Fan Blade Sensor Layout for Compact Flutter Detection
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Solution Overview
Problem
Fan blade sensor systems in integral drive turbine engines face challenges in fitting within the limited space available due to the presence of a gearbox assembly, leading to issues with sensor accuracy and the inability to detect synchronous flutter without increasing the engine's dimensions, which affects aerodynamic performance.
Innovation Solution
Positioning fan blade sensors outside the lubricant sump and using variable reluctance, pressure, and vibration sensors to measure fan speed, pitch angle, and flutter without direct line of sight, and spacing sensors circumferentially to detect synchronous flutter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fan blade sensors are positioned inside the lubricant sump to achieve direct line of sight for accurate measurement, then measurement precision is improved, but device complexity and space requirements increase, affecting engine dimensions and aerodynamic performance
Solution Approach 1:
The patent replaces direct optical/mechanical line-of-sight sensing with variable reluctance sensing that detects changes in magnetic field caused by fan blade passage. This substitution allows sensors to be positioned outside the lubricant sump while still achieving accurate fan speed measurement, resolving the contradiction between measurement precision and device complexity
Solution Approach 2:
The patent introduces magnetic field changes as an intermediary between the fan blades and the sensors. The variable reluctance sensors detect magnetic field variations caused by the ferromagnetic fan blades passing by, enabling indirect measurement without requiring direct line of sight, thus allowing sensor positioning that maintains both accuracy and compact engine dimensions
2Adaptability or versatility
If sensors are spaced circumferentially to detect synchronous flutter, then measurement capability is improved, but device complexity increases
Solution Approach 1:
The patent makes the variable reluctance sensors multi-functional by positioning them to perform both fan speed measurement and synchronous flutter detection. The same sensors that measure rotational speed can also detect synchronous flutter when properly spaced circumferentially, eliminating the need for separate dedicated flutter sensors and thereby improving adaptability without proportionally increasing device complexity
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 accurate measurement of fan speed, pitch angle, and flutter detection without increasing engine dimensions, improving sensor accuracy and maintaining aerodynamic performance.
Implementation Method 1
Positioning fan blade sensors outside the lubricant sump and using variable reluctance, pressure, and vibration sensors to measure fan speed
Implementation Method 2
using variable reluctance, pressure, and vibration sensors to measure fan speed, pitch angle, and flutter
Implementation Method 3
using variable reluctance, pressure, and vibration sensors to measure fan speed, pitch angle, and flutter
Data Source
AI summary
A turbine engine includes a fan having a plurality of fan blades, a nacelle that surrounds the fan, and a fan blade sensor system. The fan blade sensor system includes a plurality of fan blade sensors disposed in the nacelle to sense the plurality of fan blades as the plurality of fan blades rotates. The fan blade sensor system also includes a controller that determines a fan speed of the fan based on a rotational time between the fan blades as sensed by the plurality of fan blade sensors.