Variable Area Fan Nozzle Control via Fiber Optic Shape Sensors
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Solution Overview
Problem
Variable area fan nozzles in bypass turbofan engines face challenges in accurately controlling nozzle areas due to deviations from predetermined positions caused by various forces, leading to inefficiencies in exhaust velocity management.
Innovation Solution
A control system incorporating fiber optic shape sensors and a VAFN control unit that measures strain along the petals, calculates nozzle area, and generates actuator commands to achieve desired nozzle areas, utilizing technologies like Fiber Bragg gratings and OFDR for precise displacement measurement and control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional control systems are used for variable area fan nozzles, then the system structure is simpler, but the measurement precision of petal position and nozzle area is insufficient due to deviations from predetermined positions
Solution Approach 1:
The patent replaces conventional mechanical position sensing systems with fiber optic shape sensors that use optical principles to measure petal positions. The fiber optic sensors detect strain and displacement through optical fiber technology, eliminating the need for complex mechanical linkages and contact-based sensors, thereby improving measurement precision while managing system complexity through non-contact measurement.
Solution Approach 2:
The patent introduces fiber optic shape sensors as intermediary elements between the petal structure and the control system. These sensors act as mediators that convert physical petal displacements into measurable optical signals through strain-induced polarization changes, enabling precise indirect measurement of petal positions without direct mechanical contact.
2Measurement precision
If fiber optic shape sensors are used to measure strain and calculate nozzle area, then the measurement precision and control accuracy are improved, but the device complexity increases
Solution Approach 1:
The fiber optic shape sensors serve multiple functions simultaneously: they measure strain on petal surfaces, calculate displacement of petal centers, determine petal orientation angles, and contribute to nozzle area calculations. This multi-functionality reduces the need for separate sensors for each measurement parameter, thereby improving overall measurement precision while limiting the increase in device complexity.
Solution Approach 2:
The patent utilizes changes in optical parameters (polarization state, strain, displacement) of the fiber optic sensors in response to petal position changes. By monitoring these parameter changes, the system achieves precise measurement of physical quantities without requiring complex mechanical measurement mechanisms, thus improving measurement precision while managing system complexity through optical parameter monitoring.
3Reliability
If real-time strain measurement and nozzle area calculation are implemented, then the control accuracy and exhaust velocity management are improved, but the use of energy increases
Solution Approach 1:
The fiber optic shape sensors are passive devices that do not require external power sources at the measurement location. They utilize the optical properties of the fiber material itself to detect strain and displacement, with the measurement process being inherently self-powered by the incident light. This self-service characteristic enables real-time measurement and control while minimizing additional energy consumption in the control system.
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 real-time, accurate control of nozzle areas, allowing for infinite petal positions and nozzle settings, thereby optimizing fan flow and exhaust velocity management.
Implementation Method 1
at least one fiber optic shape sensor extending along at least one of the plurality of petals... measure a strain along the at least one fiber optic shape sensor based on the reflected light
Implementation Method 2
technologies like Fiber Bragg gratings and OFDR for precise displacement measurement
Data Source
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AI summary
A control system (60) for a variable area fan nozzle (variable area fan nozzle) (24) having a plurality of petals (30) is disclosed. The control system may include at least one fiber optic shape sensor (62) extending along at least one of the plurality of petals, and a light source (64) operatively connected to the at least one fiber optic shape sensor. The control system includes a receiver (66) operatively connected to the at least one fiber optic shape sensor and a variable area fan nozzle control unit (70) in operative communication with the plurality of petals and the receiver. The variable area fan nozzle control unit may be configured to receive a signal from the receiver indicative of the measured strain along the at least one fiber optic shape sensor, and calculate a nozzle area of the variable area fan nozzle based on the measured strain.