Collinear Optical Probe Packaging for Jet Engine Blade Inspection
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Solution Overview
Problem
Placing optical probes in the gas path of jet engines is challenging due to limited space and the need to minimize disturbances to the gas flow path, making on-board optical inspection for detecting damaged blades difficult.
Innovation Solution
A collinear light source and optical sensor packaging is integrated into a single unit, positioned within the fan case, with a lens, beam splitter, and optical sensor aligned along a common optical axis, allowing for minimal space usage and effective imaging of blades while minimizing disruption to the gas flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical probes are placed in the gas path for blade inspection, then blade damage detection capability is improved, but space requirements and gas flow disturbance increase
Solution Approach 1:
The patent combines the light source and optical sensor into a single integrated optical probe unit that fits within the fan case. This merging of components reduces the overall space requirement compared to separate light source and sensor placements, while maintaining the capability for blade damage detection through optical reflection measurement.
Solution Approach 2:
The optical probe is nested within the fan case structure, with the light source and sensor housed in a compact configuration that utilizes existing space. The optical components are arranged in a nested manner where the sensor is positioned to receive reflected light from blades without requiring additional external space.
2Measurement precision
If optical probes are placed in the gas path for blade inspection, then blade damage detection capability is improved, but gas flow disturbance increases
Solution Approach 1:
The optical probe is positioned to extend through the fan case into the gas flow path only where necessary for blade inspection, minimizing the intrusion into the gas flow. The light source and sensor are arranged to perform measurements with minimal physical presence in the gas path, extracting only the necessary measurement function while reducing flow disturbance.
Solution Approach 2:
The optical measurement is performed locally at specific blade positions where damage detection is most critical, rather than requiring continuous or extensive probing through the gas path. The light source and sensor are positioned to illuminate and detect reflections from specific blade regions, concentrating the measurement function where needed while minimizing overall gas flow disturbance.
3Measurement precision
If light source and optical sensor are positioned separately for blade inspection, then imaging capability is improved, but device complexity and space requirements increase
Solution Approach 1:
The light source and optical sensor are merged into a single integrated probe unit with a compact configuration. The optical components are arranged in a simplified layout where the sensor is positioned to receive reflected light from blades through a defined optical path, reducing the complexity of separate positioning while maintaining imaging capability.
4Measurement precision
If lens is exposed to gas flow path for optimal imaging, then imaging quality is improved, but lens protection from debris becomes difficult
Solution Approach 1:
The optical probe structure acts as an intermediary between the lens and the gas flow path containing debris. The lens is positioned within the protected housing of the optical probe, which extends into the gas flow path only where necessary. This intermediary structure allows the lens to maintain optimal positioning for imaging while being shielded from direct exposure to debris in the gas flow.
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 configuration enables efficient detection of blade damage with reduced impact on the gas flow, using a single hole and protecting the lens with a shutter, and allows for controlled rotation of the optical pipe to avoid debris, thus enhancing the reliability and efficiency of blade inspection.
Implementation Method 1
The beam splitter may be a dichroic mirror. The optical sensor may be positioned to capture an image reflected by the beam splitter.
Implementation Method 2
The light source may be positioned to project light through the beam splitter.
Data Source
AI summary
An apparatus may include a fan case and an optical pipe. The fan case may define a gas flow path. The optical pipe may have a portion extending through the fan case into the gas flow path. The optical pipe may include a lens, a beamsplitter, a light source, and an optical sensor. The lens may be positioned within the fan case. The beam splitter may be aligned with the lens. The light source may be positioned on a first side of the beam splitter. The optical sensor may be positioned on a second side of the beam splitter in a manner that an optical axis of the optical sensor is colinear with an optical axis of the light source at the lens.