Progress towards non-intrusive optical measurement of gas turbine exhaust species distributions

We report on the development of three systems intended to provide fast, non-intrusive measurement of cross-sectional distributions of pollutant species within gas turbine exhaust flows, during ground-based testing. This research is motivated by the need for measurement systems to support the introduction of technologies for reducing the environmental impact of civil aviation. Tomographic techniques will allow estimation of the distributions of CO₂, unburnt hydrocarbons (UHC), and soot, without obstruction of the exhaust, bypass or entrained flows, from measurements made in a plane immediately aft of the engine.