Aircraft Engine Optical Thrust Measurement Using Rayleigh Scattering
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Solution Overview
Problem
Current methods for determining thrust and mass flow in gas turbine engines rely on estimated values rather than direct in-flight measurements, leading to inaccurate information and the need for expensive altitude test chambers.
Innovation Solution
An optically-based propulsion mass flow and thrust measurement system using lasers and spectrally-sensitive cameras to perform direct, non-intrusive measurements of thrust and mass flow by analyzing Rayleigh scattering of airflow in and out of the engine during flight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If estimated values are used to determine thrust and mass flow, then the measurement process is simple, but the accuracy of the measurements is poor
Solution Approach 1:
The patent replaces mechanical measurement systems (altitude test chambers, physical thrust stands) with an optical measurement system using lasers and cameras to detect Rayleigh scattering. This substitution enables accurate in-flight thrust measurements without complex mechanical infrastructure, resolving the contradiction between measurement accuracy and device complexity.
Solution Approach 2:
The patent introduces Rayleigh scattering as an intermediary phenomenon to indirectly measure thrust and mass flow. By measuring the scattering of laser light by air molecules in the engine flow, the system derives thrust and mass flow data without direct mechanical contact, achieving high accuracy while maintaining system simplicity.
2Reliability
If ground-based extrapolations are used to determine in-flight thrust, then the measurement process is simple, but the reliability of the data is poor
Solution Approach 1:
The system performs preliminary calibration and setup of the optical measurement system before in-flight operation. The laser and camera system is pre-configured to measure Rayleigh scattering, enabling direct in-flight measurements that are more reliable than ground-based extrapolations while maintaining operational efficiency.
Solution Approach 2:
The patent replaces ground-based mechanical measurement systems with an optical system that operates during flight. This substitution provides direct in-flight measurement capability, eliminating the need for extrapolation and significantly improving data reliability while maintaining productivity.
3Measurement precision
If altitude test chambers are used for thrust measurement, then measurement accuracy is high, but the cost and complexity of the measurement system is high
Solution Approach 1:
The patent replaces expensive mechanical altitude test chambers with a compact optical measurement system using lasers and cameras. This substitution maintains measurement accuracy while dramatically reducing system cost and complexity, making the measurement capability accessible without expensive infrastructure.
Solution Approach 2:
The system creates an optical copy or representation of the flow field through Rayleigh scattering measurements. Instead of requiring physical test chambers, the optical system captures light scattering patterns that represent the flow characteristics, enabling accurate measurements at lower cost.
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
Provides accurate and reliable in-flight measurements of thrust and mass flow, supporting engine and airframe manufacturers in optimizing engine operation and reducing reliance on ground-based extrapolations.
Implementation Method 1
An optically-based propulsion mass flow and thrust measurement system using lasers and spectrally-sensitive cameras to perform direct, non-intrusive measurements of thrust and mass flow by analyzing Rayleigh scattering of airflow in and out of the engine during flight.
Data Source
AI summary
An aircraft includes a first gas turbine engine configured to ingest a first mass flow and a second gas turbine engine configured to exhaust a second mass flow. A first optically-based measurement system is configured to determine the first mass flow in response to performing a first imaging process on the first gas turbine engine. A second optically-based measurement system is configured to determine the second mass flows in response to performing a second imaging process on the second gas turbine engine.