Terahertz Enhanced Foreign Object Debris Discrimination
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Solution Overview
Problem
Current optical particulate ingestion sensor systems for gas turbine engines are inadequate for discriminating Foreign Object Debris (FOD) with complex geometries and multiple materials, and are affected by reflective and transient conditions such as moisture, fog, dust, ash, or smoke, particularly failing to accurately differentiate between smaller damaging particles like sand grains and larger visible objects.
Innovation Solution
A system employing a multi-wavelength, multi-angle light source and sensor arrangement, including LEDs and photodetectors, with additional terahertz sensors, to provide detailed light scattering cross-section analysis and discrimination between hard and particulate FOD, using algorithms to determine size, type, and hazard level, and adjust engine operations accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multi-wavelength, multi-angle scattering light sources and sensors are used to identify FOD, then the ability to detect particulate FOD is improved, but the system cannot accurately discriminate FOD with complex geometries and multiple materials
Solution Approach 1:
The patent introduces terahertz frequency parameter to the existing optical detection system. By adding terahertz scattering cross-section measurements to the visible and infrared measurements, the system gains the ability to discriminate between different FOD materials and geometries that appear similar under optical wavelengths alone.
Solution Approach 2:
The patent combines multiple detection technologies (visible light scattering, infrared scattering, and terahertz scattering) into a composite sensing system. This multi-modal approach allows the system to leverage the complementary strengths of each wavelength range to accurately identify diverse FOD types including sand grains, ice particles, and other particulate matter with varying geometries and material compositions.
2Reliability
If optical sensors are used to detect FOD, then detection capability is provided, but the system is affected by reflective and transient conditions such as moisture, fog, dust, ash, or smoke
Solution Approach 1:
The patent uses terahertz radiation as an intermediary measurement modality that penetrates atmospheric conditions differently than visible or infrared light. Terahertz waves can pass through certain atmospheric obscurants that block optical wavelengths, providing a complementary detection channel that maintains reliability when optical sensors are degraded by moisture, fog, dust, ash, or smoke.
3Reliability
If smaller particles like sand grains are targeted for detection, then damage prevention is improved, but the particles are barely visible and difficult to detect
Solution Approach 1:
The patent extends the detection dimension from purely optical wavelengths to include terahertz frequencies. This dimensional expansion in the electromagnetic spectrum provides enhanced sensitivity to small particles like sand grains, whose scattering characteristics at terahertz frequencies make them more detectable than at visible wavelengths, thereby improving engine damage prevention capability.
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
Enhances the ability to accurately discriminate and identify FOD types, including smaller damaging particles, improving engine safety and reducing damage by providing precise particulate concentration and hazard assessments, and enabling robust detection in challenging visibility conditions.
Implementation Method 1
a terahertz sensor to provide a scattering cross section at a terahertz frequency
Implementation Method 2
a visible and infrared sensor to provide a scattering cross section at visible and infrared wavelengths
Data Source
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AI summary
A method of foreign object debris discrimination incudes illuminating particulates located within a sensing volume with a first electromagnetic radiation pulse emitted from a first source, and illuminating the particulates within the sensing volume with a second electromagnetic radiation pulse emitted from a second source, wherein the second electromagnetic radiation pulse has a second wavelength range within the terahertz (THz) regime. The first electromagnetic radiation returns and the second electromagnetic radiation returns are compared to determine a scattering ratio from the comparing step. The scattering ratio is then utilized to determine a resultant foreign object debris type of the solid objects.