Turbine Rotor Blade Contoured Tip for Shroud Wear Control
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Solution Overview
Problem
Gas turbine engines face inefficiencies due to large flowpath steps and uneven tip clearances, leading to significant efficiency penalties and potential stall margin loss, particularly caused by the interaction between rotor blades and shrouds during rub events.
Innovation Solution
The design incorporates a rotor blade with a contoured tip featuring multiple sloped regions, including a first sloped region that matches the shroud's slope and a second steeper region, which creates a sculpted pocket with a reduced forward facing flowpath turn, minimizing the interference zone and reducing the impact of rub events on shroud wear and flowpath steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the rotor blade tip is designed to rub against the shroud during operation, then the shroud wear is controlled and rotor tip interference is minimized, but large flowpath steps and uneven tip clearances are created causing efficiency penalties
Solution Approach 1:
The blade tip is divided into multiple zones with different slope characteristics: a first zone with a first slope matching the shroud slope, a second zone with a second slope creating a pocket, and a third zone with a third slope. This local differentiation allows the blade to create a sculpted pocket that controls wear in specific areas while maintaining smooth flowpaths in other areas, thus reducing efficiency penalties while controlling shroud wear.
Solution Approach 2:
The blade tip employs curved and sloped surfaces rather than flat or sharp edges. The contoured tip with multiple sloped regions creates a sculpted pocket with smooth transitions, eliminating large flowpath steps and reducing turbulence. This curvature approach maintains aerodynamic efficiency while enabling controlled rub interaction with the shroud.
2Ease of manufacture
If a traditional rotor blade tip design is used, then manufacturing is simpler, but large flowpath steps create uneven tip clearances and potential stall margin loss
Solution Approach 1:
The blade tip is pre-contoured during manufacturing with multiple sloped regions and a sculpted pocket geometry. This preliminary shaping ensures that when the blade operates and contacts the shroud, the interference is distributed evenly and the resulting wear pattern maintains uniform tip clearances. The pre-designed geometry prevents the formation of large flowpath steps that would cause clearance unevenness.
3Reliability
If the rotor blade creates a pocket radially outward during rub events, then shroud wear is managed, but large flowpath steps are generated causing significant efficiency penalties
Solution Approach 1:
The invention changes the geometric parameters of the blade tip, specifically implementing multiple sloped regions with different angles. The first slope matches the shroud slope, the second slope creates a controlled pocket depth, and the third slope completes the contoured shape. This parameter optimization allows the pocket to be sculpted with smooth transitions, managing shroud wear while minimizing flowpath disruptions and maintaining engine efficiency.
Data Source
AI summary
A rotor blade for a gas turbine engine includes a blade extending from a root and a contoured tip portion at a first end of the blade. The first end is opposite the root. The contoured tip portion includes a first sloped region and a second sloped region. The second sloped region is steeper than the first sloped region, relative to a platform.