Combined Optic-Acoustic Monitoring of Combustion in a Gas Turbine

Giuliani, F. (Speaker)

Activity: Talk or presentationTalk at conference or symposiumScience to science

Description

The need for better combustion monitoring in gas turbines has become more acute with the latest technical requirements, standards, and policies in terms of safety, environment, efficiency, operation flexibility and operation costs.

Combustion Bay One e.U. and FH JOANNEUM GmbH initiated 2015 an experimental research program about the feasibility and first assessments of placing optical systems near the combustor. The project's acronym "emootion" stands for "Engine health MOnitOring and refined combusTION control based on optical diagnostic techniques embedded in the combustor". It is financed by the Austrian Research Promotion Agency (FFG) under its aviation program called "TAKE OFF".

The motivation of the project is twofold. On the one side, one wants to exploit the radiative feature of the flame and transform it into a piece of reliable information about the combustion status. On the other side, this information can be useful in terms of data interpretation or data reconciliation with other information coming from further sensors such as temperature probes, fast pressure probes or accelerometers. The focus is put on the detection of the flame, on the monitoring of the ignition process, on the quality assessment of combustion based on its spectral contents (including soot formation) and on the detection of possible combustion instabilities.

This contribution sums-up the know-how acquired so far and unveils the work in progress. Promising results were obtained using photodiodes, that offer an adequate trade-off between narrow-band sensitivity and signal time response.
It is shown that it is convenient to combine a fast-pressure sensor with an optical sensor in a compact form, this combination has lead to the so-called Rayleigh Criterion Probe (RCP). The split in red, green and blue (RGB) light components and their further analysis allows mapping the different types of operation. Regarding the probe packaging aspect, it is discussed that the level of light collection needed to keep an acceptable signal-to-noise ratio has been so far a restrain for the use of optical fibers. Solutions are proposed to bring the optical sensor as near as possible to the optical interface and make it operational and reliable prevailing heat. The contribution closes with a description of the ongoing tests on a pressurised combustion facility, and a sketch for a 3-RCPs based compact combustion monitoring system.
Period20 Nov 2019
Held atThe European Virtual Institute for Gas Turbine Instrumentation
Event typeConference
Conference number9
LocationGraz, Austria
Degree of RecognitionInternational