Turbomachine Fan Blade Breaking Zone for Tip Clearance Control
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Solution Overview
Problem
Turbomachine rotary fan blades experience self-engagement issues due to reduced radial clearance at high speeds, leading to potential damage and aerodynamic performance degradation, as existing solutions either increase clearance, which worsens aerodynamics, or fail to prevent damage effectively.
Innovation Solution
A turbomachine rotary fan blade with a predetermined breaking zone made of composite material featuring a three-dimensional weave of fiber reinforcement and resin matrix, incorporating discontinuities in the warp and weft strands to allow progressive detachment during tangential friction, thereby preventing self-engagement and maintaining aerodynamic performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the radial clearance at the blade tip is increased to avoid self-engagement and damage, then the reliability of the blade is improved, but the aerodynamic performance deteriorates due to increased leakage flow rate
Solution Approach 1:
The blade tip is segmented into a predetermined breaking zone with reduced fiber reinforcement density, creating a localized weak zone that can detach independently from the main blade structure. This segmentation allows the tip to be sacrificed to protect the rest of the blade, enabling reduced clearance without compromising overall reliability.
Solution Approach 2:
The fiber reinforcement density is varied locally, with the breaking zone having lower density than the main blade body. This local quality change creates a gradient in mechanical properties, allowing the tip to detach at lower stresses while the main blade retains full strength, thus enabling optimized clearance without aerodynamic penalty.
2Strength
If the fiber reinforcement density is increased to maintain blade strength, then the strength of the blade is improved, but the risk of self-engagement damage increases
Solution Approach 1:
The blade is divided into zones with different fiber reinforcement densities. The breaking zone has reduced density to prevent self-engagement damage, while the main blade maintains high density for strength. This segmentation allows simultaneous optimization of both parameters.
Solution Approach 2:
The blade uses composite materials with variable fiber reinforcement density throughout its structure. By controlling the composite structure, the breaking zone has lower strength to prevent damage during self-engagement, while the main blade has higher strength for structural integrity, resolving the contradiction between strength and damage prevention.
3Reliability
If the blade tip is made more resilient to prevent damage during contact, then the reliability is improved, but the clearance requirement increases leading to aerodynamic loss
Solution Approach 1:
The tip is segmented into a breaking zone with reduced fiber reinforcement, creating a sacrificial element that can detach during contact events. This allows the main blade to operate with reduced clearance without risking damage to the critical sections, thus maintaining aerodynamic performance while improving reliability.
Solution Approach 2:
The breaking zone acts as a pre-designed cushioning element that is intended to fail first during self-engagement events. By placing this weak zone at the tip, the blade is protected from serious damage even when operating with reduced clearance, thus maintaining aerodynamic efficiency without compromising reliability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables progressive wear and detachment of the blade tip, reducing damage and leakage flow while maintaining aerodynamic efficiency, allowing for reduced tip clearances and minimizing the need for part replacement during critical events.
Implementation Method 1
tangential friction extending in the second thickness direction against the blade tip edge
Implementation Method 2
the body is made of a composite material comprising a fiber reinforcement obtained by three-dimensional weaving of warp strands extending at least along the third height direction and of weft strands extending at least along the first longitudinal direction, and a resin matrix in which the fiber reinforcement is embedded
Implementation Method 3
when the blade operates at high speed, it is deformed under the centrifugal effect and aerodynamic forces
Implementation Method 4
when the blade operates at high speed, it is deformed under the centrifugal effect and aerodynamic forces
Data Source
AI summary
The invention relates to a turbomachine rotary-fan blade having a predetermined breaking zone, which extends from the upstream edge along a given length and from the blade-tip edge over a given height. According to the invention, the body is made of a composite material comprising a fibre reinforcement obtained by three-dimensional weaving of warp and weft strands, and a resin matrix in which the fibre reinforcement is embedded, and has, in or in the vicinity of the zone, a discontinuity of at least some of the strands, configured such that the zone partially detaches when there is tangential friction in the thickness direction against the blade-tip edge, the height being less than 3% of the aerodynamic stream height of the blade.