Real-Time Gas Monitoring in Aircraft Turbines (AeroCo₂Sensor)
Enabling precise emission control in extreme aerospace environments
The aviation industry faces mounting pressure to reduce emissions while maintaining optimal engine performance. Traditional gas sensors struggle to operate in the extreme conditions found near aircraft turbines—temperatures exceeding 1000°C, constant vibrations, and highly corrosive environments render conventional monitoring solutions ineffective.
The SMOGLESS (Smart Monitoring of Gas Levels in Extreme and Severe Settings) project developed a breakthrough fiber optic gas measurement system capable of real-time monitoring of CO, CO₂, NO, and NO₂ directly in combustion flows. Leveraging innovative mid-infrared (MIR) wavelength technology and silica anti-resonant hollow core fibers, this embedded system withstands temperatures up to 1000°C while delivering precise, instantaneous measurements.
This collaborative European initiative brought together photonics experts, aerospace manufacturers, and research institutions to create a solution that enables fuel consumption optimization, emission reduction, and predictive engine maintenance—critical capabilities for next-generation sustainable aviation.
Industry challenge: the need for high-temperature gas sensing
Stringent environmental regulations + technical barriers in extreme environments
The aerospace industry operates under increasingly strict environmental frameworks. Airlines and engine manufacturers need accurate, real-time emissions data to demonstrate compliance and optimize performance:
- CORSIA (Carbon Offsetting and Reduction Scheme for International Aviation) mandates carbon-neutral growth from 2020 onwards
- European Green Deal targets net-zero emissions by 2050, with aviation under intense scrutiny
- ICAO standards continuously tighten NOx emission limits for new aircraft engines
- Extreme temperatures: Combustion zones routinely exceed 1000°C, degrading most optical and electronic components within seconds.
- Severe vibrations: Continuous mechanical stress during flight cycles requires shock-resistant mounting and robust optical connections.
- Space constraints: Limited installation space near turbines demands miniaturized, compact sensor designs without compromising performance.
- Corrosive atmosphere: Combustion byproducts and kerosene particulates accelerate sensor degradation.
- Real-Time Requirements: Pilots need instantaneous feedback for combustion optimization—delayed measurements reduce operational value.
Technical solution: MIR fiber optic sensing
System architecture
IDIL Fibres Optiques developed a comprehensive embedded optical system comprising three integrated subsystems:
- Optical interrogator: The interrogator unit houses the laser source operating in the mid-infrared spectrum (3.8–4.7µm) and signal processing electronics. Advanced algorithms convert absorption spectra into real-time gas concentration measurements.
- Optical Harness: Custom-designed fiber optic cabling utilizing anti-resonant hollow core fibers (ARF) transmits MIR light between the interrogator and measurement probe. This specialized fiber maintains signal integrity despite extreme temperatures and mechanical stress.
- Optical Probe (Transducer): The measurement head positions directly near the aircraft turbine, exposing target gases to the optical beam. Compact design (critical in space-constrained engine bays) incorporates anti-vibration mounting and thermal protection.
Technology advantages: Why fiber optic sensing?
Compared to traditional sensors
Traditional gas measurement approaches fail in aerospace applications. The industry required a fundamentally different approach—one that could operate in situ at extreme temperatures while maintaining measurement accuracy.
| Feature | SMOGLESS fiber optic | Electrochemical | Thermocouple |
| Temperature limit | 1000°C | 200°C | 1400°C |
| Vibration resistance | Excellent | Poor | Good |
| Multi-gas capability | Yes (simultaneous) | No (one per sensor) | No |
| Response time | < 100ms | Seconds to minutes | Fast |
| Drift/aging | None (absolute measurement) | High (consumable) | Moderate |
| Calibration | Infrequent | Frequent | Regular |
| Chemical selectivity | Excellent (spectroscopic) | Limited | None |
The SMOGLESS project demonstrates that fiber optic technology has matured to address the most demanding industrial sensing challenges. By combining breakthrough hollow core fiber development, advanced mid-infrared spectroscopy, and aerospace-grade engineering, this collaborative effort created a gas monitoring solution capable of operating where conventional sensors fail.
- Multi-gas monitoring: Real-time measurement of CO, CO₂, NO, NO₂ in kerosene combustion flow
- Extreme temperature: Operating near the turbine (600°C validated in testing)
- Intrinsic safety: Passive optical sensors contain no electrical components at the measurement point—eliminating ignition risks in flammable environments.
- Immunity to EMI: Optical signals are unaffected by electromagnetic interference from ignition systems, generators, or radio transmitters—critical in aerospace applications.
- Remote sensing: Fiber optic architecture separates sensitive electronics (interrogator) from harsh measurement environment (probe), protecting expensive components while enabling measurements in inaccessible locations.
- Multiplexing capability: Single interrogator can address multiple measurement points through fiber optic switching, reducing system cost and complexity for multi-zone monitoring.
- Compact probe design: Optical measurement heads are smaller than equivalent electronic sensors, fitting in space-constrained installations
