Rotating Airfoil Tip Pocket for Gas Turbine Fan Blades
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Solution Overview
Problem
The efficiency and weight of gas turbine engines, particularly the fan section, are hindered by the collective weight of fan blades, which contributes to aircraft fuel consumption and structural mass, necessitating a reduction in weight while maintaining aerodynamic performance.
Innovation Solution
The design incorporates a fan blade with a tip pocket defined by collapsible external walls and metering passages that deliver airflow to the tip pocket, reducing weight and allowing for deformation upon contact with the fan case, thereby optimizing weight distribution and aerodynamic efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If fan blade weight is reduced to improve fuel efficiency, then weight decreases and fuel consumption reduces, but structural strength and aerodynamic performance may deteriorate
Solution Approach 1:
The fan blade incorporates composite material construction with the tip pocket structure, combining different materials to achieve both weight reduction and structural strength maintenance. The composite structure allows optimization of mechanical properties while reducing overall mass.
Solution Approach 2:
The tip pocket structure segments the fan blade tip region, creating a localized structural modification that reduces weight in the critical tip area while maintaining overall blade integrity. This segmentation allows targeted weight reduction without compromising essential structural functions.
2Weight of moving object
If fan blade weight is reduced to improve fuel efficiency, then weight decreases and fuel consumption reduces, but aerodynamic performance may deteriorate
Solution Approach 1:
The tip pocket structure applies local quality modification at the fan blade tip, creating a specialized aerodynamic feature in the critical tip region. This localized structural change optimizes aerodynamic performance specifically where it matters most while maintaining overall blade functionality.
Solution Approach 2:
The collapsible external walls of the tip pocket create a dynamic structure that can adapt during operation. The walls are designed to collapse under centrifugal force, allowing the structure to transition from a static weight-saving feature to a dynamic element that maintains aerodynamic integrity during rotation.
3Strength
If rigid fan blade structure is used to maintain strength, then structural integrity is maintained, but impact energy during blade liberation causes damage to fan case
Solution Approach 1:
The tip pocket structure serves as a pre-designed energy absorption feature that activates during blade liberation events. The collapsible walls are positioned to absorb impact energy before it can reach the fan case, providing beforehand cushioning against catastrophic damage.
Solution Approach 2:
The tip pocket structure converts the harmful impact energy from blade liberation into a beneficial energy absorption mechanism. The collapsible walls are designed to fail in a controlled manner, transforming the destructive force into a protective feature that saves the fan case from damage.
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
This design reduces the overall weight of the fan section, decreases centrifugal stress, and tunes vibratory modes, leading to improved fuel efficiency and reduced aerodynamic losses, while also providing a deformable structure to absorb impact during blade liberation.
Implementation Method 1
the external walls are deformable in response to contact with a fan case
Implementation Method 2
the one or more metering passages cause airflow to be delivered to the radially outer face of the tip portion in response to rotation of the fan blade
Data Source
AI summary
A fan blade for a gas turbine engine according to an example of the present disclosure includes, among other things, an airfoil section that has a pressure sidewall and a suction sidewall that meet together at both a leading edge and a trailing edge, and extends radially between a root portion and a tip portion. A tip pocket is defined by collapsible external walls of the tip portion, and has a pocket opening at a radially outer face of the tip portion.