Gas Turbine Shaft Break Detection via Axial Movement
Solution Overview
Problem
Modern gas turbine engines face challenges in rapidly detecting shaft failures, which can lead to unmanaged turbine acceleration and potential disintegration, resulting in significant damage due to the long detection times of existing systems.
Innovation Solution
A gas turbine engine design incorporating a shaft system with a first and second portion, where the second portion is free to move axially rearward under gas load in case of a shaft break, and a shaft break detector using phonic wheels or microwave sensors to quickly identify rotational speed differences or axial movement, thereby reducing turbine terminal speed and preventing damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional shaft failure detection systems are used, then the system structure remains simple, but the detection time is long (20-30 ms) allowing unmanaged turbine acceleration
Solution Approach 1:
The shaft system is divided into a first portion (axially located by the first thrust bearing) and a second portion (free to move axially rearwardly). This segmentation allows the second portion to provide inherent safety through axial movement detection while the first portion maintains structural integrity for normal operation.
Solution Approach 2:
The second portion of the shaft system provides self-detection capability through its inherent axial movement under gas load when a shaft break occurs. The shaft break detector passively monitors this movement without requiring active sensing systems, enabling automatic detection and turbine speed management.
2Difficulty of detecting and measuring
If the second portion of the shaft system is made free to move axially rearwardly, then shaft break detection is enabled through axial movement, but the structural complexity increases
Solution Approach 1:
The shaft break detection function is achieved through the shaft system's own axial movement under gas load when a break occurs. The second portion naturally moves axially rearwardly, providing the detection signal without requiring external active sensing mechanisms.
Solution Approach 2:
The shaft break detector acts as an intermediary that monitors the axial movement of the second portion. It detects the relative position between the first and second portions, translating the mechanical movement into a detectable signal for turbine speed management.
3Reliability
If rapid shaft break detection is implemented, then turbine terminal speed is reduced and damage is prevented, but the detection system becomes more complex
Solution Approach 1:
The shaft system is segmented into located and unlocated portions, creating a passive detection mechanism where the second portion's axial movement inherently indicates a shaft break. This segmentation enables rapid detection without complex active sensing systems.
Solution Approach 2:
The shaft break detector provides continuous feedback on the axial position of the second portion. When a shaft break occurs, the detector immediately detects the axial movement and triggers turbine speed management to prevent disintegration.
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 rapid detection of shaft failures, reducing turbine terminal speed and preventing damage by quickly isolating the failed shaft portion, thus enhancing the safety and efficiency of the gas turbine engine.
Implementation Method 1
a shaft break detector, configured to detect a shaft break in the shaft system
Implementation Method 2
a shaft break detector using phonic wheels or microwave sensors to quickly identify rotational speed differences
Implementation Method 3
the rear portion is free to move axially rearwardly under a gas load
Implementation Method 4
the mechanical linkages extending from the turbine to the compressor is commonly referred to as the torque path
Data Source
AI summary
A gas turbine engine for an aircraft. The engine including: an engine core with a turbine, a compressor, a fan located upstream of the compressor and including a plurality of fan blades, and a core shaft connecting the turbine to the compressor; a gearbox which receives an input from the core shaft and outputs drive, via a driveshaft, to the fan so as to drive the fan at a lower rotational speed than the turbine, the drive shaft and core shaft forming a shaft system.