TDLAS Humidity Sensor for Aircraft Icing Detection
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Solution Overview
Problem
Current aircraft lack the capability to accurately and instantaneously measure ambient humidity at high altitudes, leading to ineffective ice mitigation strategies that result in unnecessary performance penalties and potential engine damage due to reliance on forecast data and inadequate humidity sensors.
Innovation Solution
A system utilizing a Tunable Diode Laser Absorption Spectroscope (TDLAS) to continuously and instantaneously detect ambient humidity, combined with existing temperature and pressure sensors, to determine if the aircraft is within an ice-forming region, thereby activating or deactivating ice mitigation systems as necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional chilled mirror or resistance humidity sensors are used, then humidity measurement is possible, but the sensors are slow responding, unstable, require frequent calibration, and are inaccurate at high altitude conditions
Solution Approach 1:
The patent replaces traditional mechanical chilled mirror sensors and resistance-based humidity sensors with a laser-based absorption spectroscopy system. This optical measurement system uses tunable diode lasers to detect humidity through absorption spectra, eliminating the mechanical and electrical limitations of traditional sensors at high altitude conditions.
Solution Approach 2:
The invention changes the measurement parameters by using laser wavelength tuning to detect specific absorption lines of water vapor. By scanning through specific wavelength ranges and measuring absorption at different frequencies, the system achieves accurate humidity measurement without the calibration and stability issues of traditional sensors.
2Reliability
If ice mitigation systems are activated based on forecast data, then ice formation is prevented, but unnecessary performance penalties are imposed when mitigation is activated unnecessarily
Solution Approach 1:
The system implements real-time feedback by continuously monitoring actual ambient humidity, temperature, and pressure conditions and using this data to dynamically control ice mitigation activation. This closed-loop approach allows the system to respond to actual conditions rather than relying on inaccurate forecasts, preventing unnecessary mitigation activation.
Solution Approach 2:
The patent enables preliminary detection of icing conditions by continuously monitoring humidity, temperature, and pressure to identify favorable conditions for ice formation before they occur. This allows proactive activation of ice mitigation only when truly necessary, based on real-time environmental assessment rather than conservative forecast-based activation.
3Reliability
If cyclical engine geometry variations are used to shed ice, then ice accumulation is removed, but engine fuel efficiency decreases and component life is reduced
Solution Approach 1:
The system uses real-time humidity and temperature monitoring with feedback control to determine precisely when icing conditions exist and when they cease. This allows engine geometry variations to be activated only during actual icing events and deactivated immediately when conditions improve, minimizing the duration and frequency of mitigation cycles to reduce fuel consumption and mechanical wear.
4Measurement precision
If instantaneous humidity measurement is implemented, then accurate ice formation detection is achieved, but device complexity increases
Solution Approach 1:
The patent integrates the laser-based humidity sensing system with existing aircraft temperature and pressure measurement systems to create a unified environmental monitoring platform. The same optical infrastructure and processing systems are used for multiple atmospheric parameter measurements, reducing overall system complexity despite the advanced sensing technology.
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
This solution enables precise monitoring of ice formation conditions, minimizing unnecessary ice mitigation and reducing fuel consumption and mechanical wear by ensuring ice mitigation is only activated when conditions are favorable for ice formation.
Implementation Method 1
A system utilizing a Tunable Diode Laser Absorption Spectroscope (TDLAS) to continuously and instantaneously detect ambient humidity
Data Source
AI summary
A system and method for monitoring icing conditions that are suitable ice formation on an aircraft and propulsion system. The system includes instrumentation that instantaneously detects ambient humidity, ambient temperature and ambient pressure. The sensed information is transmitted to a controller that evaluates the information to determine whether certain pressure, temperature and humidity criteria are favorable for icing and, declaring icing conditions. The system also includes an aircraft engine-mounted ice mitigation system. When conditions for ice formation are favorable, the controller either informs the pilot that conditions for ice formation are favorable or automatically activates the ice mitigation system, or both. The pilot optionally may inactivate the ice mitigation system. When sensed conditions indicate that conditions for ice formation are not favorable, the controller determines whether the ice mitigation system is activated and inactivates the system if activated.