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Setting new emissions standards for cleaner skies

Research at the School of Engineering has helped set the standard for today’s aviation industry towards improved local air quality and reduced health impacts of air pollution.

Our world has come to rely on air travel to link distant people and places for both business and leisure. However, current aircraft create air pollution that is damaging to both the environment and human health, with one of the most significant pollutants being particulate matter.

Aviation gas turbines emit ultra-fine (15-80 nanometres in diameter) non-volatile Particulate Matter (nvPM), which are typically smaller in size than automotive diesel engine emissions. The World Health Organisation recognises that ultra-fine particles cause and aggravate respiratory problems, including lung cancer. It is estimated that 14,000 annual early deaths are caused by aircraft particulate matter. Due to the tiny size of these particles, they are notoriously difficult to measure and regulate, and historical mass and visibility-based metrics are not sensitive enough to accurately report them.

Research from the School of Engineering has enabled new international standards for nvPM emissions, including the first internationally adopted nvPM mass and number reporting standard and an inaugural mass concentration standard requiring compliance of all in-production and future aircraft engines. This work also created immediate industrial impacts with millions of pounds savings witnessed by Rolls-Royce in development and certification costs, due to the real-time nature of the new sampling and measurement methodologies.

Defining regulatory limits and best practice

Together with Rolls-Royce and the German Aerospace Centre, the School of Engineering delivered the European Union Aviation Safety Agency (EASA) funded SAMPLE project, which aimed to find traceable methods for measuring nvPM mass and number concentrations.

As part of subsequent SAMPLE projects, research at the Cardiff Gas Turbine Research Centre led to the development of the world’s first prototype real-time aviation nvPM sampling and measurement system. This methodology was subsequently adopted by the Society of Automotive Engineers E31 technical committee and now forms the basis of international best practices and regulatory standards.

EASA commissioned the Cardiff team to design, develop, and operate the European nvPM reference system required to reproducibly measure nvPM emissions from aircraft engines. Through further SAMPLE and MANTRA projects, researchers from the School of Engineering demonstrated the operability of the proposed system.

Using the Cardiff-developed European nvPM reference system, the research team led the measurement of certification-level emissions data. These are necessary for the development of an International Civil Aviation Organization nvPM database, used to set now-adopted regulatory standards.