Gas Turbine Rotor Blade Tip Lean Design
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Solution Overview
Problem
In gas turbine engine design, smaller diameter core sections face reduced efficiency and stall margin due to large tip clearance to rotor blade span and chord ratios, which compromise compressor performance.
Innovation Solution
The rotor blade design features a cross-sectional median line that extends radially from the blade root to a lean point between the root and tip, with the lean point located between 80% to 95% of the radial span, and the median line offsets radially by a magnitude equal to between 5% and 20% of the rotor blade radial span or tip clearance, reducing blockage and loss associated with the tip clearance vortex.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If smaller diameter core sections are used to increase overall pressure ratio and bypass ratio, then engine compactness is improved, but compressor efficiency and stall margin are reduced due to large tip clearance ratios
Solution Approach 1:
The rotor blade is designed with non-uniform geometry along its span, specifically with tip lean that creates different effective clearances at different radial positions. The tip region has reduced effective clearance compared to the root region, locally addressing the tip clearance problem without changing the overall blade span or engine diameter.
Solution Approach 2:
Instead of addressing tip clearance purely in the radial dimension, the invention introduces a lean dimension where the blade tip is offset axially from the radial plane. This creates a three-dimensional clearance configuration that reduces the effective tip clearance path while maintaining the same radial blade span.
2Volume of moving object
If smaller diameter core sections are used to increase overall pressure ratio and bypass ratio, then engine compactness is improved, but stall margin is reduced due to large tip clearance to chord ratios
Solution Approach 1:
The rotor blade is designed with non-uniform geometry along its span, specifically with tip lean that creates different effective clearances at different radial positions. The tip region has reduced effective clearance compared to the root region, locally addressing the tip clearance problem without changing the overall blade span or engine diameter.
3Ease of manufacture
If traditional radial rotor blade design is used, then manufacturing simplicity is maintained, but compressor efficiency is compromised due to tip clearance vortex blockage and losses
Solution Approach 1:
The rotor blade is designed with non-uniform geometry along its span, specifically with tip lean that creates different effective clearances at different radial positions. The tip region has reduced effective clearance compared to the root region, locally addressing the tip clearance problem without changing the overall blade span or engine diameter.
Data Source
AI summary
A rotor blade of a gas turbine engine includes a pressure side, and a suction side opposite the pressure side and defining a rotor blade profile therebetween, the pressure side and the suction side each extending from a blade root to a blade tip. The rotor blade defines a cross-sectional median line midway between the pressure side and the suction side. The cross-sectional median line extends in a generally radial direction from the blade root to a lean point between the blade root and the blade tip. The cross-sectional median line extends off of radial from the lean point to the blade tip, defining a lean of the rotor blade between the lean point and the blade tip.