It has been demonstrated in the last five years, via AEROJET and AEROJET II, that non-intrusive techniques like Fourier Transform Infrared spectroscopy and Laser Induced Incandescence are relevant to the measurement of aero-engine exhaust gases. These methods have been compared with intrusive methods within AEROJET II. This success has opened the path for their standardisation. Simultaneously, the aircraft engine industry stresses the need for a measurement method compatible with cost effectiveness, short-term implementation, fast availability of results and accuracy, meeting ICAO emission certification needs.
Relevance to EU policy:
The solution to reduction of NOx emissions relies mainly on low emission combustor concepts with emphasis on the innovation in the injection module. Potential options are lean combustion technologies, multi-point fuel injection systems, and the rich quenched lean combustion concept. To support the optimisation of such sensitive technologies, work is required in the physical modelling of critical phenomena like fuel atomisation, droplet vaporisation, combustion chemistry, autoignition, flash-back, instabilities… ACARE mentioned the need to 'improve both intrusive or non intrusive measurement techniques'. Improvements in technology in AEROTEST shall be applicable to combustion rig diagnostics.
The aim of the AEROTEST project was to achieve a high level of confidence in aircraft engine emission measurements with a view to using the remote optical technique for engine emissions certification.
Two major objectives will allow meeting the engine manufacturers' need:
- the first and major objective was to address the standardisation issues, the ultimate aim being to promote non-intrusive techniques to ICAO for engine emission certification, following a complete quality assurance (QA) and quality control (QC) approach, and developing procedures for calibration, set up and operation;
- the second objective was to develop validated techniques for gas turbine monitoring using emissions data, which was to be used routinely by engine manufacturers, both in development test programmes, in ageing studies and for engine health monitoring (EHM).
The two previously listed objectives were driving the project and its methodology.
To reach the first objective, four work packages have been defined to perform all the necessary work to achieve a high level of quality:
- WP1 - addressed all quality aspects that must be taken into account and defines the QA/QC approach to be followed to achieve the level of confidence and reliability needed for certification. It also addresses standards matters and correlation with previous intrusive data.
- WP2 - was dedicated to the measurement methods improvements and calibration, namely the LII and the FTIR techniques. The calibration and measurements was done both in laboratory and in test bed environments.
- WP3 - was about the integration of the LII and the FTIR equipment into a unified software system controlling both the LII and FTIR, and acquisition and processing. Input or control parameters were reduced to the minimum and the data processing was automated. Measurements have been obtained by non-expert operators with this system.
- WP4 - focused on emerging technologies. The consortium needed to be aware of such technologies that may appear and that could bring simplification to the system.
- The second objective was covered by WP5. It highlighted the fact that the technique can serve not only as a certification tool but also for other purposes, such as the application to gas turbine health monitoring. A model of engine emissions affected by component failure shall be developed and correlated to engine emissions measurements.
- WP6 - focused on the dissemination of the results and the outcome of the project. Awareness feedback from standards and regulation authorities was very important to the project, and was achieved in this WP.
The results are confidential.
The final aim of AEROTEST project was the acceptance of non-intrusive methods for gas turbine monitoring. A first step has been reached at the end of the project by a presentation of AEROTEST work and results to the SAE E31committee ('Aircraft Exhaust Emissions Measurement Committee'). An Aerospace Information Report (AIR) on non-intrusive emissions measurement has also been produced, outlining technology for discussion, with supporting data.