See, size and seize the flame: the emotion project

Combustion Bay One.e.U. works currently in co-operation with FH Joanneum/Aviation on the development of an embedded optical sensor for real-time monitoring of the flame condition in aeroengine combustors.

This feasibility study is financed by the Take-Off programme from the Austrian Research Promotion Agency (FFG).



The very promising first results will soon be presented at the following conference:

Kraft, G., Giuliani, F., Pfefferkorn, L. and Andracher, L.
Toward embedded optical measurement techniques for precision combustion monitoring in aeroengines
Proceedings of the XXIIIth Biannual Symposium on Measuring Techniques in Turbomachinery
Stuttgart, Germany,1 - 2 September 2016  


Certification policies on aeroengines are very demanding and technically challenging, since they combine an obligation of safety with technical specifications on performance and environmental issues. Over the last 15 years, fuel consumption was reduced by 30% per available seat per kilometer [1]. Drastic efforts were successfully made to reduce considerably NOx and noise emissions [2]. In the continuity of this effort, new regulations driven by the ICAO/CAEP10 are about to be decided concerning limitations on carbon monoxide and soot emissions.

In order to meet these future requirements, aeroengine manufacturers will have to make a better management of the current operation margins. More precision is requested in determining the operation status as well as refined controls. This paper is about the development of lightweight and small-size optical sensors that monitor the quality of combustion in real-time with great precision.

A broad panel of optical measurement techniques is available for advanced combustion diagnostics [3]. However, if a few applications exist for the monitoring of industrial burners, regarding gas turbine technology optical measurement techniques remain bounded to laboratories or test benches. The miniaturization of optical elements combined to the improvement of high-temperature glass or transparent ceramics open a new path toward robust optical probes, able to perform well under aggressive flow conditions (high pressure and temperature air flow, erosion, strong radiative heat transfer, strong vibrations).

The challenges are the design of the optical interface, the cooling and temperature stabilization of the sensitive parts of the sensor, and the compactness of the measurement chain.

The project "emotion" stands for engine health monitoring and refined combustion control based on optical diagnostic techniques embedded in the combustor.




The emotion project is financed by the Austrian Research Promotion Agency (FFG) within the frame of its programme on aeronautics called "Take-Off". Partners in this project are the company Combustion Bay One e.U. (CBOne), an engineering office specialized in advanced combustion management, and the Fachhochschule Joanneum/Aviation Institute from Graz (FH Joanneum). CBOne is project leader and focuses on strategies, feasibility study and testing, while FH Joanneum focuses on the integral aspect of the portable measurement chain for demonstration purpose.



A first consultation of the aeroengine manufacturers set the objectives of using embedded optical monitoring as follows. It should provide the following:

  • inform about the presence/absence of the flame
  • provide a qualitative information of the operation,
  • report on the flame stability
  • report on the ignition success. Additionally, the

Furthermore, inspection of the combustor's interior at rest using built-in cameras could replace in the future the inspection, using an endoscope. The project emotion is introduced, and the early results using a combustion test rig are presented.

Two strategies are investigated. These are image-based monitoring, using CCD chips situated in the vicinity of the flame, and fast-response photo-sensitive sensors. Imaging provides qualitative features on the flame such as shape, intensity and chromatic contents. The photo-sensitive sensors report on the highly-resolved time signal of light intensity filtered at a given wavelength. For instance the UV component related to the OH* emission is an indicator for the thermal power of the flame.

This contribution details the second strategy and explain why the use of photosensors is the most promising option regarding rapid integration in flying systems.



[1] Airbus SAS, Flying by numbers - global market forecast 2015-2034. D14029463 issue 2. August, 2015.

[2] Dron, S.. "Toward ACARE 2020: innovative engine architectures to achieve the environmental goals?." 26th International Congress of The Aeronautical Sciences. 2008.

[3] Warnatz, J., Maas, U., Dibble, R.W. and Warnatz, J., 2001. Combustion (Vol. 3). Berlin: Springer.