Blade Tip Cross-Section Reduction for Vibrational Stress
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Solution Overview
Problem
Existing blade tips in continuous-flow machines, such as aircraft engines, experience significant vibrational stresses leading to potential cracking and reduced service life, despite previous designs like tapered squealer tips that only partially address these issues.
Innovation Solution
A runner blade design with a blade tip that gradually reduces its cross-section from the middle section towards both the leading and trailing edges, featuring varying widths on both the pressure-side and suction-side walls, which minimizes vibrational stresses and allows for high-strength armoring, while maintaining aerodynamic efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional blade tip designs (including tapered squealer tips) are used, then manufacturing is simplified, but vibrational stresses in the blade tip area remain high leading to cracking and reduced service life
Solution Approach 1:
The blade tip is divided into multiple distinct sections: a middle section with constant or slightly varying cross-section, and two partial sections (front and rear) with gradually reducing cross-sections. This segmentation allows different geometric characteristics in different zones to optimize both stress distribution and manufacturing feasibility.
Solution Approach 2:
Different sections of the blade tip are given different cross-sectional characteristics tailored to their specific functional requirements. The middle section maintains structural integrity while the partial sections gradually reduce in size to minimize vibrational stresses at the critical tip regions, applying local quality variations to solve the overall problem.
2Reliability
If blade tip cross-section is reduced to minimize vibrational stresses, then cracking risk is reduced, but aerodynamic efficiency may be compromised
Solution Approach 1:
The cross-section reduction is applied partially and selectively only to the partial sections near the leading and trailing edges, while the middle section maintains adequate cross-sectional dimensions for aerodynamic performance. This partial application of tapering achieves stress reduction without excessive sacrifice of aerodynamic efficiency.
Solution Approach 2:
The cross-section reduction is implemented gradually over the length of the partial sections rather than as an abrupt change, creating a smooth three-dimensional transition. This dimensional approach allows stress minimization while maintaining aerodynamic flow characteristics.
Data Source
AI summary
A blade for a continuous-flow machine is disclosed, especially an aircraft engine, whereby, starting from the middle section, the cross section of the blade tip is reduced with respect to the middle section, at least over a front partial section in the direction of the leading edge and over at least a rear section in the direction of the trailing edge, and a continuous-flow machine having at least one row of blades including such blades is also disclosed.