Gas Turbine Technology

Gas Turbine Emissions

These reductions in emissions mitigate the impact that the growth in air traffic has on the environment and reduce the emissions resulting from power generation.

Smiths Aerospace Components - Burnley Ltd. (SAC-B)
Development of a novel variable fuel placement injector
Background
The global drive to reduce the impact of aviation on global and local air quality is leading to a continual tightening of the regulations concerning aviation gas turbine emissions. Manufacturers of aerospace gas turbines are therefore imposing more and more challenging emissions targets on suppliers of fuel injectors. QinetiQ have been working with SAC-B to design and develop a novel fuel placement fuel injector that will be capable of meeting future emissions requirements.

Challenge
The targets for reduced NOx emissions effectively require the combustion process to take place with a lower flame temperature. This leads to higher air:fuel ratios and less stable flames that can create problems with combustion acoustics and increase the likelihood of flame extinction on turn down. The challenge is to design a fuel injection system that can deliver stable, reliable combustion at high air:fuel ratios.

Solution
The SAC-B /QinetiQ variable fuel placement injector has a main combustion zone that runs at very high air:fuel ratios and a pilot zone that runs much richer. At high power conditions the main zone flow dominates the combustion and very low levels of emissions can be achieved, while at low powers the flame is stabilised by the pilot zone.

Results
Development of the fuel injector is continuing, results obtained to date meet preliminary targets and further testing and analysis is ongoing to establish technology readiness for future markets.

Aviation Emissions and the Environment
Our gas turbine technologists use their knowledge and expertise in gas turbines to model future and current aircraft emissions. This includes the design of an inventory of aviation emissions and predictions of emissions at major London airports, as well as providing advice to the UN on regulating aviation internationally. Combined with QinetiQ's extensive noise and ATM capabilities, we provide complete modelling of airport airside environmental efficiency.

The Government White Paper, The Future of Air Transport, predicts that UK international air travel will grow at a rate of 4.6% per year. With emissions from other modes of transport in decline, aviation has therefore come under pressure to mitigate its impact on the environment - both in terms of climate change and local air quality. QinetiQ provide advice and modelling to regulators and industry on how to manage sustainable growth.

Department for Transport (DfT)
Offering sound, independent advice on aircraft emissions

The UK Department for Transport (DfT) has major policy responsibilities in UK and Internationally for the control of emissions from aviation. To formulate policy, they require technical information of the highest quality on all aspects of aircraft emissions from engine combustion through airline operations to climate and air quality impacts.

Through the technical knowledge and impartial position of the Gas Turbine Technology Group, QinetiQ provide such expert advice and policy-relevant research to the DfT. Examples include

• improving the assessment of aircraft emissions at Heathrow Airport
• collaboration with US and European regulators and aviation stakeholders in formulating global regulation and other measures
• research into particulate emissions, global emission inventories and contrail formation