Turbomachine Propeller Feathering via Annular Spring Mechanism
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Solution Overview
Problem
The integration of a feathering system for turbomachine blades, particularly in turbomachines with low hub ratios, is complicated due to the heavy counterweight mechanism required for blade feathering, which poses challenges in reducing mass and facilitating structural modifications.
Innovation Solution
A turbomachine module incorporating an annular row of springs around the fixed casing, with first ends attached to a ferrule of the fixed casing and second ends attached to the internal ring of the load transfer bearing, allowing for passive feathering of blades without significant structural modifications, providing a compromise between effort, mass, and size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a heavy counterweight mechanism is used for blade feathering, then reliable feathering is achieved, but the mass of the turbomachine increases and structural integration becomes complicated
Solution Approach 1:
The patent replaces the traditional mechanical counterweight system with a spring-based mechanism. The springs are arranged in an annular row around the fixed housing, with ends bearing on the inner ring of the load transfer bearing, providing the necessary feathering force without the mass penalty of counterweights.
Solution Approach 2:
The patent introduces springs as an intermediary element between the fixed housing and the load transfer bearing. These springs serve as the mediating mechanism that provides the feathering force, replacing the direct counterweight-to-blade connection and enabling mass reduction while maintaining reliability.
2Reliability
If a heavy counterweight mechanism is used for blade feathering, then reliable feathering is achieved, but the device complexity and integration difficulty increase
Solution Approach 1:
The patent replaces the complex mechanical counterweight system with a simpler spring-based mechanism. The annular row of springs integrates directly with the existing fixed housing and load transfer bearing components, reducing overall device complexity while maintaining feathering reliability.
Solution Approach 2:
The spring-based mechanism serves multiple functions: it provides feathering force, integrates with the existing housing structure, and works with the load transfer bearing system. This multi-functionality reduces the need for separate dedicated components, thereby reducing overall device complexity.
3Productivity
If blade pitch control system is equipped for variable pitch operation, then propulsive efficiency is improved, but the system becomes more vulnerable to failures requiring feathering capability
Solution Approach 1:
The patent implements a passive spring-based feathering mechanism that is always ready to provide feathering force, serving as a pre-prepared safety measure. This passive system provides beforehand cushioning against control system failures, ensuring that feathering capability is available without requiring active intervention or additional complex safety systems.
Solution Approach 2:
The spring-based feathering mechanism is a self-acting system that automatically provides feathering force when needed. It requires no external power source, control signals, or active intervention, making it a self-service safety mechanism that enhances reliability by being inherently fail-safe.
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 spring-based system ensures reliable feathering of propeller blades with zero failure rate, optimizing the return to feathering position, especially in case of control system failure, while maintaining the structural integrity and operability of the pitch change system.
Implementation Method 1
an annular row of springs arranged around said fixed housing and extending axially, the springs being regularly spaced around the longitudinal axis X and comprising first axial ends bearing on a ferrule of the fixed housing, and second opposite axial ends bearing on said inner ring
Data Source
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AI summary
The invention relates to a module of a turbomachine of longitudinal axis X, the module comprising: • - a rotary casing (31) that rotates about the longitudinal axis and bears a propeller (2; 20, 21, 22) which is provided with a plurality of blades (32); • - a fixed casing (48) comprising a cylindrical wall (49) extending between an inner wall (40) and an outer wall (41) of the rotary casing (31); and, • - a system (30) for changing the pitch of the blades of the propeller, mounted around the fixed casing and comprising: a control means (55) comprising a movable body (57) that is able to move axially on said fixed casing, at least one load transfer bearing (56) comprising an inner ring (65) that is connected to the movable body (57), and an outer ring (66); and a connection mechanism (61) for connecting the outer ring (66) to the blades of the propeller. According to the invention, the module further comprises a feathering device (70) for feathering the blades of the propeller, this device (70) comprising an annular row of springs (71) that are arranged around said fixed casing and extend axially, the springs (71) comprising first axial ends (72) that bear against a ferrule (51) of the fixed casing, and opposite second axial ends (73) that bear against said inner ring (65).