Variable Pitch Fan Blade Axial Insertion via Spherical Receiver
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Solution Overview
Problem
Existing blade positioning and support systems in gas turbine engines face challenges in achieving a variable-pitch design due to spatial conflicts between the blade tip and the rub strip, particularly when the rub strip's leading edge has a smaller inner diameter than its center section, making axial blade insertion impossible.
Innovation Solution
A blade positioning and support system that allows axial insertion and pitch angle adjustment of blades by using a blade receiver with multiple axial positions and spherical shapes, enabling the blade to translate along its axis and maintain clearance with the rub strip, utilizing materials with damping properties for vibration reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the blade tip and rub strip are made spherically shaped to maintain clearance in variable-pitch design, then the blade can rotate relative to the rub strip, but the blade cannot be inserted axially along the central longitudinal axis because the tip will not clear the rub strip leading edge
Solution Approach 1:
The blade insertion process transitions from a single axial dimension to a two-dimensional path involving both axial movement and radial displacement. The blade is first inserted radially through the leading edge of the rub strip, then moved axially into the blade receiver, allowing spherical shapes to maintain clearance while enabling successful insertion.
Solution Approach 2:
The blade receiver acts as an intermediary mechanism that facilitates the complex insertion process. It provides a receiving cavity that accommodates the blade during the multi-stage insertion, allowing the blade to be positioned correctly without requiring the tip to clear the rub strip leading edge in the traditional axial manner.
2Ease of manufacture
If the blade receiver allows axial insertion along the central longitudinal axis, then the installation process is simple, but the blade tip cannot clear the rub strip leading edge when the leading edge has a smaller inner diameter
Solution Approach 1:
The insertion path is changed from a simple axial line to a composite motion involving radial entry through the leading edge followed by axial movement into the receiver. This dimensional change allows the blade tip to clear the rub strip leading edge while maintaining a reliable clearance during operation.
3Adaptability or versatility
If the blade receiver provides multiple axial positions for the blade, then the blade pitch angle can be adjusted continuously or in step changes, but the device complexity increases
Solution Approach 1:
The blade receiver is designed with dynamic positioning capability, allowing the blade to be held at multiple axial positions within the receiver cavity. This enables continuous or step-change pitch angle adjustment by moving the blade to different axial locations, providing adaptability while keeping the overall structure relatively simple.
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
Enables continuous or step-change blade pitch angle adjustment, facilitating multiple propulsion modes without requiring engine or nacelle modifications, improving installation efficiency and reducing costs by allowing axial blade installation at multiple radii.
Implementation Method 1
The blade receiver supports the blade along the axis between the tip and the root after the blade is inserted into the blade receiver
Implementation Method 2
The blade or blade receiver may include a material having dampening properties, such as a polymer, metal alloy or ceramic, to dampen vibrations in certain modes of operation
Data Source
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AI summary
A blade positioning and support system (40) for a gas turbine engine includes a blade (32), the blade (32) having a root (38) and a tip (36), with the root (38) having a surface (41) oriented away from the tip (36), the surface (41) having a forward end (42) and an aft end (43), the forward end (42) projecting farther away from the tip (36) than the aft end (43), The system further comprises a blade receiver (44), the blade receiver (44) having a face (46) and a facet (48), with the face (46) being oriented away from the facet (48), the face (46) having a forward end (49) and an aft end (50), the aft end (50) projecting farther away from the facet (48) than the forward end (49).